All Physiology Final Condensed Flashcards
internal respiration
intracellular mechanisms which consume oxygen and release carbon dioxide
external respiration
sequence of events that lead to the exchange of oxygen and carbon dioxide
ventilation - exchange - transport - exchange
Boyle’s Law
as the volume of gas increases the pressure exerted by the gas decreases
i.e. air flows down a concentration gradient
lung to thorax linkage
negative intrapleural pressure and the intrapleural fluid cohesiveness (polarity dependent)
inspiration vs expiration
active process
passive process
what does a pneumothorax do to the pressures
abolishes the transmural pressure gradient
what causes lung recoil
elastic connective tissue and alveolar surface tension
surfactant
decreases surface tension
secreted by T2 alveoli
Law of LaPlace
smaller alveoli are more likely to collapse
surfactant has a greater affect on the smaller alveoli
forces keeping alveoli open
transmural pressure gradient
pulmonary surfactant
alveolar interdependence
forces promoting alveolar collapse
elasticity of the lungs
alveolar surface tension
major muscles of inspiration
accessory muscles
active expiratory muscles
diaphragm and external intercostals
sternocleidomastoid, scaleus and pectoral
abdominal muscles and internal intercostals
Tidal volume
Inspiratory reserve volume
expiratory reserve volume
residual volume
volume of air entering and leaving the lungs
extra vol of air that can be inspired above TV
extra vol of air that can be expired above TV
minimum vol of air that the remains in the lungs even after forceful expiration
inspiratory capacity
forced residual capacity
vital capacity
total lung capacity
max vol of air that can be inspired at the end of normal inspiration
vol of air left in the lungs at the end of normal expiration
max vol of air that can be moved out in a single breath following maximal inspiration
total vol of air that the lungs can hold –> not possible to be measured
spirometry
restrictive and obstructiev lung disease diagnosis
FVC = forced vital capatcity
FEV1 = forced expiratory volume in 1 second
FEV1/FVC normally >70%
primary determinant of airway resistance
radius of conducting airway
flow =
change in pressure /radius
what % energy expenditure is work of breathing
3%
increases when resistance increases and compliance decreases
pulmonary ventilation sum and meaning
TV x RR
air breathed out per min
alveolar ventilation
vol of air exchanged between the alveoli and atmosphere per minute
inspired air available for gas exchange
less than PV because of anatomical dead space
what is ADS and how to calculate
space not available for gas exchange
ADS = (RV - dead space vol) x RR
ventilation meaning
perfusion meanng
rate at which gas passes through the lungs
rate at which blood is passing through the lungs
alveolar dead space meaning
areas with inadequate perfusion
pulmonary arterioles vs systemic arterioles response to decreased oxygen
PA = vasoconstriction
SA = vasodilation
and vice versa
alveolar membrane gas exchange rate determined by
partial pressure
diffusion coefficient
surface area
thickness of the membrane
Dalton’s Law
partial pressure - total pressure exerted by a gas –> sum of the partial pressures of all the individual components in a gas mixture
what pressure does water vapour account for in the lungs
47mmHg
respiratory exchange ratio in a mixed diet
0.8
diffusion coefficient
solubility of gas in a membrane
large grandient between PAO2 and PaO2 means
problems with gas exchange or L to R shunt in the heart
Fick’s Law
amount of gas moved across a membrane is proportional to the SA and inversely proportional to the thickness of the membrane
non-resp function of lungs
route for water loss and heat elimination
enhanced venous return
helps maintain acid base balance
enables speech and vocalisation
defence against inhaled foreign bodies
smell by nose
removes, modifies or inactivates various materials passing through the circulation
Henry’s Law
amount of gas dissolving in a vol at a constant temp is proportional to the partial pressure
what is the main deteminant of Hb saturation
PO2
oxygen delivery index =
oxygen content of arterial blood x cardiac index
Bohr effect
shifting of sigmoid to right is incr temp incr 2,3-BP incr in PO2 incr in [H+]
HbF vs HbA
F = 2 alpha, 2 gamma (higher affinity for O2 as less interaction with 2,3-BP) A = 2 alpha, 2 beta
presence of myoglobin
muscle damage
found in cardiac and skeletal muscle
Haldane effect
removal of oxygen from Hb allows it to pick up CO2 genertaed H+
chloride shift
as bicarbonate moves out cell Cl moves in to maintain charge
what controls the rhythm of respiration
Pre-Botzinger complex
neurons above the medulla vs below medulla in resp
above = prolong ventilation below = cease ventilation
normal expiration
forceful expiration
normal inspiration
passive - gaps in firing of dorsal neurons
active - firing of ventral neurons
active - firing of dorsal neurons
pneumotaxic centre
apneustic centre
terminates inspiration prolongs inspiration (changes rhythm)
Hering-Bruer Reflex
pulmonary strech receptors only activated at high tidal volumes (cease inspiration)
what do peripheral chemoreceptors sense
tension of oxygen and carbon dioxide
[H+] in the body
what do central chemoreceptors sense
[H+] of the CSF
separated from body by the BBB
CSF contains less protein and so less change in ion concs and the BBB is impermeable to many ions
pacemaker potential
funny current
(slow Na influx)
decreased K efflux
transient Ca influx (T channels)
rising phase of nodal cells
Ca influx (L channels)
falling phase of nodal cells
K efflux
AVN cells are
slow condution
small in diameter
to increase nodal delay to allow atrial systole to precede ventricular systole
Phase 0 Phase 1 Phase 2 Phase 3 Phase 4
0 = fast Na influx 1 = transient K efflux 2 = Ca influx (L channels) 3 = K efflux 4 = resting membrane potential restored
what dominated on the SAN in resting conditions
vagal tone
ACh affect on HR and its opposite
ACh slows HR
Atropine incr HR - compeitive inhibitor
SAN and AVN - ANS supply
sympathetic and parasympathetic
what do desomsomes enrsure in cardiac cells
tension develops - as myosin and actin slide over one another
Role of calcium in contraction
Ca binds to troponin on actin
exposes the myosin binding site
allows contraction (slide over one another using ATP)
prolonged Ca influx = stronger contraction
Frank-Starling curve
more the ventricle is filled in diastole the greater the volume ejected
optimal length of cardiac vs skeletal muscle
C = when contracting S = when resting
normal length of systole and diastole
S = 0.2s D = 0.5s
an increase in the opening of calcium channels and so peak pressure leading to an increased length of systole is mediated by what
cAMP
5 events in cardiac cycle
Passive filling atrial contraction isovolumetric ventrciular contraction ventricular ejection isovolumetric ventricular relaxation
blood pressure definition
outwards (hydrostatic) pressure exerted by the blood on the blood vessel walls
pulse pressure range
30-50 (difference between systolic and diastolic)
MAP calculations and normal range
[(2 x diastolic) + systolic]/3
1/3 pulse pressure + diastolic
70-105
MAP of what is needed to perfuse vital organs
60
short term and long term control of MAP
Short term = baroreceptor reflex
Long term = hormones and blood volume
resistance to flow is proportional and inversely proportional to …
proportional to blood viscosity and length of blood vessel
inversely proportional to radius of blood vessel
adrenaline on A vs B2 and were are they predominant
A = vasocontriction - skin, gut, kidney arterioles B2 = vasodilation - cardiac and skeletal muscle
humoral agents causing vasoconstriciton
serotonin
TXA2
endothelin
humoral agents causing vasodilation
histamine
bradykinin
nitrous oxide
production of NO
eNOS (enzyme) from L arginine
NO diffuses and activates cGMP (secondary messenger) to bring about vascular smooth muscle relaxation
endothelial vasodilators
anti-thrombotic
anti-inflammatory
anti-oxidant
endothelial vasoconstrictors
pro-thrombotic
pro-inflammatory
pro-oxidants
venous return is determined by
venomotor tone (sympathetic)
another name for ADH
arginine vasopressin
describe RAAS
renin released from kidneys
renin binds to angiotensin –> angiotensin I
angiotensin I converted to angtiotensin II by ACE
angiotensin II stimulates aldosterone release from adrenal cortex
where is ACE produced
pulmonary vascular endothelium
what is the rate limiting step in RAAS
renin release
where is renin released from
juxtaglomerular apparatus of the kidneys
what controls the RAAS system
renal artery hypotension
stimulation by renal sympathetic nerves
decreased Na concentration in renal tubular fluid
when is NP released
due to cardiac distension or neurohormonal stimuli
ANP vs BNP
ANP = 28 AA synthesised and stored in atrial muscle, released in response to atrial distension (hypervolaemic)
BNP = 32 AA synthesised by ventricles and brain - prepro-BNP –> pro-BNP –> BNP
serum BNP and N terminus of prepro-BNP can be measured in suspected heart failure
where is ADH stored
posterior pituatry
what do you give in
cardiogenic shock
anaphylatic shock
septic shcok
no fluids - inotropes
adrenaline
vasopressors
ATP is a potent …
vasodilator
grey or white matter is very sensitive to hypoxia
grey
what arteries form the circle of Willis
basilar and carotid
when does autoregulation to the brain fail
when MAP isnt between 60-160mmHg
if less than 50mmHg then brain damage quickly ensues
cranial perfusion pressure =
MAP - ICP (intracreanial pressure - normally 8-13mmHg)
pulmonary circulation pressure and resistance
20-25mmHg
10% of that of the systemic circulation
where do precapillary sphincters regulate blood flow
mesentery
how are exchangable proteins moved across the capillary wall
by vesicular transport
Net filtratuion pressure =
(Pc + PIi) - (PIc + Pi)
how does excess fluid return to the circulation
via lymph and lymphatics
causes of oedema
raised capillary pressure
reduced plasma osmotic pressure
lymphatic insufficiency
changes in capillary permeability
4 layers of GI tract wall and what do they contain
mucosa - mucous membrane containing the lamina propria and the muscularis mucosae
submucosa - connective tissue containing the large blood and lymph vessels, glands and submucous plexus
muscularis externa - circular muscle layer containing the myenteric plexus, longitudinal muscle layer
serosa - connective tissue
smooth muscle in the GI tract is electrically coupled by
gap junctions
how are GI pacemaker cells modulated
by enteric and autonomic
what is force in the GI tract related to
number of action potentials
where are the ICCs
in between the smooth muscle layers coupling together and with the smooth muscle
slow waves can be referred to as
basal electronic rhythm - rate varied along the tract
excitatory and inhibitory influences on the GI tract
E = incr gastric, pancreatic and small intestine secretions, blood flow and smooth muscle contraction I = relaxation of some sphincters and receptive relaxation of the stomach
what do the myenteric and submucous plexuses regulate
Myenteric = motility and sphincters Submucosal = epithelia and blood vessels
local, short and long reflexes examples
peristalsis intestino-intestinal inhibitory reflex (distension causes inhibition of muscle activity in adjacent areas) gastroileal reflex (vago-vagal reflex - incr gastric activity causes incr propulsive activity in terminal ileum)
what happens to the propulsive segment in response to distension
longitundinal muscle relaxes - release of VIP and NO from inhibitory motoneurone
circular muscle contracts - release of ACh and substance P from exitatory motoneurone
what happens to the receiving segment in response to distension
longitudinal muscle contracts - release of ACh and substance P from exitatory motoneurone
circular muscle relaxes - release of VIP and NO from inhibitory motoneurone
what do the ANS and CNS regulate in terms of obesity
ANS = activity of the neuroendocrine activity CNS = energy balance through behaviour
lesioning the
- ventromedial hypothalamus
- lateral hypothalamus
causes:
ventromedial = obesity lateral = leanness
CCK
satiation signal
secreted from enteroendocrine cells in D and J
stimulates hindbrain
released in proportion to lipids and proteins
PYY (3-36)
satiation signal
secreted from endocrine mucosal L cells
inhibits motility and slows emptying, reducing food intake
GLP-1
satiation signal
pro-glucagon gene released from L cells in response to food ingestion
inhibits gastric emptying, reducing food intake
OXM
satiation signal
released from oxynitic cells and L cells
after meal to suppress appetite
Obestatin
released from cells in the stomach and duodenum
ghrelin
hunger signal
released from oxynitic cells
levels increase before meals and decrease after meals
what hormones relay fat store to the brain
leptin (made and released from fat cells) –> reduced levels mimic starvation causing an unrestrained appetite. circulated in proportion to adiposity. pleiotrophic hormone. can develop resistance
insulin (made and released from pancreatic cells) - circulates in proportion to adiposity
obesity drugs
orlistat - inhibits pancreatic lipase decreaseing TAG absorption
liraglutide - GLP-1 receptor agonist
orad vs caudad stomach
O = tonic contractions, oxynitic gland area C = phasic contractions, pyloric gland area
duodenal factors
fat
acid
hypertonicity
distension
HCl
oxynitic secretion
activates pepsin to pepsinogen
denatures proteins and kills microorganisms
Pepsinogen
oxynitic secretion
inactive precursor of pepsin
Intrinsic factor and gastroferrin
oxynitic secretion
bind vit B12 and Fe2+ respectively
Histamine
oxynitic secretion
stimulates HCl secretion
mucus
oxynitic secretion
protective
gastrin
pyloric secretion
stimulates HCl secretion
somatostatin
pyloric secretion
inhibits HCl secretion
mucus
pyloric secretion
protective
what cranial nerve controls the cephallic phase
vagus
what produces mucosa
prostaglandins - reduce acid secretion and increase mucus and bicarbonate secretions and increase mucosal blood flow
what triggers the MMC (migrating motor complex) and what suppresses it
motilin
gastrin and CCK
what cells secrete: gastrin CCK secretin motilin GIP GLP-1 ghrelin
G cells - gastrin I cells - CCK S cells - secretin M cells - motilin K cells - GIP L cells - GLP-1 Gr cells - ghrelin
what enzyme catalyses the conversion of inactive proteases to active ones in the mucosal cells
enterokinase
what are the exocrine secretions of the pancreas
digestive enxymes
aqueaous NaHCO3- solution
whats the only enzyme that can break the alpha 1,6 linkages
isomaltose
primary vs secondary lactase insufficiency
congenital
primary = lack of lactase persistance allele secondary = damage/infection to proximal small intestine congenital = rare autosomal recessive disorder
undigested lactose causes
acidication of the colon and increase in osmotic load
glucose absorption is mediated by …
SGLT1 secondary transport - symport of Na and glucose into the cell
fructose absorption is mediated by …
GLUT 5
monosaccharide exit mediated by …
GLUT 2
what active enzymes are endopeptidases and what is the product
trypsin
chymotrypsin
elastase
–> oligopeptides
what active enzymes are exopeptidases and what is the product
carboxypeptidase A
carboxypeptidase B
–> single amino acids
what enzyme completes protein digestion
pancreatic proteases
cytoplasmic peptidases
hydrolyse di and tri peptides
cystinuria and Hartnup disease
C = B0AT1
H = b0+AT
Na dependent and Na independent protein absorption on the brush border
gastric lipase
secreted in response to gastrin
produces fatty acids and diacylglycerol
pancreatic lipase
secreted from acinar cells in response to CCK which also stimulates bile flow
procolipase activated by …
trypsin
Ca absorption
passive
regulated by 1,25 dihydroxyvitamin D3 and parathyroid hormone
absorption of iron
ferrous form (Fe2+) binds to gastroferrin which reduces it to the absorbable ferric form (Fe3+)
what takes up vit B12 in the saliva
hepatocorin
functions of the colon
release K, HCO3 and mucus
absorb Na, Cl and H2O and short chain fatty acids
what mediates electrolyte absorption by osmosis
colonocytes
mechansisms for water reabsorption of water
Na/glucose cotransport - causes simultaneous absorption of Cl
Na/AA cotransport - NHE2 and NHE3 contribute to the movement of Na across the membrane, NHE1 is a pH housekeeper
Na/H exchange - stimulated by luminal HCO3- - regulated by cGMP, cAMP and Ca
Parallel Na/H and Cl/HCO3- exchange
ENaC - epithelial sodium channels - aldosterone opens them, places them in the membrane and increases their synthesis
CFTR activation is …
secondary due to the generation of secodary messengers such as cGMP, cAMP, and Ca
causes of diarrhoea
impaired absorption of NaCl
excessive secretions
hypermotility
non-absorbable or poorly absorbable solutes in the intestinal lumen
emesis is coordinated by …
VC in the medulla oblongata
how does vomiting come about
stimulus –> enterochromaffin cells in mucsa release mediators like 5-HT –> depolarisation of sensory afferent terminals in mucosa –> AP discharge from vagal afferents to brainstem –> coordination of vomiting
what does the CTZ lack and where is it
lacks a BBB
area postrema
what is the NTS
nucleus tractus solitarus
what does fat metabolism involve
processing chylomicron remnants
synthesis of lipoproteins and cholesterol
ketogenesis in starvation
what does protein metabolism involve
synthesis of plasma proteins
transamination and deamination of AA
conversion of ammonia to urea
what are secondary bile acids conjugated with in the liver
glycine or taurine
what do resins do
bind to bile salts and prevent their reabsorption –> lowers LDL
what is CYP450
haem protein in the ER of liver hepatocytes mediating oxygenation reactions
what are theraputic options for encephalopathy
lactulose
antibiotics
