Anatomy and Physiology Flashcards
Where does the GI tract mainly lie on?
Viscera and pelvis
What’s another name for GI tract?
Alimentary canal
Describe the features of the alimentary tract:
- Alimentary canal
- Continuous hollow tuve
- Oesophagus to rectum approx 8 meters long
Function of the GI tract?
Breakdown the ingested food into small molecules which can be taken into body tissue
What are the two types of digestion?
- Chemical (secretion of enzymes = amylase CHO)
- Mechanical (motility = mixing and grinding, mastication - chewing)
What is absorption in the GI tract?
Movement of small molecules across the gut wall and into the circulation
Components of the small intestine
The first part is called the duodenum. The jejunum is in the middle and the ileum is at the end
Components of the large intestine
The appendix, cecum, colon, and rectum
What chemical factors are used to break down food into smaller molecules?
Digestive juices, such as stomach acid, bile, and enzymes
Does the small intestine have villi?
Yes, only the small intestine does
What is the autonomic nervous system?
The nerves that are involved in controlling any of our functions beyond our conscience and awareness
What two branches are there for autonomic nervous system?
Parasympathetic and sympathetic
Concerning digestion what are parasympathetic nerves involved in?
Stimulating digestion
Concerning digestion what are sympathetic nerves involved in?
Inhibiting digestion
What is peristalsis?
The movement of organ walls in the gastrointestinal tract. Peristalsis moves food and liquid through the gastrointestinal tract and mixes the contents within each organs
Role of the oesophagus
- Delivers food to the stomach
- Muscular tube = 25cm in length and 2cm in diameter
- Pharynx to the stomach
- Fast transport: peristalsis
Bolus direction is generally…
Mouth to anus = oral contraction to aboral relaxation
Role of the stomach
- Reservoir = stores food
- Begins digestion (mechanical and chemical)
- Satiety = stretching of the stomach wall produces a hormone that tells the brain you are starting to feel full
What substances are released during digestion?
- HCl
- Pepsinogen
- Mucus
- Gastrin (hormone)
Gastric juice - HCl
- Low pH = 2
- Prevents bacterial growth
- Catalyses cleavage of pepsinogens to pepsin
Gastric juice - pepsinogen
- Proenzyme (enzyme that is not yet activated) of pepsin
- Digestion of proteins into peptides
Gastric juice - mucus
- Protects the gut mucosa from the HCl
Gastric juice - gastrin
- Acid production (hormone that tells gastric gland to make gastrin)
Role of the small intestine
- Digestion, absorption of food into the blood and movement of material
- Most absorption takes place
- Absorptive epithelium
- Peristaltic movement
Features of the jejunum and ileum
- Highly coiled
- 4-6m long
- No definable junction
- Highly folded = plicae
- Large surface area
What does the duodenum receive?
Secretions from gall bladder (bile)
Role of the pancreas
- Exocrine gland 95%
Neutralise duodenal contents to prevent damage and pH fro enzymes
1. Water and ions
2. Bicarbonate
3. Enzymes = essential for normal digestion - Endocrine gland 5% = islets of Langerhans
- alpha cells = glucagon
- beta cells = insulin
What is chyme?
the pulpy acidic fluid which passes from the stomach to the small intestine, consisting of gastric juices and partly digested food
What is enzymatic digestion and where does it lake place?
Macromolecules digested into nutrients
- Duodenum and jejunum
What enzymes are released from the pancreas for enzymatic digestion?
- Peptidase
- Lipases
- Nucleases
- Amylases
- Lactases
What happens during absorption?
- Nutrients are taken into the bloodstream
- Large surface area = facilitates absorption
Role of the large intestine
- 1.5m length
- No nutrients in chyme
- Removes water, salts, sugars and vitamins vital for the body
- Slow movement of contents
Regions of the large intestine
1st cecum = compress material into fecal matter 2nd ascending colon (up) 3rd transverse colon (right to left) 4th descending colon (down) 5th Sigmoid colon 6th rectum
- No villi
- Tightly packed mucosa = goblet cells for mucus secretion
What is tenia coli in the large intestine?
3 bands longitudinal muscle
What is haustra in the large intestine?
Pockets undergoing segmentation
What is the vermiform appendix?
- ‘worm shaped’
- Finger like, blind-ended tube connected to the cecum
- Found in the lower right (iliac) quadrant of the abdomen
Role of the appendix
- Initially believed to be redundant
- Now believed to have an immune function
- Store cupboard for ‘good bacteria’ and lymphoid cells
- Site of appendicitis
Colon motility
- Segmented contraction = 99% of the time (materials are moved backwards and forwards)
- Retains material in the proximal colon (water reabsorption and fermentation)
- Mixing contents
Storage and defacation of waste
- Known as a gasto-colic response = 2-3 times a day
- Involves mass movement of materials into aboral end of colon ready for defecation
Where is waste stored?
Rectum
How many lobes does the liver have?
4
What is the largest organ in the body?
The liver
Liver - what type of blood is found in the hepatic artery?
Oxygenated
Liver - what type of blood is found in the portal vain?
Nutrient rich blood
Liver - what type of blood is found in the vein?
Deoxygenated
How is the liver divided?
- Into lobules
- Portal triad = bile duct, portal vein and hepatic artery
- Central canal = hepatic vein
What is a sinusoid?
Irregular tubular space for the passage of blood, taking the place of capillaries and venules in the liver
What are kupfer cells?
- Known as liver macrophages
- Found sitting in the sinusoid
- Collecting degenerating red blood cells, pigment granules and iron
Role of the liver
Metabolic powerhouse if the body with more than 500 vital functions.
- Regulation of nutrient levels in the blood (fats, aa and sugars)
- Synthesis of plasma proteins and cholesterol
- Detoxification of poisons
- Breakdown of haemoglobin
- Storage of nutrients and vitamins
- Production of bile
Role of the gall bladder
- Function of bile = emulsification of fat
- Concentration, storage and release of bile
Where is the gall bladder found
Located in the right hypochondriac region beneath the right lobe of the liver
How much bile is produced in a day?
- 250ml to 1000ml
- Due to its small size bile is very concentrated (water is removed)
What does bile contain?
- Water and ions = alkali
- Bile acids 70%
- Bile pigments = breakdown products of haemoglobin
- Organic molecules (cholesterol 4% and phospholipid - lecithin 20%)
Main function of bile
- Adequate pH for enzymes
- Emulsification of fat = formation of micelles
- Excretion of waste products (cholesterol)
General purpose of bile and gall bladder
- Neutralise chyme for pancreatic enzymes to work
2. Emulsify fats for better digestion
Function of micelle
Emulsify dietary fat for lipase breakdown - enables efficient breakdown and absorption of fats
The lining of the GI tract is divided into layers:
- Mucosal
- Submucosal
- Muscle layers
The urinary system consists of:
- two kidneys
- two ureters
- one urinary bladder
- one urethra
Abdominal aorta
Branches into the kidneys (renal arteries) - perfect location to receive blood flow
Function of the kidneys
- Filter blood and regulate blood content and pressure
- Regulate electrolyte composition (Na and K)
- Regulate blood pH
- Excrete metabolic waste products (urea and creatinine)
- Endocrine function (produce hormones erythropoietin, renin and 1,25-hydroxycholecalciferol = Vitamin D)
Structure of the kidney
- Each kidney weighs 115g-170g
- Outer region = cortex
- Inner region = medulla
What are the medulla and cortex composed of?
Nephrons
What are nephrons?
A nephron is the filtration unit of the kidney
How does the kidneys filter the blood and produce urine?
The nephrons work through a two-step process: the glomerulus filters your blood, and the tubule returns needed substances to your blood and removes wastes.
What is the functional unit of the kidney?
Nephrons
How many nephrons are there per kidney?
1 million
Role of nephrons
- Regulate the conc of water and soluble subtances like sodium salts by filtering the blood
- Reabsorption of ions
- Excretion of urine
Glomerulus
Invagination of a ball of capillaries into the bowman’s capsule
What substances are filtered in the glomerulus?
The glomerulus filters water and small solutes out of the bloodstream. The resulting filtrate contains waste, but also other substances the body needs: essential ions, glucose, amino acids, and smaller proteins.
- Role of the glomerular filter
Ensures that water solutes and small proteins can pass
- Fenestrations (small holes for water, solutes and some proteins)
- Endothelial cells negatively charged - prevents large anion proteins (eg RBC)
Consequence of a damaged glomerular filter?
Damages to the membrane creates a potential for substances that should be retained to be lost in urine eg proteins
Reabsorption and secretion of essential components - kidneys
Filtrate collected by the bowman’s capsule is then reabsorbed into the peritubular capillaries (blood vessels that surround the nephrons)
Simultaneously - components from plasma are also secreted into the nephron for excretion
- Proximal convoluted tubule
Reabsorbs ions, water and nutrients, removes toxins and adjusts filtrate pH
- Distal tubule
Selectively secretes and absorbs different ions to maintain blood pH and electrolyte balance
- Descending hoop of Henle
Aquaporins allow water to pass from the filtrate into the interstitial fluid
- Ascending loop of Henle
Reabsorbs Na+ and Cl- from the filtrate into the interstitial fluid
- Collecting duct
Reabsorbs solutes and water from the filtrate
The lower urinary tract - ureters
- Filtrate passes tot he renal pelvis and into the ureters
- Ureters deliver the urine to the urinary bladder = stored
- Micturition = urine is excreted via urethra
No further modifications occur in the ureter, bladder or urethra
Role of ureters
Tube that delivers urine from the kidneys to the bladder
- Peristaltic waves that help push urine and transit = prevent ‘reflux’
- Kidney stones pass through the ureter causing intense pain
The bladder
- Located in the hypogastric region (pubic area)
- Different in males and females
The process of micturition - urinary bladder
- Urine storage and release is a controlled process
- Stretch receptors in the bladder wall indicate when 200-300ml of urine has accumulated
- Coordinated control of the bladder requires: detection of fulness, sphincter control and contraction of bladder smooth muscle
What is otitis media?
Otitis media is an infection of the middle ear that causes inflammation (redness and swelling) and a build-up of fluid behind the eardrum. Anyone can develop a middle ear infection but infants between six and 15 months old are most commonly affected
What are the two main areas of sensory physiology?
- Sensation = the process of sensing our environment
- Perceptions = interpretation of these signals
Where does sensory processing take place?
Thalamus
Thalamus:
- Relays information to the visual cortex
- Outer region of the cerebral cortex linked to visual function
Function of the thalamus
- Acts as a translator
- Inputs are processed
- Sensory information is relayed to the cerebral cortex
- Outer layer of the eye
- Cornea = protective epithelial layer (transparent)
- Sclera = tough connective tissue (white of the eye)
- Middle layer of the eye
- Iris
- Ciliary body = ciliary muscle
- Choroid = beneath the sclera, absorbs light, prevents reflection
- Inner layer of the eye
- Retina = contains photoreceptors (sensors)
The iris consists of two smooth muscles…
- Inner circular muscle (involved in constriction)
- Outer radial muscle (involved in dilation)
What cell pigments the iris?
Melanocyte
The retina consists of three layers:
- Inner layer = contains neurons called ganglion cells
- Middle layer = contains neurons called bipolar cells
- Outer layer = contains photoreceptors: rods and cones)
Light has to pass through the inner and middle layer and blood vessels before reaching the photoreceptors
Rods
- Black and white vision
- High sensitivity
- Low light conditions
- Low visual acuity
Cones
- Colour vision
- Low sensitivity
- High light conditions
- High visual acuity
What is rhodopsin?
Rhodopsin is found in specialized light receptor cells called rods
- Destroyed by bright light
What is tritanopia?
S-cone defect = blue=yellow spectrum
What is deuteranopia?
M-cone defect = green-yellow spectrum
What is propanopia?
L-cone defect = red-yellow spectrum
What are sound waves?
Sound waves are chemical waves caused by air molecules put into motion = transferring kinetic energy to the next molecule they bump in to
What does the CNS consist of?
Spinal cord and brain
What does the peripheral nervous system (PNS) consist of?
- Cranial and spinal nerves = have sensory (afferent) and motor (efferent) components
- Ganglia = located outside the brain and spinal cord, are small masses of nervous tissue , containing cell bodies of neurons
- Sensory receptors = are either part of neurons or specialized cells that monitor changes in the internal or external environment
- Enteric plexuses = regulate the digestive system
Function of the nervous system
- Sensory function = the system senses changes in the internal and external environment through sensory receptors
- Integrative function = analyse the sensory info, store some aspects, and make decisions regarding appropriate behaviours
- Motor function = respond to stimuli by initiating action
What is the PNS system subdivided into?
- Somatic nervous system (voluntary)
- Autonomic nervous system (involuntary)
- Enteric nervous system
Spinal cord - external structure
The spinal cord begins at the medulla oblongata and terminates around the second lumbar vertebra
- There are 31 pairs of spinal nerves (PNS)
Spinal cord - protection
Protected by:
- vertebra
- two connective tissue coverings (meninges - 3 coverings around brain and spinal cord and vertebral column - a flexible bony covering)
= cushion of cerebrospinal fluid
Spinal cord - internal structure
- Spinal cord us divided into grey and white matter
SC - what does grey matter comprise of?
- Cell bodies of motor neurons
- Association neurons
- Unmyelinated axons of afferent neurons
SC - what does white matter comprise of?
- Bundles of myelinated axons of motor and sensory neurons
Dorsal (sensory) root
sensory nerve fibers conduct nerve impulses into the spinal cord
Ventral (motor) root
motor neuron axons conduct impulses out to the periphery
Spinal cord - input
Sensory fibers enter through the dorsal horn and terminate in specific sites according to:
- fibre type
- modality
- intensity
Sensory fibers synapse onto second order neurons that ascend to the brain through white matter
Spinal cord - tracts
The white matter is divided into columns
Each column contains bundles of axons that have a common origin or destination and carry similar information - called tracts
- sensory (ascending) tracts conduct nerve impulses towards the brain
- motor (descending) tracts conduct impulses down the cord
Tract names:
- Spinothalamic = spinal cord to thalamus
- Corticospinal = cortex to spinal cord
(tract names always link to origin and destination)
Brain - principal parts
- The brain is protected by the cranial meninges and the cranial bones
- The principle parts of the brain are:
>brain stem
>diencephalon
>cerebrum
>cerebellum
Brain - brain stem
- Most cranial nerves originate from the brain stem
- Primitive region, involved in basic needs = sleep, breathing, autonomic
Brain - cerebrum
- Largest part of the brain
- The cerebral cortex is composed of grey matter
- The cerebral white matter contains tracts that connect to other parts if the nervous system
Each cerebral hemisphere is further subdivided into four lobes:
- occipital
- pariental
- frontal
- temporal
Cerebral functional areas
- Sensory areas of the cerebral cortex = concerned with the reception and interpretation of sensory impulses
- Motor areas = regions that govern muscular movement
- Association areas = concerned with complex integrative function such as memory, emotions, reasoning, will, judgement, personality and intelligence
Examples of flat bones:
- Sternum
- Scapulae
- Ribs
- Cranial bones
Examples of long bones:
- Humerus
- Tibia
- Femur
- Fibula
- Ulna
- Metatarsal
- Metacarpal
- Phalanges
Examples of short bones:
- Carpals
- Tarsals
Examples of irregular bones:
- Vertebrae
- Sacrum
Axial skeleton
Made up of the bones in your head, neck, back and chest
Appendicular skeleton
Your appendicular skeleton is made up of everything else — the bones that attach (append) to your axial skeleton. Your appendicular skeleton includes the bones in your shoulders, pelvis and limbs, including your arms, hands, legs and feet
Bone architecture
- Cortical bone (compact bone) = strong, dense, regular structure
- Trabecular bone (cancellous, spongy bone) = lightweight, irregular lattice, porous
- Marrow cavity
Bone composition
- 30% = organic (2%cells and 98% matrix)
- 70% mineral
- Made up of collagen, hydroxyapatite, osteoblasts, osteocytes and osteoclasts
Unlike concrete, bone i snot fixed or static
Osteoblasts (BuiLders)
- Form bone
- Derived from mesenchym stem cell line = similar to fibroblast, chondroblast
- Found on the surface of bone marrow cavity = secrete proteinous organic matrix (high mitochondria and golgi content), mineralisation of matrix by secreting alkaline phosphatase
What do osteoblasts become when trapped by new bone?
Osteocytes, osteoblasts also secrete factors to activate osteoclasts and other cells
What happens to the remaining osteoblasts?
They undergo apoptosis - cell death
Osteoclasts (CLearance)
- Breakdown bone (bone clearance)
- Derived from blood cell line (similar to macrophage, monocyte)
- Formed on fusion of precurser cells to make large, multinucleated syncytium (stimulated by RANK receptors)
Bone resorption
Resorption is the breakdown and assimilation of old bone in the cycle of bone growth. The process of resorption (remodelling) involves the removal of hard bone tissue by osteoclasts followed by the laying down of new bone cells by osteoblasts
- H+ ions, proteases, collagenase released under ruffles border
What is bone resorption required for?
- Radial growth
- Bone remodelling
- Maintaining vascularity
- Liberating ions
Is bone the perfect material?
- Strong as iron, light as wood
- Adapts to functional requirements
- Repairs itself
Functions of the skeleton:
- Structural support for heart, lungs and marrow
- Protection for brain, uterus and other internal organs
- Attachment sites for muscles allowing limb movement
- Mineral reservoir for calcium and phosphorus
- Defence against acidosis
- Trap for some dangerous minerals such as lead
Muscle types
- Skeletal (leg…)
- Cardiac (heart)
- Smooth (internal organs)
Skeletal muscle
- Striated, voluntary
- Attach to bone by tendon and connective tissue
Cardiac muscle
- Striated and involuntary
Smooth muscle
- Involuntary and non-striated
How does muscle attach to bone?
- Indirect attachment (most common) = epimysium extends beyond muscle as a tendon
- Direct attachment = epimysium adheres/fuses to periosteum
Origin muscle attachment
- Proximal attachment
- Muscle attaches to least moveable area of the bone of axial skeleton
Insertion muscle attachment
- Distal attachment
- Muscle attaches to the bone that moves most
Anatomy of skeletal muscle
- Perimysium = binds muscle fibers together
- Epimysium = sheath enveloping entire muscle
- Endomysium = sheath surrounding muscle fibre
- Sarcolemma = contains cytoplasm (sarcoplasm)
- Myofibrils = contains actin and myosin
- Sarcomeres = contains actin and myosin
What are the three types of movement?
- Reflex
- Rhythmic
- Voluntary
Reflex movement
- External initiation
- Least complex with integration at spinal cord
- Knee (patellar) reflex, couch, posture
Rhythmic movement
- Voluntary initiation and termination
- Moderate complexity, integration at spinal cord (acts as pattern generator) but needs higher centre input
- Walking
Voluntary movement
- External stimuli or at will
- Complex, integrated in cerebral cortex
- Learned behaviour , can develop into ‘muscle memory’ = shows plasticity
- Playing piano
Neurons
Transmit information by electrical signals
- Afferent neuron
- Efferent neuron
- Interneuron
Epithelial cells
- Vary in shape
- Cells join together to form a barrier. Allows restricted passage of material
- Found where body fluids must be separated from external environment lining
Connective tissue
In most cases:
- Widely scattered cells embedded in a mass of noncellular material, the extracellular matrix = contains a dense meshwork of proteins and other large molecules
In broader sense:
- Encompasses fluids eg. blood and lymph
- Connects the various parts of the body by providing means of communication
Structure of the heart
- Bulk of the heart is made up of cardiac muscle cells, termed the myocardium
- Inner surface of myocardium is lined with a thin layer of cells known as endothelial cells
Function of the heart
Right ventricle pumps deoxygenated blood to the lungs - low pressure little resistance to blood flow and short distance to the lungs
Left ventricle pumps oxygenated blood to all organs of the body - higher pressure, thick muscular wall
How does the heart pump blood around the body?
The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve. The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body.
Valves of the heart
- Atrioventricular valces (bicuspid/mitral and tricuspid)
- Semi lunar valves (aortic and pulmonary)
Chordae tendinae
- Atrioventricular valves are attached firmly to specialised tendon called chordae tendinae
- Regulated by the papillary muscles
- When the ventricles contract the papillary muscles also contract. This tightens the chordiae tendinae and prevents the valve cusps from everting (turning inside out) into the atria
Function of platelets (thrombocytes)
Cell fragments that play a crucial role in blood clotting
- Conc = 3000,000mm3
- Size = a diameter of 2-4um
Function of WBC (leukocytes)
To defend the body against pathogenic organisms
- Size = diameter of 10-20um
Types of WBCs
- Neutrophils = phagocytosize pathogens
- Lymphocytes = produce antibodies and antimicrobial chemicals
- Monocytes = phagocytosize pathogens
- Eosinophils = involved in defense against parasites and in the allergic response
- Basophils = secrete histamine and heparin (anti-thrombotic agent)
What is plasma composed of?
Watery liquid containing many dissolved substances
- Water
- Plasma proteins
- Non-protein organic compounds
- Inorganic compounds
Types of blood vessels
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
Red blood cells (erythrocytes)
- Make up 45% of the total blood volume in men and 42% in women
- Diameter = 7um, these are shaped as biconcave disc
What are cardiac monocytes?
They contain majority of the contractile elements for the heart (eg. actin and myosin filaments)
Three phases of cardiac action potential
- Rapid depolarisation of plasma membrane (sarcolemma) = voltage gated Na+ channels open, Na+ influx into cell
- Plateau (slower phase) = voltage gated Ca2+ channels open, Ca2+ entry
- Repolarisation = voltage gated K+ channels open K+ outflow
P wave - ECG
- SA node fires, atrial depolarisation
- Atrial systole
QRS complex - ECG
- AV node fires, ventricular depolarisation
- Ventricular systole
- Atrial repolarisation and diastole - signal obscured
T wave - ECG
- Ventricular repolarisation
What is blood pressure?
Is a measurement of the force exerted by the blood circulating in the arteries against the walls
- Normal blood pressure is 120/80 mm Hg
The 2 readings taken from blood pressure:
- Systolic pressure (ventricular contraction)
- Diastole pressure = (ventricular relaxation)
Stroke volume (SV) is measured by:
SV = EDV - ESV (130-60 = 20mL)
Cardiac output (CO) is measured by:
CO = SV x HR
