Final Exam Review Flashcards
The formation of what is one of the most important intracellular processes that require energy?
formation of peptide linkages
How many high-energy phosphate bonds are needed to form one peptide linkage?
4 high-energy phosphate bonds (48,000 cal).
but each peptide bond only stores 500-5000 cal
Which steps in the ornithine (urea) cycle occur in the mitochondria?
> Ammonia + CO2 –> Carbamoyl Phosphate
> Carbamoyl Phosphate + Ornithine –> Citrulline
Which steps in the ornithine (urea) cycle occur in the cytoplasm?
> Citrulline + Aspartate –> Argininosuccinate
> Argininosuccinate –> Arginine + Fumarate
> Arginine –> Urea + Ornithine
- *Fumarate can enter the citric acid cycle
- *Ornithine can be recycled through another cycle
True or False:
Most chemical reactions in the body occur in series.
True
What is the overall rate of a series of chemical reactions determined by?
Rate of Reaction of the slowest step in the series.
- *Called the rate-limiting step in the entire series.**
- *ADP is the major rate-limiting factor for almost all energy metabolism in the body.**
What molecule is the major rate-limiting factor for almost all energy metabolism in the body?
ADP
What is the best known stimuli for increasing the rate of thyroid stimulating hormone (TSH) release?
Cold
List factors that influence metabolic rate.
- Arousal vs. Sleeping
- Skeletal Muscle
- Age
- Thyroid Activity
- Testosterone
- Growth Hormone
- Fever
- Sleep
- Malnutrition
True or False:
Cold is one of the best known stimuli for increasing the rate of thyroid stimulating hormone (TSH).
True
What is most of the glucose absorbed after a meal stored as in the body?
Stored as glycogen in the liver.
What hormone regulates glucose uptake mechanisms in the liver?
Insulin
> Insulin inactivates liver phosphorylase.
Insulin activates glucokinase and enhances uptake of glucose from blood.
Insulin increases activities of enzymes needed for glycogenesis.
What role does insulin have on glucose uptake mechanisms for the liver?
- Insulin inactivates liver phosphorylase.
- Insulin activates glucokinase and enhances uptake of glucose from blood.
- Insulin increases activities of enzymes needed for glycogenesis.
What is one of the most important functional roles of insulin in the body?
Control from moment to moment whether fat (decreased insulin) or carbohydrate (increased insulin) will be used by cells for energy.
What hormone controls from moment to moment whether fat or carbohydrates will be used by cells for energy?
Insulin
this is one of the most important functional roles of insulin in the body
True or False:
The liver has a high blood flow and a high vascular resistance.
False - liver has high blood flow and low vascular resistance.
> 1050 ml from portal vein + 300 ml from hepatic artery flows into sinusoids each minute.
27% of resting cardiac output.
What is the portal pressure into the liver?
9 mm Hg
What is the pressure from the liver to the vena cava?
0 mm Hg
What is the effect of cirrhosis on blood flow?
Increases blood resistance to blood flow.
What is the effect on a clot blocking the portal vein or a major branch?
- Blockage of return blood from spleen and intestines.
- Increase in capillary pressure in intestinal wall –> loss of fluid –> death.
What molecule are hepatic sinusoids highly permeable to?
Proteins
efferent lymph has a protein concentration of 6 g/dl (almost equivalent to plasma concentration).
What does a higher than normal pressure in hepatic veins cause?
Large amount of fluid in abdominal cavity = ascites.
- Back pressure causes fluid to translude into lymph.
- Fluid leaks through liver capsule into abdominal cavity.
- Fluid is almost pure plasma.
- Large amount of fluid in abdominal cavity = ascites.
What organ produces and secretes hepatic bile?
Liver
True or False:
Bile from the gallbladder is hepatic bile that has been stored and concentrated.
True
What are the components of bile stored in the gallbladder?
- Cholic and chenodeoxycholic acids (synthesized by hepatocytes).
- Deoxycholic acid and lithocholic acid (converted by bacteria).
- Water and electrolytes.
- Cholesterol and phospholipids (esp. lecithin).
- Pigments and organic molecules (major pigment is bilirubin).
What is the major pigment found in bile secreted by the gallbladder?
bilirubin
What molecule transports heme in the blood?
transferrin
What enzyme converts heme into biliverdin?
heme oxygenase
What does heme oxygenase convert heme into?
biliverdin
Once biliverdin is converted to free (unconjugated) bilirubin, what does it attach to for transport in the blood stream?
Free bilirubin is transported in the blood stream attached to plasma albumin to liver hepatocytes.
Where is free bilirubin, that is transported in the blood stream attached to plasma albumin, being transported to?
to liver hepatocytes
True or False:
Free bilirubin is released from plasma albumin within the liver cells and conjugated.
True
In which organ is free bilirubin released in and conjugated?
Free bilirubin is released from plasma albumin within the liver cells and conjugated.
80% of free bilirubin is conjugated in liver cells with glucuronic acid. What enzyme conjugates bilirubin + glucuronic acid –> Bilirubin Glucuronids?
UDP glucuronyl transferase
What are the 2 ways in which conjugated bilirubin is removed from the body?
(1) SECRETED (active transport) into the intestine.
(2) EXCRETED into the urine.
What is conjugated bilirubin broken down into in the terminal ileum?
Conjugated bilirubin converted to urobilinogen via bacterial action.
urobilinogen can then enter enterohepatic circulation -> liver -> re-excreted by the liver OR excreted in the urine
Or: urobilinogen can be oxidized into urobilin + stercobilin in the colon and then excreted in the feces
What characteristics would a patient with metabolic syndrome present with?
- obesity (esp. abdominal fat)
- insulin resistance
- fasting hyperglycemia
- increased lipid triglycerides
- decreased HDL levels
- hypertension
In the down regulation of receptors, the number of active receptors may decrease because of?
- increased hormone concentration
- increased binding to receptors
down regulation decreases the target tissue’s responsiveness to the hormones
In the down regulation of receptors, the number of active receptors may decrease because of increased hormone concentration and increased binding to receptors. This can occur as a result of what?
- Inactivation of some of the intracellular protein signaling molecules.
- Temporary sequestration of the receptor inside the cell.
- Inactivation of some of the receptor molecules.
- Destruction of the receptors by lysosomes after they are internalized.
- Decreased production of receptors.
True or False:
Down regulation of receptors decreases the target tissue’s responsiveness to the hormones.
True
In the up regulation of receptors, the number of active receptors or intracellular signaling molecules may increase. This may occur as a result of?
- The stimulating hormone may induce greater than normal formation of receptor or intracellular signaling molecules.
- The stimulating hormone may induce greater availability of the receptor for interaction with the hormone.
True or False:
The up regulation of receptors increases the target tissue’s responsiveness to the hormones.
True
What are the two ways in which calcium entry may be initiated for triggering the calcium-calmodulin phospholipid second messenger system?
- Changes in membrane potential that open calcium channels.
- A hormone interacting with membrane receptors that open calcium channels.
In the calcium-calmodulin phospholipid second messenger system, when 3-4 binding sites on calmodulin are filled, what multiple effects are initiated?
- activation of protein kinases
- inhibition of protein kinases
What does calcium bind to to initiate the calcium-calmodulin phospholipid second messenger system?
Calmodulin
What is the name of the promoter sequence of DNA that activated hormone-receptor complex binds to to initiate transcription?
Hormone Response Element
List lipid soluble hormones that bind to intracellular receptors.
- adrenal and steroidal hormones
- thyroid hormones
- retinoid hormones
- vitamin D
What are the 5 cell types that can be differentiated in the anterior pituitary (adenohypophysis)?
- Somatotropes (acidophils)
- Corticotropes
- Thyrotropes
- Gonadotropes
- Lactotropes
What hormone is released from somatotropes?
Human Growth Factor (HGF)
What hormone is released from corticotropes?
ACTH
What hormone is released from thyrotropes?
TSH
What hormone is released from gonadotropes?
LH and FSH
What hormone is released from lactotropes?
Prolactin
How many mg of iodine (iodides such as sodium iodide) are required each year?
50 mg of iodine.
Thus, our body does a very good job of recycling iodine.
True or False:
Iodine is absorbed from the gut tract in the same manner as chlorides.
True
In which membrane of the thyroid cell is the sodium-iodide symporter (2:1) located?
Basal Membrane
Where does the sodium-iodide symporter in the basal membrane of the thyroid cell get energy from?
Sodium-Potassium ATPase Pump
How much more can iodide be concentrated inside the thyroid cell compared to the plasma concentration?
30-250x
Through what transporter is iodide transported across the apical membrane of the thyroid cell into the follicle?
Via a chloride-iodide counter-transporter = pendrin.
What does pendrin do?
Transports iodide across the apical membrane of the thyroid cell into the follicle via a chloride-iodide counter-transporter = pendrin.
What membrane enzyme catalyzes conversion of iodide into iodine (I2)?
peroxidase
What enzyme catalyses the organification of iodine?
peroxidase
What is iodine combined with during the organification of iodine?
Combining of iodine with tyrosine on thyroglobulin.
What does the combining of iodine with tyrosine on thyroglobulin result in?
monoiodotyrosine (MIT) and diiodotyrosine (DIT)
The organification of iodine results in monoiodotyrosine (MIT) and diiodotyrosine (DIT). What are these recombined into?
DIT + DIT = thyroxine (T4)
T4 is formed more than T3
DIT + MIT = triiodothyronine (T3)
T3 more active than T4
What does the thyroglobulin molecule have attached to it when it is stored in the colloid until needed?
- MIT
- DIT
- T3
- T4
Are MIT or DIT ever secreted like T3 and T4 are?
No - they are recycled within the thyroid.
only T3 and T4 are secreted
Look over figure 77-2 on slide 24 of the review.
Iodine transport mechanism in thyroid cell.
True or False:
Thyroid cells also secrete thyroglobulin (MW=335,000) into the follicle.
True
each thyroglobulin molecule has about 70 tyrosine amino acids which bind iodine to form thyroid hormones
What does iodide ions have to be converted to before they can bind directly to tyrosine amino acids on thyroglobulin molecules?
Iodide ions are converted to an oxidized form of iodine:
> either nascent iodine (I2) or I3-
> these oxidized forms can bind directly to tyrosine
Which hormone, T3 or T4, is the major hormonal product?
Thyroxine (T4)
What two molecules are joined together to form thyroxine (T4)?
2 molecules of diiodotyrosine (DIT).
What are the causes of hyperthyroidism?
- Graves’ disease
- Adenoma
What are the symptoms of a patient with hyperthyroidism?
- high state of excitability
- intolerance to heat
- increased sweating
- mild to extreme weight loss
- varying degrees of diarrhea
- muscle weakness
What hormone is the major mineralocorticoid?
aldosterone
What affect does aldosterone have on electrolytes?
- increases Na ion reabsorption by kidney tubules (acts on principal cells in late distal tubule)
- increases K ion secretion by kidneys (acts on principal cells in late distal tubule)
- increases H ion secretion by kidneys (acts on intercalated cells in late distal tubule)
True or False:
Hyperkalemia increases aldosterone secretion.
True
What is the secretion of aldosterone mainly controlled by?
- angiotensin II
- potassium concentration
Which layer of the adrenal cortex is aldosterone (mineralocorticoids) secreted by?
zona glomerulosa
Look over slide 29 in the review well.
Decrease in blood volume mechanism for aldosterone synthesis and secretion.
What hormone is the major glucocorticoid?
Cortisol is major glucocorticoid.
What response is cortisol essential for?
Stress Response
What hormone released from the anterior pituitary mainly controls the secretion of cortisol?
ACTH
- ACTH up-regulates it own receptor.
- Under the influence of CRH (corticotropin-releasing hormone) from neurosecretory cells located in the paraventricular nuclei.
- Second messenger for both CRH and ACTH is cAMP.
Which layer of the adrenal cortex is cortisol secreted by?
zona fasciculata
What is the second messenger for both CRH and ACTH?
cAMP
True or False:
Cortisol has negative feedback response to both CRH and ACTH
True
What are the functions of glucocorticoids (cortisol)?
- Stimulates Gluconeogenesis
- May lead to “adrenal diabetes”
- Resist Stress
- Resists Inflammation
- Causes resolution of inflammation
- Inhibits immune response
- Maintains vascular response to catecholamines
What are the causes of hyperadrenalism (Cushing’s disease)?
Excess ACTH secretion is cause of Cushing’s disease:
- administration of glucocorticoids
- adenomas of anterior pituitary
- abnormal function of hypothalamus
- ectopic secretion of ACTH by tumor
- adenomas of adrenal cortex
What are the characteristics of hyperadrenalism (Cushing’s disease)?
- increase in cortisol and androgen levels
- “buffalo torso”
- moon face
- acne and hirsutism
- hypertension
- increased blood glucose
- increase in protein catabolism and muscle wasting
What is the cause of primary hypoadrenalism (Addison’s disease)?
injury to adrenal cortex
What is the cause of secondary hypoadrenalism?
- mineralocorticoid deficiency (aldosterone)
- glucocorticoid deficiency (cortisol)
- melanin pigmentation
What disturbances are due to a mineralocorticoid deficiency?
- decreased extracellular fluid volume
- hyponatremia
- hyperkalemia
- mild acidosis
- rise in RBC concentration
- decrease in cardiac output
- decrease in blood pressure
- metabolic acidosis
- death from shock
What disturbances are due to a glucocorticoid deficiency?
- loss of ability to maintain normal blood glucose concentrations between meals –> hypoglycemia
- reduction in both proteins and fats leading to depression of other bodily functions
- weight loss, nausea, vomiting
- muscle weakness
- highly susceptible to stress
What disturbances are due to melanin pigmentation?
- may be caused by loss of negative feedback to pituitary, allowing increased amounts of MSH
- results in uneven distribution of pigmentation, especially in thin skin areas
What does hypocalcemia do to the nervous system?
Causes nervous system excitement and tetany.
this is due to increased neuronal membrane permeability to Na ions
How does hypocalcemia cause nervous system excitement and tetany?
due to increased neuronal membrane permeability to Na ions
In patients with hypocalcemia, where does the first sign of tetany typically occur?
Hand, resulting in carpopedal spasm.
In hypocalcemia, when does tetany ordinarily occur?
When the blood concentration of calcium falls from its normal level of 9.5 mg/dl to about 6 mg/dl (35% below normal calcium concentration).
What calcium concentration is usually lethal?
4 mg/dl
What does the administration of PTH cause the rapid loss of?
phosphate in the urine
this is due to the effect of the hormone to diminish proximal tubular reabsorption of phosphate ions
Besides the administration of PTH causing a rapid loss of phosphate in the urine, what other affects does PTH have?
- increases renal tubular reabsorption of calcium
- increases the rate of reabsorption of magnesium ions and hydrogen ions
- decreases the reabsorption of sodium, potassium, and amino acid ions.
Do osteoclasts have membrane receptor proteins for PTH?
No
What is the major secondary signal that is sent from activated osteoblasts and osteocytes to activate preosteoclast cells? This secondary signal is sent after these cells are activated by PTH?
Osteoprotegerin Ligand - activates receptors on preosteoclast cells and transforms them into mature osteoclasts that remove bone over a period of weeks or months.
What are the 2 stages that occur in the activation of the osteoclastic system?
(1) Immediate activation of the osteoclasts that are already formed.
(2) Formation of new osteoclasts.
What is the active form of vitamin D?
1,25-dihydroxycholecalciferol
What affect does 1,25-dihydroxycholecalciferol have?
Causes intestines, kidneys, and bones to increase absorption of calcium and phosphate into the extracellular fluid and contribute to feedback regulation of these substances.
True or False:
Vitamin D receptors are present in most cells in the body and are located mainly in the nuclei or target cells.
True
**the vitamin D receptor has hormone-binding and DNA-binding domains.
** the vitamin D receptor forms a complex with another intracellular receptor, the retinoid-X receptor, and this complex binds to DNA and activates transcription in most instances.
** sometimes vitamin D suppresses transcription.
Look over figure 80-7 on slide 45 of the review.
Vitamin D synthesis.
Where is the active form of vitamin D synthesized?
Kidney - under the control of PTH.
What does 1,25-dihydroxycholecalciferol itself promote intestinal absorption of?
calcium
*by increasing, over a period of about 2 days, formation of calbindin, a calcium-binding protein, in the intestinal epithelial cells
> this protein functions in the brush border of the epithelial cells to transport calcium into the cell cytoplasm
- then the calcium moves through the basolateral membrane of the cell by facilitated diffusion
- calbindin remains in the cell for weeks after the 1,25-dihydroxycholecalciferol has been removed from the body
How does 1,25-dihydroxycholecalciferol itself promote intestinal absorption of calcium?
By increasing, over a period of about 2 days, formation of calbindin, a calcium-binding protein, in the intestinal epithelial cells.
this protein functions in the brush border of the epithelial cells to transport calcium into the cell cytoplasm
What is the function of calbindin?
This protein functions in the brush border of the epithelial cells to transport calcium into the cell cytoplasm.
Calbindin functions in the brush border of the epithelial cells to transport calcium into the cell cytoplasm. By what type of diffusion does calcium move through the basolateral membrane of the cell?
facilitated diffusion
Does the preganglionic sympathetic or postganglionic sympathetic fibers pass through the white rami?
preganglionic sympathetic fiber
Does the preganglionic sympathetic or postganglionic sympathetic fibers pass through the gray rami?
postganglionic sympathetic fiber
What type of fibers are postganglionic sympathetic fibers classified as?
type C fibers
True or False:
Preganglionic fiber can pass for variable distances through the chain and then through one of the sympathetic nerves to synapse in a peripheral sympathetic ganglion.
True
True or False:
Preganglionic fibers can synapse with postganglionic neurons upward or downward in the paravertebral chain.
True
What percentage of fibers in the average nerve consist of postganglionic sympathetic fibers?
8%
What do postganglionic sympathetic fibers control?
- blood vessels
- sweat glands
- piloerector muscles
What are splanchnic nerves composed of?
- preganglionic fibers
- visceral sensory fibers
What do splanchnic nerves supply?
abdominal viscera
Where do splanchnic nerves synapse?
prevertebral ganglia
From what thoracic vertebrae does the greater splanchnic nerves arise from?
T5-T9
From what thoracic vertebrae does the lesser splanchnic nerves arise from?
T10-T11
From what thoracic vertebra does the least splanchnic nerve arise from?
T12
What are the 3 splanchnic nerves?
- greater
- lesser
- least
Where does the greater splanchnic nerve synapse?
celiac ganglion
Where does the lesser splanchnic nerve synapse?
superior mesenteric ganglion
Where does the least splanchnic nerve synapse?
aorticorenal ganglion
In which cranial nerve is about 75% of all parasympathetic fibers in?
Vagus Nerve (CN X)
True or False:
Most preganglionic fibers pass all the way to the organ that is to be innervated.
True
What neurotransmitter is used by postganglionic parasympathetic fibers?
acetylcholine (Ach)
Where are postganglionic parasympathetic fibers located?
in the wall of the organ
What are the functions of the oculomotor nerve (CN III)?
- Supplies 4 of the 6 extrinsic muscles of the eye.
- Supplies the levator palpebrae superioris.
- Parasympathetic function
Which nucleus does the oculomotor nerve preganglionics arise from and to which ganglion does it go to?
- From Edinger-Westphal nucleus.
- To the ciliary ganglion.
Where do the postganglionics of the oculomotor nerve come from and go to?
- From the ciliary ganglion.
- To the sphincter pupillae muscle.
What are the functions of the facial nerve (CN VII)?
- Primary motor nerve to muscles of facial expression.
- Carries sensation of taste from anterior 2/3 of the tongue.
- Parasympathetic functions.
Which nucleus does the facial nerve preganglionics arise from and to which ganglion does it go to?
- From superior salivatory and lacrimal nuclei.
- To submandibular/sublingual ganglia.
Where do the postganglionics of the facial nerve come from and go to?
- From submandibular/sublingual ganglia.
- To lacrimal gland, submandibular gland, sublingual gland, and mucous glands of the mouth and nose.
What are the functions ofthe glossopharyngeal nerve (CN IX)?
- Carries general sensation and sensation of taste from posterior 1/3 of the tongue.
- Parasympathetic function.
Which nucleus does the glossopharyngeal nerve preganglionics arise from and to which ganglion does it go to?
- From inferior salivatory nucleus.
- To otic ganglion.
Where do the postganglionics of the glossopharyngeal nerve come from and go to?
- From otic ganglion.
- To parotid gland.
What are the functions of the vagus nerve (CN X)?
- Motor supply to muscles of the 4th and 5th pharyngeal arches and is important in swallowing and speaking.
- Parasympathetic function.
What are the parasympathetic functions of the vagus nerve?
> Major parasympathetic supply to thoracic and abdominal organs.
> Preganglionics –> from dorsal motor nucleus.
> Postganglionics –> myenteric plexus of wall of gut tube all the way to the left colic flexure.
What is the course of the vagus nerve?
- Runs parallel to esophagus (innervates esophagus).
- Passes posterior to root of lung on each side.
- Pierces diaphragm with esophagus.
- Becomes gastric nerve.
- Supplies viscera in thoracic cavity.
What is the first step in norepinephrine synthesis?
hydroxylation of tyrosine to dopa
True or False:
In the adrenal medulla, 20% of the norepinephrine is methylated to form epinephrine.
False - in the adrenal medulla, 80% of the norepinephrine is methylated to form epinephrine.
From which amino acid is norepinephrine derived from?
Tyrosine
What are the ways in which norepinephrine is removed?
- reuptake
- diffusion
- destruction by monamine oxidase
- destruction by catechol-O-methyl transferase (COMT)
Where is catechol-O-methyl transferase (COMT), which destructs norepinephrine to remove it, present?
present in all tissues
Where is monamine oxidase, which destroys norepinephrine, found?
in nerve endings
True or False:
Norepinephrine/epinephrine is active for only a few seconds when secreted directly into the tissues but when secreted into the blood (via the adrenal medulla) it remains active until destroyed by COMT in surrounding tissues, especially the liver.
True
What are the two types of acetylcholine receptors?
- muscarinic
- nicotinic
Where are muscarinic (acetylcholine) receptors found?
On all effector cells stimulated by postganglionic cholinergic neurons.
Where are nicotinic (acetylcholine) receptors found?
In autonomic ganglia at synapses between preganglionic and postganglionic neurons.
Present in neuromuscular junctions in skeletal muscles.
Which class of adrenergic receptors does norepinephrine mainly excite?
Norepinephrine excites mainly alpha receptors but also beta receptors to a lesser extent.
True or False:
Epinephrine excites both alpha and beta adrenergic receptors almost equally.
True
What physiological responses are alpha adrenergic receptors associated with?
- vasoconstriction
- iris dilation
- intestinal relaxation
- intestinal sphincter contraction
- pilomotor contraction
- bladder sphincter contraction
- inhibition of neurotransmitter release (alpha2)
What are the physiological responses caused by beta1 adrenergic receptors?
- cardioacceleration
- increased myocardial strength
- lipolysis
What are the physiological responses caused by beta2 adrenergic receptors?
- vasodilation
- intestinal relaxation
- uterus relaxation
- bronchodilation
- calorigenesis
- glycogenolysis
- bladder wall relaxation
What are the physiological responses caused by beta3 adrenergic receptors?
thermogenesis
List the sympathomimetic drugs.
- norepinephrine
- epinephrine
- methoxamine
- phenylephrine (alpha receptors)
- isoproterenol (beta receptors)
- albuterol (beta2 receptors)
Which drugs cause the release of norepinephrine?
- ephedrine
- tyramine
- amphetamine
Which drug blocks the synthesis and storage of norepinephrine?
Reserpine
What does reserpine do?
blocks synthesis and storage of norepinephrine
Which drug blocks the release of norepinephrine?
Guanethidine
What does guanethidine do?
blocks release of norepinephrine
Which drug blocks sympathetic alpha receptors?
Phenoxybenzamine/Phentolamine
What does phenoxybenzamine/phenotolamine do?
block sympathetic alpha receptors
Which drug blocks sympathetic beta1 and beta2 receptors?
Propranolol
What does propranolol do?
blocks sympathetic beta1 and beta2 receptors
What drug blocks mostly sympathetic beta1 receptors?
Metoprolol
What does metoprolol do?
blocks mostly sympathetic beta1 receptors
Which drug blocks the transmission through autonomic ganglia?
Hexamethonium
What does hexamethonium do?
blocks transmission through autonomic ganglia
What are the characteristics of parasympathomimetic drugs?
- Not rapidly destroyed by cholinesterase.
- Include pilocarpine and methacholine.
- Act directly on muscarinic receptors.
Which acetylcholine receptor do parasympathomimetic drugs directly act on?
muscarinic receptors
List the 3 drugs that inhibit acetylcholinesterase?
- Neostigmine
- Pyridostigmine
- Ambenonium
List the 3 drugs that block cholinergic activity?
- Atropine
- Homatropine
- Scopolamine
Where are sperm cells stored until ejaculated?
epididymis
Sperm cells must remain in epididymis for a minimum of how many hours in order to gain motility?
18 - 24 hours
How long does it take for sperm cells to pass through the epididymis?
requires several days
Which cells form testosterone?
cells of Leydig
In which ages of life are cells of Leydig numerous?
- Newborn Males
- Adult Male after puberty
True or False:
Cells of Leydig are almost nonexistent in testes during childhood.
True
What percentage of testosterone is loosely bound with albumin or tightly bound with beta globulin after secretion from cells of Leydig?
97% - which circulates in blood for 30 minutes to several hours.
Then transferred to tissues or degraded to inactive products that are subsequently secreted.
What happens to testosterone that enters tissues?
Mostly converted to dihydrotestosterone, especially in prostate and in fetal external genitalia.
What happens to testosterone that is not fixed in tissues?
Converted in liver to:
- androsterone and dehydroepiandrosterone
Conjugated as either glucuronides or sulfates.
Excreted into gut via bile or urine via kidneys.
What are the functions of testosterone?
- Responsible for distinguishing characteristics of masculine body.
- Stimulates descent of testes.
- Responsible for enlargement of external genitalia and formation of secondary male sexual characteristics.
- Responsible for male hair pattern growth.
- Associated with baldness.
- Responsible for hypertrophy of larynx.
- Increased skin thickness and secretion rate of sebaceous glands.
- Responsible for increase in protein formation and muscle formation.
- Responsible for increase in bone matrix and calcium retention.
- Responsible for increased BMR.
- Responsible for increased hematocrit.
- Increases reabsorption of sodium in distal kidney tubules.
Where are sertoli cells located?
Within the seminiferous tubules.
What cell type is located within the seminiferous tubules?
Sertoli Cells
What is the function of sertoli cells?
Act as nurse cells (sustentacular cells) that surround primary spermatocytes and “nurse” them through the process of spermatogenesis and spermiogenesis (differentiation of spermatids into mature sperm).
Form estrogens from testosterone (thought to be important for spermiogenesis).
Where are cells of Leydig found?
In interstitial spaces in testes.
What cell is found in the interstitial spaces in testes?
cells of Leydig
What do cells of Leydig secrete?
testosterone
Which hormone secreted by the anterior pituitary stimulates the cells of Leydig to secrete testosterone?
LH = luteinizing hormone
FSH is also necessary for spermatogenesis.
What is a paired structure that is located behind the prostate?
seminal vesicles
What is each seminal vesicle lined with?
Each vesicle is a loculated tube lined with secretory epithelium.
What is secreted by seminal vesicles?
A mucoid material.
What does the secreted mucoid material from seminal vesicles contain?
- Fructose
- Citric Acid
- Additional Nutrients
- Prostaglandins
- Fibrinogen
What is the important role that fructose plays that is found in the mucoid material that is secreted by seminal vesicles?
provides energy for sperm
What percentage of the total volume of semen is made up by the mucoid material that is secreted by the seminal vesicles?
60% of total volume of semen.
Where are the contents of the seminal vesicles emptied into?
ejaculatory ducts containing sperm
What is the important role of prostaglandins that are contained in the mucoid material that is secreted by seminal vesicles into the ejaculatory ducts containing sperm?
Make cervical mucous more receptive to sperm movement and may cause retro-peristaltic contractions of uterus and fallopian tubes.
Which molecule is important for making cervical mucous more receptive to sperm movement and may cause retro-peristaltic contractions of uterus and fallopian tubes?
prostaglandins
which are contents of the mucoid material that is secreted by the seminal vesicles
What percentage of total volume of semen does the milky fluid secreted by the prostate gland make up?
30%
What does the milky fluid that is secreted by the prostate gland contain?
- calcium
- citrate ions
- phosphate ions
- clotting enzyme
- profibrinolysin
Why is it important that the milky fluid that is secreted by the prostate gland is slightly alkaline?
May help to neutralize acidity of other seminal fluids and vaginal secretions of the female.
What is gonadotropin-releasing hormone also known as?
LH-releasing hormone
What is LH-releasing hormone produced by?
Neurons located in arcuate nuclei of hypothalamus.
Neurons located in arcuate nuclei of the hypothalamus produce LH-releasing hormones. How is it transported to the anterior pituitary?
Via hypothalamic-hypophyseal system.
What stimulates the anterior pituitary to produce LH (mostly) and FSH (gonadotropic hormones)?
LH-releasing hormone
Does LH-releasing hormone stimulate the anterior pituitary to produce mostly LH or FSH?
LH - is the major form released, which signals the cells of Leydig to release testosterone.
What type of protein is luteinizing hormone (LH)?
glycoprotein
which activates cAMP second messenger system in target tissues
What does LH cause the cells of Leydig to secrete?
Testosterone
testosterone has a negative feedback effect on the hypothalamus
What cell secretes inhibin?
sertoli cells
What is secreted by sertoli cells?
inhibin
What does inhibin do, which is secreted by sertoli cells?
Inhibits secretion of FSH by the anterior pituitary.
Also inhibits secretion of GnRH to a lesser extent.
Look over figure 82-8 on slide 82 of the review lecture.
Interaction of follicular cells in estrogen production.
Are FSH receptors found on theca or granulosa cells?
Granulosa Cells
What important conversion does FSH signal once it binds to the FSH receptor on granulosa cells?
Conversion of androgens to estrogens.
What are the 2 anterior pituitary sex hormones?
- FSH
- LH
What are the 2 ovarian hormones?
- estrogen
- progesterone
What is the hypothalamic releasing hormone that signals the release of FSH and LH from the anterior pituitary?
gonadotropin releasing hormone (GnRH)
increases much less drastically than the other two sources. it is secreted in short pulses averaging once every 90 minutes, as occurs in males
True or False:
FSH and LH are secreted throughout childhood in females.
False - almost NO secretion throughout childhood.
Which second messenger system are FSH and LH receptors associated with for their signal transduction pathways?
cAMP Second Messenger System
Is LH or FSH levels highest in the few days leading up to ovulation?
LH concentration rapidly spikes at day 12 and the rapidly decreases at day 14 when ovulation occurs.
Know figure 82-4 well for the exam.
Normal sexual cycle - on slide 85 of the review.
What is the single layer of cells that surround the primordial follicles?
Primordial follicles are surrounded by single layers of granulosa cells.
What is the role of the single layer of granulosa cells that surround the primordial follicles throughout childhood?
- Provide nourishment for the ovum.
- Secrete oocyte maturation-inhibiting factor that keeps ovum suspended in its primodial state.
Which cell type provides nourishment for the ovum throughout childhood?
granulosa cells
Which cell type secretes maturation-inhibiting factor that keeps the ovum suspended in its primordial state throughout childhood in females?
granulosa cells
Need to review the menstrual cycle.
Know what hormone levels are doing throughout the 28 day cycle. Also, know the concentration correlations with the day that it is happening.
