human anatomy Flashcards
anatomical position
Standing, with head, palms and feet facing
forward, penis erect
prone (face down) & supine (face up)
superior (cranial) meaning
toward crown/nearer to the head
inferior (caudal) meaning
toward sole/nearer to feet
anterior (ventral)
toward/nearer to front of body
posterior (dorsal)
toward/nearer to back of body
medial
toward midline
lateral
away from midline
proximal
toward centre
distal
away from centre
superficial
near surface
deep
away from surface
transverse/horizontal/axial plane
splits the body into superior (upper) and inferior (lower) sections
coronal/frontal plane
splits the body into anterior (front) and posterior (back) sections
sagittal plane
splits the body into left and right sections. the median or mid-sagittal plane sits directly in the midline of the body.
describe where the 5th intercostal space is
the 5th intercostal space is the gap inferior to the 5th rib, superior to the 6th rib.
what is faecal mass
waste matter eliminated from the bowels; excrement.
what is fascia?
a sheet or band of fibrous connective tissue enveloping, separating, or binding together muscles, organs, and other soft structures of the body
what does necrotic mean?
dead
what is the inguinal ligament?
the tough, fibrous ligament that stretches between the lateral edge of the pubic bone and the anterior superior iliac spine
what is pericarditis?
inflammation of the lining around the heart (pericardium) causing chest pain and accumulation of fluid around the heart (pericardial effusion)
what is the pyloric sphincter?
a ring of smooth muscle fibres around the opening of the stomach into the duodenum
what is severe peritonitis?
inflammation of the peritoneum
can result from infection, injury and bleeding, or diseases
what is the peritoneum?
the tissue layer of cells lining the inner wall of the abdomen and pelvis
what are gonadocorticoids?
sex hormones, e.g. testosterone and oestrogen
what is a ureter?
a tube that carries urine down from the kidney to the bladder
what is systemic sepsis?
the presence of bacteria or other infectious organisms or their toxins in the blood or in other tissue of the body.
what is the vermiform appendix?
a small outpouching from the beginning of the large intestine
what is dorsum?
dorsal surface part of hand or foot, opposite to palm/sole.
what is meant by contralateral?
opposite side of median plane
what is meant by ipsilateral?
same side of median plane
how many cervical vertebrae are there?
7, termed C1-C7
how many thoracic vertebrae are there?
12, T1-T12
how many lumbar vertebrae are there?
5, termed L1-L5
how many sacral vertebrae are there
5, termed S1-S5
what are the sections of the vertebrae (from superior to inferior)?
cervical vertebrae
thoracic vertebrae
lumbar vertebrae
sacral vertebrae
coccygeal vertebrae
name 2 important structure that sit within the neck
larynx and oesophagus
what are the 3 sections of the trunk?
thoracic, abdominal, and pelvic cavities
what are the boundaries of the thorax?
superior boundary - superior thoracic inlet
inferior boundary - diaphragm
posterior boundary - ribs and thoracic vertebrae
anterior boundary - ribs, costal cartilage and sternum
what are the regions of the thoracic cavity?
left pleural cavity, right pleural cavity, mediastinum.
mediastinum sits medially and contains the heart, pericardium and associated structures.
what are the main organs found in the abdominal cavity?
liver, gallbladder, oesophagus, stomach, spleen, small intestine, large intestine, kidneys, adrenal glands
name 2 ways of describing the regions of the abdomen
the nine region model and the four quadrant model
what are the three parts to the pelvic cavity?
ilium, ischium, pubis
the ilium articulates with the sacrum posteriorly
define a body system
a group of body organs that together perform one or more vital functions
features and and function of cardiovascular system
consists of heart, blood vessels, and blood
function - transport nutrients and o2-rich blood to all parts of the body and carry deoxygenate blood back to the lungs
features and function of respiratory system
consists of nasal cavity, larynx, trachea-bronchial tree, and lungs
function - breathing and gas exchange
features and function of skeletal system
consists of all bones, cartilage, tendons and ligaments in the body.
function - structure and locomotive
features and function of integumentary system
consists of epidermis, hypodermis, associated glands hair, and nails.
function - largest organ of the body that forms a physical barrier between the external and internal environment
features and function of muscular system
consists of specialised cells (muscle fibres) that are attached to bones or other structures.
function - movement
features of genitourinary (GU) /urogenital system
consists of kidney, ureters, bladder, urethra, sexual organs.
this system is sometimes split into the urinary and reproductive systems
features and function of gastrointestinal (GI)/digestive system
consists of the mouth, pharynx, oesophagus, stomach, small & large intestine, rectum, and anus, as well as salivary glands, liver, gallbladder, and pancreas.
function - these help make digestive juices and enzymes which help the body digest food and liquids
features and function of the immune system
consists of a network of biological processes that protect an organism from diseases.
function - detects and responds to a wide variety of pathogens.
features and function of the nervous system
consists of the brain, spinal cord, peripheral nerves, sensory organs and other nervous tissue.
function - coordinates actions and sensory information by transmitting signals to and from different parts of the body.
features and function of the endocrine system.
consists of feedback loops of the hormones released by internal glands into the circulatory system, regulating target organs.
four main functions of the skeleton
- protection of major organs
- forming the mechanical basis for movement
- haemopoesis
- storage of salts in bone
two types of mature (Haversian) bone
compact and spongy
describe compact bone
strong and dense, all the bones have a superficial, thin layer of it
describe spongy bone (cancellous bone)
less dense, with numerous air spaces and forms the core of most bones, except when replaces by a medullary (marrow) cavity. this means that bones are lighter which aids movement, while the compact layer provides strength.
3 types of cartilage
hyaline cartilage, fibrocartilage, elastic cartilage
where is hyaline cartilage found?
-most widely present type of cartilage in the body
-present in adults as articular cartilage in joints and in the respiratory system as support for the airways
where is fibrocartilage found?
-found in articular disks within joints, in intervertebral discs and around the edge of ball and sockets to enlarge the surface area of the socket
-tougher than hyaline cartilage
where is elastic cartilage found?
-highly resilient due to the elastic fibres contained in its structure
-found in external ear, auditory tube, epiglottis and parts of the larynx
what does the axial skeleton include?
-all the bones along the body’s long axis
-includes the bones that form the skull, vertebral column, and thoracic cage
what does the appendicular skeleton include?
limbs and girdles that ‘append’ to the axial skeleton
e.g. pelvis, legs and arms etc.
what is osteomalacia?
soft bones, often caused by vitamin D deficiency
what is the neck of the femur/
joins the head of the femur to the shaft of the femur or thigh bone
what is the head of the femur?
the most proximal part of the femur, which articulates with the pelvis at the acetabulum
what is osteoporosis?
-a disease of aging
-characterised by a decrease in bone mass and bone strength with no change in the proportion of calcified to uncalcified base material
how does cartilage obtain oxygen and nutrients?
via continuous diffusion and via osmosis from bone
what is osteoarthritis?
progressive degeneration of the hyaline cartilage between bones in a joint. leads to bones rubbing against each other, causing pain and inflammation.
what does the CNS consist of?
brain and spinal cord
what does the PNS consist of?
all the neurones carrying information to (affecter neurones) or from (effector neurones) the CNS
3 parts of a neuron
- axon
- cell body
- dendrites
how is information relayed electrically along axons and dendrites?
through the movement of ions
what does myelin do to an action potential?
ensheathes many axons and increases speed of conduction of action potentials
what does the axon do?
carries information away from the cell body
what do dendrites do?
carry information to the cell body
what is multiple sclerosis (MS)
-a disease with a chronic relapsing course
-unknown cause
-consists of ‘plaques’ of demyelination and axon loss throughout the CNS
what does the CNS do?
-information is relayed to the CNS by afferent neurons in the PNS
-the CNS collects and processes this information, this is stored and responded to (if appropriate).
-information is transported out of the CNS to effector cells by the efferent neurons of the PNS
function of the left hemisphere of the brain
controls logic, numbers and language. processes the sensory and motor pathways for the right side of the body.
function of the right hemisphere of the brain
involved with creativity, imagination and rhythm and processes the sensory and motor pathways of the left side of the body.
what joins the two hemispheres of the brain?
corpus callosum
what is the corpus callosum?
a neural bridge of nerve fibres. allows the two halves of the brain to communicate
how can the corpus callosum be seen/
superiorly by looking down the deep fissure between the two halves of the brain, or in a medial view by separating the cerebral hemispheres
what does the brain consist of?
forebrain, midbrain, hindbrain
what does the forebrain consist of?
cerebrum, thalamus, hypothalamus
what does the hindbrain consist of?
cerebellum, pons, medulla
what does the brainstem consist of?
midbrain, pons, medulla
function of the midbrain
controls higher functions than the other regions of the brainstem, for example eye movements and the auditory system
function of the medulla
controls very basic, life-sustaining functions such as breathing and heart rate
function of the pons
roles in consciousness and posture
structure of the cerebellum
two mounds of folded tissue posterior to the brainstem
how is the cerebellum connected to the brainstem?
3 peduncles (bands of neurons resembling a stalk)
function of the cerebellum
concerned mainly with motor functions. plays a vital role in motor learning, as all motor skills are stored in cerebellar memory.
where does the cerebellum receive inputs from?
-ascending sensory pathways from the body
-descending motor pathways from the cerebrum
-other information from the brainstem
function of the thalamus
the majority of information passing to the cerebral hemispheres passes through the thalamus first. the thalamus then relays the information to the relevant part of the cerebrum.
function of the hypothalamus
main function is homeostasis.
directly controls:
-blood pressure
-body temp
-fluid and electrolyte balance
-body weight
heart rate, vasoconstriction, digestion and sweating are controlled by the hypothalamus via inputs to the medulla.
function of the cerebral cortex/cerebrum
intelligence, personality, interpretation of sensory impulses, motor function, planning and organisation, touch sensation
what is the cerebral cortex/cerebrum?
most of the volume of the cerebral hemispheres consists of white matter. white matter contains axons. these axons connect the cell bodies found in the grey matter.
this grey matter makes up the cerebral cortex/cerebrum.
what are sulci?
infoldings of the brain. often used to demarcate (mark the boundary of) different functional areas
what are gyri?
sticky out bits between sulci. these are areas of functional grey matter. adjacent gyri may have very different functions
what are meninges?
a layer of tissue separating the CNS from the rest of the body
what are the 3 layers of the meninges
- pia mater - adherent to the brain itself and dips down into the sulci of the brain
- arachnoid mater - in the middle
- dura mater - outermost and very tough layer
what is the CNS bathed in, within the meninges?
cerebrospinal fluid (CSF)
what do the meninges and CSF do?
cushion the brain and protect it from damage
what is the CSF produced by?
specialised epithelium (choroid plexus) lining cavities within the brain known as ventricles
what does the choroid plexus do?
actively secretes components of blood plasma into the ventricles, producing a clear fluid that is lower in proteins, cells and most ion than plasma
describe CSF movement
circulates through the ventricles (cavities) within the brain before exiting onto the surface of the brain (still within the meninges) to bathe the brain and spinal cord.
CSF is then reabsorbed into the venous circulation at specialised points called arachnoid granulations
what are arachnoid granulations?
where CSF is reabsorbed into the venous circulation
what does the CSF have a higher concentration than plasma of?
sodium, chloride and magnesium ions, as these chemicals are actively transported by the epithelium into the CNS
what are ventricles (brain?
spaces or cavities within the brain linked by passageways called aqueducts.
allow CSF to circulate through the brain and open onto the surface of the CNS or into the central canal of the spinal cord.
where is the end of the spinal cord in children?
level with the L3 vertebrae
where is the end of the spinal cord in adults?
level with L1, it is no longer a single cord, but made up of several spinal nerves that all run through the vertebral canal
what is the spinal cord protected by?
vertebrae
what is the vertical tunnel running through a vertebra called?
vertebral foramen
what do the foramen form?
the vertebral canal, that runs the whole length of the vertebral column (spine), contains the spinal cord and provides it with some protection
what does a vertebra consist of?
a vertebral body and vertebral arch, which form the vertebral foramen
what is the vertebral arch formed of?
2 pedicles
2 lamina
2 transverse process
1 spinous process
4 articular processes
function of vertebral body
support of body weight
function of vertebral arch
protection of spinal cord
function of spinous process and transverse processes
muscle attachment and movement
function of articular processes
restriction of movement
function of the lamina
connects the spinous process and the transverse process
function of the pedicle
serve as a bridge, joining the front and back parts of the vertebra
what is a symphysis?
a fibrocartilaginous joint
purpose of the invertebral disc forming a symphysis between 2 adjacent vertebrae?
to allow slight movement, act as shock absorbers and to hold the 2 together
what does the invertebral disc contain?
annulus fibrosus - outer fibrous ring made up of laminae of fibrocartilage to withstand compression
nucleus pulposus - gel-like centre that helps distribute pressure evenly across the disc to act as a shock absorber
a layer of hyaline cartilage
what is the outer section of the spinal cord formed of?
white matter - consists of axons of neurons that form ascending or descending pathways
what do ascending pathways of spinal cord do?
travel from the body to the brain. tend to carry sensory information, such as touch, pain, and proprioception.
what do descending pathways of spinal cord do?
travel from the brain to the body. they tend to carry motor instructions, to initiate and control movement.
what is the inner section of the spinal cord formed of?
grey matter - where cell bodies of neurons are located and where synapses occur between these cell bodies, their dendrites, and the axons of other neurons
how do nerves from the body enter the spinal cord?
through the dorsal roots (dorsal horn)
how do nerves exit the spinal cord?
through the ventral root (ventral horn)
what is the ventral median fissure?
a deep groove, a useful landmark for the anterior surface of the spinal cord. useful to identify as the other regions of the spinal cord are names for whether they are ventral or dorsal (anterior or posterior)
what type of nerves do the ascending and descending tracts carry?
somatic nerves
where do autonomic nerves run?
alongside the spinal cord in a separate chain or neurons and ganglia
name some ascending tracts within the spinal cord
dorsal column - ascending sensory neurons carrying fine touch and proprioception information from the limbs
anterolateral fasciculus - ascending sensory neurons carrying pain and temperature fibres
name a descending tract within the spinal cord
lateral column - descending motor tracts from the cerebral cortex
What are the nerves inferior to the termination of the spinal cord, within the meninges called?
the cauda equina
what is a lumbar puncture/spinal tap?
when the CSF is removed from the space below the end of the spinal cords, with a needle.
there is not enough space around the spinal cord to allow safe removal of CSF superior to its termination.
below L1, if a needle is inserted, the spinal nerves can float out of the way. above L1, the needle would be at risk of piercing the spinal cord.
what can increased levels of white blood cells indicate (from CNS)?
infection such as meningitis
what can increased levels of red blood cells indicate (from CNS)?
a brain haemorrhage or stroke
why does the PNS exist?
to carry information to and from the CNS
which nerves travel to the CNS?
afferent nerves (afferents arrive)
which nerves travel from the CNS?
efferent nerves (efferents exit)
what are the two main divisions of the PNS?
autonomic and somatic nervous systems
define homeostasis
the maintenance of a constant, balanced environment within the body
what is a ganglia
plural of ganglion - in the PNS they are groups or knots of cell bodies
what is the autonomic nervous system?
the ‘subconscious’ control of our bodies, generally innervating smooth muscle of tissues or glands.
which actions is the PNS involved with?
involved with actions such as temperature control (via sweating and vasomotor), continence, secretions and gastric motility
where do autonomic neurons arise?
from the brain and spinal cord.
where do autonomic neurons have ganglia?
outside the spinal cord, where their axons synapse.
how many neurons does it take the autonomic system to reach its target?
two - there are pre-ganglionic and post-ganglionic autonomic neurons
what does the sympathetic system do?
prepares the body for intense physical activity (‘fight or flight’)
what does the parasympathetic system do?
relaxes the body and inhibits high energy functions (‘rest and digest’)
what does activation of sympathetic nervous system do?
-increased heart rate and force of contraction
-dilation of pupil
-relaxation of airway smooth muscle
-reduced peristalsis
-decreased gut motility
what does activation of parasympathetic nervous system do?
-decreased heart rate and force of contraction
-constriction of pupil
-contraction of airway smooth muscle
-increased stomach motility and gastric secretions
-increased peristalsis
-increased gut motility
where are sympathetic cell bodies present?
in the thoracis and lumbar spinal cord segments. these connect to a paravertebral ganglion chain, the sympathetic chain, or to individual ganglia that are still quite distant from the target organ.
where do parasympathetic neurons arise?
from the cranial nerves or from the lumbo-sacral spinal cord.
where are parasympathetic ganglia located?
located close to the target organ, they are not grouped together in a chain
what do somatic sensory nerves (afferent) do?
detect pain, temperature, touch and proprioception
what is the somatic nervous system responsivle for?
conscious control of our bodies and the corresponding feedback
what do somatic efferent nerves do?
they are motor to effector skeletal muscle
what do somatic neurons do once they’ve left the CNS?
they project directly to their target cell via a single neuron, they do not synapse
what are the 2 types of somatic nerves?
spinal nerves - arise from spinal cord
cranial nerves - arise directly from the brain
describe where the spinal nerves leave the spinal cord
below each vertebra (T1, T2 etc) except in the cervical region where they exit superior to the vertebrae.
C7 has one above (C& nerve) and one below (C8 nerve)
how many spinal roots are there?
- there is an additional root from the coccyx
where do dorsal and ventral roots emerge from?
the spinal cord, at each vertebral level
what are the dorsal (posterior) roots?
usually afferent/sensory, carrying information from the periphery to the CNS
what are the ventral (anterior) roots?
usually efferent/motor, carrying information from the CNS to the periphery in somatic motor and autonomic neurons
what is a plexus?
a network of vessels or nerves in the body.
many spinal nerves may blend together to form a plexus such as the lumbar plexus
what makes up the lumbar plexus?
spinal nerves arising from the spinal cord below vertebrae T12-L5
what are dermatomes?
a distinct area of skin supplied by spinal nerves
what are myotomes?
a group of muscles supplied by spinal nerves
where does the sciatic nerve run?
muscles - motor to muscles of posterior thigh (the hamstrings that act to flex the knee)
sensory - sensory afferent from the skin over the lateral side of leg (below knee) and skin on soe and dorsum of foot
how is the region between hip and ankle divided anatomically?
thigh - above knee
leg - below knee
where does the femoral nerve run?
muscles - motor to muscle of anterior thigh (the quadriceps that act to extend the knee)
sensory - sensory afferent from anterior thigh and medial leg
how many cranial nerves are there?
- they mainly innervate structures of the head and neck
what do cranial nerves supply?
‘special senses’ e.g. taste
as well as the usual somatic and autonomic functions
function of CNI - olfactory nerve
special sense. innervates nasal mucosa, carries information related to smell.
function of CNII - optic nerve
special sense. afferent for vision from the retina
function of CNIII - oculomotor nerve
somatic division controls movements of the eye and some control of eyelid. autonomic division is motor to pupil constrictors.
function of CNIV - trochlear
somatic - motor to one muscle that moves the eye
function of CNV - trigeminal
somatic - afferent from surface of face, senses touch from skin of face. motor efferent to muscles of mastication.
function of CNVI - abducent
somatic - motor efferent to one muscle of the eye
function of CNVII - facial nerve
special sense - taste from anterior tongue and palate
somatic division - motor efferent to muscles of facial expression
autonomic division - motor efferent to glands that secrete saliva
function of CNVIII - vestibulocochlear nerve
special sense - hearing from cochlea of ear. balance from vestibular apparatus of ear.
function of CNVXI - glossopharyngeal nerve
special sense - taste from posterior tongue
somatic division - motor efferent to help with swallowing. afferent sensation from external ear.
autonomic division - secretomotor to one saliva gland (parotid)
function of CNX - vagus nerve/’wandering nerve’
somatic division - motor to muscles of pharynx, larynx and palate.
autonomic division - parasympathetic innervation of smooth muscle in trachea, bronchi, GI tract and cardiac muscle. afferent sensation from GI tract, heart and airways
function of CNXI - accessory nerve
somatic - motor to two big muscles in the neck
function of CNXIII - hypoglossal nerve
somatic - motor to the muscles of the tongue
what is Bell’s palsy?
an idiopathic (of unknown cause) palsy of the facial nerve CNVII.
result in unilateral facial paralysis due to loss of motor innervation to muscles of facial expression.
what is Guillain-Barre syndrome (GBS)?
a condition that can occur after an infection. the immune system fights off the infection but then attacks the myelin sheath of peripheral nerves, which disproportionately affects the long nerves first.
people often develop tingling (parasthesia) and muscle weakness (paresis) in their feet and hands. as the disease progresses, the symptoms become more severe distally (e.g. paralysis) and ascend proximally, up the arms and legs - often called a ‘glove and stocking’ distribution. it is a common feature of other peripheral neuropathies.
what are the two systems that the heart pumps blood around?
the pulmonary and systemic systems
what are the four chambers of the heart
2 atria and 2 ventricles
what is the specialised cardiac muscle of the heart known as?
myocardium
define a heartbeat
each cycle of contraction and relaxation
what is systole
contraction of the ventricles
what is diastole
relaxation of the ventricles
is the pulmonary circulation pumped at high or low pressure? why?
low. not much force is required to send blood the short distance through the lungs from the right to the left heart and high pressure in pulmonary capillaries would force fluid out of the blood, into the lung tissue and we would drown.
does blood pumped from the right ventricle to the lungs have a high or low oxygen concentration?
low
where does the systemic circulation feed?
into and out of all the organs of the body, except the lungs
where is the origin and termination of the systemic circulation?
origin - left ventricle
termination - right atrium
does the systemic circulation operate at a high or low pressure?
a high pressure (compared to the pulmonary). considerable force is required to adequately perfuse all the tissues in the human body and the blood has a much larger distance to travel from left to right heart than right to left
what does the thoracic cage do?
protects the contents of the thorax
what does the thoracic cage do?
protects the contents of the thorax
what does the thoracic cage consist of?
ribs, costal cartilage, sternum, and thoracic vertebrae
how many ribs are there on each side?
12
where is the mediastinum?
the central compartment of the thoracic cavity, situated between the lungs.
it extends from the superior thoracic aperture (superiorly) to the diaphragm (inferiorly) and from the sternum and costal cartilages (anteriorly) to the bodies of the thoracic vertebrae (posteriorly)
describe the structure of the mediastinum
-contains all the thoracic structures except the lungs
highly mobile region because it consists primarily of hollow visceral structures which are joined by loose connective tissue.
what is the sternal angle?
the joint between the manubrium (top part) and the body (middle part) of the sternum
what is the thoracic plane?
imaginary horizontal plane drawn from the sternal angle to the level between T4 and T5
what compartments does the thoracic plane divide the mediastinum into?
superior mediastinum and inferior mediastinum
name the subdivisions of the inferior mediastinum
anterior mediastinum, middle mediastinum, and posterior mediastinum
what does the anterior mediastinum contain?
mainly consists of fat and the thymus
what does the middle mediastinum contain?
mainly the heart and pericardium
what does the posterior mediastinum contain?
the descending aorta, the oesophagus, the thoracic duct, the azygos system of veins and the sympathetic chains
what is the azygos system of veins?
a H-shaped configuration of the azygos, hemiazygos, and accessory hemiazygos veins
what does the azygos system of veins do?
drains the posterior thoracic wall
where are the sympathetic chains?
external to the spinal column, adjacent to the vertebral bodies. it is a paired structure (one on each side of the body)
what is the thoracic duct? what does it do?
the main lymphatic vessel for the return of chyle/lymph to the systemic venous system.
it drains lymph from both lower limbs, abdomen (except the convex area of the liver), left hemithorax, left upper limb and left side of face and neck.
what is the thymus?
a T-cell producing lymphoid organ that plays a role in the development of the immune system particularly, maturation of T-cells.
what is the phrenic nerve?
a paired nerve (one of the left and one on the right) that supplies the diaphragm. it comes from the nerve roots C3, C4, C5.
what is the vagus nerve?
-tenth cranial nerve (CNX).
-paired
-provides the bulk of the parasympathetic input to the gastrointestinal system and to the heart.
-a complex mixed sensory, motor and parasympathetic nerve.
what is the pericardium?
a membrane that covers the heart
what are the 2 layers of the pericardium?
- an outer fibrous layer
- an inner thin serous layer that reflects from the inside of the fibrous sac onto the surface of the heart
characteristics of the fibrous pericardium
-outer layer
-continuous with great vessels adventitia (aorta and pulmonary trunk)
-blended inferiorly with the central tendon of the diaphragm.
-rigid structure
characteristics of the serous pericardium
-contained within the fibrous pericardial sac
-analogous to pleural membrane
-double layer: visceral layer/epicardium (inner layer) and parietal layer (outer layer).
between the double layer is a lubricating fluid
functions of the pericardium
protection from infection
fixes the heart in the mediastinum and limits its motion
lubrication
prevents rapid overfilling of the heart
what is cardiac tamponade?
blood/fluid accumulates in the pericardium, compresses the heart, preventing the ventricles from expanding fully and impeding its blood supply
what is pericarditis?
inflammation of the pericardium
what is a dissecting aortic aneurysm?
a tear occurs in the inner layer of the (aorta). blood rushes through the tear, causing the inner and middle layers of the aorta to split (dissect)
what is an acute myocaridla infection?
blood flow to the heart muscle is abruptly cut off, also known as a heart attack
what is pericardiocentesis?
a procedure done to remove fluid that has built up in the sac around the heart (pericardium)
which great vessels are on the right side of the heart?
superior vena cava, inferior vena cava, and the pulmonary trunk
what does the superior vena cava do?
brings deoxygenated blood to the right atrium from the systemic circulation superior to the heart
what does the inferior vena cava do?
brings deoxygenated blood to the right atrium from the systemic circulation inferior to the heart
what does the pulmonary trunk do?
exits the right ventricle, taking deoxygenated blood to the lungs.
immediately superior to the heart it bifurcates into the right and left pulmonary arteries which run into their respective lungs
which great vessels are on the left side of the heart?
the pulmonary veins and the aorta
what do the pulmonary veins do?
enter the left atrium on the posterior aspect of the heart, carrying oxygenated blood from the pulmonary circulation.
there are 4 pulmonary veins:
left superior and left inferior, right superior and right inferior.
what does the aorta do?
carries high pressure, oxygenated blood to the body in the systemic circulation
where is the anterior (sternocostal) surface of the heart?
formed mostly from the right ventricle, this surface is related anteriorly to the sternum and ribs
where is the inferior (diaphragmatic) surface of the heart?
formed mostly by the left and partly from the right ventricle. it is related inferiorly to the centre of the diaphragm.
where is the left (pulmonary) surface of the heart?
formed mostly by the left ventricle. it is related laterally with the left lung and occupies a depression in this lung know as the cardiac impression.
where is the base of the heart situated?
on the posterior aspect, directed towards the vertebrae T6-9
what does the base of the heart consist of?
formed mostly from the left and partly from the right atrium and extends from the bifurcation of the pulmonary trunk superiorly to the atrioventricular groove inferiorly
where is the apex of the heart located?
lies posterior to the 5th intercostal space in the midclavicular line. it is directed antero-inferiorly and to the left
what is the right border of the heart?
formed by the right atrium, extends from the superior to inferior vena cava.
what is the inferior border of the heart?
roughly horizontal and mostly formed by the right ventricle, with a small contribution by the left ventricle
what is the left border of the heart?
mostly formed from the left ventricle with the superior portion being formed by the auricular appendage of the left atrium
what is the superior border of the heart?
formed by both atria, the aorta and pulmonary trunk arise from this border and the superior vena cava enters the heart at the right side of the superior border
where does the superior border of the heart reach?
as high as the third costal cartilage on the right side of the sternum and the second intercostal space on the left side of the sternum
where does the right margin of the heart extend to and from?
from the right third costal cartilage to near the right sixth costal cartilage
where does the left margin of the heart extend to and from?
descends laterally from the second intercostal space to the apex located near the midclavicular line in the fifth intercostal space
where does the lower margin of the heart extend to and from?
extends from the sternal end of the right sixth costal cartilage to the apex in the fifth intercostal space near the midclavicular line
what are the 3 layers of the heart?
epicardium, myocardium, endocardium
what does the epicardium consist of?
a layer of connective tissue and provides a protective layer over the heart (most superficial)
what is the myocardium?
muscular component of the heart wall, it consists of myocytes or cardiac muscle cells
what is the endocardium?
layer of epithelium and connective tissue lines the heart and covers the heart valves. continuous with the endothelial lining of blood vessels (most deep)
describe the cardiac muscle
striated, not under voluntary control, highly branched interconnecting network of fibres - allows the heart to operate as a functional syncytium
how does the cardiac muscle contract?
a sliding filament mechanism between thick and thin muscle filaments of the sarcomeres
what is a syncytium?
an electrical stimulus to any one part of the heart can cause contraction of the whole myocardium
what are the cardiac cells divided by?
the sarcolemma around the fibrils and intercalated discs between the cells
what do intercalated discs do?
holds the cells firmly together through the action of desmosomes. although separating the cells, they allow electrical excitation to pass between cells through gap junctions
what is the fibrous skeleton of the heart?
a supporting structure that the cardiac muscle is anchored to.
the support is provided by dense collagen, whose network forms four fibrous rings that surround the valve openings and two fibrous trigones which lie between these rings. it also provides the membranous parts of the interatrial and interventricular septa.
what are the purposes of the fibrous skeleton?
- prevents the valve openings from collapsing or distending
- provides a base for attachment for the leaflets and cusps of valves
- forms an electrical barrier between the atria and ventricles, preventing them from contracting together.
what are the atria separated by?
the interatrial (IA) septum
what does the right atrium fill with?
deoxygenated blood from the systemic circulation
what does the left atrium fill with?
oxygenated blood from the pulmonary circulation
are the ventricles or the atria more muscular?
ventricles are more muscular than the atria, the left ventricle is especially muscular as it has to push blood around the whole body, as opposed to just the lungs
what are the ventricles divided by?
the interventricular (IV) septum
are the atria thin or thick walled?
thin
describe the atrioventricular orifice (right)
the aperture in which blood flows from the right atrium to the right ventricle. the tricuspid valve is positioned here.
describe the atrioventricular (AV) node
the electrical relay station between the atria and ventricles. it is located in the posteroinferior region of the interatrial septum near the opening of the coronary sinus
describe the crista terminalis
means terminal crest. t is the origin of the pectinate muscles. the sulcus terminalis (on the external surface) acts as a surface marking for the internal crista terminalis
describe the fossa ovalis
an embryological remnant of the foramen ovale. the foramen ovale is a hole between the two atria in a foetal heart
describe the interatrial septum
the fibromuscular wall between the left and right atrium. the fossa ovalis and AV node is located here
describe the opening of the coronary sinus
the coronary sinus is the main cardiac vein. it is where the deoxygenated blood drained from the heart itself returns to the heart’s circulation
describe the pectinate muscles
parallel ridges in the wall of the atrium
describe the right auricle
also known as the right atrial appendage, it is a muscular pouch that acts to increase the capacity of the atrium
describe the sinoatrial (SA) node
the pacemaker of the heart. it is located in the posterior wall of the right atrium, inferolateral to the opening of the superior vena cava, along the superior part of the crista terminalis.
describe the sulcus terminalis
a shallow depression marking the point of fusion between the venous part of the right atrium and the true right atrium. the crista terminalis sits on the internal surface on this structure
describe the atrioventricular orifice (right)
the aperture in which blood flows from the left atrium to the left ventricle. the bicuspid (mitral) valve is positioned here.
what are the papillary muscles?
extensions of the muscle of the ventricular wall in both the left and right ventricles
how are the papillary muscles attached to the mitral and tricuspid valves?
via the inextensible papillary tendons (AKA chordae tendineae)
what happens to the papillary muscles during systole?
the papillary muscles contract and prevent the valves from inverting as a result of the high pressures created in the contracting ventricle
what would happen if there was backflow of blood into the atria?
would damage the atria walls and valves. it would also reduce the efficiency of ventricular contraction in pumping blood into the pulmonary and systemic circulations
describe the atrioventricular valve (tricuspid)
- the valve sitting in the atrioventricular orifice
- has three cusps so it is known as the tricuspid valve on the right side
- prevents reflux of blood into the right atrium.
describe the chordae tendineae
- means tendinous cords
- commonly referred to as ‘heart strings’
- they attach to the cusps of the atrioventricular valves and to the papillary muscles of the ventricle.
- they act to hold the valves in place and prevent reflux.
describe the conus arteriosus
the anterosuperior region of the right ventricle from which the pulmonary trunk arises
describe the interventricular groove
the groove or sulcus on the external surface of the heart. this demarks the division between the two ventricles
describe the interventricular septum
the fibromuscular wall between the left and right ventricles
describe the moderator band
a thick muscular structure that arises from the interventricular septum and ends at the right anterior papillary muscle. tt acts as a shortcut for electric impulses from the right bundle tract.
describe the pulmonary valve
a semilunar valve between the right ventricle and the pulmonary trunk
describe the trabeculae carneae
meaning - meaty ridges. irregular muscular columns found on the internal surface of the ventricles
describe the aortic valve
a semilunar valve between the left ventricle and the aorta
describe the atrioventricular valve (bicuspid/mitral)
- the valve sitting in the atrioventricular orifice.
- has two cusps so it is known as the bicuspid valve on the left side.
- can also be referred to as the mitral valve.
- prevents reflux of blood into the left atrium.
which structures prevent inversion of the valves?
papillary muscles and chorda tendineae
what are the aortic sinuses?
- spaces behind the aortic valves
- blood flow back towards the heart at the end of systole causes these sinuses to fill with blood, ballooning and closing the valve
what is auscultation?
listening to the sounds of the heart with a stethoscope
what are the two audible heart sounds and what do they correspond with?
lub - closure of av valves
dub - closure of sl valves
how is a heart murmur caused
by blood leaking through an incompletely closed or excessively narrowed (stenosed) valve
what is the cardiac cycle?
the pattern of contraction and relaxation of the heart during one complete heartbeat
what is the intrinsic conducting system?
made up of specialised cardiac muscle cells, these initiate a heartbeat.
what is the extrinsic conducting system?
controlled by nerves. it controls things like heart rate, contraction force, etc
what does the sa node do?
- the pacemaker of the heart
- its repeated, automatic depolarisation sets the rhythm of the heartbeat
- is a cluster of cells situated on the posterior wall of the right atrium, close to the superior vena cava
- the rate at which it fires is modified by autonomic input: sympathetic increasing heart rate, parasympathetic decreasing heart rate
what are the purkinje fibres?
fast-conducting fibres which spread the impulse throughout the ventricular myocardium, causing an upward wave of contraction.
what is the moderator band?
-also known as septomarginal trabecula
-in the right ventricle
-provides a shortcut for electric impulses of the right bundle branch from the interventricular septum to the anterior papillary muscle of the right ventricle
where are electrodes attached for an ECG?
left arm, right arm and left leg
right leg has a neutral lead attached
what does the P-wave of an ECG correspond to?
atrial depolarisation and atrial systole closely follows
what does the QRS-complex of an ECG represent?
conduction of the impulse through the interventricular septum and ventricular depolarisation.
atrial repolarisation also takes place in the QRS complex, though it is not immediately obvious.
what does the T-wave of an ECG represent?
ventricular repolarisation and, therefore the end of the cardiac cycle
what are the three sinuses of the aortic valve?
-the posterior aortic sinus (no artery arises)
-the left aortic sinus (left coronary artery arises)
-the right aortic sinus (right coronary artery arises)
what does the left coronary artery supply?
-left atrium
-most of the left ventricle
-some of the right ventricle
-anterior part of the IV septum
-the SA node (40% of population)
what does the left coronary artery divide in to?
the anterior interventricular branch - travels down the anterior surface of the heart along the interventricular groove towards the apex of the heart. supplies the anterior walls of both ventricles
the smaller circumflex branch - passes along the coronary groove on the left border of the heart to the posterior surface of the heart. also gives off a left marginal artery which runs on the left border of the heart, supplying the left ventricle.
what does the right coronary artery supply?
-right atrium
-most of right ventricle
-some of left ventricle
-posterior IV septum
-SA node (60% of population)
what does the right coronary artery give off?
-an ascending sinoatrial node branch that supplies the SA node (in 60%)
-descends in the right av groove, giving off a marginal branch at the right margin of the heart that supplied the right border of the heart
-at the crux of the heart, the RCS gives off the large posterior interventricular branch that descends in the posterior interventricular groove
what is venous drainage?
a network of cardiac veins drain deoxygenated blood from the heart tissue and deposit it in the coronary sinus.
this drains directly into the right atrium.
what is a myocardial infarction?
a heart attack - a coronary artery becomes blocked and the myocardium becomes ischaemic.
what vessels lead into the right and left atria?
the superior and inferior vena cava run into the right atrium. the right and left superior and inferior pulmonary veins run into the left atrium
what vessels exit from the right and left ventricles?
the aorta exits from the left ventricle. the pulmonary trunk exits from the right ventricle.
characteristics of arterioles?
- diameter: <0.1cm
- main resistance vessels because of narrow lumen and large numbers
- proximal arterioles have many layers of smooth muscle and are richly innervated by sympathetic nerve fibres
- distal arterioles have only 1-3 layers of smooth muscle and are poorly innervated by sympathetic fibres.
- arterioles are the main site of blood flow regulation to tissues
characteristics of capillaries?
- diameter: 0.004-0.007
- the wall of the vessels consist of only a single layer of endothelial cells
- greatest total CSA because they are so numerous
- blood is at its lowest pressure, and therefore at its slowest. this facilitates exchanges of nutrients, gases and waste products.
- 3 types: continuous, fenestrated and sinusoid
characteristics of elastic arteries?
- diameter: 1-2cm
- tunica media is rich in elastin
- walls are very distensible
- walls expand during systole to receive the stroke volume of ventricular ejection and recoil during diastole to create an almost constant flow in more distal tissues. the blood pressure created by this elastic recoil is the diastolic blood pressure.
examples - aorta, pulmonary artery and iliac arteries
what does the three layered wall in capillaries consist of?
tunica intima (inner most layer)
tunica media (middle layer)
tunica adventitia (outer layer)
what is the tunica intima wall?
consists of a single sheet of endothelial cells resting on a thin layer of connective tissue.
this layer is mechanically weak however the endothelium is the main barrier to plasma proteins and also secretes many vasoactive products
what is the tunica media wall?
consists of a layer of smooth muscle of varying thickness in a matrix of elastin and collagen
this layer supplies mechanical strength, elasticity and contractile power to the vessel.
what is the tunica adventitia wall?
a connective tissue sheath with no distinct outer border.
it’s main role is to tether vessels loosely in place.
in large arteries it contains a small blood vessel network called the vasa vasorum which are responsible for nourishing the media. in larger arteries the vessels also penetrate the outer tunica media.
characteristics of conduit (muscular) arteries?
- diameter: 0.1-1cm
- tunica media is thicker relative to the lumen of the vessel compared to the elastic arteries
- media contains more smooth muscle which prevents collapse at sharp bends (elbow)
highly innervated by the autonomic nervous system and can contract or relax - muscular arteries play a big role in limitation of blood loss in major trauma
examples - radial, cerebral and coronary arteries
characteristics of arteriovenous anastomosis?
- diameter: 0.02-0.135cm
- only found in a few tissues - skin and nasal mucosa
- wide ‘shunt vessel’ which bypass the capillary beds
- richly innervated with sympathetic nerve fibres
- in nasal mucosa they help to warm inspired air, in skin they are involved in temp regulation
characteristics of veins and venules?
- diameter: 0.05-0.2cm (venules), >0.2cm (veins)
- thin tunica media composed of smooth muscle and collagen
- thin walls means easily distended and often collapse
- in limbs, tunica intima possesses pairs of valves that prevent backflow.
- veins and venules are more numerous than arteries and arterioles so they offer a low resistance to flow.
- many veins are innervated by sympathetic (vasoconstrictor) nerve fibres which make the smooth muscle contract and displace blood from this ‘reservoir’ of blood in the veins during times of physiological stress.
what is hypertension?
-high blood pressure
-2 types: primary and secondary
-unknown cause for primary
-secondary caused by abnormality in an organ/system of the body
what are the 4 parts of the aorta?
ascending, arch, descending, abdominal
what branches from the ascending aorta?
left and right coronary arteries which then supply the heart
where is the aortic arch found?
after the ascending aorta (around the level of T4/T5)
what branches off the aortic arch?
- brachiocephalic trunk - divides into the right subclavian artery and the right common carotid artery
- left common carotid artery
- left subclavian artery
at what level do the common carotid arteries divide into internal and external carotid arteries? what do these supply?
at the level of C3
internal carotid artery - major blood supply to the brain
external carotid artery - major blood supply to the neck, facer and scalp on its respective side
what does the subclavian artery supply?
arm, thoracic wall, shoulder and neck on its respective side
where does the descending aorta sit and what does it supply?
sits left of the vertebral column in the thorax. gives off branches that supplies structures of the thorax
when does the descending aorta become the abdominal aorta?
as it passes through the aortic hiatus of the diaphragm at the vertebral level of T12
what does the abdominal aorta supply?
-gives off many branches that supply structures of the abdomen, pelvis and lower limb. these include the coeliac trunk, superior mesenteric artery, renal arteries, and the inferior mesenteric artery.
the abdominal aorta then splits into two common iliac arteries travelling towards the pelvis and lower limb.
characteristics of the coeliac trunk
-first unpaired branch of the abdominal aorta
-supplies the foregut structures of the abdomen including the stomach, liver, gallbladder, pancreas and spleen
-comes off the abdominal aorta at the vertebral level of T12
characteristics of the superior mesenteric artery
-second unpaired branch of the abdominal aorta.
-supplies midgut structures of the abdomen including most of the small intestine and the proximal portion of the large intestine.
-it comes off the abdominal aorta at the vertebral level of L1.
characteristics of the renal arteries
-paired branches of the abdominal aorta.
-they supply the kidneys and come off the abdominal aorta at the vertebral level of L1/L2.
characteristics of the inferior mesenteric artery
-third unpaired branch of the abdominal aorta.
-it supplies hindgut structures of the abdomen which is the distal portion of the large intestine.
-it comes off the abdominal aorta at the vertebral level of L3.
what are the common iliac arteries?
-form from the bifurcation of the abdominal aorta at the vertebral level of L4.
-common iliac artery on each side will split into an internal iliac and external iliac artery
-internal - supplies structures of the pelvis cavity and perineum
-external - continues as the femoral artery and supplies the lower limb on the respective side
what are the superior vena cava tributaries?
internal jugular vein - drains most of the head and neck
subclavian vein - drains the upper limb
the internal jugular and subclavian veins join together to form a brachiocephalic vein on each side of the body. these join together to form the superior vena cava.
the azygos system, which drains the posterior thoracic wall, also drains into the superior vena cava.
what are the inferior vena cava tributaries?
-IVC is formed from the common iliac veins. these drain structures of the lower limb and pelvis. the main tributaries include renal, lumbar and hepatic veins.
what is the portal venous system?
-collection of veins which drain into the liver before draining into the IVC.
-these veins originate from the digestive organs within the abdomen, therefore the deoxygenated blood contains nutrients that have been absorbed along the GI tract.
-the liver filters and metabolises these substances within the blood. -the filtered blood is then returned to the heart via the hepatic veins and IVC.
what is deep vein thrombosis?
the formation of a blood clot within a deep vein. most common location to get DVTs are the lower limbs
why is thrombosis more common in veins than arteries?
the veins are lower pressure and the blood moves slower, giving the clot more time to form. this is why a risk factor for DVT is immobility.
why does a thrombus lead to inflammation?
it restricts the flow of blood through the vein, which causes a backlog of pressure and indirectly reduces perfusion to the tissue associated with the vein
what is the first line treatment for a DVT?
anticoagulation to prevent this from happening, but it does not actually break down the initial clot - the body does that.
what does the upper respiratory tract include?
-the nasal cavity and paranasal sinuses
-the pharynx
-the larynx, above the level of the vocal cords
what is the purpose of the upper respiratory tract?
to condition inspired air before it reaches the lungs. the air is:
-warmed to body temperature
-humidified
-filtered for particulates (>10micrometres)
what does the lower respiratory tract include?
-the larynx below the level of the vocal cords
-the trachea, bronchi, bronchioles
-the lungs - sometimes classed as separate, they contain bronchioles, alveolar ducts, alveolar sacs and alveoli
what is the purpose of the lower respiratory tract?
it is concerned with gas exchange, by conducting inspired air to the tissues involved in gas exchange, and further trapping and removal of particulates
what controls the rhythm of breathing and where is it located?
the respiratory centres of the brainstem. the respiratory centre is located in the lower part of the brainstem, in an area called the medulla oblongata
how is a rhythmic cycling pattern of inspiration and expiration maintained?
inspiratory neurones and expiratory neurones.
the automatic rhythm can be modified by the afferent information, which comes from chemoreceptors, the brain, and receptors in the lungs
main function of the lungs
to oxygenate blood by bringing inspired air into close relation with deoxygenated blood in the pulmonary circulation
how do healthy lungs look in living people?
light, soft, spongy
may see dark/black deposits as a result of breathing polluted air
which lung is larger and why?
the right - the middle mediastinum, containing the heart, bulges more to the left than to the right
what are the 3 surfaces of the lungs?
- costal - close to ribs/costal cartilages and intercostal spaces
- mediastinal - close to mediastinum anteriorly and vertebral column posteriorly. this surface contains the hilum of the lung.
- diaphragmatic (base of lung) - sits on the diaphragm
what are the 3 borders of the lungs?
- inferior - separates the base from the costal surface
- anterior - separates costal surface from mediastinal surface. the anterior border of the right lung is relatively straight, whereas the anterior border of the left lung has a deep cardiac notch.
- posterior - separates costal surface from mediastinal surface. the other two borders are sharp, but the posterior border is smooth and rounded.
how many lobes/fissures does the right lung have?
3 lobes separated by 2 fissures
how many lobes/fissures does the left lung have?
2 lobes separated by 1 fissure
what are the different lobes of the right lung?
-superior (upper) - mainly in contact with the anterior thoracic wall and projects into the root of the neck
-middle - mainly in contact with the anterior and lateral thoracic wall
-inferior (lower) - mainly in contact with the posterior and inferior thoracic wall
why is the position of the lobes of the lungs important?
it dictates where a stethoscope should be placed to listen to each lobe of the lung
what does the oblique fissure separate?
the inferior lobe from the superior lobe
and the middle lobe in right lung
what does the horizontal fissure separate?
the superior lobe from the middle lobe
what are the 2 lobes of the left lung?
-superior (upper) - mainly in contact with the upper part of the anterior and lateral thoracic wall and projects into the root of the neck
-inferior (lower) - mainly in contact with the posterior and inferior part of the thoracic wall
what is a lingula?
in the left lung, a tongue-like projection that extends over the anterior surface of the heart
what is the hilum of the lung?
the area at which structures that attach the lungs to the heart and trachea enter and leave the lung
name the structures that make up the root of the lung and enter/leave at the hilum
a pulmonary artery, two pulmonary veins, a main bronchus, bronchial vessels, nerves, lymphatics
how to distinguish between the bronchi, pulmonary arteries and pulmonary veins at the hilum?
wall thickness - thickest to thinnest is bronchi, pulmonary arteries, pulmonary veins
position at the hilum - pulmonary artery is more superior, pulmonary veins are inferior and bronchi are more posterior in position
what is the most superior aspect of the lungs and where does it lie?
their apex, lies just above the first rib superiorly, level with T1
what is the most inferior aspect of the lungs and where does it lie?
level with T12 at their most inferior point in the posterior thorax on inspiration. the inferior aspect of the lungs is in contact with the diaphragm
where does the inferior margin of the lungs travel during quiet respiration?
around the thoracic wall, following rub 6 down to rib 8, from vertebral level T10 posteriorly (rib 6 in the midclavicular line, rib 8 in the midaxillary line, and vertebra 10 posteriorly)
where is the oblique fissure in posterior, lateral and anterior terms?
posteriorly - in the midline, near the spine of vertebra T4
laterally - descends diagonally, crossing the 4th and 5th intercostal spaces to reach rib 6
anteriorly - follows rib 6 and its costal cartilage
where does the horizontal fissure lie anteriorly?
following the contour of rib 4
what is the pleura?
a thin membrane that encloses the lungs. also lines the walls of the thoracic cavity
what is the parietal pleura?
the pleura associated with the walls of the cavity.
lines the pulmonary cavities and is adherent to the thoracic wall, the mediastinum and the diaphragm
what is the visceral pleura?
the pleura that is associated with the lungs. covers the lungs and is adherent to all its surfaces, including the horizontal and oblique fissures, it cannot be separated from the lungs
are the layers of the pleura continuous or not?
yes - they are one giant sheet of membrane that folds to cover the lungs and line the cavity. the two plurae are continuous at the root of the lung, as the visceral pleura reflects off the lungs to become the parietal pleura and vice versa
what is the space between the two layers of pleura called?
it is a potential space known as the pleural cavity
what is a potential space?
a cavity that does not normally exist in healthy people. it is usually present where 2 membranes are closely packed together. normally, the space will only contain a tiny quantity of fluid. is has the potential to become a space in illness or injury - if air, blood, or pus abnormally fills it and causes it to expand.
what type of membrane is pleura?
a serous membrane - this means it produces serous fluid, a lubricating fluid that is present in the potential space between the visceral and parietal layers of pleura
what is the function of the pleura and serous fluid?
-to allow smooth movement of the lungs as they expand and collapse throughout respiration.
-the fluid also provides the surface tension that keeps the surface of the lung in contact with the thoracic wall; consequently the lung expands and fills with air when the chest expands and the diaphragm flattens
what are the 4 regions of the parietal pleura?
- costal pleura - covers the internal surfaces of the thoracic wall
- mediastinal pleura - covers the lateral aspects of the mediastinum
- diaphragmatic pleura - covers the superior aspect of the diaphragm on each side of the mediastinum
- cervical pleura - extends through the superior thoracic aperture forming domes pleura over the apex of the lung (also known as dome of pleura or pleural cupola)
where does the pleural cavity extend to superiorly?
it projects as much as 3-4cm above the first costal cartilage
where does the pleural cavity extend to anteriorly?
left and right pleural cavities approach each other posterior to the sternum
however, more inferiorly, the parietal pleura does not come as close to the midline on the left side as it does on the right because the middle mediastinum, containing the pericardium and heart, bulges to the left
where does the pleural cavity extend to inferiorly?
-the costal pleura extends to rib 8 in the midclavicular line and to rib 10 in the midaxillary line.
-more posteriorly, the inferior margin courses horizontally, crossing ribs 11 and 12 to reach vertebra T12.
-from the midclavicular line to the vertebral column, the inferior boundary of the pleura can be approximated by a line that runs between rib 8, rib 10, and vertebra T12.
what happens if a significant amount of air or fluid enters the pleural cavity?
the surface tension adhering the visceral and parietal pleura is broken and pleural cavity becomes a real space (no longer potential)
as a result, the lung collapses, due to the elastic nature of the lung tissue
what is a pneumothorax?
when air rushes into the pleurla cavity as a result of a puncture wound to the thorax
what is hydrothorax?
accumulation of fluid in the pleural cavity as a result of pleural effusion
what is haemothorax?
when blood enters the pleural cavity. it is usually a result of injury to a major intercostal vessel (usually a fractured rib), rather than laceration to the lung
what is the function of the bones of the thorax?
-provide attachment points for the muscles of respiration
-move to facilitate breathing
-provide protection for the vulnerable organs within the thorax
what are the bones of the thorax?
the sternum, 12 pairs of ribs, their costal cartilages, and the 12 thoracic vertebra (T1-T12)
what does the sternum consist of and where does it sit?
-it sits anteriorly
-consists of the manubrium, sternal body and xiphoid process
what are true ribs?
ribs 1-7
ribs that articulate directly with the sternum anteriorly, via short costal cartilages.
every true rib has its own costal cartilage
what are false ribs?
ribs 8-12
false ribs articulate indirectly with the sternum anteriorly, via long, shared costal cartilages, or do not articulate with the sternum at all.
what are floating ribs?
ribs 11-12
they do not articulate with the sternum anteriorly, and are shorter and pointier than the other ribs
which nerves innervate the diaphragm?
the right and left phrenic nerves, which have their origins at the 3rd and 5th cervical spinal nerves (c3-c5)
c3, c4,c5 keeps the diaphragm alive
where is the highest point of the diaphragm while at rest?
level with T9
inferiorly it is attached to the body wall level with T12
where does blood supply of the diaphragm originate from?
the intercostal arteries
where does venous drainage of the diaphragm go to?
the inferior vena cava
which 3 major structures travel through the diaphragm?
the aorta, the inferior vena cava, the oesophagus
what happens during contraction of the diaphragm?
diaphragm flattens, thorax volume increases, rib margins are lifted and moved out, transverse diameter of the thorax increases. all of these aid inspiration
how much does the apex move inferiorly by during quiet breathing and deep breathing?
quiet breathing: 1-2cm
deep breathing: 10cm
what are the 3 types of intercostal muscles?
external, internal, and innermost
how many sets of each type of intercostal muscles are there?
11
where does the blood supply of the intercostal muscles come from?
intercostal arteries
how is venous drainage of the intercostal muscles done?
via the intercostal veins
which nerves innervate the intercostal muscles?
intercostal nerves
how do fibres of the external intercostals run?
obliquely anteroinferiorly (diagonally forward and down)
what does contraction of the external intercostals do to the ribs?
pulls them up and out
how do fibres of the internal intercostals run?
obliquely posteroinferiorly (diagonally backward and down)
what does contraction of the internal intercostals do to the ribs?
pulls them down and inward
when are the external intercostals most active?
during inspiration, where they pull the ribs upwards and forwards
where do the external intercostals run?
around the wall of the thorax, from the tubercles of each rib posteriorly, to the cartilages of the ribs anteriorly.
they end anteriorly in thin membranes, the external intercostal membranes, which continue forward to the sternum
where do the internal intercostal muscles run?
between the most inferior lateral edge of the costal grooves of the ribs above, to the superior margins of the ribs below.
they begin anteriorly, at the sternum in the spaces between the cartilages of the true ribs and at the most anterior edge of the cartilages of the false ribs.
they extend downward as far as the angles of the ribs, where they continue to the vertebral column as thin membranes called the internal intercostal membranes
when are the internal intercostals used?
during active respiration
how are the innermost intercostal muscles separated from the internal intercostal muscles?
by the bundle of intercostal blood vessel and nerves
which muscles assist in expansion of the thoracic cavity to maximise respiratory efficiency during forced respiration?
sternocleidomastoid, pectoralis major, and the scalene muscles.
however all main functions are not related to breathing
which planes do the ribs move in during breathing?
forwards and backwards (anteroposterior) - compared to a pump handle action where the ribs are the handle
laterally - compared to a bucket handle where the ribs are a handle pivoting at the spine and sternum
what are the treelike structures in each lung called?
vascular tree - composed of arteries, veins and capillaries which conduct poorly oxygenated blood to the lungs and returns highly oxygenated blood to the heart
airway tree - consists of air-filled branching tubes, originating from the trachea, which conduct ‘new’ atmospheric air to the gas exchange surfaces and return ‘used’ air to the environment
what is pulmonary oedema?
a build up of fluid in the interstitial space in the lungs. this increases the diffusion distance of gases between blood and the alveoli.
the increase diffusion distance leads to hypoxia as the blood loads with less oxygen.
what are the early and late symptoms of pulmonary oedema?
early - shortness of breath, cough and various disruptions to the rate and rhythm of breathing
later - cyanosis and a cough with a foaming red sputum
which of the conducting airways is responsible for most of the airway resistance and why?
trachea - it is the widest but has the smallest total cross sectional area
what prevents the trachea collapsing on inspiration?
rings of hyaline cartilage
where does the bifurcation of the trachea occur?
at vertebral level T4
which important landmarks are level at vertebral level T4?
-level of sternal angle
-level where the trachea bifurcate into the 2 main bronchi
-level of the arch of the aorta
-where the second rib articulates with the sternum
what is the difference between the right and left primary bronchi?
-the right bronchus is wider and shorter and runs more vertically than the left to enter the hilum of the lung
-the left bronchus is oriented more horizontally, and runs inferior to the aortic arch and anterior to the oesophagus and thoracic aorta, to reach the hilum of the lung
what do the main bronchi divide into?
secondary/lobar bronchi (one per each lobe of the lung), and then into tertiary/segmental bronchi/ each tertiary bronchus supplies a different segment of the lung
what forms the conducting zone of the lower respiratory system?
the first 17 generations of airway (the trachea and 16 successive airway branches)
at which division of the bronchi are the bronchioles found?
~12th
which structures form the respiratory zone of the lower respiratory system?
the structures from the respiratory bronchioles to the alveoli
what is a lung lobule?
a cluster of alveoli supplied by a single respiratory bronchiole, surrounded by the connective tissue of the lung
what is the apical surface of alveoli covered in?
a surfactant into which gases dissolve to aid their diffusion
what is emphysema?
a condition largely associated with smoking.
it is caused by gradual damage to the alveoli, usually by irritants or infection, which makes them lose their natural elasticity.
lungs feel continually overinflated so patient struggles to force air in and out of lungs.
leads to a state of chronic hypoxia causing fatigue and breathlessness
what is COPD?
chronic obstructive pulmonary disease.
when emphysema is combined with chronic bronchitis (lungs unable to clear mucus which becomes infected)
what is asthma?
current theory is that asthma is an immunological disease caused by the immune system over-reacting to an antigen that would normally be over looked
status asthmaticus is then later triggered by an irritant. in a non-asthmatic, the irritant would not cause the same degree of reaction, however in an asthmatic the airways are ‘hypersensitive’. the reaction causes varying degrees of bronchoconstriction.
what type of epithelium is present throughout the upper respiratory system?
respiratory type epithelium - pseudostratified columnar, with cilia and goblet cells
how does the epithelium change in the lower respiratory tract?
-bronchioles are lined by simple (not pseudostratified) ciliated columnar epithelium and goblet cells are sparse
-most proximal components are the respiratory bronchioles which are lined with cuboidal ciliated epithelium.
-alveolar ducts are lined with flattened epithelium.
what is the site of gaseous exchange in the lower respiratory tract?
the distal respiratory tract
what do the alveoli consist of?
type 1 and 2 pneumocytes that lie on the basement membrane, and alveolar macrophages
what does the alveolar wall contain and why?
elastin - allows lungs to stretch and recoil, and acts as a support, attaching airways with no cartilage firmly to the connective tissue of the lung
what are type 1 pneumocytes?
-thin cells that allow gaseous diffusion.
~40% of the no. of alveolar cells but ~90% of the SA lining the alveoli
-flattened cells with flattened nuclei and joined by tight junctions
-have few organelles
what are type 2 pneumocytes?
-secrete surfactant
-represent 60% of no. of alveolar cells, but only 5-10% of SA lining the alveoli
-rounded in shape and contain numerous mitochondria
-some act as precursor stem cells for type 1 pneumocytes
what is surfactant?
acts as a detergent, reducing alveolar surface tension, preventing collapse of the alveoli during expiration and facilitating inspirational expansion
what alveolar macrophages?
-‘patrol’ the alveolar air spaces and the interalveolar septa (the walls of the alveoli) and can pass freely between the 2
-they phagocytose inhaled debris and pathogens
-then may pass into the lymphatic system or adhere to mucous-coated ciliated epithelium and continue up to the mucociliary escalator to the trachea where they are cleared by coughing
what are neutrophils and where are they found?
-the most predominant type of granulocyte in the blood
-phagocytic cells and are the most numerous component of the innate immune response
-found at sites of acute inflammation
what are eosinophils and what are some characteristics of them?
-granulocytes
-important in defence against parasitic infections because their numbers increase during a parasitic infection
-involved in atopic reactions such as asthma
-their granules are easily stained by eosin and other acidic dyes, granules contain basic proteins
what are basophils and what are some characteristics of them?
-granulocytes found in relatively low numbers in normal blood
-function is probably similar and complementary to that of eosinophils and mast cells
-granules are stained by basic dyes and therefore contain acidic proteins, granules also contain histamine, leukotrines, vasoactive mediators and platelet activating factor
what are granulocytes?
-the most common type of white blood cells
-contain enzyme granules that form in the cytoplasm
-neutrophils, eosinophils, basophils
what are macrophages?
-major phagocytic cells which play a critical part in innate immunity
-widely distributed in all body tissues
what is a monocyte?
a circulating cell which differentiates into a macrophage upon migration into the tissues
name the different forms of lymphocytes
B-cells
T-cells
natural killer (NK) cells
mast cells
what do B cells do once activated?
differentiate into antibody secreting plasma cells as part of the specific immune response
what are T cells? what are the 2 types and what does each do?
thymus-matured lymphocytes
- cytotoxic T lymphocyte (CTL) - kills virus infected cells
- helper T-lymphocytes - activate other cells such as B-cells and macrophages
what are natural killer cells?
large, granular lymphocytes which form part of the innate immune response
can detect and attack some virus-infected cells despite lacking in antigen-specific receptors
where are mast cells found and what do they do?
-found across many tissues, mainly near small blood vessels
-upon activation, they release substances from their granules that affect vascular permeability. the granules contain histamine and heparin.
-best known for their role in allergy, also thought to play a part in protecting mucosal surfaces from pathogens
where are all immune cells created and matured? what are they produced from?
in primary lymphoid tissues (the thymus and bone marrow)
produced from haematopoietic stem cells
lymphocytes and some mononuclear phagocytes can re-circulate between non-lymphoid tissues and secondary lymphoid tissues. what does this do?
increases the likelihood they will be exposed to pathogens picked up in tissues from all over the body
what are primary lymphoid tissues/central lymphoid organs?
tissues where lymphocytes develop and mature to a stage where they are able to recognise antigens
consist of the bone marrow and the thymus
what is derived from the bone marrow?
all immune cells, red blood cells and platelets
what are the 2 types of bone marrow?
red - involved in haematopoiesis
yellow - made up of adipocytes
where does haematopoiesis take place at birth and during adulthood?
birth - all medullary cavities of bone
adulthood - restricted to the axial skeleton and all other medullary cavities are left with only adipocytes
describe lymphoid development
-lymphocytes descend from a common lymphoid progenitor.
-B cells mature entirely in the bone marrow and enter the blood, though most die within a few days as they fail to meet their antigen.
-T cells leave the bone marrow as immature progenitors and travel to the thymus, via the blood, to complete maturation and undergo selection.
where does the thymus sit?
within the thorax, the superior and anterior mediastinum
anterior/superficial to the heart and pericardium but posterior to the sternum
what is the function of the thymus?
where T cells complete maturation
it gradually enlarges through childhood when it is most active, but after puberty it begins to reduce in size and function.
during maturation most developing T cells die in the thymus as they fail to produce a T cell receptor that is useful to the immune system
what does positive selection of T cells select for?
T cells capable of recognising self MHC (major histocompatibility complex) molecules and peptides
what are major histocompatability complex molecules?
responsible for antigen presentation at a cellular level
the presented antigens are ‘examined’ by cells of the immune system, most notably T-cells
what are the two classes of MHC molecules and the difference between them?
MHC-I and MHC-II - different types of T cell are sensitive to each
in the thymus, those cells which are able to detect MHC-I plus peptide go on to become cytotoxic T-cells. meanwhile those able to detect MHC-II plus peptide go on to become helper T cells
what happens if the T cell does/doesn’t recognise the protein-MHC complex?
doesn’t - T cell dies by apoptosis after 4 days (95% of T cells that make it to the thymus fall to this fate)
does - receives ‘survival signals’ which prevent it entering apoptosis, advance to the medullary region
what is negative selection of t cells?
in the medullary section, eliminates those t cells which would recognise self-peptide and therefore be dangerous to the body
what do dendritic cells in the medulla do?
dendritic cells present self-antigen to the T-cells on MHC-I and MHC-II.
this time, those cells which recognise and bind antigen are given a “death signal” and they are told to undergo apoptosis.
those that do not bind after four days are deemed “useful” and leave the thymus, entering the blood stream.
where are secondary lymphoid tissues/peripheral lymphoid organs found and what do they include?
-found in sites where mature lymphocytes are exposed to and stimulated by antigens
-include: lymph vessels, lymph nodes, spleen, mucosa associated lymphoid tissue (MALT)
how do lymphocytes enter the secondary lymphoid tissues?
via high endothelial venules, which express specific adhesion molecules on their endothelium to which lymphocytes bind
adhesion then leads to the lymphocyte squeezing through the endothelium into the node
what do lymph vessels do?
drain tissue fluid from connective tissue
fluid/cells known collectively as lymph
where do the lymph vessels empty to primarily?
via the thoracic duct to the left venous angle between the interior jugular vein and subclavian vein
where are antigens from pathogens/foreign materials drained from and to
from the site of infection (usually connective tissues) and carried to lymph nodes
function of lymph nodes
filter lymph from tissues, antigen is trapped in the lymph node and taken up by APCs, then presented to lymphocytes passing through the node
structure of lymph nodes?
highly organised, bean-shaped
aggregated in particular sites e.g., neck and groins
where do HEVs enter the lymph node?
in the paracortex
where in the cortex are B and T cells located?
B-cells - primary and secondary follicles in the cortex
T-cells - paracortex region
what are primary and secondary follicles?
lymphoid tissues contain lymphoid follicles made up of lymphoid dendritic cells and B lymphocytes
primary follicles contain resting B lymphocytes and are the site at which germinal centres form when they are entered by activated B cells, forming secondary follicles
describe the location of the spleen
associated posteriorly with the left ribs 9 to 11, though separated from them by the diaphragm superiorly. it rests on the left colic flexure of the large intestine. the tail of the pancreas points towards the spleen.
it sits on the left side of the abdomen within the hypochondrium region.
function of the spleen?
collects antigen from the blood, presenting it to lymphocytes.
serves to filter the blood, removing and disposing of ageing red blood cells and immune complexes
what are the two distinct components of the spleen?
- red pulp is a well perfused-tissue responsible for the filtration role of the spleen, removing ageing and damaged red blood cells from the circulation.
- white pulp has many similarities to a lymph node. it is packed with T cells, B cells and dendritic cells and sifts antigen from the blood instead of the lymph
where are T cells and B cells in the spleen located?
T cells - in the periarteriolar lymphoid sheath (PALS)
B cells - beyond the sheath in a corona around a germinal centre
what are MALT found?
under the epithelium of the respiratory tract, gastrointestinal tract, genitourinary tract
what are GALT?
part of the overall MALT, they include tonsils and adenoids, Peyer’s patches, appendix
what are the different types of tonsils and where are they located?
palatine tonsils - back of the oral cavity on each side
tubal tonsils - near the nasopharynx near the opening to the inner ear internally
lingual tonsil - sits at the base of the tongue
pharyngeal tonsil (adenoids) - high in the nasopharynx behind the nasal cavity and soft palate
create ‘Waldeyer’s ring’
what is the function of the tonsils?
present antibody to the cells of immune system
if an immune cell recognises the antigen it begins to rapidly divide, it is this rapid division that causes the tonsils to swell
what are Peyer’s patches and where are they located?
located in the mucosa throughout the small intestine, particularly in the ileum
specialised lymphoid tissue for collecting antigen present in the GI tract
comprise primary and secondary follicles located immediately beneath specialist epithelium known as follicular-associated epithelium. T cell zones lie more deeply
what is the appendix?
part of the large intestine, associated with the caecum, susceptible to infection
what does the GI tract consist of?
-oral cavity
-oesophagus
-stomach
-small intestine (duodenum, jejunum, ileum)
-large intestine (caecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum)
-anal canal and anus
the liver, the gall bladder and the pancreas are associated with the GI tract.
what are the mechanisms of the mouth designed to deal with?
digestion and pathogen defence
what are the 3 main salivary glands? what do each of them secrete?
parotid - serous saliva, submandibular - serous and mucous saliva, sublingual - mucous saliva
where is saliva produced? what by?
in the acini of saliva glands, by active filtration of ions from blood.
autonomic stimulation of the glands changes the composition and volume of saliva secreted. what do parasympathetic stimulation and sympathetic stimulation produce?
parasympathetic stimulation - large volume of watery saliva
sympathetic stimulation - small amount of mucous saliva
name some functions of saliva
-lubrication due to mucin content
-digestion due to presence of α-amylase
-protection of oral mucosa through lubrication, rinsing action and alkaline pH
-antibacterial through actions of antimicrobial thiocyanate
-thirst stimulation
-speech
-absorption in the mouth
what do the muscles of the tongue and cheeks (buccinator muscles) do with food?
aid pulverisation and bolus formation
what do the muscles of mastication do?
move the mandible (lower jaw bone), bringing its teeth into contact with the teeth of the maxilla (upper jaw bones). the joint that moves is known as the temporomandibular joint (TMJ)
what are the four muscles of mastication?
temporalis
masseter
lateral pterygoid
medial pterygoid
found on both sides of the face so there is a left and right of each. the pterygoid muscles sit deep
which muscle is the major effector in closing the mouth/elevating the jaw?
the temporalis. the posterior fibres can also retract the lower jaw if it has been protruded
what does the masseter do?
elevates and protrudes the lower jaw
what do the lateral and medial pterygoids do?
help protrude the lower jaw unilaterally which create lateral or ‘side to side’ movements
what are the two stages of swallowing?
the pharyngeal stage and the oesophageal stage
what happens during the pharyngeal stage of swallowing?
-the initiation of swallowing is voluntary
-the muscles of the tongue push the bolus posteriorly
-the oral cavity opens into the oropharynx
-when the bolus of food contacts the back of the pharynx the swallow reflex is triggered
-the soft palate rises to block off the nasopharynx and elevation of the larynx moves the epiglottis over the trachea
-the larynx is lifted by muscles of the throat (suprahyoid muscles) to close off the trachea
-the pharyngeal constrictors contract sequentially to push the food down the pharynx and into the oesophagus
what happens during the oesophageal stage of swallowing?
food enters the oesophagus and the involuntary action of the smooth muscle pushes the food towards the stomach
at the junction between the oesophagus and stomach there is no anatomical sphincter but bands of muscle from the diaphragm, (the lower oesophageal sphincter), further increase tension produced by the oesophageal wall, preventing reflux of the stomach’s contents into the oesophagus
the oesophagus is lined throughout its length with stratified squamous epithelium
where is the oesophagus?
a muscular tube passes from the pharynx all the way down to the stomach, passing through the diaphragm at the vertebral level of T10
when does a hiatus hernia occur?
when the upper part of the stomach squeezes through a gap between the oesophagus and diaphragm (hiatus)
how common is a hiatus hernia?
quite common, present in about 10% of the population
no symptoms and only presents when it causes reflux of stomach contents into the oesophagus
usually affects overweight middle-aged women, elderly people and pregnant women. can almost always be resolved by losing weight
how is reflux usually treated?
with drugs and by altering lifestyle
antacids neutralise the refluxed stomach contents reducing pain and damaging effects of the acids
how can reflux be avoided?
-eating frequent small meals
-reducing caffeine, alcohol and spicy meals
-raising the upper body slightly when sleeping
what does keyhole surgery do?
aims to replace the stomach in the abdomen and strengthen the diaphragm surrounding the hiatus
what do pharyngeal constrictors do?
they contract sequentially to push food down into the oesophagus
what does the stomach do?
acts as a food blender and reservoir, the most dilated part of the GI tract
why is there a low pH environment in the stomach? what provides these conditions?
aids digestion and provides an important physiological barrier against pathogens
provided by gastric secretions
where does the stomach lie?
just below the diaphragm, to the left of the abdominal cavity
the oesophagus empties into the stomach, which opens into the duodenum at the pyloric office
what do the fundus and body of the stomach secrete?
acid from parietal cells and pepsin precursor, pepsinogen, from peptic (or chief cells)
what does the antrum of the stomach produce?
endocrine secretions which control gastric secretion itself as well as gastric motility. these are: gastrin, histamine, somatostatin
describe the secretions of the stomach mucosa
highly acidic and contain factors that influence digestion
what does the oblique layer of smooth muscle of the stomach do?
allows distension (swelling) of the stomach
how is the lining of the stomach protected from the low pH?
the epithelium consists of columnar epithelia - tight junctions here prevent damage to underlying tissues from acid secretions
constitutive secretion of the alkaline mucus layer by mucous cells in the gastric mucosa provides a mechanical barrier to acid secretions and pathogens
what are the 3 parts of the small intestine?
duodenum, jejunum, ileum
what are the 4 parts of the duodenum and where does each travel?
- superior part - travels slightly superiorly and posteriorly at the side of the vertebral column (at the level of L1)
- descending part - travels inferiorly, over part of the kidney to L3
- horizontal part - travels medially to the left, crossing the aorta at L3
- ascending part - travels superiorly on the left of the aorta to L2 where it becomes the jejunum
where does the descending duodenum receive further digestive secretions from?
from the liver and gallbladder via the common bile duct and the pancreas via the main pancreatic duct
where does the jejunum begin?
at the duodenojejunal junction, to the left of the L2 vertebrae
where does the jejunum become the ileum?
at an anatomically indistinct junction
how are the jejunum and ileum anchored to the posterior body wall? what is their function?
by the mesentery. they are the primary site of nutrient absorption
what is the main function of the large intestine?
the absorption of ions and water. some nutrients are absorbed, especially in the proximal colon.
when do intestinal contents become a more solid mass?
as they enter the large bowel they are liquid, absorption of water in the colon produces a more solid mass
what do the muscles of the colon do?
act to move the intestinal contents towards the anus
what are the 3 bands of longitudinal smooth muscle found in the large intestine known as?
taeniae coli
where is the caecum of the large intestine? what is it and what does it contain?
begins at the ileocaecal junction in the right inferior quadrant.
it is a pouch of the large intestine and contains the vermiform appendix
what are the 4 parts of the colon and where does each travel?
- ascending colon - travels superiorly from right lower to right upper quadrant. bends left 90 degrees (right colic flexure) into the transverse colon
- transverse colon travels from right upper to left upper quadrant, forms a 90 degree bend (left colic flexure) into the descending colon
- descending colon travels from left upper quadrant to the left lower quadrant, becomes the sigmoid colon
- sigmoid colon, s-shaped, connects the descending colon to the rectum
where do the rectum and anal canal sit?
within the pelvic cavity posterior to the vagina/prostate
what junction is the vermiform appendix close to?
iliocaecal junction
at which vertebral level does the rectum begin?
S3
where is the liver found?
in the right upper quadrant of the abdomen, directly beneath the diaphragm
name some functions of the liver
-glucose storage
-protein, lipoprotein and cholesterol synthesis
-digestion - production of bile and bile salts
-storage of fat soluble vitamins
-toxin and drug, metabolism and excretion
what are bile salts?
detergents that emulsify fats in the intestines, increasing their surface area and facilitating their absorption
what vitamins are fat soluble?
A,D,E and K
what are the 4 lobes of the liver?
right, left, caudate, quadrate
what is the gallbladder?
a fluid-filled sac that stores and concentrates bile
it is made up of a fundus, body and neck. the neck leads to the cystic duct which transports bile to and from the gallbladder
what does the hepatobiliary system do?
looks at the production and flow of bile
what are the functions of bile?
-its bicarbonate content produces an alkaline pH that serves to decrease the acidity of gastric contents released from the stomach, thus preventing damage to the intestines
-decreased pH also facilitates the emulsion of fats from the stomach by salts contained in the bile. the emulsification of fats by bile salts increases the surface area of these insoluble nutrients and increases the rate of their digestion
what produces bile and where is it stored and concentrated?
produced by hepatocytes, stored and concentrated in the gallbladder until it is needed (i.e. when you eat a high-fat meal)
what are hepatocytes and how are they arranged?
liver cells - epithelial cells that are arranged to form a 3D lattice.
sinusoids run between each layer of hepatocytes in the liver, which allow close contact between the hepatocytes and the portal blood supply.
what are canaliculi?
small channels between the hepatocytes that remove the products of hepatocyte function.
they drain into bile ducts.
how does bile drain from the liver?
via the right and left hepatic ducts which join to form the common hepatic duct
where can bile from the common hepatic duct go?
can travel up the cystic duct to be stored in the gallbladder of carry on to the descending duodenum via the common bile duct.
what does the presence of food in the duodenum do?
stimulated the gallbladder to contract. bile travels down the cystic duct to the common bile duct and then to the duodenum - all of thee ducts combine to form the biliary tract
where does the main pancreatic duct join the common bile duct?
at the hepatopancreatic ampulla which opens into the duodenum
where does the pancreas lie?
horizontally across the posterior abdominal wall, posteriorly to the stomach
what are the 5 regions of the pancreas?
uncinate process, head, neck, body, and tail
what do exocrine tissues of the pancreas release?
pancreatic juice, a major digestive secretion containing digestive enzymes
what are the 2 components of pancreatic juics?
- alkaline secretion - high bicarbonate and low enzyme content. helps neutralise the acidity of gastric contents
- enzyme rich secretion - contains major enzymes involves in digestion. secreted as pre-enzymes that are activated int he gut so that they don’t digest the pancreas
what does sympathetic/parasympathetic stimulation of the pancreas do?
sympathetic - decreases secretions
parasympathetic - increases secretions
how is pancreatic juice transported to the duodenum?
via the main pancreatic duct. their entrance to the descending duodenum is controlled by the Hepatopancreatic Sphincter (of Oddi)
what is the peritoneum?
a layer of connective tissue that covers the walls and all of the viscera of the abdomen
what is the greater omentum?
the first structure visible if you were to remove the anterior abdominal wall
‘flap’/reflection of the peritoneum that covers the abdominal contents
what is the mesentery?
a major reflection of the peritoneum from the posterior abdominal wall surrounding the majority of the small intestines
what is the peritoneal cavity?
potential space continuous around all the abdominal organs
what does the peritoneum do?
anchors floppy abdominal organs to the posterior body wall so they don’t squash each other or move around too much when we jump.
carries the blood supply to the organs
describe the thickness of the different types of epithelium
-simple: 1 layer
-stratified: >1 layer
-pseudostratified: 1 layer that pretends to be 2
-squamous: flat cells
-columnar: column-like cells
what are the 3 components of mucosa?
- epithelium - forms a selective barrier that digested molecules must cross, may contain mucous secreting goblet cells and endocrine cells secreting digestive hormones
- lamina propria - layer of loose connective tissue, good blood supply, often contains lymphatics and numerous WBCs, first immunological barrier to pathogens in the GI system
- muscularis mucosa - consists of a thin layer of smooth muscle cells causing localised contractions in the mucosa
what is the submucosa?
a layer of dense connective tissue that contains the submucosal plexus (controls secretion and blood flow, and relays info from gut epithelium and stretch receptors in the wall)
what is the enteric nervous system?
a branch of the autonomic nervous system, but can operate independently of the CNS
consists mostly of two major plexi within the GI wall - the myenteric and submucosal plexi
what layers does the GI wall consist of?
2 layers of smooth muscle - an inner circular and outer longitudinal layer, peristalsis occurs in these layers
what is the myenteric plexus?
the second plexus of the enteric nervous system, lies between the layers of smooth muscle.
mainly involved with the control of GI motility
what is the serosa?
a layer of epithelium forming part of the peritoneum
what does the capillary network and the blind-ended lymph vessel of the capillary network do?
capillary network - transports absorbed amino acids and monosaccharides
lymph vessel - transports absorbed fat
what are the 4 specialised cells present within the epithelium of the villi?
- absorptive cells - secrete digestive enzymes and absorb nutrients.
- goblet cells - produce mucus that lubricates and protects the epithelium from mechanical damage
-these ascend villi from the base of the crypts - granular cells - secrete enzymes and protect epithelium from bacteria
- APUD cells - produce endocrine secretions that regulate secretion and motility of the GI tract and associated glands
-remain at the base of the crypts
how does the microanatomy of the large intestine compare to the small intestine?
-epithelium is not villous as in the small intestines, contains crypts but not villi
-goblet and absorptive cells are present, APUD cells are present but sparse
-goblet cells are more numerous here than in the small intestine, so amount of mucus is greater
-lamina propria, muscularis mucosa and submucosa are similar in the large and small intestines
what are the 3 branches supplying the GI tract and where are they?
-the coeliac trunk is the most superior, arising at the T12 vertebral level
-the superior mesenteric artery leaves the abdominal aorta at the lower border of L1, inferior to the coeliac trunk
-the inferior mesenteric artery is the most inferior of the 3, leaving the abdominal aorta at L3
what is the female reproductive system designed for?
what does it consist of and where do these sit?
designed primarily for conceiving and developing the offspring
consists of the vagina, the uterus, the fallopian tubes and the ovaries. they sit in the lesser pelvis
what is the male reproductive system designed for? what does it consist of and where do these sit?
designed for the introduction of the male sex cell into the female reproductive system
organs consist of: testes, epididymides, ductus deferentes, seminal vesicles, ejaculatory ducts, prostate, bulbourethral glands.
the testes sit outside the body in the scrotum, the other components sit within the lesser pelvis
what do the kidneys do?
-excrete most of the wate products of metabolism
-filter the blood, removing waste products and producing urine
-control water volume and ion concentrations and maintain the acid/base balance of the blood
what is the purpose of the urinary system? what does it consist of and where do they sit?
purpose - the excretion of urea and other toxins along with maintenance of blood volume and osmolarity
consists of paired kidneys and ureters, a muscular urinary bladder and urethra. these sit in the abdomen, pelvic cavity and extend into the perineum/external genitalia
what do nephrons in the cortex and medulla do?
filter wate products from the blood, forming urine
describe the pathway of urine from the kidney
the pyramids of the cortex drain urine into the minor calyces.
2-3 minor calyces drain into each of the 2-3 major calyces.
the major calyces drain into the renal pelvis, which empties through the ureters towards the bladder
what is the hilum
the point where structures enter or exit the kidney. these include the renal vein, renal artery, ureter, lymphatics and sympathetics
describe the parts of a nephron and what each does
-blood entering the kidneys for filtration passes through knots of capillaries called glomeruli - contained within the Bowman’s capsule where all constituents of plasma are filtered out of the blood (not proteins >64KDa). in particular water and waste products
-in the PCT, glucose and ions are reabsorbed
-in the Loop of Henle, water is reabsorbed
-in the DCT, waste products not filtered out in the capsule are secreted into the lumen of the nephron
describe what happens in the collecting duct
water and ions are reabsorbed into the blood. this controls the volume of urine produced.
the action of antidiuretic hormone on the collecting duct makes it more water permeable, allowing reabsorption of water
describe the blood supply of the kidney
the renal arteries are 2 large branches of the abdominal aorta that arise just below the level of L1. these divide into afferent arterioles which feed into the glomeruli
efferent arterioles run from the glomeruli and wrap around the nephron
around the loop of Henle these are called the vasa recta, which drain into the renal veins which empty into the inferior vena cava
describe the location of the kidneys
-lie behind the peritoneum on the posterior body wall
-one on each side of the vertebral column at the level of T12 to L3 vertebrae
-partially protected by ribs 11-12
-right kidney lies lower than the left due to the large right lobe of the liver
-related inferiorly to the diaphragm which also acts to separate them from the pleural cavities and the 12th ribs
which hormones are secreted from the adrenal cortex and medula?
cortex - cortisol, aldosterone, sec hormones
medula - adrenaline, noradrenaline
what are kidney stones?
crystal aggregations that form in the collecting ducts of the kidneys and may be deposited anywhere from the kidney to the urethra
may be caused by dehydration, diet and have numerous predisposing illnesses
at which regions do the ureters narrow?
- the junction between the ureters and the renal pelvis
- where the ureters cross the brim of the pelvic bone
- in the entrance of the ureters into the bladder
describe glomeruli
knots of capillaries within the cortex of the kidneys. each glomeruli sits in a capsule of connective tissue (Bowman’s capsule)
what is the minimum amount of urine the bladder must contain?
approx. 50ml
describe the walls of the bladder
3 layers of smooth muscle: an internal, middle and external - form the detrusor muscle
the fibres of the internal and external layers are in a similar longitudinal directional alignment. the middle layer is aligned in a roughly circular direction.
bladder musculature is a distorted continuation of the three layers of spiral smooth muscle that surround the ureters
describe the epithelium lining the system from the renal pelvis to the urethra
a specialised epithelium, transitional epithelium or urothelium
these can stretch, shift over one another and flatten. the epithelium of a distended bladder may appear only 2-3 cells thick, whereas an empty bladder is usually 5-6 cells thick.
non-distended urothelium has a cuboidal base layer, polygonal celled middle layers and tall columnar cells in the surface layer
describe where the bladder sits
adults, empty - sits anteriorly in the lesser pelvis inferior to the peritoneum.
adults, full - extends superiorly in the extraperitoneal fat of the anterior body wall
> 6yo - sits in the abdomen, even when empty
what is the trigone of the bladder?
a smooth triangular area on the posterior wall between the ureteric orifices. contrasts to the rugae (ridges) that line the majority of the empty bladder, flattening our as the bladder fills
what is the internal urethral sphincter?
only found in males, prevents ejaculatory reflux of semen into the bladder. controlled by autonomic innervation
what is the external urethral sphincter?
a skeletal muscle sphincter, under voluntary control
what are the 4 parts of the male urethra?
- pre-prostatic (intramural)
- prostatic
- membranous (intermediate)
- penile (spongy)
why is the incidence of UTIs higher in females than in males?
due to the shorter length of the female urethra and its proximity to the anus
how many ovaries are there in the female pelvis?
2 - left and right. almond shape and sized
where are ovaries developed and where do they lie?
develop high in posterior abdominal wall then descend before birth, bringing vessels and nerves with them.
they stop descending at the lateral wall of pelvic cavity and lie just inferior to pelvic inlet within the peritoneum
what do the ovaries do?
the site of ovum release and the production and release of the female sex hormones oestrogen and progesterone
where does the uterus sit?
in the lesser pelvis, the body usually lies on the superior surface of the empty urinary bladder.
it is normally anteverted, tipped anteriorly relative to the vagina and anteflexed, the body is flexed anteriorly relative to the cervix
what is the size of the uterus in a non-pregnant female?
7.5cm long, 5cm broad, 2cm thick. it can enlarge considerably during pregnancy
what are the 2 parts the uterus can be divided into?
- the body, the upper 2/3 of the uterus, 2 divisions: fundus - rounded ‘roof’, isthmus - narrow part
- cervix, the canal that projects into the vagina
what are the 3 layers of the wall of the body of the uterus?
- perimetrium - outer, thin layer of connective tissue
- myometrium - middle, smooth muscle that provides the contractile strength required during labour and menstruation
- endometrium - mucous lining that proliferates and degenerates in the menstrual cycle. during pregnancy the proliferated endometrium provides the site for implantation of the blastocyte
what is an ectopic pregnancy?
when implantation occurs somewhere other than the uterus, e.g. in the uterine tubes, ovaries etc.
where does the cervical canal run?
between the external os (inferior opening of the vagina) and the internal os (superior opening)
what does the cervical canal guide?
-sperm
-a baby
-cervical mucus
-menstrual blood and uterine tissue
-contraceptive methods act on the cervix
describe the epithelium of the cervical canal in the adult female
squamous at the internal os but becomes stratified at the external os to protect itself from the acidic environment of the vagina. this area of changed tissue is predisposed to cancerous changes
what is the vagina?
a musculo-membranous tube that connects the uterus to the external genitalia
what is a speculum used for?
dilating the vaginal canal, particularly during a cervical screening
what is the vulva made up of?
-external part of clitoris (glans)
-labia majora and minora
-various skin folds
-vestibule
what is the clitoris made up of?
erectile tissue and is formed of a body and glans, formed respectively from the crura of the clitoris and the bulbs of the vestibule.
only the glans clitoris is part of the external genitalia of the female; whereas, the other aspects of the clitoris sit deep within the perineum
what is a prepuce?
where the labia minora bisect and envelop the clitoris anteriorly - a homologue to the foreskin of the penis
how are the labia majora and minora distinguished?
labia majora - hair-lined skin folds
labia minora - hairless skin folds
minora sit medial to the majora
what is the vestibule of the vagina?
a depression between the labia minora. it is where the vaginal and urethral openings are located
what are the testes? what is their function?
firm, mobile, ovoid organs that are suspended in the scrotum by the spermatic cord
their function is to produce sperm and hormones, principally testosterone
what is the tunica albuginea?
covers the testes
describe how the testes are divided internally
each testes is divided into lobules by fibrous septa. coiled seminiferous tubules lie within the lobules. the tubules open into a network of channels called the rete testis. efferent ductules join the rete testes to the epididymis
what is the epididymis?
a long coiled tube that lies posterior to the testes, so tightly compacted that it appears solid.
how does the height of epithelial cells differ from the head of the epididymus at the superior head of the testis to the tail of the epididymis?
it decreases
what does the length of the epididymis do?
acts as storage and a maturation site for spermatazoa
what is the tunica vaginalis?
a double layer of connective tissue - a closed peritoneal sac.
what are the two layers of the tunica vaginalis andwhere are they?
-the visceral layer is closely applied to the testis, epididymis, and the inferior part of the ductus deferens
-the parietal layer extends further superiorly than the visceral layer and reaches into the distal spermatic cord
a small amount of fluid in the cavity between the two layers reduces friction and allows the testis to move freely
what does the spermatic cord do?
suspends the testis in the scrotum and contains structures running to and from the testis
what is the spermatic cord covered by?
the internal spermatic fascia, the cremasteric fascia and the external spermatic fascia.
these are derived from the layers of the abdominal wall as the testis passes through them as it descends into the scrotum in early childhood.
what does the spermati ccord consist of?
-the ductus deferens, carrying sperm
-blood vessels, supplying and draining testicular blood
-sympathetic and somatic nerves
-lymphatic vessels
what is the ductus deferens?
the continuation of the epididymis.
it ascends in the spermatic cord into the abdominal cavity, loops over the ureter on its respective side and descends posterior to the urinary bladder.
it combines with the duct of the seminal vesicle to form the ejaculatory duct
what is the main function of the accessory structures of the male reproductive tract?
to produce seminal fluid/semen. seminal fluid help sperm survive in the female reproductive tract. sperm is only 1% of the volume of seminal fluid
what do the seminal vessels secrete?
components of seminal fluid that mixes with the sperm as they pass into the ejaculatory ducts. they produce an alkaline fluid that protects sperm from the acidic nature of the urethra and female reproductive tract.
the seminal vesicles produce 60-70% of the final volume of seminal fluid.
they do not store sperm
how long are the seminal vesicles?
about 5cm long, they lie posteroinferior to the bladder, anterior to the rectum and inferior to the peritoneum.
how big are the ejaculatory ducts and where are they?
short tubes (2.5cm long)
arise from the combination of the ductus deferens with the ducts of the seminal vesicles.
they arise near the neck of the bladder and pass through the posterior part of the prostate.
they open into the urethra within the prostate, known as the prostatic urethra
how big is the prostate gland?
3 cm long, the largest accessory gland of the male reproductive system.
base of the prostate is closely related to the neck of the bladder. the anterior surface is deep to the pubic symphysis. the posterior surface is closely related to the rectum. the prostatic ducts open into the prostatic urethra.
describe the consistency and function of the prostatic fluid?
thin and milky and supplies 20-25% of the volume of semen. the secretions aid mobility of the sperm
where do the bulbourethral glands lie?
lie immediately inferior to the prostate gland at the level of the membranous urethra.
their ducts open into the penile/spongy urethra soon after the external urethral sphincter
describe the secretion from the bulbourethral glands
transparent and viscous. it adds some volume to semen. these glands produce what is known as ‘pre-ejaculate’ which flushes out the urethra and acts as a lubricant
what is the erectile tissue found between the penis?
the corpus spongiosum and corpora cavenosa.
the corpus spongiosum is a spongy tissue; this is where the penile/spongy urethra travels through. the sponginess of the tissue avoids occlusion of the urethra during an erection.
what is the penis made up of?
a root, body and glans. the root is mostly made up of the bulb of the penis and this sits deep within the perineum
what is the frenulum?
connects the skin of the body of the penis to the glans penis
