Overview Flashcards
Function of Parietal Cells
Secrete: -Gastric acid - intrinsic factor Stimulated by: - acetylcholine - Gastrin - Histamine Function: - Activate pepsin - kill bacteria
Function of ECL cells
Secrete: - Histamine Stimulated by: - Acetylcholine - Gastrin Function: - Stimulate gastric acid secretion
Function of Chief Cells
Secrete: - pepsinogen - gastric lipase Stimulated by: - Acetylcholine - Acid Secretion Function: - Break down proteins - Break down lipids
Function of D Cells
Secrete: - Somatostatin Stimulated by: - Stomach acid Function: - Inhibit gastric acid secretion
Function of G Cells
Secrete: - Gastrin Stimulated by: - Acetylcholine - Peptides - Amino Acids Function: - Stimulate gastric acid secretion
Regulation of stomach function in the cephalic phase is different than the gastric phase because?
Cephalic phase stimulates:
G cells + Parietal Cells + ECL cells
Gastric phase stimulates:
G cells only
Function of Secretin
Produced by cells lining the duodenum in response to acid in the stomach
What is secretin’s pathway?
IN: enters pancreas via arterial blood supply
OUT: exits pancreas via duct
Long Reflexes vs. Short Reflexes of the GI tract?
LONG: - Controlled by CNS - Regulated by GI activity - Use Feedforward - Control cephalic phase SHORT: - Controlled by ENS - Regulate motility & secretion - Use Feedback - Control gastric phase
Intestine inhibits secretion of gastrin with?
CCK
GLP-1
Secretin
What is the function of CCK?
Provide gall bladder stimulation
Pancreatic enzyme secretion
What hormones cause insulin to be released?
GIP
GLP-1
Preparing for glucose
Target of insulin vs glucagon
Insulin:
Striated muscle, adipose & liver
Glucagon:
Liver
Where do sympathetic pre-ganglionic fibres originate?
thoracic and lumbar segments of the spinal cord
lateral horn of grey matter
Wilder Penfield
neurosurgeon treating epilepsy
Creating maps of sensory and motor areas of the brain
Merkel’s Disk
superficial
small
slow
Sustained fine touch
Meissner’s Corpuscle
superficial
small
fast
change in fine touch
Ruffini’s Corpuscle
deep
large
slow
sustained gross touch
Pacinian Corpuscle
deep
large
fast
vibration
Consensual pupil response
Light shining into left eye
Split at the optic chasm
Travels down both optic tracts
Midbrain controls reflex to constrict/dilate pupils
Macula
Heavily pigmented area
Where all optic nerves leave
What retinal cells generate AP’s?
Ganglion cells
Which photoreceptor cells have the higher acuity and lower convergence?
Cones
Dark Current
Opsins (GPCR) not active = cation channels open
Influx of Na, Ca = cell depolarization
Cell releases NT when no light stimulus is occurring
What is unique about the renal circulation?
Two capillaries connected with arteriole blood vessel - not the usual venous connection
Where does the majority of reabsorption occur in the nephron?
Proximal tubule
Filtration Fraction
% of blood plasma that is filtered into the tubules
Typically 20%
GFR changes with blood pressure
GFR stays constant for BP between 80-180
What is the main regulator of GFR?
vasoconstriction of afferent arteriole
What causes vasoconstriction of the afferent arteriole
High BP
Paracrine factors released by macula densa as a result of high NaCl passing through
Extreme drop in pressure from dehydration / bleeding
What are the macula densa and what are their function?
Modified tubular epithelium between afferent and efferent arterioles
Release paracrine factors as a result of high [NaCl] passing by + high GFR
What are the granular cells and what are their function?
Smooth muscle cells that secrete renin for Na balance
TRUE/FALSE: Kidneys only receive sympathetic innvervation
True
What part of the nephron tubule is part of the juxtaglomerular apparatus?
a) renal pelvis
b) collecting duct where it joins the ureter
c) ascending loop of Henle where it connects with the distal tubule
d) proximal tubule where it connects the descending loop of Henle
e) descending loop of Henle where it connects to the ascending loop
c) ascending loop of Henle where it connects with the distal tubule
It wraps back around, as the proximal tubule - descending loop as on the other side of the juxtaglomerular apparatus
Glucose reabsorption across the epithelium of the proximal tubule is accomplished by:
a) transport across the apical membrane against its concentration gradient, coupled with Na+
b) transport across the apical membrane down its concentration gradient, coupled with Na+
c) facilitated diffusion across the basolateral membrane down its concentration gradient
A and C
apical = lumen
basolateral = interstitial fluid
Glucose HIGH in the proximal cells
Glucose LOW on the two sides
Why would GFR stop?
low blood volume
conservation of blood
How does the firing rate of osmoreceptors increase?
increase in plasma osmolarity = shrinking = increase firing = release of vasopressin
How does the firing rate of osmoreceptors decrease?
decrease in plasma osmolarity = expansion = decrease firing
What does vasopressin cause?
increased expression of aquaporins on the apical (lumen) membrane of the collecting duct of the nephron
What is vasopressin’s main goal?
Save water
What causes vasopressin to be released by the posterior pituitary gland?
high plasma osmolarity = high salt concentration in ECF
low blood volume / pressure
In response to increased plasma osmolarity, central osmoreceptors would?
shrink and increase firing rate
Ascending limb of the loop of Henle is permeable to water
a) in the presence of vasopressin
b) never
c) in the presence of aldosterone
d) always
never
only permeable to ions to ensure osmolarity gradient in renal medulla
What are loop diuretics?
inhibit Na K transport in ascending loop to prevent water reabsorption by descending loop
Preventing concentrated urine
What is aldosterone’s main goal?
Save Sodium!
Where does aldosterone takes its effects on the nephron?
Distal nephron
