Theme 1 : Anatomy part 2 Flashcards
What is the lymphatic system?
Morphologic counterpart of the immune system and monitors the body’s surfaces and internal fluid compartments and returns it to the venous system
What are the functions of the lymphatic system?
Fluid recovery
= Picks up excess tissue fluid (ECF and proteins) and returns into the blood stream
Immunity
= Filtration of fluids and Immune cells
Lipid absorption
= Lacteals absorb dietary lipids
What are the 4 main components of the lymphatic system?
Lymph
Lymphatic vessels
Lymphoid organs
Lymphocytes
What enters the lymphatic vessels?
Tissue fluid (interstitial fluid)
What is the tissue fluid comprised of?
Contains white blood cells.
Has a relatively high protein concentration
What is the normal lymphatic flow?
2L to 3L per day
What are the 2 components that fluids are made out of?
Intracellular fluid (ICF) 2/3
Extracellular fluid (ECF) 1/3
What is extracellular fluid comprised of?
Interstitial fluid 80%
Plasma 20%
How is the lymph formed?
when the interstitial fluid is collected through tiny lymph capillaries (not reabsorbed by the venous end)
Describe the lymph flow
Begins in the interstitial space (interstitial fluid)
Lymphatic plexuses
Lymphatic vessels
Lymph nodes
Lymphatic vessels
Lymphatic trunks
Lymphatic ducts
Venous circulation
Blood capillaries (blood)
Formation of lymph in interstitial space (cycle)
Describe what the Lymphatic Plexuses is structured like
Highly attenuated (thin) endothelium with valve-like flaps and no basement membrane. – one way valves
Where can I find Lymphatic Plexuses?
Originate blindly (blind end) in the extracellular spaces tethered to surrounding tissue
what areLymphatic Plexuses?
lymphatic capillaries that form large networks of channels
What are lacteals?
special types of lymphatic capillaries in the small intestine
What do lacteals pick up?
interstitial fluid, dietary lipids and lipid-soluble vitamins.
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What do lymphatic vessels do?
Lymphatic vessels drain lymph from the lymphatic capillaries (aka plexuses)
What are the 3 layers of the lymphatics vessels?
Endothelium
Tunica media
Tunica adventitia
How do lymphatic vessels differ from veins?
They are thinner than veins and have more numerous valves than in veins
What are interposed at the intervals of lymphatic vessels?
Lymph nodes
What is the difference between afferent and efferent lymphatic vessels?
Afferent lymph vessels bring unfiltered fluids from the body into the lymph node where they are filtered.
Efferent vessels, meaning away from, carry the clean fluid away and back to the bloodstream where it helps form plasma.
Describe the Superficial lymphatic vessels
Converges towards and follows venous drainage and eventually drains into deep lymphatic vessels
Describe the Deep lymphatic vessels
Accompany arteries and Receives drainage of internal organs
What are the similarities between superficial and deep lymphatic vessels?
Both traverse lymph nodes
Become larger and enter lymphatic trunks
What are the lymphatic trunks?
large collecting vessels that receive lymph from multiple lymphatic vessels.
Also known as collecting vessels
What does the union of the lymphatic trunks form?
either the right lymphatic duct or the thoracic duct
What are the 9 main lymphatic trunks we must know about?
The right and left…
Jugular trunk
Subclavian trunk
Bronchomediastinal trunk
Lumbar trunk
The intestinal trunk
What are lymphatic ducts?
collecting ducts that empty lymph fluid into the venous system
What does the right lumphatic duct do?
Drains lymph from the body’s right upper quadrant
(right side of the head, neck, and thorax plus the right upper limb)
To the junction of the right internal jugular and right subclavian vein
What does the thoracic duct do?
Drains lymph from the remainder of the body into the left internal jugular and left subclavian vein
What is the Cisterna chyli?
a dilated collecting sac formed by the merging of the lymphatic trunks draining the lower half of the body (originates)
What is the thoracic duct?
Largest lymphatic channel with numerous valves
Where does the thoracic duct originate?
cisterna chyli
Where does the thoracic duct ascend through?
aortic hiatus in the diaphragm
Where does the thoracic duct lie?
on the anterior surface of the vertebral bodies
What is the mediastinum?
A space in your chest that holds your heart and other important structures.
It’s the middle compartment within your thoracic cavity, nestled between your lungs.
What is the posterior mediastinum comprised of?
Left – thoracic aorta
Right – azygous vein
Anteriorly – oesophagus
Posteriorly – vertebral bodies
What are the primary lymphatic organs?
The bone marrow and the Thymus
Where do lymphocytes travel through?
enter the blood or lymphatic vessels to colonise secondary lymphatic organs and tissues, where they undergo the final stages of antigen-dependent activation
What are the secondary lymphatic organs?
Lymph nodes
Aggregation (cluster) of lymphatic nodules
Spleen
What are the Supporting elements of the lymph node?
Capsule – dense Connective tissue
Trabeculae – dense Connective tissue
Reticular tissue:
Reticular cells and fibres
Dendritic cells
Macrophages
What is the general architecture of the lymph node?
Cortex
Superficial – B cells & macrophages
Deep (paracortex) – T cells
Medulla
Lymph nodes filter lymph along the pathway of…
lymphatic vessels and initiate adaptive immune responses to antigens
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Describe the Superficial lymph nodes
Relative to the deep fascia
They run alongside superficial veins and drain the lymph to the deep lymph node
Describe the deep lymph nodes
closely located to vasculature and viscera
What does the Diffuse lymphatic tissue do?
Guard the body against pathogenic substances in the GI tract (GALT), respiratory system (BALT), and genitourinary tract (MALT).
Why is the diffuse lymphatic tissue important when you are sick?
Site for the initial immune response.
What is the diffuse lymphatic tissue Characterised by?
B cells and subsequent development oflymphatic nodules
What are Lymphatic nodules?
Dense oval masses of lymphocytes and macrophages - congregate in response to pathogens or are a permanent feature.
Where are lymphatic nodules found?
Are found in the GALT (tonsils, Peyer’s patches, solitary lymph nodules, and vermiform appendix), BALT (bronchial tree), and MALT (mucosa of urogenital system).
What are the 4 functions of the spleen?
Filters blood
Reacts immunologically to blood borne antigens
Removes senescent and defective erythrocytes
Recycles iron from degraded haemoglobin
What is the Largest lymphatic organ and is located in the abdominal cavity?
Spleen
What are the two major functional zones of the spleen?
White pulp – consists of lymphatic tissue
Red pulp - large numbers of erythrocytes, macrophages, and other immune cells.
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What is the mesothelium?
Layer with basement membrane covering internal surface of the thoracic cage and some organs
What is atherosclerosis?
thickening or hardening of the arteries. It is caused by a buildup of plaque in the inner lining of an artery.
Why is Atherosclerosis is not the same as arteriosclerosis?
Atherosclerosis happens when your arteries become narrow due to a buildup of plaque. It’s caused by inflammation in the arteries.
Atherosclerosis is a type of arteriosclerosis, a condition in which your arteries become stiff. Arteriosclerosis is caused by elastin fibers in your arteries losing elasticity.
What are the consequences of an acute thrombus?
Occlusion of the vessel and blood flow reduces or stops
Ischaemia (lack of blood flow) in the downstream areas
What do the consequences of an acute thrombus lead to?
Hypoxia (lack of oxygen)
Accumulation of harmful metabolites
Reversible cell injury
Irreversible cell injury
Cell death
What happens at 12 hours of someone with acute myocardial infarction?
coagulative myocardial necrosis?
When do eosinophils and neutrophils usually come in coagulative myocardial necrosis?
18 hours
In coagulative mycardial necrosis, which day does nuclei disapear in the
When is there no nuclei left in coagulative myocardial necrosis?
cardiac muscles
day 2
When do neutrophils flood in, in coagulative myocardial necrosis?
day 2 and 3
What happens from day 5 to someone with coagulative myocardial necrosis?
Macrophages causes Vasodilation (angiogenesis) and cause Early formation of granulation tissue
When does early fibrosis occur in coagulative myocardial necrosis?
Day 7 to 14
What can coagulative myocardial necrosis lead to?
myocardial scar but risk of myocardial rupture because granulation tissue is weak due to no collagen tissue
How many neurons are there?
~86 billion in human brain
What do neuroglia do?
- Support neurons
What is the soma?
The cell body of a neuron that synthesises proteins (e.g., ion channels and lots of ion channels)
Why is the soma important?
Important for cellular metabolism (lots of mitochondria)
What do dendrites do?
Receives inputs
Convey information towards the soma
Large surface area (spines) for synapse formation
What is the axon hillock?
This is the Origin of the axon
This is where an action potential would originate – where u can find sodium channels
What is a unipolar neuron (pseudounipolar neuron)?
Neurons with only one axon e.g. primary sensory neurons
Where are cell bodies primarily at?
Dorsal root ganglia
- found close to intervertebral foramen
What is a Bipolar neuron?
One axon and one dendrite
Give an example of a bipolar neuron and where is it found?
Specialized sensory neurons
Found in the retina, olfactory epithelia
What is a multipolar neuron?
Neuron with One axon and multiple dendrites
Give examples of multipolar neurons
Majority of neurons in brain
Motor neurons
Autonomic ganglia
What can myelinated axons enable? (1-10µm diameter)
saltatory conduction
Action potential passes from node to node
= Very rapid (up to 120m/s)
What fibre is unmyelinated? (<1µm diameter) How slow is it?
Pain fibre (nociceptor)
Very slow (<1.5m/s)
What are the 2 directions of conduction?
Afferent – Axons that carry information to central nervous system
Efferent – Axons that carry information away from central nervous system
What are the 3 types of neuroglia?
Astrocyte
Oligodendrocyte
Microglia
What are the 7 functions of astrocytes
Provide structural support
Scaffold for neurons during development
Supply nutrients (glucose and lactate)
Maintain ionic environment (remove K+)
Neurotransmitter uptake
Repair of the nervous system (form glial scar)
Form barrier around vessels
What do oligodendrocytes do?
One oligodendrocyte myelinates multiple axons
What are oligodendrocytes?
Tumour/bulbous-looking cells that ‘grouped’ together the axons
What are microglia?
They are immune cells that:
Secrete cytokines
Phagocytic (like macrophages)
Cytotoxic (releasing H2O2)
What is the function of microglia?
Promote repair - clear debris
What are the Neuroglia of the peripheral nervous system?
Schwann cells
What are the Schwann cells’ functions?
One Schwann cell myelinates one axon via spiral wrapping with layers of myelin
Secrete cytokines, and are phagocytic
Provide substrate for axon to grow along in regeneration
What is the communication of the Peripheral nervous system between?
the CNS and periphery
What is the most superior part of the brain?
dorsal surface
What is the forward part of the brain?
Rostral
What is the backward part of the brain?
Caudal
What are the 3 different regions of the brain?
forebrain, midbrain and hindbrain
What is grey matter?
Neuronal cell bodies, synapses, dendrites
What is white matter?
Myelinated axons
What are the 3 main parts of the forebrain?
Cerebral hemispheres, thalamus, hypothalamus
Describe the cerebral hemispheres’ composition
Divided into lobes
The outer grey matter is the cerebral cortex
What are the functions of the Cerebral hemispheres?
Processing motor and sensory information - Visual, somatosensory, olfactory, auditory, gustatory
Cognition - Language, intelligence
How many neurons are in the cerebral hemisphere? And how thick is it?
10-20 billion neurons / 2.5 mm thick
What is the thalamus?
Centrally located - the relay centre of the brain
Where does sensory information pass in the forebrain?
Beforemeeting the cortex
via the thalamus before reaching the cortex
Where is the hypothalamus?
In the forebrain and sits below the thalamus
What does the hypothalamus control?
Autonomic nervous system
Endocrine system
What is the brainstem formed by?
the midbrain and hindbrain
Why is the brainstem functionally very important?
Connects cortex to spinal cord
Controls respiration and the cardiovascular systems
Keeps us alive – keeping you breathing and beating
What does the cerebellum coordinate?
muscular activity
Where is the spinal cord?
Extends from atlas (C1) to first lumbar vertebra (L1)
Sits within vertebral canal
What surrounds the spinal chord between the vertebral body and spinous process?
Vertebral canal
What is the function of the spinal cord?
Conveys information = Brain to PNS (motor)
PNS to brain (sensory)
Involved in reflexes = Local circuits
What is the spinal cord segmentally organised into?
Segments that correspond to where the spinal nerves that extend from the spinal cord exit the vertebral column
Cervical - Upper limb/head/neck
Thoracic - Thorax/abdomen
Lumbar - Pelvis/lower limb
Sacral - Lower limb
What is the spinal cord composed of?
an inner core of grey matter (Neuronal cell bodies) and outer white matter (Myelinated axons)
In the spinal cord, how are the 2 types of axons (directional) enter via peripheral nerves?
Efferent=
Afferent =
Efferent axons exit ventrally
Afferent axons enter dorsally
What does the peripheral nervous system connects the central nervous system with?
periphery
What does the peripheral nervous system supply nerves to?
muscles, glands, skin, vessels, viscera
What does the peripheral nerves supply information through?
motor, sensory and autonomic axons
How are axons organised in?
Bundles
in bundles (fascicles)
Epineurium
Perineurium
Endometrium
What are the 2 components of the peripheral nervous system?
- Somatic (voluntary) component
(Supply skeletal muscles, sensory from skin, muscles, joints)
- Autonomic (involuntary) component
(Supply viscera, smooth muscle, glands and vessels)
Not always anatomically separate - peripheral nerves can contain axons from both
Where do all peripheral nerves arise from? and as what (2)
Brain/brainstem as cranial nerves
Spinal cord as spinal nerves
What do the spinal nerves provide in the somatic system?
Motor (somatic motor) and sensory (somatosensory) supply to whole body, except head and parts of neck
What do the spinal nerves provide in the autonomic system?
Sympathetic supply to whole body
What do the efferent spinal nerves connect to?
Ventral root
What do the afferent spinal nerves connect to?
dorsal root
What do the efferent nerve fibres contain?
somatic motor and sympathetic axons
What do the afferent nerve fibres contain?
somatosensory axons
What are the dorsal root ganglia?
Cluster of cell bodies
Where do nerve roots sit within?
vertebral canal
What does the much larger Ventral primary rami supply?
rest of the body, except the head/parts of the neck
e.g. skin and musculoskeletal system
What does the Segmental organization of spinal nerves results in?
dermatomes and myotomes
What is a dermatome?
An individual strip of skin innervated by a single spinal nerve (primary ramus)
What is a myotome?
An individual muscle group innervated by a single spinal nerve (primary ramus)
Where do Dermatomes and myotomes develop from?
Somites
What are somites?
paired blocks of paraxial mesoderm that form horizontal bands
What does one pair of spinal nerves (formed from ectoderm) grow into?
One pair of somites
What does Loss/altered sensation/pain from dermatome indicate?
injury to spinal cord, nerve root or spinal nerve
What can visceral (organ) pain can be referred to skin (dermatomes) as?
cutaneous pain
E.g., Diaphragm irritation referred to shoulder (C3-C5 dermatomes)
Where are myotomes conserved at?
Thorax
What are Intercostal muscles supplied by?
intercostal nerves (T1-T11)
What is Each muscle block is innervated by?
an individual spinal nerve
Why are Myotomes are more complicated in the limbs ?
More than one spinal nerve is innervating the large muscle groups
How many cervical spinal nerves? But what’s so special about the least nerve pair?
8, C1-7 exit above the vertebrae, C8 and below exit below
How many thoracic spinal nerves?
12
How many lumbar spinal nerves?
5
How many sacral spinal nerves? How do they exit?
5 = between respective vertebrae
What is the last pair of spinal nerves?
Coccygeal
Where can you find the nerve roots?
Within vertebral canal
What are the 2 nerve roots spinal nerves connect to? And what kind of nerves
Ventral root – Efferent (contain somatic motor and sympathetic axons)
Dorsal root – Afferent (contain somatosensory axons)
What is Between dorsal and spinal nerve?
Dorsal root ganglia = cluster of cell bodies
What do mixed nerves contain?
somatic motor, somatosensory and sympathetic axons
What do the spinal nerves divide into (mixed nerves)
- Dorsal/posterior primary rami
- Ventral/anterior primary rami (ramus) (thicker)
What does the dorsal primary rami supply?
skin over paravertebral gutter that cover the erector spinae muscle, erector spinae muscles (3 strips of muscle that go down the spine, like the lines of the vagina but to the xiphoid process), facet joints of vertebral column
What does the ventral primary rami supply?
rest of the body, except head/parts of neck
What can ventral primary rami form?
intercostal nerves and four nerve plexuses
What are nerve plexuses?
ventral primary rami merge to form peripheral nerves (e.g. median nerve)
What does Segmental organization of spinal nerves result in?
dermatomes and myotomes
What is a dermatome
An individual strip of skin innervated by a single spinal nerve (primary ramus)
What is important about a dermatome?
Loss/altered sensation/pain from dermatome indicates injury to spinal cord, nerve root or spinal nerve - Easy to determine location of injury from dermatomes
Also, visceral (organ) pain can be referred to skin (dermatomes) as cutaneous pain
What is a myotome, where r they conserved
An individual muscle group innervated by a single spinal nerve (primary ramus)
Myotomes are conserved in the thorax
Where do myotomes and dermatomes develop from?
somites in the embryo
What are somites?
Somites = paired blocks of paraxial mesoderm that form horizontal bands
segmental axial structures of vertebrate embryos that give rise to vertebral column, ribs, skeletal muscles, and subcutaneous tissues
What were the Intercostal nerves formed by?
ventral primary ramus of T1-T11 spinal nerves
What does Intercostal nerves innervates to?
T1-T11 dermatomes
What is the dermatome
umbilicus = 10th thoracic spinal nerve
What is the origin of the SYMPATHETIC
Thoracic/lumbar spinal cord
What is the origin of the PARASYMPATHETIC
Brainstem and Sacral spinal cord
Describe the 2 circuits of the autonomic ns
to effector organs and another target…
Preganglionic neuron (myelinated) -> synapse -> Autonomic ganglia -> Postganglionic neuron (Unmyelinated) -> EFFECTOR ORGAN (Smooth muscle, Cardiac muscle, Glands)
Exception= sympathetic supply to adrenal gland: preganglionic axons only (to adrenal medulla secreting Adrenalin/Noradrenalin into circulatory system)
in the sympathetic ns where can you find the preganglionic neurons?
thoracic/lumbar spinal cord
in the sympathetic ns where can you find the preganglionic neurons?
thoracic/lumbar spinal cord - body cells r here
Preganglionic axons exit via… to enter…
thoracic/lumbar spinal cord
ventral roots to enter the spinal nerves
After the spinal nerves, where do preganglionic enter?
sympathetic trunk (bulbus looking next to vertebrae on rib)
Describe the sympathetic trunk
- Interconnected paravertebral (autonomic) ganglia
- Extends length of vertebral column
(Spinal nerves T1-L2) From the sympathetic trunk, postganglionic axons enter…, without passing sympathetic trunk
Primary rami (dorsal/ventral) to musculoskeletal system = (Constriction of blood vessels, piloerection, sweating)
Branches to heart, lungs or head = (Increase cardiac output, bronchodilation, pupil dilation, sweating)
Some preganglionic axons pass through the sympathetic trunk and enter:
Splanchnic nerves to prevertebral ganglia into the abdomen – these Postganglionic axons innervate abdominal/pelvic organs (Inhibit peristalsis/gastric secretions, stimulates glucagon release)
What do Postganglionic axons innervate
In the abdomen
abdominal/pelvic organs (Inhibit peristalsis/gastric secretions, stimulates glucagon release)
What does sympathetic have that didn’t get parasympathetic one
Sweat glands, Hair follicles, Blood vessels
What does Preganglionic axons pass through ?
vagus nerve to thorax and abdomen
= innervating viscera
Preganglionic axons pass through… to…
Preganglionic axons pass through pelvic splanchnic nerves to innervate pelvic viscera = Bladder (Urination), Rectum (Defecation), Sexual function
