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528 Cards in this Set

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Gastrointestinal system is responsible for
transferring organic molecules, salts, and water from the external environment to the body's internal environment
Processes of the GI track
Digestion
Secretion
Absorption
Motility
Defecation
Digestion
ingested macromolecules dissolved and broken down
Secretion
HCL, bile and enzymes
Absorption
molecules move from lumem of tract into blood or lymph
Motility
contractions of smooth muscles move contents thru tract
Defecation
bacteria and undigested material eliminated from body
Carbohydrate
* 250 - 300 of 800 g food / day
* 2/3 plant starch (polysaccharide)
1/3 sucrose/lactose
Dehydration synthesis
monosaccharide + monosaccharide --> disaccharide + water
Hydrolysis
disaccharide + water --> monosaccharide + monosaccharide
protease
(PROH-tee-ase)
an enzyme capable of breaking peptide bonds in a protein
proteolysis
the process whereby peptides and proteins are cleaved into smaller molecules, by the actions of specific enzymes (proteases)
prothrombin
inactive precursor to thrombin; produced by liver an normally present in plasma
Is Dehydration Synthesis and Hydrolysis reversible?
yes, they are reversible reactions
starch is partially digested by
salivary amylase in mouth and upper stomach
starch digestion continues in
small intestine by pancreatic amylase
starches are broken down to
monosaccharides by enzymes in plasma membranes of small intestine epithelial cells. then transported across epithelial cells into blood
Protein
we ingest/need
ingest 70 - 90 (or 125) g per day
need 40 - 50 g per day
enzyme(s) in the stomach that break(s) down protein
pepsin
enzyme(s) in the small intestines that break down protein
trypsin and chymotrypsin
The major proteases secreted by the pancrease
trypsin and chymotrypsin
amino acid to capillaries
amino acids actively transported (along with Na+) across intestinal wall into capillaries
most protein is digested/absorbed in
the first part of the small intestine
Peptide + Water <===
===> amino acid + amino acid
Protein + enzyme pepsin =
= peptide fragments
(stomach)
protein + typsin /chymotrypsin =
= peptide fragments
(small intestines)
peptide fragments +
carboxypeptidases/
aminopeptidases =
= amino acids
(small intestine)
carboxypeptidase
enzyme that splits off amino acids from the carboxyl end of peptide chains
aminopeptidase
enzyme that splits off amino acids from amino end of peptide chain
How do amino acids get absorbed?
amino acids are actively transported (along with Na+) across intestinal wall into capillaries
Most protein is digested/absorbed where?
most protein is digested/absorbed in the first part of the small intestine
give the hydrolysis/dehydration synthesis equation for peptides
peptide + water <==> amino acid + amino acid
NH2 is a what?
an amine
______ace =
enzyme
Name the two common disaccharides in our diets
sucrose and lactose
sucrose
table sugar
lactose
milk sugar
most carbohydrates are digested/absorbed where?
in the first 20% of the small intestine
monosacharide has how many sugars?
one
polysacharide has how many sugars?
1000 or more
fructose gets across by what method?
facilitated diffusion
glucose and galactose get across by what method?
secondary active transport
tripsinogen is the zymogen for
trypsin
zymogen
(ZY-moh-jen)
enzyme precursor requiring some change to become active
Wolffian duct
(WOLF-ee-an)
part of embryonic duct system that, in male, remains and develops into reproductive system ducts, but in female, degenerates
vitamin K
a lipid-soluble substance absorbed from the diet and manufactured by bacteria of the alrge intestine; required for production of numerous factors involved in blood clotting
cellulose is partially broken ...
cellulose partially broken by bacteria in large intestine
How much fat do we have in our diet?
70-100 g per day
most fat we consume is in the form of
triacylglycerols
triacylglycerols are composed of
composed of three FA attached to a glycerol skeleton
fat digestion occurs in
fat digestion is entirely in the small intestine
triacylglycerols are soluble or insoluble?
triacylglycerols are insoluble in water (aggregate in droplets)
bile salts are formed where?
bile salts are formed in the liver
what are bile salts formed from?
cholesterol
are bile salts hydrophilic or hydrophobic?
bile salts are amphipathic
bile salts increase ...
bile salts increase the rate of fat digestion and absorption
what are the two functions of bile salts?
1. emulsify fat
2. form part of micelles (keep most insoluble fat products in small aggregates)
micelles
(MY-sell)
soluble cluster of amphipathic molecules in which molecules' polar regions line surface and nonpolar regions orient toward center
what makes up micelles?
formed from fatty acids, monoglycerides and bile salts
micelles are formed when and where?
during fat digestion in small intestine
phosphate + carbon chain =
fatty acid
fatty acid
carbon chain with carboxyl group at one end through which chain can be linked to glycerol to form triglyceride
carboxyl group
(kar-BOX-il)
--COOH; ionizes to carboxyl ion (--COO-)
carboxypeptidase
enzyme secreted in small intestine by exocrine pancreas as precursor, procarboxypeptidase; breaks peptide bond at carboxyl end of protein
catabolism
(kuh-TAB-oh-lizm)
cellular breakdown of organic molecules
Epinephrine
(E)
amine hormone secreted by adrenal medulla and involved in regulation of organic metabolism; a biogenic amine (catecholamine)
Norepinephrine
(NE)
biogenic amine (catecholamine) neurotransmitter released at most sympathetic postganglionic endings, from adrenal medulla, and in many CNS regions
Catecholamine
dopamine, epinephrine, or norepinephrine, all of which have similar chemical structures
Thyroxine
(T4)
tetraiodothyronine; iodine-containing amine hormone secreted by thyroid gland
Triiodothyronine
(T3)
iodine-containing amine hormone secreted by thyroid gland
Antidiuretic hormone
(ADH, aka vasopressin)
peptide hormone synthesized in hypothalamus and released from posterior pituitary; increases water permeaility of kidney's collecting ducts and causes vasoconstriction
Oxytocin
(OT)
peptide hormone synthesized in hypothalamus and released from posterior pituitary; stimulates mammary glands to release milk and uterus to contract
Follicle-stimulating hormone
(FSH)
protein hormone secreted by anterior pituitary in males and females that acts on gonads; a gonadotropin
gonadotropic hormone
(gonadotropin)
hormone secreted by anterior pituitary that controls gonadal function; FSH or LH
Luteinizing hormone
(LH)
peptide gonadotropic hormone secreted by anterior pituitary; rapid increase in females at midmenstral cycle initiates ovulation; stimulates Leydig cells in males
Leydig cell
(interstitial cell)
testosterone-secreting endocrine cell that lies between seminiferous tubules of testes
leptin
adipose-derived hormone that acts within the brain to decrease appetite and increase metabolism
lecithin
(LESS-ih-thin)
a phospholipid
lipase
enzyme that hydrolyzes triglyceride to monoglyceride and fatty acids
Growth hormone
(GH)
peptide hormone secreted by anterior pituitary; stimulates insulin-like growth factor I release; enhances body growth by stimulating protein synthesis
growth hormone-releasing hormone
(GHRH)
hypothalamic peptide hormone that stimulates growth hormone secretion by anterior pituitary
anabolism
cellular synthesis of organic molecules
androgen
any hormone with testosterone-like actions
Peptide hormone
any of a family of hormones, like insulin, composed of approximately two to 50 amino acids; generally soluble in acid, unline larger protein hormones which are insoluble
Amine hormone
hormone derived from amino acid tyrosine; includes thyroid hormones, epinephrine, norepinephrine, and dopamine
steroid hormone
any of a family of hormones, like progesterone, whose structure is derived from cholesterol
Thyroid-stimulating hormone
(TSH)
glycoprotein hormone secreted by anterior pituitary; induces secretion of thyroid hormone; also called thyrotropin
thyroid-releasing hormone or
thyroid-releasing factor
(TRH or TRF)
hypophysiotropic hormone that stimulates thyrotropin and prolactin secretion by anterior pituitary
triacylglycerol ----(lipase)--->
monoglyceride + 2 fatty acids
OR
glycerol + 3 fatty acids
What happens to the fatty acids and monoglycerides after lipase breaks them down in the lumen of the SI?
fatty acids and monoglycerides enter the epithelial cells from lumen of SI
Inside the epithelial cells lining the lumen of SI, what happens to FA and monoglycerides?
fatty acids and monoglycerides are resynthesized into triacylglycerols on smooth ER, coated with protein in Golgi and packaged in vesicles
What happens to triacylglycerols once they are coated on ER and packaged at Golgi into vesicles?
the vesicles are released on the other side into interstitial fluid as cyhlomicrons
chylomicrons
small droplet of triacylglycerol coated with protein
what happens to chylomicrons released into interstitial fluid?
chylomicrons absorbed into lacteals then entr venous circulation
monoglyceride
glycerol linked to one fatty acid side chain
triglyceride or triacylglycerol
subclass of lipids composed of glycerol and three fatty acids
What type of control mechanisms are there for digestion?
neural and hormonal
gastrointestinal reflexes are initiated by ...
1. distension of wall
2. chyme osmolarity
3. chyme acidity
4. concentration of products
where are the receptors for the gastrointestinal reflex triggers of distension, osmolarity, acidity, and concentration, and what do they do?
these stimuli receptors are in the wall of the tract and they trigger reflexes that influence muscles and glands
how many nerve networks are in the enteric nervous system and what are their names?
1. myenteric plexus
2. submucosus plexus
facts re enteric nervous system
* local NS
* neurons synapse with other neurons in plexes or innervate smooth muscle or glands
* plexes influence eachother
* both plexes receive ANS fibers
* stimulation conducted up and down tract
what are the types of reflex arcs?
1. short reflexes
2. long reflexes
where are the hormones secreted from that regulate digestion?
hormones secreted by endocrine cells scattered thru epithelium of stomach and small intestine
what are the major hormones of the digestive tract?
1. secretin
2. cholecystokinin (CCK)
3. gastrin
4. glucose insulinotropic peptide (GIP)
effector cells of the GI tract contain receptors for ...
more than one hormone
potentiation
one hormone in the presence of another hormone produces an exaggerated effect
secretin
(SEEK-reh-tin)
peptide hormone secreted by upper small intestine; stimulates pancreas to secrete bicarbonate into small intestine
cholecystokinin
(CCK)
peptide hormone secreted by duodenum that regulates gastric motility and secretion, gallbladder contraction, and pancreatic enzyme secretion; possible satiety signal
gastrin
peptide hormone secreted by antral region of stomach; stimulates gastric acid secretion
glucose insulinotropic peptide
OR
glucose-dependent insulinotropic peptide
(GIP)
intestinal hormone; stimulates insulin secretion in response to glucose and fat in small intestine
What are the phases of neural and hormonal control of the GI system?
Cephalic phase
gastric phase and
intestinal phase
Cephalic phase -
receptors in HEAD stimulated by ...
1. sight, smell, taste and chewing
2. emotional states
gastric response during cephalic phase is mediated by ...
parasympathetic (vagus) and sympathetic fibers to plexuses which cause secretion and contraction
Gastric phase -
receptors in STOMACH stimulated by ...
1. distension
2. acidity
3. presence of amino acids
4. presence of peptides
gastric response during gastric phase is mediated by ...
short/long reflexes and release of gastrin
Intestinal phase -
receptors in INTESTINE stimulated by ...
1. distension
2. acidity
3. osmolarity
4. digestive products in the chyme
gastric response during intestinal phase is mediated by ...
short and long reflexes; secretin, CCK and
GIP
the GASTROINTESTINAL TRACT consists of
Mouth
Stomach
Pancreas
Liver
Small Intestine
Large Intestine
pressure of food in the mouth activates what?
mechanoreceptors
chewing is controlled by what?
somatic nerves to skeletal muscles
name the salivary glands;
parotid
submandibular
sublingual
saliva
watery solution of salts and proteins, including mucins and amylase, secreted by salivary glands
which autonomic stimulation influences saliva?
both sympathetic and parasympathetic
name the gland cells secreting in the stomach
parietal cells
chief cells
goblet cells
enterochromaffin-like cells
G cells
parietal cells
gastric gland cell that secretes hydrochloric acid and intrinsic factor
chief cells
gastric gland cells that secrete pepsinogen, precursor of pepsin
goblet cells
secrete mucus
enterochromaffin-like cells
(ECL)
histamine-secreting cell of the stomach
(serotonin?)
G cells
secrete gastrin
pepsinogen --(HCl) -->
pepsin
protein --(pepsin)-->
peptides
protein --(trypsin) -->
peptides
protein --(chymotrypsin)-->
peptides
peptides --(carboxypeptidases) -->
amino acids
pepsin
family of several protein-digesting enzymes formed in the stomach; breaks protein down to peptide fragments
pepsinogen
inactive precursor of pepsin; secreted by chief cells of gastric mucosa
chymotrypsin
enzyme secreted by exocrine pancreas; breaks certain peptide bonds in proteins and polypeptides
trypsin
enzyme secreted into small intestine by exocrine pancreas as precursor trypsinogen; breaks certain peptide bonds in proteins and polypeptides
serotonin=
vasoconstrictor
histamine =
vasodialator
gastric juice =
HCl + pepsin
HCO3-
bicarbonate
amylase
enzyme that partially breaks down polysaccharides
ribonuclease
enzyme that breaks down RNA
deoxyribonuclease
enzyme that breaks down DNA
exocrine portion of pancreas secretes
HCO3-
trypsin
chymotrypsin
carboxypeptidase
lipase
amylase
ribonuclease
deoxyribonuclease
pancreatic enzymes secreted in inactive form then activated in ...
duodenum by proteolytic enzyme enterokinase
proteolysis
the process whereby peptides and proteins are cleaved into smaller molecules, by the actions of specific enzymes (proteases)
proteolytic
breaks down protein
protease
(PROH-tee-ase)
an enxyme capable of breaking peptide bonds in a protein
pancreatic secretion increases during ...
a meal
secretin stimulates
HCO3- secretion
CCK stimulates
secretion of digestive enzymes
largest gland in the body
liver
functions of liver
1. metabolize hormones
2. secrete angiotensin
3. produce clotting factors
4. synthesize albumin
5. convert glucose to glycogen
6. convert amino acids to fatty acids
7. produce urea/uric acid
8. synthesize cholesterol
9. detoxify blood
10. secrete bilirubin/bile pigments
11. produce bile
angiotensin I
small polypeptide generated in plasma by renin's action on angiotensinogen
angiotensin II
hormone formed by action of angiotensin-converting enzyme on angiotensin I; stimulates aldosterone secretion from adrenal cortex, vascular smooth-muscle contraction, and thirst
angiotensin-converting enzyme
(ACE)
enzyme on capillary endothelial cells that catalyzes removal of two amino acids from angiotensin I to form angiotensin II
angiotensinogen
plasma protein precursor of angiotensin I; produced by liver
renin
(REE-nin)
peptide hormone secreted by kidneys; acts as an enzyme that catalyzes splitting off of angiotensin I from angiotensinogen in plasma
bile is secreted by
the liver
what does the gall bladder do?
stores and concentrates bile
what are the components of bile?
1. bile salts
2. cholesterol
3. lecithin
4. bicarbonate
5. bile pigments
6. trace metals
name the parts of the small intestine
duodenum
jejunum
ileum
net absorption of chyme and water happens where?
small intestine
brush border
small projections (microvilli) of epithelial cells covering the villi of the small intestine; major absorptive surface of the small intestine
name the brush border enzymes
1. sucrase
2. maltase
3. lactase
4. aminopeptidase
5. enterokinase
6. alkaline phosphatase
sucrase
enzyme involved in the hydrolysis of sucrose to fructose and glucose
maltase
one enzyme produced by the cells lining the small intestine to break down disaccharides. It comes under the enzyme category carbohydrase (which is a subcategory of hydrolase), and the disaccharide it hydrolyses is maltose
lactase
small intestine enzyme that breaks down lactose (milk sugar) into glucose and galactose
aminopeptidase
one of a family of enymes located in the intestinal epithelial membrane; breaks peptide bond at amino end of polypeptide
enterokinase
enzyme in luminal plasma membrane of intestinal epithelial cells; converts pancreatic trypsinogen to trypsin
alkaline phosphatase
a hydrolase enzyme responsible for removing phosphate groups in the 5- and 3- positions from many types of molecules, including nucleotides, proteins, and alkaloids. The process of removing the phosphate group is called dephosphorylation. As the name suggests, alkaline phosphatases are most effective in an alkaline environment
name the parts of the large intestine
1. cecum
2. colon
3. rectum
4. anal canal
5. anus
what is the name of the little thingie attached to the cecum?
(appendix)
name the parts of the colon
1. ascending
2. transverse
3. descending
4. sigmoid
surface area of large intestine
less than small intestine
what does the large intestine actively absorb?
Na+ and K+ ions and water
what does the large intestine absorb other than ions and water?
vitamins synthesized by bacteria
what does the large intestine lack?
digestive enzymes
what does the large intestine secrete?
mucus
what does the large intestine do?
stores and concentrates fecal material
what are the functional states of organic metabolism?
absorptive state and
postabsorptive state
absorptive state
ingested materials entering blood from GI tract
postabsorptive state
GI tract empty and energy must be derived from body stores
absorptive state:
what specifically enters blood?
glucose, amino acids and triacylglycerol
ABSORPTIVE STATE:
glucose absorbed...
1. by liver for storage or conversion to VLDL which enter the circulation and are carried to adipose tissue for storage
2. by body cells and catabolized for energy
3. by skeletal muscle for catabolism and stored as glycogen
4. by adipose tissue for catabolism (but most transformed to triacylglycerols and stored)
ABSORPTIVE STATE:
amino acids absorbed...
1. by liver for protein synthesis or converted to keto acids
2. by muscle for protein synthesis
3. by liver and converted to fatty acids
4. by body cells for protein synthesis
ABSORPTIVE STATE:
triacylglycerols absorbed ...
1. as fatty acids (released from chylomicrons) which leave the blood and enter adipose tissue (in fat cells reassembled into triacylglycerols and stored)
POSTABSORPTIVE STATE:
what must be done?
plasma glucose concentration must be maintained
POSTABSORPTIVE STATE:
how is plasma glucose concentrations maintained?
1. increase sources of glucose
2. glucose sparing occurs
POSTABSORPTIVE STATE:
what stops and starts?
1. net synthesis ceases
2. net catabolism begins
POSTABSORPTIVE STATE:
sources of glucose
1. glycogenolysis in liver
2. glycogenolysis in muscle
3. catabolism of triacylglycerols
4. catabolism of protein in muscle and other tissue
POSTABSORPTIVE STATE:
glucose sparing -- what do most organs do?
most organs greatly reduce their glucose catabolism (sparing glucose for the nervous system)
POSTABSORPTIVE STATE:
glucose sparing
1. glycogen, fat and protein synthesis is curtailed
2. gluconeogenesis by liver and kidneys
3. glycogenolysis
4. lipolysis
5. NS still uses glucose
Hormones involved in control of metabolism
1. Insulin
2. glucagon
3. epinephrine
4. cortisol
5. Growth Hormone
where is Insulin made?
beta cells in the islets of langerhans (in the pancreas)
what is the most important hormone controller of metabolism
insulin
what does insulin do to plasma glucose?
lowers plasma concentration of glucose
insulin causes ...
1. increased target cell membrane's capacity to transport glucose and amino acids into cells
2. increased activity of enzymes for glycogen synthesis
3. inhibition of enzyme of glycogen catabolism
where is glucagon made?
alpha cells and lining of GI tract
(alpha cells of pancreatic islets of Langerhans
what does glucagon do to plasma glucose?
(opposite effect of insulin)
increases plasma concentrations of glucose, fatty acids, glycerol and ketones
glucagon causes ...
1. increased glycogen breakdown in liver
2. increased lipolysis
3. increased gluconeogenesis by liver
4. synthesis of ketones by liver
HORMONAL CONTROL OF METABOLISM:
What secretes epinephrine?
epinephrine is secreted by the adrenal medulla
HORMONAL CONTROL OF METABOLISM:
What controlls the release of epinephrine?
release controlled by sympathetic preganglionic fibers in adrenal medulla
HORMONAL CONTROL OF METABOLISM:
Epinephrine causes ...
1. inhibition of insulin
2. stimulation of glucagon
3. glycogenolysis
4. gluconeogenesis
5. lipolysis
6. inhibition of glucose uptake by skeletal muscle
HORMONAL CONTROL OF METABOLISM:
Cortisol is a ...
glucocorticoid produced by adrenal cortex
HORMONAL CONTROL OF METABOLISM:
Cortisol's presence in small levels maintains ...
presence in small levels maintains required enzyme levels for gluconeogenesis and lipolysis
HORMONAL CONTROL OF METABOLISM:
Cortisol during stress ...
during stress can oppose insulin
HORMONAL CONTROL OF METABOLISM:
Growth Hormone stimulates ...
stimulates growth and protein anabolism
HORMONAL CONTROL OF METABOLISM:
Growth hormone effects are like ...
effects like cortisol (opposite insulin)
HORMONAL CONTROL OF METABOLISM:
Growth hormone causes ...
1. stimulates lipolysis
2. increases liver gluconeogenesis
3. decreases glucose uptake in peripheral tissues
Kidneys and regulation of water -
regulation of the extracellular (plasma/tissue fluid) environment
1. regulate the volume of blood plasma
2. regulate the concentration of waste products in the blood
3. regulate the concentration of electrolytes
Kidneys and regulation of water -
system consists of:
* kidney
* ureters
* urinary bladder
* urethra
Functional unit of kidney:
nephron
nephron conmposed of:
1. renal corpuscle
2. tubule
renal corpuscle composed of:
glomerulus
bowman's capsule
name the two types of nephrons
juxtamedullary
cortical
juxtamedullary nephrons:
where do they originate?
originate in inner 1/3 of cortex
cortical nephrons:
where do they originate?
originate in outer 2/3 of cortex
juxtamedullary nephrons:
describe their loops
longer loops
cortical nephrons:
describe their loops
shorter loops
glomerular capillaries have large pores called
fenestrae
bowman's capsules have slits called
filtration slits
what does not filter?
protein, RBC, WBC
water and solutes pass from
plasma into glomerulus to capsule and into lumen of tubule
filtrate passes thru fenestra and then
a basement membrane and a layer of cells called podocytes
podocyte
epithelial cells lining bowman's capsule, whose foot processes form filtration slits
filtered molecules pass thru slits between cytoplasmic extensions on podocytes called
pedicels
fluid entering caplsule from glomerulus is called
ultrafiltrate
what is glomerular filtration rate measuring?
volume of filtrate produced by both kidneys per minute
what percentage of plasma volume flowing into renal artery is filtered ?
20% of plasma volume that flows into renal artery is filtered
what is the term to describe the 20% plasma volume that flows into renal artery that is filtered?
filtered fraction
if the kidney receives 1580 L / day, and the hematocrit is 45%, what is the renal plasma flow?
renal plasma flow = 870 L/day
if the kidney receives 1580 L / day, and the hematocrit is 45%, what is the filtered fraction?
174 L/ day
if the kidney receives 1580 L / day, and the hematocrit is 45%, what is the hourly amount filtered?
7.25 L/hr
What is the typical hydrostatic force in glomerular capillaries?
45 mmHg
What is the typical hydrostatic force in capsule?
10 mmHg
if your glomerular capillaries hydrostatic force is 45 mmHg, and your capsule hydrostatic force is 10 mmHg, what is the net hydrostatic driving force?
35 mHg OUT
what is the osmotic pressure in clomerular capillaries from?
negative charged proteins that don't filter
What is the typical osmotic pressure in the glomerular capillaries
25 mmHg
What is the typical osmotic pressure in the capsule
0 mmHg
if your glomerular capillaries osmotic pressure is 25 mmHg, and your capsule osmotic pressure is 0 mmHg, what is the net osmotic pressure?
25 mmHg IN
If you Hydrostatic pressure is 35 mmHg OUT, and your osmotic pressure is 25 mmHg IN, what is your net filtration force?
10 mmHg net filtration OUT
Alterations in filtration rate occur when:
1. filtration increases when glomerular hydrostatic capillary pressure rises
2. filtration increases when osmotic pressure is reduced in glomerulus
3. filtration decreases if hydrostatic pressure in capsule rises (ureters occluded)
4. filtration increases if proteins escape into capsule
5. filtration decreases when sypathetic stimulation causes afferent arteriolar constriction
What can cause glomerular hydrostatic capillary pressure to rise?
* due to afferent arteriole dilation
* due to efferent arteriole constriction
what happens to filtration when glomerular hydrostatic capillary pressure rises?
filtration increases when glomerular hydrostatic capillary pressure rises
what happens to filtration when osmotic pressure is reduced in glomerulus?
filtration increases when osmotic pressure is reduced in glomerulus
what happens to filtration if hydrostatic pressure in capsule rises, and what can cause this?
filtration decreases if hydrostatic pressure in capsule rises (ureters occluded)
What happens to filtration if proteins escape into capsule?
filtration increases if proteins escape into capsule
what happens to filtration when sypathetic stimulation causes afferent arteriolar constriction?
filtration decreases when sypathetic stimulation causes afferent arteriolar constriction
GFR is not fixed, but is subject to ...
physiological regulation
What control mechanisms can change GFR?
neural/hormonal input to afferent / efferent arterioles change GFR
REABSORPTION:
What percentage of filtrate is reabsorbed, and where is it sent?
99% of the filtrate is returned to the vascular system
REABSORPTION:
What percentage of filtrate is not reabsorbed, and where is it sent?
1% is excreted in urine
REABSORPTION:
What must be done with most filtered water?
most filtered water must be returned to vascular system
REABSORPTION:
What method is water trasported by?
water transport is always passive osmosis
REABSORPTION:
what is the osmolarity of filtrate vs. plasma?
osmolarity of filtrate is same as plasma
EXCEPT FOR THE PROTEIN, WHICH MAKES THE OSMOLARITY VERY DIFFERENT
REABSORPTION:
osmosis won't occur unless ...
osmosis won't occur unless concentration of filtrate different than blood (peritubular capillary)
Mechanism by which reabsorption occurs:
What is the concentration of Na+ in epithelial cells vs. filtrate?
concentration of Na+ is less in epithelial cells than in filtrate
Mechanism by which reabsorption occurs:
Why is concentration of Na+ in epithelial cells less than in filtrate?
because Na+/K+ pump actively transports Na+ out of epithelial cells
Mechanism by which reabsorption occurs:
What does the lower concentration of Na+ in epithelial cells vs. filtrate cause?
Na+ diffuses from filtrate to epithelial cells
Mechanism by which reabsorption occurs:
What happens to Na+ that diffuses into epitheial cells?
Na+ is pumped out of epithelial cell into interstitial fluid by Na+/K+ pump
Mechanism by which reabsorption occurs:
What does the pumping of Na+ into the interstitial fluid from the epithelial cell result in?
creates potential difference across wall of tubule
Mechanism by which reabsorption occurs:
What does the potential difference across the wall of the tubule acheive?
electrical gradient favors passive transport of Cl- toward high Na+ concentration in interstitial fluid
Mechanism by which reabsorption occurs:
What does the potential difference across the wall of the tubule cause?
Cl- to passively follow Na+ from filtrate to interstitial fluid
Mechanism by which reabsorption occurs:
When Cl- follows Na+ from epithelial into interstitial fluid, what does this create?
an osmotic gradient is created
Mechanism by which reabsorption occurs:
When Cl- follows Na+ from epithelial into interstitial fluid, what does water do?
water moves by osmosis:
from filtrate in lumen to
epithelial cell to
interstitial fluid to
capillary
Mechanism by which reabsorption occurs:
85% of salt/water reabsorption occurs where?
65% of salt/water in filtrate reabsorbed in proximal tubule
20% in loop of Henle
Mechanism by which reabsorption occurs:
What percentage of the body's calories are used in the 85% reabsorption of salt/water in the proximal tubule and loop of Henle?
6% of the body's calories are used
Mechanism by which reabsorption occurs:
Where does the last 15% of water/salt reabsorption occur?
remaining 15% in distal tubule and collecting duct
Mechanism by which reabsorption occurs:
in order for water to be transported by osmosis, filtrate ad interstitial fluid ...
cannot be isotonic
Mechanism by which reabsorption occurs:
in order for water to be transported by osmosis, interstitial fluid must be ...
hypertonic
(4x more than plasma)
Mechanism by which reabsorption occurs:
the mechanism for water reabsorption is dependent on ...
partially due to geometry of tubule
(gradient in one tubule influences interstitial fluid between which influences gradient of neighbor tubule)
Counter Current Multiplier System:
Which limb is
NOT PERMEABLE TO WATER?
ascending limb is not permeable to water
Counter Current Multiplier System:
Which limb is
almost impermeable to NaCl?
descending limb is almost impermeable to NaCl
Counter Current Multiplier System:
NaCl is extruded from which limb to tissue fluid?
NaCl is extruded from ascending limb to tissue fluid
Counter Current Multiplier System:
What does the extrusion of NaCl into interstitial fluid acheive?
interstitial fluid becomes hypertonic, drawing water from the neighboring water-permeable descending limb
Counter Current Multiplier System:
Water drawn out of the filtrate goes where?
water drawn out enters blood capillaries
Counter Current Multiplier System:
This system has what effect on the concentration and volume of filtrate?
concentration of filtrate is INCREASED
volume of filtrate is DECREASED
Counter Current Multiplier System:
For the system to work, what must happen to the interstitial water and NaCl?
1. NaCl from ascending limb must STAY in tissue fluid of medulla
2. WATER that leaves descending limb must be REMOVED by the blood
Counter Current Multiplier System:
Which limb does the water come from?
descending limb
Counter Current Multiplier System:
Which limb does the NaCl come from?
ascending limb
What are the Vasa Recta?
vessels that form long capillary loops parallel to loops of Henle of juxtamedullary nephrons
What do the vasa recta do?
vasa recta maintain hypertonic renal medulla
colloid
large molecule, mainly protein, to which capillaries are relatively impermeable; also, part of the inner structure of the thyroid gland
net glomerular filtration pressure =
glomerular capillary blood pressure - fluid pressure in bowmans space - osmotic force due to protein in plasma
mesangial cells
modified smooth-muscle cells that surround renal glomerular capillary loops; they help to control glomerular filtration rate
formula to calculate filtered load
multiply the GFR by the plasma concentration of the substance:
180 L/day * 1 g/L glucose = filtered load of glucose is 180 g/day
formula to calculate percent reabsorbed
amount filtered - amount excreted = amount reabsorbed
amount reabsorbed / amount filtered = percent reabsorbed
metabolism by the tubules
tubules can synthesize glucose and add it to the blood. they can also catabolize certain organic substances (ie peptides, etc) taken from the tubules or capilaries, thereby eliminating these substances from the body
renal clearance is measured in
volume of plasma per unit of time
NaCl and solutes in medulla tissue fluid diffuse INTO blood in the ...
descending loop of the vasa recta
NaCl and solutes diffuse OUT of blood in the ...
ascending loop of vasa recta (where concentration is less)
concentrations of NaCl and solutes inside and outside vasa recta become ...
concentrations become same inside/outside vasa recta
colloid osmotic pressure in vasa recta is _______ than tissue fluid? Why?
higher
due to proteins
What does a higher colloid osmotic pressure in vasa recta cause?
water to move into capillaries
vasa recta does what to NaCl and water in the medulla?
vasa recta holds NaCl in medulla
vasa recta transports water out of medulla
Describe the permeability of the walls of the collecting ducts
walls of collecting ducts permeable to water but NOT NaCl
describe the osmotic pressure situation between the tissue fluid in the medulla and the collecting ducts
* what does this cause
tissue fluid in medulla HYPERTONIC to fluid in collecting duct
* so water is drawn out of collecting duct osmotically
What determines the reabsorption rate from the collecting duct?
reabsorption rate determined by PERMEABILITY of collecting duct
What determines the permeability of the collecting ducts?
permeability of collecting duct determined by concentration of ADH in blood
ADH
Antidiuretic hormone
aka Vasopressin
peptide hormone synthesized in hypothalamus and released from posterior pituitary; increases water permeability of kidney's collecting ducts and causes vasoconstriction
what stimulates the production of ADH?
osmoreceptors in the hypothalamus
What do osmoreceptors in the hypothalamus respond to?
respond to increase in blood osmotic pressure (increase solute concentration or less water) with an increase in ADH production
When ADH levels are up ...
tubule more permeable to water = more water reabsorption
When ADH levels are down ...
tubules are less premeable to water = less water reabsorption
Aldosterone
(al-doh-STEER-own or
al-DOS-stir-own)
mineralocorticoid steroid hormone secreted by adrenal cortex; regulates electrolyte balance
mineralocorticoid
steroid hormone produced by adrenal cortex; has major effect on sodium and potassium balance; major mineralocorticoid is aldosterone
What does ALDOSTERONE regulate?
regulates excretion/retention of minerals
What does ALDOSTERONE do to Na+ reabsorption?
increases Na+ reabsortion (retention)
What does ALDOSTERONE do to water?
Aldosterone increases Na+ reabsortion (retention), and WATER FOLLOWS
What does ALDOSTERONE do to K+ secretion?
increases K+ secretion (loss)
what is the name of the mechanism that regulates aldosterone secretion?
juxtaglomerular apparatus
macula densa
specialized sensor cells of renal tubule at end of loop of henle; component of juxtaglomerular apparatus
juxtaglomerular apparatus
(JGA)
renal structure consisting of macula densa and juxtaglomerular cells; site of renin secretion and sensors for renin secretion and control of glomerular filtration rate
juxtaglomerular cell
(JG)
renin-secreting cells in the afferent arterioles of the renal nephron in contact with the macula densa
juxtamedullary nephron
functional unit of the kidney with glomeruli in the deep cortex and a long loop of Henle, which plunges into the medulla
keto acid
a class of breakdown products formed from the deamination of amino acids
ketone
product of fatty acid metabolism that accumulates in blood during starvation and in severe untreated diabetes mellitus; acetoacetic acid, acetone, or B-hydroxybutyric acid; also called ketone body
kinase
enzyme that transfers a phosphate (usually from ATP) to another molecule
where will you find the juxtaglomerular apparatus?
where afferent arteriole (with granular cells or juxtaglomerular cells on it) and distal convoluted tubule (macula densa) touch
Juxtaglomerular apparatus:
when BP is low it causes juxtaglomerular cells (granular cells) to do what?
when BP low causes granular cells to secrete RENIN (enzyme) into blood
Renin
(REE-nin)
peptide hormone secreted by kidneys; acts as an enzyme that catalyzes splitting off of angiotensin I from angiotensinogen in plasma
Juxtaglomerular apparatus:
renin catalyzes conversion of
renin catalyzes conversion of angiotensinogen produced by the liver to become ANGIOTENSIN I
Juxtaglomerular apparatus:
ANGIOTENSIN CONVERTING ENZYME (ACE) catalyzes the conversion of
angiotensin I to angiotensin II
Juxtaglomerular apparatus:
angiotensin II stimulates
adrenal cortex to secrete ALDOSTERONE
Juxtaglomerular apparatus:
aldosterone promotes
aldosterone promotes reabsorption of Na+ (and water)
result of juxtaglomerular apparatus
* increased Na+ reabsorption
* increased blood volume
* increased BP
Aldosterone secretion leads to what the reabsorption of how much Na+?
90% Na+ filtered is reabsorbed
Secretion:
molecules move from
molecules move from peritubular capillary into tubule cells and are then actively transported into lumen of tubule
Secretion:
what molecules are secreted?
molecules that DIDN'T FILTER
Secretion:
most important molecules secreted are ..
H+
K+
organic cations
drugs
Secretion:
molecules secreted-- give some examples of organic cations
urea, creatinine, ammonia, uric acid
Secretion:
molecules secreted-- give some examples of drugs
atropine, saccharin, morophine, antibiotics, neurotransmitters, pigments
endocrine glands produce
hormones
hormones act on
target organs
what produces hormones?
some discrete glands,
some cells and
some organs with other functions
neurohormone
chemical messenger that is released by a neuron and travels in bloodstream to its target cell
hypothalamus secretes
neurohormones ADH and Oxytocin
what are the three chemical classes of hormones?
1. amines
2. peptides and proteins
3. steroids
Amines:
what glands produce amine hormones?
thyroid gland
adrenal medulla
Amines:
thyroid gland produces what?
2 iodine containing hormones:
Thyroxine (T4)
Triiodothyronine (T3)
Amines:
What are the steps to T3/T4 synthesis?
1. iodine ingested
2. combined with tyrosine in gland
3. stored as thyroglobulin
4. T3/T4 enzymatically split secreted
thyroglobulin
large protein precursor of thyroid hormones in colloid of follicles in thyroid gland; storage form of thyroid hormone
tyrosine
amino acid; precursor of catecholamines and thyroid hormones
Amines:
What do T3/T4 do?
regulate metabolic rate, development and growth
Amines:
adrenal medulla secretes
amines
catecholamines
Amines:
adrenal medulla is like
medulla is like a sympathetic ganglion whose cell bodies do not send out fibers but release their secretions into the blood
Amines:
adrenal medulla
epinephrine/norepinephrine exert
epinephrine/norepinephrine exert actions similar to those of sympathetic nerves
Peptides/Proteins:
Name the peptide hormones
ADH, OT, TRF, GRF, GH, prolactin, angiotensin
Peptides/Proteins:
Name the proteins
insulin, glucagon, calcitonin, GI hormones
Peptides/Proteins:
how much of hormones are peptides/proteins?
most hormones
Peptides/Proteins:
How are they made?
1. synthesized on ribosomes as preprohormones
2. cleaved by proteolytic enzymes to prohormones in granular ER
3. prohormone cleaved to active hormone and packaged in vesicles in Golgi apparatus
4. released from vesicles when Ca++ from ER or extracellular fluid enters cell via voltage sensitive channels
5. hormone secreted by exocytosis when cell stimulated
Steroids:
steroids are
lipids
Steroids:
produced by
adrenal cortex, gonads and placenta
Steroids:
name them
estrogen, progesterone, testosterone, aldosterone and cortisol
Steroids:
precursor is
cholesterol and it is made in the liver
Steroids:
diffuse
diffuse readily across plasma membrane
Steroids:
Adrenal Cortex produces
1. aldosterone (mineralocorticoid)
2. cortisol
3. corticosterone
4. dehydroepiandrosterone
5. androstenedione
Steroids:
Gonads produce
testosterone, estradiol and progesterone
response to a hormone secretion depends on
response to a hormone secretion depends on the presence of specific receptors on target cells
receptors for steroids are
proteins INSIDE cells
receptors for thyroid hormones are
proteins INSIDE cells
receptors for peptides are
proteins ON THE PLASMA MEMBRANE of cells
receptors for catecholamines are
proteins ON THE PLASMA MEMBRANE of cells
power of homone action can be influenced by
up regulation/down regulation of receptors
Steroid and Thyroid effects:
increased protein synthesis by target cells
steps to steroid and thyroid actions
1. hormone enters target cell
2. binds to receptor in cytoplasm
3. transported into nucleus
4. combines with receptor in nucleus
5. activated receptor interacts with specific DNA to trigger transcription of mRNA for protein synthesis
peptide and catecholamine effects
receptors use signal transduction or 2nd messenger leads to cell response
INPUTS for hormone secretion
1. changes in plasma mineral ion concentration
2. changes in plasma organic nutrient concentration
3. neurotransmitter released from neuron
4. another hormone (tropic)
5. chemical and physical factors in GI tract
* sometimes more than one input
Pituitary Gland:
anterior pituitary makes
tropic hormones
Pituitary Gland:
posterior pituitary releases
oxytocin and ADH
Hypothalamus produces
produces 2 peptide hornones released from POSTERIOR pituitary:
oxytocin (OT)
antidiuretic hormone (ADH/vasopressin)
what is the structure in the hypothalamus that produces the hormones
neuron cell bodies in hypothalamus produce hormones
what is the structure associated with hypothalamus hormone secretion?
axons extend down into posterior pituitary and release hormones there
how does the hypothalamus interact with the anterior pituitary?
hypothalamus secretes hormones that control the secretion of all the anterior pituitary hormones
the hypothalamic releasing and inhibiting hormones do what?
regulate release of anterior pituitary hormones
median eminence
region at base of hypothalamus containing capillary tufts into which hypophysiotropic hormones are secreted
hypophysiotropic hormones
any hormone secreted by hypothalamus that controls secretion of an anterior pituitary hormone
portal vessel
any blood vessel that links two capillary networks
Hypothalamus:
median eminence
capillaries at base of hypothalamus form portal vessels which pass down hypothalamic-hypophyseal stalk
How does the hypothalamus neurons cause release of tropic hormones in anterior pituitary:
when neurons in hypothalamus secrete RELEASING HORMONES they travel thru portal system to anterior pituitary to cause release of tropic hormones
hypothalamic releasing homone -->
tropic hormone --> target gland cells
neural control of hormone release
* sympathetic control of adrenal medulla
* hormones from hypothalamus
hormonal control of hormone release
tropic hormones
Anterior Pituitary Hormones
6 peptides
1. follicle stimulating hormone (FSH)
2. luteinizing hormone (LH)
3. growth hormone (GH)
4. thyroid stimulating hormone (TSH)
5. prolactin (PRL)
6. adrenocorticotropic hormone (ACTH)
candidate hormones
* suspected to be hormones
* function not confirmed
* not sure blood transports
name the main candidate hormone:
melatonin
melatonin
* pineal gland
* synthesized from serotonin
* role in humans unclear
* secretion follows circadian rhythm
* high - nite/low - day
endocrine disorders
1. hyposecretion (too little)
2. hypersecretion (too much)
hyposecretion
Primary: gland not functioning
Secondary: not enough tropic hormone
hypersecretion
Primary: gland secreting too much
Secondary: excessive tropic hormone
gametes
germ cell or reproductive cell; sperm in male and egg in female; 23 chromosomes (haploid)
meiosis
process of cell division leading to gamete (sperm or egg) formation; daughter cells receive only half the chromosomes present in original cell
diploid
Having a pair of each type of chromosome, so that the basic chromosome number is doubled
haploid
Having the same number of sets of chromosomes as a germ cell or half as many as a regular cell
oogenesis
gamete production in female
spermatogenesis
sperm formation
zygote
a newly fertilized egg
homologous
corresponding in origin, structure, and position
autosomes
chromosome that contains genes for proteins governing most cell structures and functions; compare sex chromosome
tetrads
grouping of two homologous chromosomes, each with its sister chromatid, during meiosis
renin-angiotensin system
hormonal system consisting of renin-stimulated angiotensin I production followed by conversion to angiotensin II by angiotensin-converting enzyme
Mullerian ducts
part of embryo that, in a female, develops into reproductive system ducts, but in a male, degenerates
Mullerian Inhibiting Factor (MIF) or
Mullerian-inhibiting substance (MIS)
protein secreted by fetal testes that causes Mullerian ducts to degenerate
reductase
Any of various enzymes that catalyze the reduction of an organic compound
dihydrotestosterone
steroid formed by enzyme-mediated alterationof testosterone; active form of testosterone incertain of its target cells
____________ from two individuals combine in a random way to form the next generation
gametes (genes)
Gametes (germ/sex cells) are formed where and by what process?
gonads by meiosis
fertilization produces what in the zygote?
23 pairs of homologous chromosomes, or 46 in number
What is the breakdown of the chromosomes in a zygote?
22 pair autosomes
1 pair sex chromosomes
autosomes and sex chromosomes are determined by
random chance
How long are gonads in the zygote undifferentiated?
gonads which develop in each sex are similar for the first 40 days of development
Where is the gene that codes for SRY?
the gene is on the short arm of the Y
SRY gene
Sex Determining Region Gene
aka TDF TestesDeterminingFactor
gene on the Y chromosome that determines development of testes in genetic male
SRY causes indifferent gonads to ...
become testes
When do the gonads develop into testes?
the 7th week of development
When do the gonads develop into ovaries?
the 11th week of development
What are the accessory organs derived from?
two systems of embryonic ducts
Name the Male Embryonic Duct System
mesonephric (Wolffian) ducts
Name the Female Embryonic Duct System
paramesonephric (Mullerian) ducts
What duct does the embryo start developing in the 5th week?
Both the mesonephric and the paramesonephric duct systems
What happens to an indifferent gonad in the presence of the SRY gene?
The indifferent gonad differentiates into a TESTIS and begins to produce TESTOSTERONE and MIF
What happens to an indifferent gonad if no SRY gene is present?
The indifferent gonad differentiates into an OVARY
What happens to the PARAMESONEPHRIC duct if there is MIF present?
the paramesonephric duct degenerates
What happens to the PARAMESONEPHRIC duct if there is no MIF present?
the paramesonephric duct develops into a uterus and oviducts
What happens to the MESONEPHRIC duct if there is TESTOSTERONE present?
the mesonephric (or Wolffian) duct develops into the epididymes, the vas deferens, the ejaculatory duct, and the seminal vesicle
What happens to the MESONEPHRIC duct if there is no TESTOSTERONE present?
The Wolffian duct degenerates
What happens to the OTHER EMBRYONIC STRUCTURES if there is no TESTOSTERONE present?
the other embryonic structures develop into a vagina, the labia, and the clitoris if no testosterone is present
What happens to the OTHER EMBRYONIC STRUCTURES if there is TESTOSTERONE present?
the other embryonic structures develop into the penis, the scrotum and the prostate if there is testosterone present
Name the Gonadotropins
LH, FSH and hCG
gonadotropin
glycoprotein hormone secreted by pituitary (LH, FSH) and placenta (hCG) that influence gonadal function
Gonadotropins cause 3 primary effects:
1. stimulate meiosis
2. stimulate steroid secretion by gonad
3. maintain structure of gonad
GnRH
gonadotropin-releasing hormone
hypophysiotropic hormone that stimulates LH and FSH secretion by anterior pituitary in males and females
hypophysiotropic hormone
any hormone secreted by hypothalamus that controls secretion of an anterior pituitary hormone
In a negative feedback loop, steroids inhibit what in regards to GnRH?
* steroids inhibit the hypothalamus secretion of GnRH
* steroids inhibit anterior pituitary response to GnRH
Inhibin
protein hormone secreted by seminiferous-tubule Sertoli cells and ovarian granulosa cells; inhibits FSH secretion
Sertoli Cells
cell intimately associated with developing germ cells in seminiferous tubule; creates blood-testis barrier, secretes fluid into seminiferous tubule, and mediates hormonal effects on tubule
testes secrete _________ (polypeptide) which along with ____________ inhibits _____ secretion
Inhibin
testosterone
FSH
this secretion is CONSTANT in males and CYCLIC in females
gonadotropin
Control of Ovarian Function
1. GnRH (hypothalamus)
2. FSH and LH (anterior pituitary)
3. Estrogen and progesterone (ovary)
Leydig cells are also known as
aka interstitial cells
Leydig cell
testosterone-secreting endocrine cell that lies between seminiferous tubules of testes also called interstitial cell
Leydig cells have receptors for what and secrete what?
have receptors for ICSH/ICTH
secrete androgens
Sertoli cells have receptors for what and do what?
have receptors for FSH and
stimulate spermatogenesis
what are the parts of the female reproductive system?
2 ovaries, fallopian tubes, uterus, vagina, vulva
gonadotropins secretion is where in a newborn?
gonadotropins secretion high first few weeks in newborns then falls off
as puberty approaches, what happens to concentrations of gonadotropins?
FSH/LH rise
perhaps pre-puberty rise in gonadotropins is due to ...
1. as brainmatures and hypothalamus increases GnRH
2. decreased sensitivity of gonadotropins to steroids (so negative feedback doesn't work)
at puberty, increase in gonadotropins causes ..
1. increased sectretion of testosterone
2. increased secretion of estradiol 17B
what develops as a result of the increased steroids at puberty?
secondary sex characteristics develop as a result of the increases in steroids
estradiol
(es-tra-DY-ol)
steroid hormone of estrogen family; major female sex hormone
estriol
(ES-tree-ol)
steroid hormone of estrogen family; major estrogen secreted by placenta during pregnancy
testosterone
steroid hormone produced in interstitial cells of testes; major male sex hormone
Testosterone is:
* major androgen
* anabolic steroid
Testosterone and FSH are needed for
completion of spermatogenesis
testosterone and inhibin are
negative feedback with anterior pituitary (requires both)
testosterone initiates and maintains body changes associated with puberty:
1. growth of testes, penis, accessory organs
2. body growth
3. growth of larynx
4. pubic, facial and axillary hair
5. Hb synthesis
6. bone growth (closing epiphyseal plate)
where do SPERMATOGONIA come from?
1,000-2,000 germ cells migrate from yolk sac to testes and become SPERMATOGONIA (2N)
spermatogonium
undifferentiated germ cell that gives rise to primary spermatocyte
spermatozoa
the male gamete, a haploid sperm cell
spermatid
immature sperm that results from division of secondary spermatocytes
spermatocyte
a male gametocyte which is derived from a spermatogonium
Initially, a spermatogonium divides by ______ into two ____________
mitosis
primary spermatocytes
A primary ________ is diploid, undergoes ________ to become two _________ spermatocytes which are ________.
spermatocyte
meiosis
secondary
haploid
spermatid + elongation and remodeling =
spermatozoa
Sertoli Cells are also known as
Nurse cells or sustentacular cells
Sertoli cells form what around circumference of tubule?
sertoli cells form tight junctions around circumference of tubule for BLOOD-TESTIS BARRIER
sertoli cells PHAGOCYTIZE
between spermatids/spermatozoa cytoplasm phagocytized by sertoli cells (to help convert spermatids into spermatozoa)
Sertoli cells secrete
MIF (or MIS) and inhibin
where do the spermatozoa mature and become mobile?
in the epididymis, where they are stored
are spermatozoa motile in the seminiferous tubules?
no, spermatozoa nonmotile when leave seminiferous tubules
what causes an erection?
when conscious sexual thoughts (cortex) and/or sensory (mechanoreceptors) stimulation via hypothalamus to sacral region cord causes
erection, re autonomic nerves
stimulation of parasympathetic nerves (and inhibition of sympathetic nerves) to small arteries of the erectile tissue (corpora) of the penis causes arteries to dilate
what happens when an erection begins?
blood fills erectile tissue and venous outflow is passively occluded.
penis becomes turgid/erect
emission
movement of semen into the urethra
ejaculation
forcible expulsion of semen from urethra out of penis due to smooth muscle peristaltic contractions (sympathetic) of tubular system, contractions of seminal vesicle and prostate and skeletal muscle contractions at the base of penis
sexual function in male requires
sexual function in the male requires synergistic action of both sympathetic and parasympathetic system
average ejaculate =
1.5 - 5 mL
erection is sympathetic or parasympathetic? ejaculation?
erection = parasympathetic
ejaculation = sympathetic
average sperm count =
60 - 150 million/mL
________ migrate to ovaries during early embryonic development and _________
germ cells
multiply
how many germ cells does a female have at 5 mo gestational and what are they called?
5 mo gestational = 6 - 7 million = oogonia
diploid primary oocyte divides into
divides into a haploid secondary oocyte and the 1st polar body
(begins in utero, completed prior to ovulation)
secondary oocyte divides into
ovum and second polar body AFTER FERTILIZATION
at the end of gestation, what is the status of the eggs in a female?
meiosis begins, cells arrested at primary oocytes
female eggs at birth
2-4 million primary oocytes
female eggs at puberty
200,000 - 400,000 primary oocytes
ovulated in whole life
400 secondary oocytes
each cycle how many primary oocytes begin to develop?
10-25
at puberty in girls, the ________ named __________ stimulates ___________ development around oocytes
gonadotropins
FSH
follicle
follicles
primary oocytes surrounded by layer of granulosa cells
granulosa cells secrete
estrogen (little progesterone and inhibin)
an ovulated sex cell is still
a secondary oocyte
at puberty, after follicles surrounded by granulosa cells, primary oocyte ...
completes 1st meiotic division forming secondary oocyte/1st polar body
when secondary oocyte leaves follicle at ovulation, granulosa cells altered become
corpus luteum
corpus luteum
ovarian structure formed from the follicle after ovulation; secretes estrogen and progesterone
corpus luteum secretes
progesterone (small amount of estrogen/inhibin)
secondary oocyte arrested at meaphase not completed until
after fertilization
secondary sex characteristics of girls
* breast development
* axillary and pubic hair
* menarche
menarche
(MEN-ark-ee)
onset, at puberty, of menstrual cycling in women
menarche starts
10 - 16 yrs old
menarche onset related to
ratio of body fat
physical activity
menstrual cycle lasts
28 days
phases to mentstral cycle?
2 phases:
* proliverative (follicular phase)
* secretory (luteal phase)
proliferative phase
stage of menstrual cycle between menstruation and ovulation during which endometrium repairs itself and grows
secretory phase
stage of menstrual cycle following ovulation during which secretory type of endometrium develops
luteal phase
last half of menstrual cycle following ovulation; corpus luteum is active ovarian structure
follicular phase
that portion of menstrual cycle during which follicle and egg develop to maturity prior to ovulation
proliferative (follicular phase)
day 1-14
follicle containing secondary oocyte develops
(this phase can vary from the 14 days)
secretory (luteal phase)
day 14-28
from ovulation - degeneration of corpus luteum
(this phase is always 14 days)
Ovarian hormones
estrogen
progesterone
inhibin
estrogen
* secreted during follicular phase by GRANULOSA CELLS
* after ovulation secreted in lesser amount by corpus luteum
progesterone
* secreted in small amounts by GRANULOSA CELLS and THECA CELLS just before ovulation
* major source corpus luteum
theca
cell layer that surrounds ovarian-follicle granulosa cells
Inhibin
secreted by GRANULOSA CELLS and corpus luteum
granulosa cell
cell that contributes to the layers surrounding egg and antrum in ovarian follicle; secretes estrogen, inhibin, and other messengers that influence the egg
antrum (ovarian)
fluid-filled cavity in maturing ovarian follicle
mechanism for testosterone action
inavtive testosterone comes to a target organ and binds to receptors. inactive testosterone + 5alphaReductase = DHT
inactive testosterone in the presence of 5alphaReductase becomes ...
dihydrotestosterone (DHT)
dihydrotestosterone
steroid formed by enzyme mediated alteration of testosterone; active form of testosterone in certain of its target cells
masculinization incomplete
androgen insensitivity syndrome
Endocrine Regulation of Reproductive Structures:
first trimester
embryonic testes secrete large amount of testosterone (to masculinize genitalia/accessory organs)
Endocrine Regulation of Reproductive Structures:
third trimester
ovaries mature
Endocrine Regulation of Reproductive Structures:
birth
gonads of both sexes inactive
Endocrine Regulation of Reproductive Structures:
prepubertal
(males/females)
steroids concentration equal
Endocrine Regulation of Reproductive Structures:
puberty
gonadotropins increase
steroids increase