Physiology Flashcards
What mm comprises the upper esophageal sphincter?
cricopharyngeus
T/F: chewing is essential for digestion
False: it just increases the surface area of the food
in which region of the stomach are parietal and chief cells located?
Body or corpus
What hormone, released in response to low pH, inhibits gastric emptying by decreasing antral contractions, increases constriction of the pyloric sphincter, and also increases bicarb secretions from the pancreas?
Secretin
In which regin of the stomach are G cells located?
Antrum (they secrete gastrin: G for gastrin)
How long is the transit time through the large intestine?
3-4 days
How long is the transit time through the small intestine?
2-4 hours
What hormone causes contractions of smooth mm, regulates interdigestive motility, and prepares the intestine for the next meal?
Motilin
What is the main function of HCL in the stomach
converts pepsinogen into pepsin
What hormone increases the intestinal secretions of electrolytes and H20, relaxes smooth mm, dilates peripheral blood vessels, and inhibits gastric secretions?
Vasoactive intestinal peptide (VIP)
What gland produces 20% of salivary secretions and contributes to almost all of the amylase secretions
Parotid gland (serous secretions)
What hormone causes contractions of the gallbladder, augments the action of secretin to produce an alkaline pancreatic juice, inhibits gastric emptying, and increases constriction of the pyloric sphincter?
Cholecystokinin (CCK)
What are the 4 functions of saliva?
- Provdies antibacterial action
- lubricates
- begins carb digestion
- begins fat digestion
What is composed of skeletal mm, innervated by the pudendal nerve, and in a voluntary constant state of contraction that relaxes for defecation?
External anal sphincter
What hormone is stimulated by glucose and fat in the duodenum, inhibits gastric secretions and motility, and stimulates insulin secretion?
Gastrin inhibitory peptide (GIP)
Which portion of the autonomic nervous system regulates salivary flow?
parasympathetic portion
a pH less than 4.5 stimulates the release of what hormone?
Secretin (it inhibits acid secretion)
what is composed of smooth mm, innervated by pelvic splanchnics and hypogastric nerves, and involuntary?
internal anal sphincter
What gland produces 70% of total salivary secretion?
submandibular gland (produces both mucous and serous secretions)
what is the tonicity of pancreatic juice?
isotonic
what organism is associated with gastric ulcers?
h pylori
what is the only gastric secretion required to sustain life?
intrinsic factor (IF)
what 3 structures increase the surface area of the GI tract?
- plicae circularis (x3)
- villi (x30)
- microvilli (x600)
what hormone is the primary regulator of HCO3 secretion from the pancreas
secretin
what cells of the GI tract secrete mucus
goblet cels
what are the five F’s associated with gallstones?
- fat
- forty
- female
- familial
- fertile
lactose intolerance is caused by a lack of what enzyme
lactase
what are the 3 end products of amylase digestion?
- maltose
- maltotetrose
- alpha limit dextrans (alpha-1,6 binding)
what percentage of bile acids are excreted daily?
5% (95% reabsorbed via enterohepatic circulation)
which glands of the upper duodenum secrete a bicarb-rich solution?
brunner’s glands
what is the major route for excretion of cholesterol?
bile
what hormone potentiates the effect of secretin?
CCK
what is the major phospholipid in bile?
lecithin
what is the rate-limiting step in the formation of bile acids?
7a-hydroxylase
what 2 aa are conjugated to bile acids to increase h20 solubility?
- glycine
2. taurine
what is absorbed in the gallbladder to concentrate bile?
water
if a substance is removed from circulation by an organ, is its arteriovenous (AV) difference positive or negative?
positive AV difference
in laminar flow, which area has the fastest flow?
the center of the tube
what are 4 ways to get an increased pump function of the heart?
- exercise
- increase HR
- increase arterial pressure
- increase contractility
what system has an increased pressure, decreased resistance, increased flow, increased compliance, and blood volume that is proportional to flow?
pulmonary circuit
what 2 organs have local metabolites as the main determinant of blood flow?
- brain (cerebral circulation)
- GI tract (after a meal)
all other organs are under neural control
what are the 3 sympathetic effects on the pacemaker cells of the heart?
- increase the slope of prepotential
- take less time to reach threshold
- increase the rate of firing
what are the 3 parasympathetic effects on the pacemaker cells of the heart?
- hyperpolarize the cells by increasing K+ conductance
- take longer to reach threshold
- decrease the rate of firing
what are the 2 major causes of arterial pressure?
- contraction of the heart
2. hydrostatic pressure
what causes an increase in cardiac performance with no increase in preload?
contractility (inotropic)
change in what intracellular ion causes a change in contractility?
calcium
what are the 2 main circulations with extrinsic regulation that are most affected by nervous reflexes?
- cutaneous circulation
2. resting skeletal mm
what is the third heart sound caused by?
ventricular filling (heard during diastole)
what is the fourth heart sound caused by?
atrial contraction (heard during diastole)
if a substance is put into circulation by an organ, is its arteriovenous difference positive or negative?
negative
What is the baroreceptor response to an increase in BP?
increase afferent activity of CN IX and CN X to decrease HR (parasympathetic)
what is a perfusion-limited situation
when alveolar and capillary blood equilibrate for a substance
which region of the lungs has a low perfusion pressure and a high resistance so that there is little blood flow?
apex
what fluid is monitored directly by central chemoreceptors
cerebrospinal fluid (H+:CO2)
On a pressure-volume loop, what is seen with: aortic regurgitation?
increase in stroke volume
On a pressure-volume loop, what is seen with: aortic stenosis?
increase in afterload, decrease in stroke volume, increase in peak tension
On a pressure-volume loop, what is seen with: increase contractility
increase in SV by decreasing the end-systolic volume
On a pressure-volume loop, what is seen with: heart failure?
increase in end-systolic volume, decrease in afterload, decrease in peak tension, increase in peak tension
What 2 compensatory mechanisms occur to reverse hypoxia at high altitutdes?
- increase in EPO
2. increase in 2,3-BPG,also called 2,3 diphosphoglcerate (increase in glycolysis)
what would you give to neutralize the excess base in an alkalotic patient?
NH4Cl (strong acid can lyse RBCs)
What would you give to neutralize the excess acid in an acidotic patient?
NaCO2 (CO2 eliminated by lungs)
what is a diffusion-limited situation?
when alveolar gas and capillary blood attempt to equilibrate but do NOT (ie CO2)
what must occur in order for PaCO2 to remain constant when there is an increase in the body’s metabolism?
need to increase alveolar ventilation (if not hypercapnia would result)
what enzyem is needed for conversion of testosterone to estradiol?
aromatase
what 2 anions compete with iodine for the iodine pump in the thyroid gland?
- percholorate
2. thiocyanate
what enzyme is associated with isteoblastic activity?
alkaline phosphatase
what form of plasma calcium is the physiologically active form and is regulated within narrow limits?
free calcium (ionized)
which 3 factors cause the release of epinephrine from the adrenal medulla?
- exercise
- emergencies (stress)
- exposure to cold
(the 3 Es)
what phase of the female cycle ALWAYS lasts for the same number of days (14 days in most women)?
luteal phase
what serves as a marker for 24 hour GH secretion?
plasma insulinlike growth factor type 1 (IGF-1) levels
what 3 things inhibit the secretion of glucagon?
- insulin
- somatostatin
- hyperglycemia
which 3 organs or structures have gluconeogenic capabilities?
- liver
- kidney
- GI epithelium
which type of diabetes is more likely to lead to ketoacidosis?
type I (insulin-dependent diabetes mellitus)
excess bone demineralization and remodeling can be detected by checking urine levels of what substance?
hydroxyproline (breakdown product of collagen)
what 2 things cause 1a-hydroxylase activity to increase?
- PTH
2. a decrease in PO4 levels
what type of membrane is permeable to water and small solutes?
selectively permeable membrane
what is the movement of ions in an electrical field known as ?
conductance
what 2 components of a body of water cannot be measured and need to be calculated?
ICF (water minus ECF)
2. interstitial fluid (ISF) - ESF-plasma volume
what phase of an action potential has the greatest rate of Na+ flux?
phase 0
which phase of an action potential requires energy?
phase 4 (via the Na+/K+ pump)
what type of mm is assoc with one T tubule and 2 cisternae (triad)?
skeletal mm
what is the region of an axon where no myelin is found
nodes of ranvier
what type(s) of mm contain the thin filament troponin
skeletal and cardiac mm
where are ADH and oxytocin produced?
the supraoptic and paraventricular nuclei of the hypothalamus
what is the only hormone to INCREASE with a DECREASE in pituitary function
prolactin
which enzyme converts cholesterol to pregnenolone?
desmolase - rate limiting step in steroid hormone synthesis
what are the 4 “stress” hormones?
- GH
- gulcagon
- cortisol
- epinephrine
pro-opiomelanocortin (POMC) is cleaved into what 2 substances?
- ACTH (adrenocorticotrophic hormone)
2. -lipotropins (melanotropins and endorphins)
what are the 6 substances that promote the secretion of insulin?
- glucose
- aa (arginine)
- GIP (gastrin inhibitory peptide)
- glucagon
- B-agonists
- ACh
what is the thin filament that has the attachment site for the cross-bridges and also activates adenosine triphosphatease (ATPase)?
actin
what types of muscle have a sarcomere?
skeletal mm and cardiac mm
where is the action potential generated on a neuron?
axon hillock
what is the name for the load that the mm is working aginst during stimulation?
afterload
what type of contraction has an active tension when the length is shortened?
isotonic contraction
what type of mm has high creatinine phosphokinase (CPK), high ATPase activity, and no myoglobin; is anaerobic; and is for short-term use?
white mm (fast)
what type of mm uses calmodulin
smooth mm
what thick filament has cross-bridges and ATPase activity?
myosin
what causes actin-myosin cross-bridge dissociation?
binding of ATP
what is used as an index of cortisol secretions?
urine 17-OH steroids
What would be the 2 major consequences if the zona fasciculata and the zona reticularis were removed?
- circulatory failure
2. inability to mobilize energy stores
how many carbonds do androgens have?
androgens are 19-carbon steroids
how many carbons do estrogens have?
estrogens are 19-carbon steroids (removal of 1 carbon from an androgen = an estrogen)
the level of what hormone tends to decrease with stress
insulin
on what 2 occasions are cortisol-releasing hormone (CRH) secretions elevated?
- Early morning
2. during stress
what is an inhibitory interneuron known as?
Renshaw neuron
what is the summation of mechanical stimuli known as?
tetany
what is the thin filament that binds to calcium?
troponin
what determines the max velocity of shortening mm?
the muscle’s ATPase activity
what type of mm has end plates?
skeletal mm
what type of contraction has an active tension, but the overall length of the contraction does not change and no work is done?
isometric contraction
what thin filament covers the attachment site in resting mm so that the cross-bridges are unavailable for binding?
tropomyosin
what is the load on a mm in the relaxed state known as?
preload
total tension - reload = what?
active tension (contraction)
what types of mm are uninuclear?
cardiac and smooth mm
in a contractile mm, what is the source of the calcium?
sarcoplasmic reticulum (the source is NOT extracellular)
what is the max force of a contraction determined by?
the number of motor units activated during the contraction
what types of mm have T tubules assoc with them?
cardiac and skeletal mm
what type of mm has myoglobin, low CPK, and low ATPase activity; is aerobic; and is used for long-term use?
red mm (slow-twitch mm)
what event signifies the first day of the menstrual cycle?
the first day of bleeding
what hormone is essential for induction of ovulation and formation of the corpus luteum?
LH
how many days before the first day of bleeding is ovulation?
14 days in most women (remember; the luteal phase is always constant)
what is required to maintain lactation?
suckling (stimulates oxytocin secretion)
what hormone , in high levels, blocks milk production?
estrogen
what hormone is necessary for maintenance of the corpus luteum for the first 3 months of pregnancy?
hCG from the trophoblast.
Up to how many hours after ejaculation are sperm able to fertilize the egg?
72 hours
what hormone induces myometrial contraction and causes milk let-down
oxytocin
what hormone is necessary for the maintenance of the uterine endometrium from the 4th month of pregnancy on?
progesterone (estrogen is needed for progesterone to be effective)
how long after ovulation does fertilization occur?
8-25 hours
what hormone thins cervical mucus, stimulates LH receptors on granulosa cells, elicits the LH surge, and increases proliferation of the uterine mucosal layers?
estradiol
what hormone is secreted by the placenta late in pregnancy, stimulates mammary growth during pregnancy, mobilizes energy stores from the mother so that hte fetus can use them and has an aa sequence like GH
Human chorionic somatomammotropin (hCS) or human placental lactogen (hPL)
what hormone causes an increase in the production of milk?
prolactin
what is the force necessary to collapse the lung known as?
lung recoil
for what hormone do Leydig cells have receptors?
LH
what vitamin needs thyroid hormone for conversion to its active form?
Vit A
What is the tonicity of fluid that leaves the loop of Henle?
Hypotonic
what enzyme converts androgens to estrogens?
aromatase
what does excess production of TSH cause?
goiter
what type of cell reabsorbs bone?
osteoclast
Blast makes
clasts take
what is the major form of androgen secreted from the adrenal gland?
Dehydroepiandrosterone (DHEA)
what cells of the GU system produces testosterone in males?
Leydig cells
What type of urine does ADH cause to be excreted?
hypertonic urine (bc of the water reabsorption in the collecting duct
what is the term for the volume of plasma removed from a substance per unit time?
clearance
what is the most potent male sex steroid?
dihydrotestosterone
what 2 substances stimulate sertoli cells?
follicle-stimulating hormone (FSH) and testosterone
at which 3 sites in the body is T4 converted to T3?
- Liver
- Kidney
- Pituitary gland (via 5’-deiodinase enzyme)
the fresh air being delivered to the respiratory zone per minute is known as what?
Alveolar ventilation (the first 150ml is not included)
What region of the lungs gets very little ventilation?
Apex
Where does polyuria orginate if the patient is dehydrated and has electrolyte deficiencies?
before the collecting duct (there is no electrolyte disturbance in the collecting duct)
what substance is free filtered but partially reabsorbed by passive mechanisms?
urea
what hormone promotes mobilization of energy stores, enhances the capacity of glucagon and catecholamines, and increases the capacity to withstand stress?
cortisol
what is used as an index of androgen secretion?
urine 17-ketosteroids
what are the pituitary hormones associated with: thyrotropin releasing hormone (TRH)?
TSH
what are the pituitary hormones associated with: cortisol-releasing hormone (CRH)?
Adrenocorticotrophic hormone (ACTH)
what are the pituitary hormones associated with: Gonadotropin releasing hormone (GnRH)?
Luteinizing hormone (LH) follicle-stimulating hormone (FSH)
what are the pituitary hormones associated with: Growth hormone relasing hormone (GH-RH)
GH
what are the pituitary hormones associated with: somatostatin?
inhibits GH secretion
what are the pituitary hormones associated with: prolactin-inhibiting factor (PIF) [dopamine]
inhibits prolactin secretion
Which hormones are released from the: zona glomerulosa?
aldosterone (salt)
Which hormones are released from the: zona fasciculata?
cortisol (sugar)