ILA Flashcards
What causes the upstroke in the nerve action potential graph?
By sodium ions rushing into the cell
What causes the downstroke in the nerve action potential graph?
By potassium ions rushing out of the cell
Which group of spinal nerves innervates the biceps reflex?
C5/C6
Which group of spinal nerves innervates the ankle reflex?
S1/S2
Which group of spinal nerves innervates the knee jerk?
L3/L4
Which group of spinal nerves innervates the triceps reflex?
C7/C8
Name 4 cells which are present in the CNS
- Astrocytes
- Ependymal cells
- Microglia
- Oligodendrocytes
Which descending motor tract originates in the cerebral cortex and synapses in the spinal cord?
Corticospinal tract
Where does the spinothalamic tract decussate?
The spinal cord
What kind of fibres does the vagus nerve compromise of?
Parasympathetic motor and sensory fibres
What is the function of DNA helicase?
Unwind the two strands of DNA
Where do free RNA nucleotides form weak hydrogen bonds with a DNA strand during transcription?
The nucleus
What does RNA polymerase do?
Joins together the free RNA nucleotides by phosphodiester bonds
How does pre-mRNA become mRNA?
By splicing to remove introns
What does a spliceosome do?
Does splicing
What does topoisomerase do?
Uncoils the DNA
Where does translation happen?
In the cytoplasm
Briefly outline translation of mRNA
- mRNA binds to ribosome
- tRNA with AA complimentary binds to a codon of mRNA sequence
- The codon and anti-codon become bound loosely by hydrogen bonding
- Another tRNA binds, allowing a peptide bond to form between AA’s
What is mis-sense?
When a single nucleotide changes, resulting in a codon which codes for a different AA
What is a single nucleotide polymorphism (SNP)?
A variation in a single nucleotide that occurs at a specific position in the genome, where each variation is present to some degree within a population. This can be in exons or introns
Where can SNP be used?
Paternity tests. It is an example of mis-sense
What is non-sense?
Adds a stop codon in the genetic sequence
What is the problem with sickle cell anaemia?
- Abnormality in haemoglobin S
- Erythrocytes become stiff and crescent shaped
- Only last 10-20 days (10% compared to standard)
How does cold/damp affect people with sickle cell anaemia?
Leads to vasoconstriction, hence amplifying the pain of blocking blood vessels
What proportion of the body is water in men and women?
- 60-65% in men
- 55-60% in women
What is the split between ICF and ECF in the body?
2/3 is ICF, 1/3 IS ECF
What is one of the main components of ECF?
Dissolved sodium ions
What are further divisions of ECF?
- 25% interstitial
- 8% plasma
- Rest is transcellular
Where can fluid be found?
In epithelial lined spaces
What percent of sodium in the body is locked up in the bone crystal?
Around 30%
What percentage of sodium in the body is exchangeable?
70%
What percentage of the total body sodium is held in the ECF?
50%
Define osmolality
A measure of the osmoles (Osm) of solute per kilogram of solvent. The units are osmol/kg or Osm/kg
Define oncotic pressure
A form of osmotic pressure exerted by proteins, particularly albumin, in a blood vessel’s plasma, that usually tends to pull water into the circulatory system
Define osmosis
The movement of water molecules from an area which is less concentrated to an area which is more concentrated
What is albumin?
A protein produced in the liver that keeps fluid from leaking out of blood vessels and nourishes tissues
What happens if albumin levels are low?
- Water not drawn into blood vessels
- Fluid surrounds tissue
- Fluid shift (when body fluids more between fluid compartments)
- Conditions such as oedema
What is fluid shift?
When body fluids move between fluid compartments
What is oedema?
The excess of tissue/interstitial fluid collecting in tissues of the body
How does albumin work?
By binding to water
What are insensible losses?
Uncontrolled/unmeasurable amount of fluids on a daily basis
What contributes to insensible losses?
Urine, faeces, sweat, respiratory tract and trans-epidermal evaporation
What can cause increased osmolality?
An increase in sodium ions
What does an increase osmolality do to osmoreceptors?
Stimulates them in the hypothalamus
What happens after osmoreceptors are stimulated?
- Stimulates the posterior pituitary gland to release ADH
- The ADH targets the collecting ducts of the kidneys with aquaporins
- The second messenger model occurs
- More water reabsorption, darker urine, increase plasma volume, reduced osmolality
What happens when there is a decrease osmolality?
- Osmoreceptors are inhibited
- Inhibition of ADH
- Less water reabsorption, paler urine, decreased plasma volume, increases osmolality
What does the hypothalamus do in relation to water control?
Makes ADH
What does the posterior pituitary gland do in relation to water control?
Releases ADH
What does an increase in water mean in terms of ADH?
Release of ADH
What does a decrease in water mean in terms of ADH?
Inhibition of ADH
Where is angiotensin produced?
The liver
Where is renin produced?
Kidneys
What chemical helps convert angiotensinogen into angiotensin I?
Renin
Where is ACE produced?
Lungs
What chemical helps convert angiotensin I into angiotensin II?
ACE
What are the 3 main jobs of angiotensin II?
- Arteriolar vasoconstriction (increase BP)
- Acts of posterior pituitary to release ADH so there is water absorption at the collecting duct
- Acts of vortex of adrenal gland for aldosterone secretion. Allows tubular Na/Cl ion reabsorption. K ions excretion and water retention
Where is renin secreted?
When there is low blood pressure in the kidneys
What does medication for hypertension tend to inhibit?
ACE, as when it’s secreted it tends to raise blood pressure
What happens when the volume of water in the blood pressure is too low?
The hypothalamus is stimulated to alarm the body of thirst, so more water is consumed
What happens in the case of dehydration?
Increased solute, increases ECF osmolality, water goes to ECF from ICF, ADH released, thirst centre stimulated
What happens when there is a water excess?
Reduced ECF osmolality, water moves from ICF to ECF, less ADH released, urine volume increases, no thirst stimulation
Define cardiac output
The amount of blood pumped by the heart per minute. It is a good indicator of fitness levels
What is the formula and units for cardiac output?
- Cardiac output = heart rate x stroke volume
- It has units of litres per minute
What could increase cardiac output?
An increased heart rate or stroke volume
Name 7 factors which increase blood pressure
- Smoking
- High BMI
- Lack of physical activity
- Too much sodium
- Too much alcohol
- Stress
- Older age
Describe how an increase in blood pressure leads to an increased cardiac output
- Greater blood pressure
- Reduced rate of flow through vessels
- Greater heart rate for same stroke volume
- Increased cardiac output
What is Starling’s law of the heart?
Stroke volume of the heart increases (until a limit) in response to an increase in the volume of blood in the ventricles, before contraction, when all other factors remain constant
What is preload?
The end diastolic volume that stretches the ventricle of the heart to its greatest dimensions under variable physiologic demands
What is afterload?
The pressure against which the heart must work to eject blood during systole
What are the four stages of the cardiac cycle (in order)?
- Filling phase
- Isovolumetric contraction
- Outflow phase
- Isovolumetirc relaxation
What occurs in the filling phase?
The ventricles fill during diastole and atrial systole
What happens during isovolumetric contraction?
The ventricles contract, building up pressure ready to pump blood into the aorta/pulmonary trunk
What occurs in the outflow phase?
The ventricles continue to contract, pushing blood into the aorta and the pulmonary trunk. Also known as systole
What happens in isovolumetric relaxation?
The ventricles relax, ready to refill with blood in the next filling phase
When does myocardial perfusion happen?
Diastole
What happens in the filling phase (detailed)?
- Both atria and ventricles relaxed
- Blood flows into atria from veins then into ventricles
- At the end of diastole, atria contract, pushing a small amount of blood into ventricles
- Pressure of ventricles > pressure of atria so AV valves close
What happens in isovolumetric contraction (detailed)?
- At start of contraction, both sets of valves are shut
- Start of systole increase ventricular pressure
What happens in the outflow phase (detailed)?
- When pressure of ventricles > aorta/pulmonary trunk, the valves of these valves open
- Blood is pumped from the heart into the great arteries
- Ventricles begin to relax, change in pressure compared to aorta causes valves to close
What happens in isovolumetric relaxation (detailed)?
- At the end of outflow phase both sets of valves are closed again
- Ventricles begin to relax, reducing pressure in ventricles so AV valves open
- Cycle begins again
What is the purpose of coronary arteries?
Supply oxygenated blood to the heart muscle
What is the purpose of coronary veins?
Remove deoxygenated blood from the heart muscle
Where do the two coronary arteries arise from and how are they distinguished?
- Arise from the aorta just beyond the semi-lunar valves
- Distinguished into left and right
What happens in diastole, linked to the coronary arteries?
Increased aortic pressure above valves forces blood into coronary arteries
Where do most coronary veins converge to and where does it drain into?
- They converge to form the coronary venous sinus
- Drains into the right atrium
What are the branches of the right coronary artery and where do they join with branches of the left coronary artery?
- Right marginal branch and posterior intraventricular artery
- Join on the left hand side
What are the names of the two branches of the left coronary artery?
Circumflex artery (posterior) and the left anterior descending (LAD)
Where does the nodal branch supply?
The SAN
What happens when there is an occlusion of the LAD?
- It provides major blood supply to the septum between ventricles
- May lead to a ‘block’ of impulse conduction between atria and ventricles (LBBB/RBBB)
What happens when there is an occlusion of the right coronary artery?
- Supplies the AVN and sinus of the heart
- Can lead to conduction abnormalities
Name 4 preventative things that can be done to reduce heart problems
- Limit alcohol consumption
- Reduce stress
- Aim for a healthy weight
- Physical activity daily
How can LBBB/RBBB be detected?
By ECG’s to detect any ventricular fibrillation
What symptom is linked with hypoxia?
Confusion
Name 4 reasons for a low pp of oxygen
- Damaged tissue
- Anaemia
- High altitude
- COPD
Name a reason for a too high pp of oxygen
- Too much oxygen e.g. gas canister
Where is air held when it enters through the nose?
The nasal cavity
Where does the air go after the nasal cavity?
The pharynx then the larynx
What is the name of the opening of the trachea?
The glottis
What branches from the trachea?
The two primary bronchi
What does the bronchi deviate into?
The bronchioles
What happens in the alveoli and how does it happen?
- Oxygen is transferred into the blood in exchange for carbon dioxide
- Air travels through alveolar ducts into the alveolar sac where it is met with capillary networks
What consists of the upper airways?
- Nose/nasal passage
- Paranasal sinuses
- Pharynx (nasopharynx, oropharynx, laryngopharynx)
- The portion of the larynx above the vocal cords
What consists of the lower airways?
- The portion of the larynx below the vocal folds
- Trachea
- Bronchi
- Bronchioles
Where is the greatest resistance to airflow?
The mediu sized bronchi
What do chemoreceptors do?
Detect changes in blood pH
What is the apneustic centre of the pons responsible for?
The ‘stimulating’ part, helps control rate of breathing
What is the pneumotaxic centre of the pons responsible for?
The ‘limiting’ part, helps control rate of breathing
What happens when carbon dioxide levels rise in arterial blood?
- Vasodialtion in arteries
- Heart rate increases
- Better blood flow/tissue perfusion
- Better oxygen delivery
- Blood flow to the heart and brain increases
- Higher respiratory rate as higher carbon dioxide levels
- Allows body to release more carbon dioxide whole increasing oxygen intake
What is normal respiration normally driven by?
Carbon dioxide levels in arteries
What happens during inspiration?
- Diaphragm contracts and pulls downwards
- Intercostal muscles contract and pull upwards
- Increase size of thoracic cavity
- Decrease in thoracic pressure
- Air moves into the lungs down a pressure gradient
What happens during expiration?
- Lungs recoils to force air out
- Intercostal muscles relax
- Diaphragm relaxes moving higher into the thoracic cavity
- Causes greater pressure in thorax, creating a pressure gradient
- Passive process
What is respiratory failure?
- When the respiratory system fails in oxygenation of carbon dioxide elimination
- May be classified as either hypodermic or hypercapnic
What is type I respiratory failure?
- Consists of hypoxemia solely
- Carbon dioxide levels may be normal or low
- Caused by lack of synchronisation between ventilation and perfusion within the body
- Caused by conditions which affects oxygenation
What is type II respiratory failure?
- This is both hypoxemia and hypercapnia
- Usually caused by inadequate alveolar ventilation
- Carbon dioxide levels build up but can’t be eliminated
- Caused by increased airways resistance, reduction in breathing effort
What does the upper GI tract consist of?
Pharynx, oesophagus, stomach and duodenum
Where is the pharynx located?
Behind the mouth and nasal cavity and above the oesophagus and larynx.
What is the function of the pharynx?
- Its muscular walls function in the process of swallowing
- Serves as a pathway for the movement of food from the mouth to oesophagus
What is the purpose of the oesophagus?
- Where the food passes by peristaltic contractions, from the pharynx to the stomach
- Serves as the conduit for food and liquids that have been swallowed into the pharynx to reach the stomach
What happens to the epiglottis during swallowing?
- Tilts backwards to prevent food going down the larynx and lungs
What is the stomach and what is its functions?
- Muscular organ which is involved in the second phase of digestion, following mastication
- Done by digestive enzymes and HCl
- Stomach muscles contract periodically, churning food to enhance digestion
What is the pyloric sphincter?
A muscular valve that opens to allow food to pass from the stomach to the small intestine
What does the pyloric sphincter do?
Controls the passage of partially digested food (chyme) from the stomach into the duodenum
What are the functions of the duodenum?
- Senses changes in pH
- Receives chyme from the stomach
- Plays a vital role in the digestion of chyme (neutralises acid) in preparation for absorption in the small intestine
- Allows entrance of bile via bile & pancreatic duct
What are serotonin inhibitor drugs used for?
Anti-sickness medications
What is gastro-oesophageal reflux?
When HCl from the stomach leaks up into the oesophagus
What is gastro-oesophageal reflux caused by?
Due to the sphincter at the bottom of the oesophagus becoming weakened, hence allowing reflux
What is an oesophageal motility disorder (EMD)?
A medical disorder where there is difficulty swallowing, regurgitation of food, and a spasm-type pain which can be brought on by an allergic reaction to certain foods
Which enzymes helps form carbonic acid from water and carbon dioxide in parietal cells?
Carbonic anhydrase
What happens to H ions in partial cells?
They move into the lumen of gastric pit in a K/H ion ATPase pump. K ions move into the parietal cells
What happens to bicarbonate ion after dissociation in the parietal cell?
It is part of a dual-transport channel with Cl ions, with bicarbonate moving into the blood and Cl ions moving into the parietal cell
What does Cl ions do when they are in the parietal cells?
Diffuse into the lumen of the gastric pit
What is the secondary source of hydrogen ions in the parietal cells?
Dissociation of water
What are the three substances which stimulate parietal cells and which one directly affects them?
- Gastrin, histamine and acetylcholine
- Histamine is the only one which directly affects
What do goblet cells do in the stomach?
Secrete mucus which protects the stomach lining
What do parietal cells do in the stomach?
Produce and secrete gastric acid
What do chief cells do in the stomach?
Secrete pepsinogen (a protease precursor)
What do D cells do in the stomach?
Secrete somatostatin which inhibits acid secretion
What do G cells in the stomach do?
Secrete gastrin which stimulates acid secretion
What is the Angle of His?
The acute angle created between the cardia at the entrance to the stomach and oesophagus
What are the names of the mucous membrane layers of the stomach and duodenum?
Gastric and duodenal mucosa
What is the pre-epithelial layer of protection?
A mucus-bicarbonate barrier, secreted from parietal cells, create a pH gradient maintaining the epithelial cell surface at near neutral pH
What is the purpose of surfactants in the stomach?
Prevents against water-soluble agents from reaching and damaging the epithelium
Name two things which contribute to intact epithelium lining
- Rapid cell turnover
- Enzymes which hydrolyse proteins (pepsin/pepsinogen)
What may be a symptom of indigestion?
Reflux
Where does the liver lie?
In the right hypochondrium
What percentage of the cardiac output is the hepatic blood supply?
25%
What percentage of the hepatic blood flow is from the portal vein?
75%
How many segments is the liver divided into?
8
What is the functional hepatic unit of the liver?
The acinus
When is cholecystokinin released?
In response to the presence of amino acids in the gut
Which system is acetylcholine part of?
The parasympathetic system
By what system is the enteropancreatic reflex done by?
Parasympathetic system
Which type of jaundice is commonly caused by gallstones in the common bile duct?
Obstructive
Name the organ which is situated within the duodenal loop
Pancreas
Which enzyme catalysed the formation of conjugated bilirubin?
UDP glucoronyl transferase
What produces stercobilinogen in the gut?
Bacterial enzyme hydrolysis
How is urobilinogen returned to the liver?
By the enterohepatic circulation
What cells secrete glucagon?
The alpha islet cells
What cells secrete insulin?
The beta islet cells
Which hormone stimulates the breakdown of glycogen?
Glucagon
Which cells secrete pancreatic polypeptide?
F islet cells
What is the central structure in a hepatic lobule?
The tributary of the hepatic vein
What system are the Kupffer cells part of in the liver?
The reticuloendothelial system
Which type of jaundice causes an increased serum unconjugated bilirubin and increased faecal urobilinogen?
Pre-hepatic
What is the cause of physiological jaundice of a newborn?
Excess breakdown of foetal haemoglobin
Give 4 causes of obstructive jaundice
- Cirrhosis
- Hepatitis
- Gallstones
- Carcinomas
What is Gilbert’s syndrome?
An elevated level of unconjugated bilirubin in the bloodstream
Give 4 functions of the liver
- Glycogen storage
- Storing vitamins A, D, E & K
- Production of cholesterol
- Conversion of T4 into T3
Where is urobilinogen produced?
Intestine
How is the liver divided?
- Into the right, left and caudate lobes
- The right and left lobes are further divided into the anterior and posterior elements
How is the common bile duct formed?
From the common hepatic duct (from liver) and the cystic duct (from the gallbladder)
What are the components of the hepatobiliary system?
Liver, gallbladder and bile ducts
What is significant about the flow in the portal triad?
The bile within the bile duct travels in the opposite direction to the blood in the portal vein and hepatic artery
What are the horizontal divisions of the midline of the body?
Subcostal (upper) and inter tubercular (lower)
What are the vertical divisions of the middle of the body?
Midclavicular
What does the common bile duct and the pancreatic duct from?
The hepatopancreatic ampulla of Vater
What is a space of Disse?
Between a sinusoid and a hepatocyte. It has movement of blood through it
What is pre-hepatic (haemolytic) jaundice?
Caused as a result of haemolytic or accelerated breakdown of erythrocytes, leading to an increase in production of bilirubin
What is hepatocellular jaundice?
Usually caused by drugs and alcohol, it is as a result of liver disease of injury. It is partially hereditary
What is post-hepatic (obstructive) jaundice?
Occurs as a result of an obstruction in the bile duct. This prevents bilirubin movement into the liver.
Why do the whites of eyes go yellow in patients with jaundice?
Due to bilirubin having a affinity for elastin
Which type of jaundice causes dark urine and dark stools?
Hepatocellular
Which type of jaundice causes dark urine and pale stools?
Post-hepatic
Which type of jaundice causes normal urine and brown stools?
Pre-hepatic
What happens to haem in bilirubin metabolism?
The enzyme haem oxygenate splits it into iron ions (which are recycled) and biliverdin
What happens to globin in bilirubin metabolism?
The amino acids are recycled
Which enzyme converts biliverdin into unconjugated bilirubin?
Biliverdin reductase
What are the stages of converting unconjugated bilirubin into conjugated bilirubin in bilirubin metabolism?
- Travels to liver
- Combines with albumin
- Catalysed with UDP glucoronyl transferase (adding glucoronic acid)
How does conjugated bilirubin get converted into urobilinogen in bilirubin metabolism?
By movement into the duodenum
What happens to the urobilinogen when it’s in the intestine in bilirubin metabolism?
- Gets converted into urobilin
- Gets converted into stercobilinogen by bacterial enzyme hydrolysis
What happens to urobilin in bilirubin metabolism?
Half goes back into bile, while the other half goes into urine
What happens to stercobilinogen in bilirubin metabolism?
It gets converted into stercobilin, which is excreted in the faeces
What are the functions of the frontal lobe?
Motor, problem solving, language, personality
What is the function of the anterior portion of the frontal lobe?
Higher cognitive function and personality
What is the function of the posterior portion of the frontal lobe?
Motor and premotor areas
Where is Broca’s area and what is it’s function?
- Inferior frontal gyrus
- Important for language production (frontal lobe, dominant hemisphere)
What is present in the temporal lobe and what’s its functions?
- Primary auditory cortex, hippocampus, amygdala and Wernicke’s area
- Involved in short term memory, equilibrium and emotion
Where is Wernicke’s area and what is it’s function?
- Superior temporal gyrus of the left hemisphere
- Linked to understanding spoken word
Where is the primary sensory area of the brain?
Parietal lobe
Which side is the dominant parietal lobe and what is it’s functions?
- Usually the left side
- Important for perception and interpretation
What is the function of the non-dominant parietal lobe?
Visuospatial functions
Where is the occipital lobes and what are their functions?
- Posterior aspect of the brain
- Involved in motor control of equilibrium, posture and co-ordination
What are some of the components of the brain stem?
- Ascending and descending tracts
- Cranial nerve nuclei
- Reticular formations
Which cranial nerves arise from the brainstem?
3-12
What are the descending tracts of the brain?
Pathways by which motor signals are sent from the brain to the lower motor neurones
How do LMN cause muscle movement?
LMN directly innervate muscles to produce movement
Where do pyramidal tracts originate and what do they do?
- Originate in cerebral cortex
- Carry motor fibres to the spinal cord and brainstem
How can pyramidal tracts be divided?
Into corticospinal and corticobulbar
Where do corticospinal tracts supply?
All the body except the head and neck
Where do corticospinal tracts begin and where do they have input from?
- Begins in the cerebral cortex
- Has input from primary motor cortex, premotor cortex, supplementary motor cortex and somatosensory cortex
What happens when the corticospinal tracts separate?
- Run as corona radiate
- Converge and travel through the internal capsule at the basal ganglia
What extra happens with the motor fibres when the corticospinal tracts separate?
The motor fibres pass through crus cerebra of midbrain, pons and into medulla with the peduncles
How can the corticospinal tracts divide?
Into lateral corticospinal tracts and anterior corticospinal tracts
What is the pathway of the lateral corticospinal tracts and where are they present?
- Cross over at the medulla
- Descend into spinal cord
- Terminate on the ventral form, synapsing with LMN
- Mainly present in limbs
What is the pathway of the anterior corticospinal tracts and where are they present?
- Remains ipsilateral
- Terminates at ventral horn of the cervical and upper thoracic segments of the spine
- Mainly present in axial muscles
Where do corticobulbar tracts supply?
The head and neck
What is the pathway of the corticobulbar tracts?
- Begins in the cerebral cortex
- Separates as the run as corona radiate
- Cornverges and travels through internal capsule at basal ganglia
- Terminates at brainstem on the motor nuclei of cranial nerves
- LMN carry motor signals to muscles of face & neck
Where do extrapyramidal tracts originate?
The brainstem
Where do extrapyramidal tracts carry motor fibres to?
To the spinal cord
What are the extrapyramidal tracts responsible for?
Involuntary and automatic control of all musculature
Name the 4 tracts which the extrapyramidal tracts can divide into
- Tectospinal
- Rubrospinal
- Vestibulospinal
- Reticulospinal
What are tectospinal tracts responsible for?
Head turning in response to stimuli (superior colliculus - head/eye movements)
What are rubrospinal tracts responsible for?
Assits in motor functions (red nucleus (midbrain) - limb flexors)
What are vestibulospinal tracts responsible for?
Muscle tone and posture (vestibular nuclei - posture and balance)
What are reticulospinal tracts responsible for?
Spinal reflexes (reticular formation (midbrain) - posture and locomotion)
Where do extrapyramidal tracts synapse?
All with LMN, no synapses with the descending pathways
Where are the cell bodies of the extrapyramidal tracts?
In cerebral cortex or brainstem. Axons remain in CNS
Which areas are supplied by the anterior cerebral artery?
- Most midline portions of frontal lobes
- 4/5ths of the corpus callosum
- Superior medial parietal lobes
- Anterior limb of the internal capsule
- Anteromedial portion of the cerebrum
Which areas are supplied by the middle cerebral artery?
- Majority of the lateral surface of the hemisphere
- Deep structures of the anterior hemisphere
Which areas are supplied by the posterior cerebral artery?
- Occipital lobe
- Posterior temporal lobe
- Medial surfaces of the thalamus
- Walls of the 3rd ventricle
- Choroid plexus
What is the function of the upper motor neurones?
- Movement control
- Muscle tone
- Spinal reflexes
- Spinal autonomic functions
- Transmission of sensory information to higher centres
What is the function of the lower motor neurones?
- Control of all voluntary movement
- Acts as a link between UMN and muscles
- Directly innervates muscles to produce a movement
What are the characteristics of UMN weakness?
- Broad, increased muscle tone (spasticity)
What are the characteristics of LMN weakness?
- Decreased muscle tone
- Muscle paralysis
- Weakness
What is the CNS?
Brain and spinal cord
What is the PNS?
Nerves, which are bundles of axons
What is a tract?
A bundle of axons in the CNS
What does nervous tissue in the CNS and PNS consist of?
Glial cells and neurones
What is the function of glial cells?
Provide a framework for tissue that supports the neurone and its activities
What is the nucleus (neuro)?
A localised collection of neurone cell bodies in the CNS
What is the ganglion?
A localised collection of neurone cell bodies in the PNS
What is sensory information?
Receiving information about the environment around
What is motor information?
Generating responses
How does sensory information travel towards the CNS?
Through then PNS nerves in specific division known as afferent (sensory) branch of the PNS
What is the somatic nervous system responsible for?
Conscious perception and voluntary motor responses. This means the contraction of muscle
What is the autonomic nervous system responsible for?
Responsible for involuntary control of the body, usually for the sake of homeostasis
When can sensory input be possible for autonomic functions?
Sweating when warm - homeostatic and autonomic
How can the autonomic nervous system be divided further?
Into sympathetic and parasympathetic branches
Briefly describe an action potential
- More K channels open than Na channels
- Stimulus allows opening of some of the Na channels
- Inside more positive than outside
- More Na allowed in
- Once the peak is met, more K channels are opened, allowing movement out fo the neurone
- Na/K ATPase pump swap ions around
Name the 5 types of sensory receptors
- Mechanoreceptors
- Thermoreceptors
- Nociceptors
- Electromagnetic receptors
- Chemoreceptors
What effect will a lesion above decussation have?
Contralateral effects
What effect will a lesion below decussation have?
Ipsilateral effects
What is the anatomical location of the kidneys?
In the retroperitoneal space
How does the urine pass through the ureter?
By peristalsis
What cell type is the ureter lined by?
Transitional epithelium
What is the outermost layer of the kidneys?
The capsule
What percent of the cardiac output passes through the kidneys?
25%
What substance shouldn’t be found in the glomerular filtrate of a healthy individual?
Albumin
Name 4 substances which may be found in the glomerular filtrate of a healthy individual
Glucose, uric acid, creatine and potassium
If the renal clearance fo a substance is 250ml/min, then what must happen to it?
It must be secreted by the nephron
What is angiotensin I converted by renin from?
Angiotensinogen
Name 2 illness which may cause pre-renal acute kidney injury
- Cellulitis
- Chronic liver failure
What causes anaemia in chronic renal failure?
Reduced production of erythropoietin
What is the chemical formula of aldosterone and what kind of hormone is it?
- C25H28O5
- Steroid hormone
What is aldosterone’s main function?
On the collecting duct to increase Na reabsorption
What is the secretion rhythm of aldosterone?
Diurnal
Where is aldosterone secreted from?
The adrenal cortex
Where is renin secreted from?
The juxtaglomerular cells
What is renin secreted in response to?
Beta-adrenergic receptors on the JGC
What is the role of the macula densa in response to changes in Na delivery?
The macula densa stimulates renin release in response to changes in Na+ delivery to distal tubules
Drugs which inhibit renin can be used for what?
To control hypertension
What is the function of atrial naturetic peptides (ANPs)?
Act on the renal collecting tubules to promote Na excretion
What is the part of the uterus which lies above the entrance of the Fallopian tubes?
The fundus
What is the epithelium of the vagina?
Non-keratinised stratified squamous epithelium
What reproductive hormone is secretly directly into the portal system?
Gonadotrophin-releasing hormone
What is the event which induces ovulation?
Increasing plasma oestrogen which triggers a surge of LH
What is secondary amenorrhea?
Absence of menstrual bleeding in a woman for 3 or more months in a woman who hasn’t been pregnant, lactating, having cycle suppression (birth control) or in menopause
When does the Morula stage of embryonic development occur?
Before blastocyst formation
Where does in vivo fertilisation take place?
Fallopian tubes
Which hormone is created by the corpus luteum?
Progesterone
What stimulates the corpus luteum to produce progesterone?
hCG
What is the outermost layer of the ovarian follicle?
Stromal cells
What is oligomenorrhoea?
Infrequent menstrual periods
What is hirsutism?
Unwanted, male-pattern hair growth in women
Name 4 symptoms which are associated with PCOS
- Oligomenorrhoea
- Hirsutism
- Obesity
- Depression
What is the anatomical position of the kidneys?
Left - T11-L2
Right - T12-L3 (lower due to liver)
What are the layers of the kidney?
- Renal capsule (tough fibrous capsule)
- Perineal fat (collection of extraperiotoneal fat)
- Renal fascia (encloses the fascia and suprarenal glands)
What is the outer cortex composed of?
Renal corpuscles and the proximal & distal convoluted tubules
What is a medullary ray?
- A structure in the renal cortex
- Collection of loop of Henle tubules and collecting ducts that originate from the nephrons which have their renal corpuscles in the outer part of the cortex
- Giving a striated appearance to cortex
What is the structure of the inner medulla of the kidney?
- 20 inverted pyramids
- Cross sectional view of the medulla
- Tubular structures: Loop of Henle, collecting ducts and blood vessels
What is the function of the inner pelvis of the kidney?
- Space where urine drains into
- Contains the fat and urine collecting system
What epithelium is the inner pelvis of the kidney lined by?
Transitional epithelium
What is the structure of the inner pelvis of the kidney?
- Continuous with collecting ducts proximally and ureters distally
- Tips of the medullary pyramids project into the renal pelvis collecting duct
What is the structure of the ureters?
- Retroperitoneal tubes which extend from the renal pelvis at the hilum of the kidney to the bladder
What artery supplies the abdominal section of the ureters?
Renal artery & testicular/ovarian artery
What artery supplies the pelvic section of the ureters?
The superior and inferior vesicle arteries
Which nerves supply the ureters?
Testicular, renal and hypogastric nerve plexus
Which nerve supplies the external sphincter of the urethra?
Pudendal nerve (somatic)
Where is the external sphincter of the urethra located?
After prostate
What is the type of nerve supply to the internal sphincter of the urethra?
Sympathetic
Where is the internal sphincter of the urethra located?
Just after the bladder
What is the structure of the bladder?
- Organ of the urinary system situated anteriorly in the pelvic cavity
- It is hollow, highly distensible and round
What is the function of the bladder?
- Collection
- Temporary storage
- Expulsion of urine
What is the vasculature of the bladder?
The internal iliac
What is the outflow of the bladder controlled by?
- The internal and external urethral sphincter
- Specialised smooth muscle walls (detrusor muscle)
Give two properties of the detrusor muscle
- Has sympathetic and parasympathetic innervation
- Contracts to force urine into urethras
What is the nerve innervation of the bladder?
- Sympathetic - hypogastric (T12-L2)
- Parasympathetic - pelvic (S2-S4)
- Somatic - pudendal nerve (S2-S4)
What is the epithelium of the urethra?
Stratified columnar epithelium
What is the structure of pre-prostatic (intramural) urethra for males?
- Begins at the internal urethral orifice, located at the neck of the bladder
- It passes through the wall of the bladder and ends at prostate
What is the structure of prostatic urethra for males?
- Passes through the prostate gland
- The ejaculatory ducts (containing spermatozoa from the testes, and seminal fluid from the seminal vesicle glands) and the prostatic ducts drain into the urethra here
What is the structure of membranous urethra for males?
- Passes through the pelvic floor, and the deep perineal pouch.
- It is surrounded by the external urethral sphincter, which provides voluntary control of micturition
What is the structure of the spongy urethra for males?
- Passes through the bulb and corpus spongiosum of the penis, ending at the external urethral orifice.
- In the glans penis, the urethra dilates, forming the navicular fossa.
- The bulbourethral glands empty into the proximal urethra.
How long is the urethra in females?
4cm
What is the structure of the urethra in females?
- Begins at the neck of the bladder and passes inferiorly through the perineal membrane and muscular pelvic floor
- Opens directly onto the perineum between labia minora
- Anterior to vaginal opening
- No internal sphincter
What happens to urine once it has been produced by the nephron of the kidney?
Drains into the renal pelvis via the collecting ducts
What to the ureters exist as a continuation of?
The renal pelvis within the hilium of the kidney
What is the ureteropelvic junction?
The point at which the renal pelvis narrows into the ureter
What is the position of the ureters as the position of the psoas major?
Retroperitoneal
In what position do the ureters descend down the abdomen?
On the anterior surface of the psoas major
What happens at the area of the sacroiliac joints?
- The ureters cross the pelvic brim and enter the pelvic cavity.
- Also cross the bifurcation of the common iliac arteries
Where do the ureters run once within the cavity?
- Run down the lateral pelvic walls
- Turn anteromedially at the ischial spines and move transversely towards the bladder (Ischial spines)
- Upon reaching the bladder wall the ureters pierce its lateral aspect in an oblique manner. One way valve: High intramural pressures collapses ureters preventing backflow
What are the segments of the nephron?
- Renal corpuscle: The filter
- Proximal convoluted tubule: Reabsorption of solutes
- Loop of Henle: Concentration of urine
- Distal convoluted tubule: Absorption of water and solutes
- Collecting duct: Reabsorption of water and controlling acid and ion balance
What is the structure of the glomerulus?
Capillary tuft from the end of an afferent arteriole within the Bowman’s capsule
What is the structure of the Bowman’s capsule?
Double walled capsule in which fluid moves into from the capillaries (Fluid Glomerulary fluid)
What is the capillary tuft supported by?
Mesangial cells which contain smooth muscle
What is the function of the smooth muscle which supports the capillary tuft?
- Structural support for the capillary and production of extracellular matrix protein
- Contraction of muscle in the glomerulus tightens the capillaries and reduces the glomerular filtration rate.
- Mesangium is also involved in the phagocytosis of glomerular basement membrane breakdown products
How many layers are there in the basement membrane of the glomerular capillaries?
3
What are the 3 layers of the basement membrane of the glomerular capillaries and what are their functions?
- The glomerular capillary wall. (Fenestrated, Holes covered by fibrils which prevent loss of proteins)
- The basement membrane. (Double thickness as composed of BM of capillary and podocytes, Charged against –ve ions)
- The podocyte foot processes.
What transporter is present in the PCT of the kidney and why?
- Na/K pump (cotransport)
- Creates conc gradient for Na which is the driving factor
What are the two cell types in the juxtaglomerular apparatus?
- Endothelium of afferent arteriole
- Macula dense
What is the function of the endothelium of the afferent arteriole of in the kidney?
- Sense BP changes
- Secretes renin in response to a reduction in BP: increases water absorption and so raises BP
What is the function of the macular densa of the kidney?
- Detects changes in sodium levels
- If the filtration is slow, more Na is absorbed
- Sends signal to reduce afferent arteriole resistance and increase filtration
What is the epithelia of the proximal convoluted tubule?
Cuboidal epithelium with microvilli to increase SA for reabsorption
Give 3 features of the proximal convoluted tubule
- Contain lots of mitochondria for the reabsorption of Na and K by active transport
- Also absorb small proteins, glucose, AA, most hormones
- Contain lysosomes which break down absorbed proteins
What is the pathway of the loop of Henle?
Each loop dips down into the medulla and returns to the cortex to form the distal convoluted tubule
What is the basic structure and function of the descending limb of the loop of Henle
Thin (Water absorption by osmosis concentrates urine)
What is the basic structure and function of the ascending limb of the loop of Henle
Thick. Ions reabsorbed by active transport. Leaves waste and water
What is the blood supply of the loop of Henle?
- Afferent arteriole (from corpuscle)
- Peritibular capillaries
- Vasa recta
- Renal veins
- IVC
What is the permeability of descending limb of the loop of Henle?
- Permeable to water
- Osmolality in filtrate increases as water moves out by osmosis
- Impermeable to salts
- Salts remain: osmolality increases
What is the permeability of ascending limb of the loop of Henle?
- Impermeable to water
- Na+ reabsorbed by diffusion and active transport (selection in thicker segment)
What is the epithelium of the distal convoluted tubule?
Cuboidal epithelium
What is the main function of the distal convoluted tubule?
- Regulating acid base balance
- Acidifies urine by secreting hydrogen ions
- Exchanges urinary sodium for body potassium
What is the epithelium of the collecting duct?
Cuboidal epithelium (plumper than loop of Henle and tubules)
What do the distal ends of the collecting ducts combine to form?
The papillae ducts
What is the function of principle cells of the collecting duct?
- Responds to aldosterone - exchanges sodium for potassium
- Responds to ADH - increased water absorption by inserting more aquaporins into apical membrane of cell
What is the function of the intercalated cells of the collecting duct?
Exchanges hydrogen ions for bicarbonate ions
What is the function of the renal pelvis?
Collecting ducts drain into the renal pelvis
What is the epithelium of the renal pelvis?
- Transitional epithelium/urothelium
- Stratified
- Can stretch in response to distension, lines tubes of the urinary tract
What is the process of glomerular filtration?
- Glomerular filtration is the passage of fluid from the blood into Bowman’s space to form the filtrate.
- The distal part of the nephron (tubule) is responsible for secretion and reabsorption.
- As the filtrate travels along the nephron, the cells lining the tubule selectively remove molecules from the filtrate and place them into the blood.
- Tubular secretion occurs mostly in the PCT and DCT where unfiltered substances are moved from the peritubular capillary into the lumen of the tubule.
What reaction does renin facilitate?
That of angiotensinogen to angiotensin I
Where is angiotensinogen from?
The liver
Where is renin from?
The juxtaglomerular apparatus in the kidneys
What reaction does ACE facilitate?
That of angiotensin I to angiotensin II
Where is ACE from?
The lungs
Give 5 effects of angiotensin II
- Aldosterone release from the adrenals
- ADH from the posterior pituitary
- Sympathetic activity (vasoconstriction)
- Thirst
- Reabsorbs Na, Cl, K excretion in DCT
Briefly describe the action of ADH
- Lack of water sensed by osmoreceptors in hypothalamus
- Impulse send to post. pituitary to release ADH
- ADH binds to receptors at collecting ducts
- Aquaporins inserted
- Increased water asborption at collecting ducts
Where are osmoreceptors found?
Hypothalamus
Where is vasopressin (ADH) released from?
Posterior pituitary
What is pre-renal kidney failure?
Anything that decreases the blood flow to the kidney
What is renal kidney failure?
Damage to the internal structure and function of the kidney
What is post renal kidney failure?
Obstruction of the urinary tract
What can cause chronic renal failure?
Commonly caused by conditions which strain the kidneys e.g. hypertension, diabetes, kidney inflammation
What part embryologically are the reproductive organs developed from?
The intermediate mesoderm
What are the two ducts which are present embryologically which eventually form the reproductive tract?
- Mesonephric ducts (Wolffian ducts)
- Paramesonephric ducts (Müllerian ducts)
Which ducts remain embryologically in females?
Müllerian ducts
What happens to the genital chord in females and when?
- Fuse to form the uterus and vagina
- Begins in the third month
What happens to the parts outside the genital cord embryologically in females?
Remain separate and each forms the Fallopian tube
What happens embryologically at around 5 months in the female reproductive system?
A ring-like constriction marks the position of the cervix of the uterus, with this thickening at around the 6th month
Where are gonads from embryologically?
The urogenital ridge
When do the reproductive systems begin to differentiate after fertilisation?
Around the 6/7th week
What do women lack which allows the formation of the female reproductive tract?
The SRY gene and MIH (Müllerian inhibiting hormone)
What are the structures of the vulva?
- Mons pubis
- Labia majora
- Labia minora
- The vestibule
- Bartholin’s glands
- The clitoris
- The vagina
What is the mons pubis?
A fat pad at the anterior of the vulva, which is covered in pubic hair
What are the labia majora?
Two hair-bearing external folds, embryonically derived from labioscrotal swellings. They fuse posteriorly and extend anteriorly to the mons pubis
What are the labia minora?
Two hairless folds of skin, embryologically derived from urethral folds. They lie within the labia majora. They fuse anteriorly to form the prepuce (hood) of the clitoris and extend posteriorly either side of the vaginal opening. They fuse again posterior to the vestibule, creating a fold of skin called the fourchette
What is the vestibule?
The area between and surrounding the labia. The external vaginal orifice (vaginal opening) and urethra open into the vestibule
What are Bartholin’s glands?
Located either side of the vaginal orifice, these glands secrete lubricating mucus from small ducts during sexual arousion
What is the clitoris?
Located under the prepuce and embryologically derived from the genital tubercle. The clitoris is formed of erectile corpora caverosa tissue, which becomes engorged with blood during sexual stimulation
What is the vagina?
A distensible muscular tube, which has roles in sexual intercourse, childbirth and menstruation
What is the cervix?
The lower portion of the uterus. It connects the vagina with the main body of the uterus, acting as a gateway between them
What are the two regions of the cervix?
The ectocervix and the endocervical canal
What is the ectocervix?
The portion of the cervix that projects into the vagina
What is the histology of the ectocervix?
Stratified squamous non-keratinising epithelium
What does the external os mark?
- Opening in the ectocervix
- Marks the transition from the ectocervix to the endocervical canal
What is the endocervical canal (or endocervix)?
The more proximal, and ‘inner’ part of the cervix
What is the histology of the endocervix?
A mucus-secreting simple columnar epithelium
What is the internal os?
Where the endocervix ends, and the uterine cavity begins
What are the functions of the cervix?
- The passage of sperm into the uterine cavity
- To maintain sterility of the upper female reproductive tract
What is the uterus?
A thick-walled muscular organ capable of expansion to accommodate a growing foetus
How is the uterus connected to the vagina and uterine tubes?
- It is connected distally to the vagina
- Laterally to the uterine tubes
What are the three parts of the uterus?
- The fundus
- Body
- Cervix
What is the structure of the fundus of the uterus in the female reproductive tract?
Top of the uterus, above the entry point of the uterine tubes
What is the function of the body of the uterus in the female reproductive tract?
Usually the site for implantation of the blastocyst
What is the function of the cervix of the uterus in the female reproductive tract
- Lower part of uterus linking it with the vagina
- Structurally and functionally different to the rest of the uterus
What are the three tissue layers which the fungus and the body of the uterus are compromised of?
- Peritoneum
- Myometrium
- Endometrium
What is the structure of the peritoneum of the fundus and body of the uterus?
- A double layered membrane
- Continuous with the abdominal peritoneum
What is the structure of the myometrium of the fundus and body of the uterus?
- Thick smooth muscle layer
- Cells of this layer undergo hypertrophy and hyperplasia during pregnancy in preparation to expel the foetus at birth
What is the structure of the endometrium of the fundus and body of the uterus?
- Inner mucous membrane lining the uterus
- Can be further divided into the deep stratum basalis and the superficial stratum functionalists
What is the structure of the deep stratum basalis of the endometrium?
- Changes little throughout the menstrual cycle
- Not shed at menstruation
What is the structure of the superficial stratum functionalis of the endometrium?
- Proliferates in response to oestrogen
- Becomes secretory in response to progesterone
- Shed during menstruation
- Regenerates from cells in the stratum basalis layer
What is the function of the uterine tubes?
To assist in the transfer and transport of the ovum from the ovary, to the uterus
What is the histology of the inner mucosa of the uterine tubes?
- Ciliated columnar epithelial cells
- Peg cells (non-ciliated secretory cells)
What do the ciliated columnar epithelial cells of the inner mucosa of the uterine tubes do?
Waft the ovum towards the uterus and supply it with nutrients
What is the function of the smooth muscle layer of the uterine tubes?
- Contracts to assist with transportation of the ova and sperm
- Muscle is sensitive to sex steroids, and thus peristalsis is greatest when oestrogen levels are high.
What is the structure of the fimbriae of the uterine tubes?
Finger-like, ciliated projections which capture the ovum from the surface of the ovary
What is the structure of the infundibulum of the uterine tubes?
Funnel-shaped opening near the ovary to which fimbre are attached
What is the structure and function of the ampulla of the uterine tubes?
- Widest section of the uterine tubes
- Fertilisation usually occurs here
What is the structure of the isthmus of the uterine tubes?
Narrow section of the uterine tubes connecting the ampulla to the uterine cavity
Where is the Pouch of Douglas found?
- Also known as recto-uterine pouch
- Between rectum and uterus
What ligament joins the ovary and uterus?
Utero-ovarian ligament
What ligament joins the ovary and abdomen?
Suspensory ligament
What ligament joins the pelvis and uterus?
Broad ligament
What is the position of the uterus compared to the vagina?
It is anteverted
What is the position of the uterus compared to the cervix?
It is anteflexed
What happens when FSH binds to granulosa cells?
- Stimulates follicle growth
- Permits conversion of androgens to oestrogen
- Stimulates inhibit secretion
What happens when LH acts on theca cells?
Stimulates production and secretion of androgens
What happens to the HPG axis when there is moderate oestrogen levels?
Negative feedback on the HPG axis
What happens to the HPG axis when there is high oestrogen levels in the absence of progesterone?
Positive feedback on the HPG axis
What happens to the HPG axis when there is moderate oestrogen levels in the presence of progesterone?
Negative feedback on the HPG axis
What is the function of inhibin?
Selectivley inhibits FSH at the anterior pituitary
Briefly describe what happens in the follicular stage of the ovarian cycle
- Follicles begin to mature and prep to release an oocyte
- Follicle begins to develop independently
- Low steroid/inhibin levels, little -ve feedback on HPG, so increase in FSH and LH levels
- Stimulates follicle growth and oestrogen production
- Oestrogen becomes high enough to initiate +ve feedback on HPG
- Levels of GnRH and gonadotrophin increases
- Only reflected in LH levels due to inhibin
Briefly describe what happens in the ovulation stage of the ovarian cycle
- Responding to LH surge, follicle ruptures and mature oocyte is assisted to Fallopian tube by fimbria
- Follicle remains lutenised, secreting oestrogen and now progesterone, giving -ve feedback on HPG
- This, with inhibin stalls the cycle in case of fertilisation
What is the corpus luteum?
The tissue in the ovary that forms at the site of a ruptured follicle following ovulation.
What is the function of the corpus luteum?
Produces oestrogen, progesterone and inhibin to maintain conditions for fertilisation and inmplatation
Briefly describe what happens in the luteal stage of the ovarian cycle
- At the end of the cycle, in the absence of fertilisation, the corpus luteum spontaneously regresses after 14 days. There is a significant fall in hormones, relieving negative feedback, resetting the HPG axis ready to begin the cycle again.
- If fertilisation occurs, the syncytiotrophoblast of the embryo produces human chorionic gonadotrophin (HcG), exerting a luteinising effect, maintaining the corpus luteum. It is supported by placental HcG and it produces hormones to support the pregnancy. At around 4 months of gestation, the placenta is capable of production of sufficient steroid hormone to control the HPG axis.
Where do the theca cells lie?
Outside of the egg
Where do the granulosa cells lie?
They are the main body of the egg
What is the function of the proliferative phase?
Prepares the reproductive tract for fertilisation and implantation. Runs alongside the follicular phase
What happens in the proliferative phase of the menstrual cycle?
- Oestrogen initiates the fallopian tube formation, thickening the endometrium
- Increased growth and motility of the myometrium
- Production of a thin alkaline cervical mucus (to facilitate sperm transport)
What happens in the secretory phase of the menstrual cycle?
- Runs alongside the luteal phase
- Progesterone stimulates thickening of the endometrium into a glandular secretory form
- Further thickening of the myometrium
- Reduction of motility of the myometrium
- Thick acidic cervical mucus production (a hostile environment to prevent polyspermy)
- Changes in mammary tissue and other metabolic changes.
What is the function of menses?
Marks the beginning of a new menstrual cycle
What is coitus?
Sexual intercourse that results in deposition of sperm in the vagina at the level of the cervix
Briefly describe the transport of sperm in the female reproductive tract
- Sperm deposited at the cervix
- Must travel to the ampulla
- Oxytocin stimulates uterine contraction which aids in transporting the sperm
- Capacitation of the sperm occurs
- Allows penetration of the zona pellucida
What is capacitation of sperm?
- Reorganises the sperm cell membrane and results in the tail movement changing from a beat-like action to a thrashing whip-like action to help propel the sperm forward
- The changes in cell membrane exposes acrosome enzymes (allows penetration)
What is the structure of DNA when a gene sequence is coded?
Single stranded DNA
What is the structure of DNA when a promotor sequence is coded?
Single stranded DNA
What binds to tRNA in translation?
Specific amino acids
What is the transcriptome compromised of?
mRNA
Where does alternative splicing, producing different gene products occur?
On mRNA
What is the structure of a protein with two peptide chains held together by cross links?
Quaternary structure
What is the significance of cis/trans and L/D isomers as proteins?
Differ in tertiary structure
Give two examples of secondary proteins
Alpha helixes and beta sheets
What causes sickle cell anaemia?
An autosomal recessive inherited condition substituting an amino acid in the beta globin chain
What happens to the haemoglobin in sickle cell anaemia in hypoxia?
It polymerises
What causes sickling in sickle cell anaemia?
By binding to the cytoskeleton
How do sickle cells cause capillary occlusion?
By binding to and activating endothelial cells, causing inflammation
How can sickle cell disease be treated?
With hydroxyurea because it increases synthesis of foetal haemoglobin
What are the three components of total body water and how is the volume divided?
- Intracellular (28L)
- Interstitial (11L)
- Intravascular (3L)
Name one component which is used to calculate osmolality
Urea
Give an example of insensible loss
Sweating due to fever
What are the consequences of a low blood albumin?
- Causes a decrease in oncotic pressure
- Water diffuses from the blood into the interstitial fluid
Where is ADH synthesised?
The hypothalamus
Where is aldosterone synthesised?
The adrenal cortex
Where is the principle site of renin production?
Juxtaglomerular cells
What does renin allow the conversion of?
Angiotensinogen to angiotensin I
What is the physiological response to excess water consumption in a short period?
- Osmolality falls
- ADH secretion stops
- Increased urine volume
How can the relationship between the cardiac output and blood pressure be described in the autonomic nervous system?
Parasympathetic nerves increase peripheral blood vessel diameter thereby decreasing vascular resistance and decreasing blood pressure
When does atrial and ventricular systole happen?
Together
What does an increase in left atrial end systolic pressure indicate?
Mitral valve stenosis
What does an increase in left ventricular end diastole pressure indicate?
Left heart failure
What is the function of the ductus arteriosus in the foetal cardiovascular system?
Allows blood to bypass the foetal lungs by shunting it from the pulmonary artery to the aorta
What is the equation for cardiac output?
Heart rate x stroke volume
What is pulmonary oedema in the presence of normal central venous pressure a sign of?
Left heart failure
What is severe pulmonary hypertension a cause of?
Right heart failure
What are some symptoms of biventricular failure?
- Shortness of breath
- Severe peripheral oedema
- Ascites after a heart attack
What is the normal pathway of conduction through the heart?
- SAN
- Contraction of atria
- AVN
- Bundle of His
- Purkinje fibres
- Contraction of ventricles
Which artery most frequently supplies the AVN?
The left coronary artery
What do chemoreceptors sense?
PaCO2 levels
What two centres are important in the control of human breathing?
Pons and medulla oblongata
Where does the larynx’s main motor function come from?
The recurrent laryngeal nerve
Where should an emergency chest drain take place?
The second intercostal space below the second rib
What is a difference in structure between the left and right bronchi?
The right main bronchus is more vertically disposed than the left main bronchus
How thick is the gas exchange surface of the lung and is it active or passive?
- 1 micron thick
- Mostly passive
What happens to the diaphragm during inspiration?
Contracts and descends
Define the physiological dead space?
The volume of air in the trachea that doesn’t contribute to gas exchange plus the volume of air in the alveoli that doesn’t contribute to gas exchange
What does hypoxia in the lung cause and why?
If part of the lung has low oxygen, you don’t want to send blood there as it can’t pick up oxygen
What factors does arterial PaCO2 depend on?
A constant, the production of carbon dioxide and alveolar ventilation
What is the equation for arterial PaCO2?
PaCO2 = (k x production of carbon dioxide) / alveolar ventilation
What is the oxygen dissociation curve influenced by?
Changing affinity for sequential oxygen molecule binding
What happens in respiratory acidosis?
- PaCO2 initially rises
- PO2 is stable roughly
Define FEV1
The volume of air expelled after one second of forced expiration
What does the carbon monoxide single breath transfer measure?
Gas exchange into the alveolar capillary
What happens to the lungs at ascent?
- Pressure of inspired oxygen falls
- CO2 goes down as you hyperventilate
What are the features of pulmonary oxygen toxicity (Lorraine Smith effect)
- Shortness of breath
- Cough
- Chest tightness
- Substernal pain
Where is somatostatin secreted from?
D cells
Where is histamine secreted from?
Enterochromaffin cells (ECL)
Where is gastrin secreted from?
G cells
What is the function of intrinsic factor?
- Produced in the stomach
- Allows absorption of vitamin B12 in the terminal ileum
What is the function of R proteins?
Carry out protection of vitamin B12 from degradation by stomach acid
How do NSAIDs irritate the stomach?
By inhibition of gastrointestinal mucosal cycle-oxygenase activity (COX)
What do NSAIDs lead to the production of?
Prostaglandins
How many layers of muscle are there in the stomach wall?
3
What is the change in cell type seen in the lower oesophagus after prolonged reflux of acid?
Stratified squamous to columnar
What is the action of the proton pump on the parietal cells of the stomach?
K into cell, H out of cell
What stimulates the release of acetylcholine from parietal cells?
The vagus nerve (parasympathetic system)
Where does the common bile duct drain?
The duodenum
What supplies atrial blood to the jejunum?
The superior mesenteric artery
What is the first location that fat is acted upon by lipase enzymes when passing through the GI tract?
The oral cavity
Name 4 things which are present in the portal hepatis
- Left & right hepatic ducts
- Left & right hepatic arteries
- Portal veins
- Hepatic branch of vagus nerve
What are the structures classed as the foregut in embryology?
- Lower 1/3 of oesophagus
- Proximal 2 parts of duodenum
- Gallbladder
- Pancreas
Where is pepsinogen produced?
Chief cells
