MRCS Physiology Flashcards
5 reasons for right shift Hb on curve?
Increased CO2, increased temp, increased H+ conc (low pH), increased DPG, HbSS
6 reasons for left shift Hb O2 curve?
Low temp, low DPG, low CO2, low H+ (increased PH), met/CO Hb and fetal Hb
What shift does fetal Hb cause in o2 Hb curve?
Left
pH of venous blood normally?
5.33
What do kupffer cells of liver do?
Recycle old red blood cells
Vitamin D production site and 2 step hydroxylation process sites?
Produced in skin via sunlight (D3)
Then hydroxylated in liver to 25hydroxy vit D calcifediol
Then hydroxylated again in kidney to 1 25 HVD calcitriol
How does activated vit D work? 3 ways
Increases Ca and Po4 uptake gut
Increases renal reabsorption of Ca and Po4
Promotes osteoclast activity
Where is calcium absorbed in GI tract?
Duodenum
What do haptoglobins do? Why might they be low?
Eliminate free Hb from plasma
In hemolytic anaemia get saturated and absorbed by RES
What does platelet derived growth factor do? What disease process is it implicated in?
Stimulates intimal smooth muscle proliferation and synthesis of collagen and elastin
Development of atheroma
What secretes platelet derived growth factor? 2 things
Macrophages
Endothelium
What is the blood supply to atheromatos plaque called?
Vasa vasorum
Bph stands for?
Benign prostatic hyperplasia
What does thymus do?
Receives immature T cells and does positive and negative selection
4 phases of wound healing w time scales?
Haemostasis - minutes
Inflammation - day 1 to 5
Regeneration - day 5 - 56
Remodelling - 6 weeks to 1 year
When does granulation tissue appear in wound healing?
Regeneration phase - day 5 to 56
Stage 1 of haemorrhagic shock?
Less than 750 ml blood (15%)
Normal everything, normal or high pulse pressure
What is circulating volume in L approx?
5L
Stage 2 of haemorrhagic shock?
750-1500 mls 15-30%
Tachycardia, falling pulse pressure, mild high RR but normal BP
Stage 3 of haemorrhagic shock?
1500-2000mls 30-40%
Tachy over 120
Bp drops
Confused
Stage 4 of haemorrhagic shock?
Anuric less than 5 ml per hour
BP drops
Lethargic and drowsy
If BP drops which stage of haemorrhagic shock?
At least 3
If tachycardia with decrease pulse pressure which stage of haemorrhagic shock?
At least 2
What is type 2 hypersensitivity? Examples?
Cytotoxic- IgG/M against cell surface antigens e.g. ABO incompatibility/AIHA, Goodpastures
Type 3 hypersensitivity? Examples?
Immune complex IgGMA deposition, soluble antigens, e.g. SLE or aspergillus
Type 4 hypersensitivity? Examples?
T cell mediated delayed immune
E g. Granuloma formation, contact dermatitis, GVHD
Mnemonic for types 1 to 4 hypersensitivity?
A naphylactic C ytotoxic I mmune complex D elayed immune Has bad allergies
3 phases of secretion of gastric acid? Mediators?
Cephalic (smell/taste) - vagal mediated Hcl and gastrin release
Gastric (stretch) - gastrin release
Intestinal (duodenal food) - CCK and secretin
3 factors increasing gastric acid secretion?
Gastrin
Vagal nerve stimulation
Histamine
3 things reducing gastric acid secretion?
CCK
Secretin
Somatostatin
How does somatostatin reduce gastric acid release?
By inhibiting histamine
What secretes gastrin? What does it do?
G cells
Increases HCl pepsinogen and IF secretion
Increases gastric motility and emptying
What secretes CCK? What does it do? In response to?
I cells in upper duodenum in response to fat TGLs and protein
Delays gastric emptying increases pancreatic secretions and causes gallbladder contraction
What secretes secretin? What does it do?
S cells in duodenum
Increases pancreatic secretions in response to acid and chyme
What does VIP do and where is it secreted?
Small intestine and pancreas - increase pancreatic secretions in response to neural stimulation
What secretes somatostatin? What does it do?
D cells in pancreas and stomach
Stops everything basically, inhibits histamine and produces mucous
Which part of the immune system is complement involved in?
Innate immune system
Which part of the complement system is involved in response to pathogen surfaces?
MBL
What arr the 3 parts of complement system?
Classic - Ag/Ab complexes
Alternative - activating surfaces e.g. pathogen or injured tissue
MBL - direct response to pathogen surfaces
What is classical complement system activated by?
AgAb complexes
What is alternative complement system activated by?
Surfaces e.g. injured tissue or pathogen
Which part of complement system activates mast cells?
Anaphylotoxin - C5a
Which part of complement system primes opsonization for phagocytosis?
C3b
What is main complement mediator for inflammation and chemotaxis?
C3a
What forms the MAC in complement and what pathway is this called?
C5b to c9
Lytic pathway
MAC Deficiency can lead to which infections?
Neisseria and gram negatives
What innervates long head of triceps and what does it do?
Radial nerve - stabilises shoulder in abduction
What cord and roots form radial nerve?
Posteiror cord
C5 to t1
What is the branch of the radial nerve in the arm innervating supinator, extensor carpi radialis longus and brevis and abductor policis longus?
Posterior interosseus
What nerve innervates brachioradialis?
Radial
7 things innervated by radial nerve?
Triceps Brachioradialis Supinator Extensor carpi radials Extensor carpi longus and brevis Abductor policis longus
What is the extrinsic pathway activated by? What does this do?
Tissue factor
Activates 7 to 7a
Which test measures extrinsic pathway?
PT
Which test measures intrinsic pathway?
APTT
What activates intrinsic pathway? What does this do?
Exposed collagen via tissue injury
Does TENET
Twelve Eleven Nine Eight Ten activation
What is the joint goal of intrisnic and extrinsic coag pathways?
Activating factor 10 for the common pathway
What does factor Xa do? What helps it?
Actiavtes prothrombin to thrombin (2 to 2a)
Reauires factor 5 to 5a and calcium
What does thrombin do in coag cascade?
Activates fibrinogen to fibrin (1 to 1a)
What clotting factor cross links fibrin to form clot with platelets?
13a
How do protein C and S work? What do they do? Relation between warfarin and protein C?
Modulate coag cascade - anticoagulants
Warfarin inhibits protein C to transients make clotting more likely
Where are the cell cycle stop checkpoints? What are they?
G1, S/G2 and M
G1 - restriction point, go to G0 fails
S/G2 - Dna damage checkpoint
M - spindle checkpoint
Outline PMAT?
P - spindle fibres form, membrane breaks down
PM - spindles attach to chromosomes
M - chromosomes align
A - centromes divide and sister chromatids migrate to opposite poles
T - nuclear membrane reforms, chromosomes decondense and fibres disappear
Where is carotid body? What about carotid sinus?
Body is behind carotid bifurcation
Carotid sinus is at origin of ICA
What type are carotid body receptors and what are the stimulated by primarily? To cause what?
Chemoreceptors stimulated primarily by low O2 to stimulate ventilation
Hormonal control of lactation?
Prolactin causes development of breast, mammary gland proliferation, milk production following suckling
Oxytocin causes contraction and milk expulsion in response to suckling
What does PTH do to phosphate?
Reduces reabsorption in PCT to lower level
Where is most phosphate reabsorbed in kidney?
PCT
Why does PO rise in AKI?
Less filtration
How does calcitonin lower calcium?
Suppresses osteoclast activity to reduce bone breakdown
With what percentage of stenosis is carotid endarterectomy indicated?
Over 70%
Which antibody type is involved in alternative complement payhway?
IgA
At which spinal level is ampulla of vater?
L2
What do alpha receptors do?
Vasoconstriction peripherally
What do beta receptors do?
Positive chronotropism and isotropic for heart
Also bronchodilation
How does norad work?
Peripheral vasoconstriction via alpha agonism
How does dobutamine work?
Beta 1 agonism - increases contractility and cardiac output
Around what days does spinal cord extend rostrally and caudally in development?
D 24 and 26 respectively
What is a Jefferson fracture?
Bilateral C1 fracture anteiror and posterior due to axial loading
What is a hangman’s fractufe?
Bilateral pars fracture due to hyperextension
Describe the low and high dose dexamethasone test?
Give low dose and check cortisol - should be suppressed
Give high dose and check cortisol - if suppressed by high but not low suggests primary cushings disease
What suggests cushings disease in dex suppression test?
High dose suppresses but not low
What if cortisol not suppressed by high or low dose dex? What to check then?
Suggests not Cushings disease - check ACTH. If high suggests ACTH oma e.g. ectopic lung, if low suggests primary hypercortisolism
What is cushings disease?
ACTH secreting pituitary adenoma (secondary hypercortisolism)
What does otic ganglion do? Associated nerve?
Parasymp to parotid
CN 9
What does ciliary ganglion do? Associated nerve?
Eye - parasymp via CN3 to pupillary sphincter and ciliary muscle
What does pterygopalatine ganglion do? Associated nerve?
Facial - greater petrosl nerve
To lacrimal glands and nasal mucosa
What does submandibular ganglion do? Associared nerve?
Chorda tympani of 7, lingual nerve of V3
To submandibular and sublingual glands secretomotor
What does stellate ganglion do? Where? Relevance?
Sympathetic - can be cut to reduce raynauds or hyperhidrosis sx
What vessels usually used for AVF in ACF?
Cephalic vein brachial artery
Or brachiobasilic
What is JVP vessel?
IJV because estimation of CVP
Adenocarcinoma is generally what to radiotherapy?
Insensitive
Which infection is associated with sulfur granules?
Actinomycosis
Where does nadolacrimal duct drain?
Inferior meatus
Which muscle specifically is affected by recurrent laryngeal nerve palsy? Effect?
Posterior cricoarytenoid - failure of abduction of vocal folds
What cartilage is at C6? Significance?
Cricoid
Trachea begins below this
What is cardiac index? Usual?
Cardiac output over body surface area
Usually 2.5-4
What is only intrinsic muscle of larynx not innervated by rec laryngeal nerve?
Cricothyroid - ext branch of sup
Sensation of ttachea below vocal cords?
Rec laryngeal nerve
What immediate volume of blood is massive haemothorax from chest drain?
1500ml
Within what distance of anal canal is AP resection suitable?
Lesss than 8cm
Flow is directly proportional to what 2 things?
4th power of radius
Pressure head of flow
Flow is indirectly proportional to what 2 things?
Viscosity
Length of tube
Most important determination factor of flow?
Radius of tube
What muscle do inf wpigastrics lie on inner surface of? What are they covered by?
Transcersus abdominis
Covered by parietal peritoneum
Blood supply to breast?
Lat thoracic from SCA and internal thoracic/mammary from axillary
What does anatomical neck of humerus fracture have risk of? Why?
AVN of head - because of circumflex vessels
Surgical neck of humerus fracture can cause what nerve damage?
Axillary
Resting myocardial blood flow?
250 ml per min 5%
Borders of popliteal fossa?
Lateral - 2 heads of gastrocneums inferiorly, biceps femoris sup lat, semimemb/tend sup med
