Chapter 11: Endocrinology and Metabolism Flashcards
the endocrine system is best used when signaling needs to occur _______ ________ ________, to diffuse recipients for long-lived actions
over large distances
similarities between endocrine and neural system
both use chemical messengers for signaling
both operate in a stimulus-response manner
chemical messenger for neural system
neurotransmitter
chemical messenger for endocrine system
hormone
differences between endocrine and neural system
signaling specificity
signaling speed
(neural needs quicker speed)
endocrine glands produce hormones that go straight to the ________
bloodstream
secrete hormones into the internal environment without ductal structures (secretes directly into the blood)
lots of vascularization
ductless glands secrete hormones
endocrine gland
a single endocrine gland can secrete ________ hormones
multiple
the endocrine system is one of the ______ major control systems in the body
two, the other one is nervous system
a chemical acting as a hormone in the endocrine system may serve as a __________ in the nervous system or as an _______/_______ agent
neurotransmitter; autocrine/paracrine
3 chemical classes of hormones
amines (thyroid hormones and catecholamines)
peptide and protein hormones
steroid hormones and vitamin derivatives
hormone derived from the amino acid tyrosine
water soluble
has 2 types
amine
2 types of amine hormones
thyroid hormones (T3, T4)
catecholamines (epinephrine, norepinephrine)
amine hormones that are produced by adrenal glands and released in the medulla
dopamine is released by the brain
catecholamines
steps of peptide hormone synthesis and how peptide hormones are released
1.) synthesis of preprohormones on ribosomes
2.) cleavage to prohormones in rough ER
3.) packaged into secretory vesicles by Golgi apparatus; cleaved again to yield active hormone
4.) remaining peptides are secreted along with hormone; may have hormonal effects
*enter/exit lipid bilayer via endocytosis/exocytosis
hydrophobic and water soluble hormone
produced by adrenal cortex, gonads, and skin
steroid hormones
molecule from which all steroid hormones are synthesized
cholesterol (it’s the precursor)
zona glomerulosa tissue produces ________
aldosterone
zona fasciculata tissue produces ________ and ________
cortisol; small amounts of androgens
zona reticularis tissue produces ________ and ________
androgens; small amounts fo cortisol
biological women cannot produce cortisol, so it shifts to male hormones
masculinization
no 17-hydroprogesterone, no
cortisol
steroid hormone produced by the gonads: in testes, ___________ is the precursor of major male androgen testosterone
androstenedione
steroid hormone produced by the gonads: in ovaries, the enzyme __________ converts testosterone into the major female sex hormone __________
aromatase; estradiol
steroid hormones produced by the skin
vitamin D
_______ ________ of vitamin D from cholesterol is dependent on sun exposure
dermal synthesis
hormones that are transported by catecholamines and free
readily dissolve in plasma
water soluble - most circulate unbound in the plasma, then bind to receptor
catecholamines and peptides
hormones that are transported bound to carrier protein
do not readily dissolve in plasma
lipid soluble, circulate in the plasma bound to carrier protein, then diffuse across cell membrane
steroid and thyroid hormones
free hormone + bound hormone = _________
total amount of non-water-soluble hormone in the blood
the concentration of free hormone is more important than the amount of total hormone because only the free hormone can diffuse across the ________ ______ and reach ________ ______
capillary walls; target cells
routes/mechanisms of hormone removal from the blood
enzymatic degradation, which usually occurs in liver cells
removal of the hormone from the blood either by its excretion by the kidneys or by its uptake into target cells
hormone measurement: antibody captures hormone onto an immobilized surface with a second antibody coupled to a chemiluminescent or radioactive signals for detection
ELIZA, RIAA
antibody capture
hormone concentration in the blood is controlled by the rate of its ________ by the endocrine gland and the rate of its ________ from the blood
secretion; clearance
rate of removal by metabolism or excretion
clearance
inputs to endocrine cells that influence hormone secretion
changes in the plasma concentrations of mineral ions or organic nutrients,
neurotransmitters released from neurons ending on the endocrine cell,
another hormone acting on the endocrine cell
location of receptors of peptide and catecholamine hormones
plasma membrane (cell membrane)
receptors of peptide and catecholamine hormones exert their effects of target cells by influencing the generation of _______ ________ __________
intracellular 2nd messenger molecules
location of receptors for steroid and thyroid hormones
intracellular (inside cell/nucleus)
low hormone levels may cause _________ receptor density
increased (up regulation), want more receptors with low levels
high hormone levels may cause ________ receptor density
decreased (down regulation), want less receptors with high levels
some hormones can up-regulate or down-regulate the density of receptors for other hormones
one hormone must be present for another hormone to have its full effect
permissiveness
permissiveness: epinephrine + thyroid hormone =
large amounts of fatty acids released
pituitary location
sticks out from the base of the brain and lies in the pocket of the sphenoid bone
connected by the infundibulum to the hypothalamus
2 lobes of pituitary
anterior pituitary gland (front)
posterior pituitary gland (back)
adenohypophysis
makes hormones
derived from same tissue as the roof of mouth
anterior pituitary
special capillary circulation allows chemical signaling agents from neuron in the hypothalamus to circulate into the ________ ________, closed circulation system
anterior pituitary
neurohypophysis
stores hormones
derived from neural tissues
posterior pituitary
axons from neurons in hypothalamus project to capillaries in the _______ _______ and release their chemical signaling agents
posterior pituitary
posterior pituitary hormones are synthesized by neurons in the __________
hypothalamus
axons carry posterior pituitary hormones to posterior pituitary and release them into ________ _________
blood circulation
2 posterior pituitary hormones
oxytocin and vasopressin
posterior pituitary hormone that stimulates secretion/release of milk from breasts during lactation
stimulates contraction of uterine smooth muscle during labor
positive feedback loop - consistent creates more contract
oxytocin
stages of love in males, cuddle hormone released in orgasm
oxytocin
posterior pituitary hormone that stimulates contraction of smooth muscle in blood vessels and causes increased blood pressure
AKA antidiuretic hormone (ADH) because it decreases loss of water through kidneys
vasopressin
posterior pituitary hormones are also produced in other parts of the brain where they act as __________
neurotransmitters
hypothalamus-pituitary portal vessels carry hypothalamic hypophysiotropic hormones to the ________ ________
anterior pituitary
releasing factors of specific anterior pituitary hormones are ________
stimulated (turned on)
inhibiting factors of specific anterior pituitary hormones are _________
inhibited (turned off)
specific releasing and inhibiting factors of the anterior pituitary hormones reach the anterior pituitary through ___________
blood circulation, direct blood flow
specific releasing factors from __________ stimulates release of specific anterior pituitary hormone into the blood circulation
hypothalamus
anterior pituitary hormone secretes a _______ _______ ______ to release a hormone into the blood circulation
third endocrine gland
hormone from the third endocrine gland acts on the _______ _______
target cells
stimulus events that occur when a releasing factor goes from the hypothalamus to the pituitary, endocrine organ, and then targets cell
stimulates hypothalamus to secrete hormone 1
causes plasma hormone 1 to increase (in hypo-pit portal vessels)
stimulates anterior pituitary to release/secrete hormone 2
causes plasma hormone 2 to increase
stimulates the third endocrine gland to secrete hormone 3
causes plasma hormone 3 to increase
causes target cells of hormone 3 to respond to the hormone 3
follicle-stimulating hormone (FSH)
luteinizing hormone (LH)
functions: germ cell development
production of estrogen/progesterone in females
production of testosterone in males
gonadotropic hormones
growth hormone (GH)
functions: stimulates protein synthesis and lipid/carbohydrate metabolism in many tissues
stimulates secretion of insulin-like growth factor 1 (IGF-1) from liver and other cells
somatotropin
thyroid stimulating hormone (TSH)
functions: stimulates thyroid to secrete thyroxin and triiodothyronine (T3 and T4)
thyrotropin
breast development and milk production
doesn’t directly affect it, but rather inhibits other hormones
decreases female fertility during breastfeeding (fertility decreases when breastfeeding)
prolactin
secretion of cortisol from adrenal cortex
adrenocorticotropic hormone (ACTH)
functions in humans not thoroughly understood
beta-lipotropin and beta-endorphin
stimulates release of ACTH (corticotropin)
corticotropin-releasing hormone (CRH)
stimulates secretion of growth hormone
growth hormone-releasing hormone (GHRH)
stimulates secretion of thyroid-stimulating hormone (TSH or thyrotropin)
thyrotropin-releasing hormone (TRH)
stimulates secretion of gonadotropins: luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
gonadotropin-releasing hormone (GnRH)
inhibits release of growth hormone
somatostatin (SS)
tonically inhibits the secretion of prolactin
inhibits works in opposite manner, under inhibitory control
dopamine (prolactin-inhibiting hormone, PIH)
neural control of hypophysiotropic hormone release: many _______ and _______ neural inputs to hypothalamic neurons that release hypophysiotropic hormones
excitatory; inhibitory
third (final) hormone in sequence (increase in plasma hormone 3 step)
acts back on the hypothalamus to inhibit secretion of hypophysiotropic hormone (turns off)
acts back on the anterior pituitary to inhibit secretion of second hormone in sequence (turns off)
long-loop negative feedback
second hormone (from anterior pituitary) in sequence
acts back on the hypothalamus to inhibit secretion of hypophysiotropic hormone (turns off)
short-loop negative feedback
occurs when endocrine gland is secreting too little hormone
destruction of adrenal cortex leads to decreased cortisol secretion
dietary iodine deficiency leading to decreased thyroid hormone secretion
primary hyposecretion
occurs when there’s not enough pituitary tropic hormone to stimulate gland
secondary hyposecretion
occurs when hypothalamus releasing factors that stimulate pituitary tropic hormone are absent, which leads to reduction of both tropic factor and endocrine hormone
tertiary hyposecretion
occurs when gland secretes too much hormone
primary hypersecretion
occurs when too much pituitary tropic factor stimulates gland
secondary hypersecretion
occurs when too much hypothalamus releasing factor stimulates pituitary
tertiary hypersecretion
2 iodine-containing thyroid hormones, produced in the thyroid
T3 and T4
T3 is considered the major thyroid hormone because T4 is ________ to T3 in the target cells
converted
T4 is the major thyroid form in the ________, but not overall
blood
thyroid hormone synthesis
thyroid gland is bilobed and wraps around the trachea
the gland is active from fetal stage throughout adulthood
thyroid tissue consists of the follicles
structures consisting of cells surrounding a protein rich core
the functional units of the thyroid
follicles
steps of thyroid hormone synthesis
- iodide trapping (carried into follicular cells by Na)
- iodide efflux (diffusion into the cell)
- iodine organification (oxidizes into an iodine free radical and binds to thyroglobulin protein)
- coupling (phenolic ring of tyrosine is coupled to another diiodotyrosine to form T3 or T4)
- endocytosis (iodinated thyroglobulin is brought back into follicular cells
- cleavage (endocytic vesicles merge with lysosomes, proteolytic enzymes digest the thyroglobulin)
- release of T3 and T4 (into the blood)
what controls thyroid function
TSH level
long negative feedback loop where TH acting on hypothalamus and anterior pituitary
elevate TSH level, decreased T4 levels
primary hypothyroidism
decreased TSH and T4 levels
secondary hypothyroidism
decreased TSH level, increased T4 levels
primary hyperthyroidism
increased TSH and T4 levels
secondary hyperthyroidism
thyroid hormone resistance
increased TSH and T4 levels
general actions of thyroid hormones: nuclei of most cells in body have thyroid hormone receptors that bind both T3 and T4
hormones act by inducing _______ _______ and _______ _______
gene transcription; protein synthesis
metabolic actions of thyroid hormones: TH stimulates carbohydrate absorption from intestine and fatty acid release from adipocytes
provides energy for ___________; heat production
Na+/K+ ATPases
permissive actions of thyroid hormones: TH upregulates ____________ receptors (especially in heart and nervous system)
beta-adrenergic
growth and development actions of thyroid hormones: TH required for production of ________ _________; absence retards growth
**especially important for nervous system
growth hormone
result of increased metabolic rate and increased oxygen consumption
causes increase in heat production from increase in glycolysis
calorigenic effect
syndrome that occurs when TH is absent in fetal development and results in poorly developed nervous system
cretinism
refers to any condition where plasma TH is below normal levels
results in lower BMI
among most common endocrine conditions
hypothyroidism
defect in thyroid gland (and hormone)
95% of all cases
caused by loss of functional thyroid tissue or inadequate iodine
primary hypothyroidism
defect in anterior pituitary
secondary hypothyroidism
defect in hypothalamus (TRH)
tertiary hypothyroidism
low iodine deficiency leads to goiter, hypothyroidism, and cretinism
treatment: reversible with addition of iodine to diet
iodine-deficiency primary hypothyroidism
caused by destruction of thyroid gland by T cells
treated with T4
autoimmune thyroiditis
enlarged/expanded thyroid gland (super large neck)
due to high stimulation of thyroid gland due to high TSH levels
cannot produce T3 and T4
goiter
happens when the thyroid gland makes too much thyroid hormone
hyperthyroidism
causes of hyperthyroidism
hormone-secreting tumors (rare)
autoimmune disease (Graves’ disease)
autoimmune disease
overproduction of thyroid hormone
most common in women
production of antibodies that activate TSH receptor leads to increased T3 and T4 and potentially goiter
Graves’ disease
signs and symptoms of hyperthyroidism
increased BMR (heart rate)
weight loss with increased appetite
heat intolerance
increased sympathetic nervous system activity
bulging eyes (due to immune attach on structures behind)
treatments for hyperthyroidism
drugs that inhibit TH synthesis
surgical removal of thyroid
destruction of thyroid using radioactive iodine followed by TH supplementation
element that is common to all stress responses
cortisol
increased secretion of glucocorticoid hormone =
increased cortisol by adrenal cortex
activation of sympathetic nervous system
increased release of epinephrine from adrenal medulla
increased hepatic and muscle glycogenolysis (provides quick source of glucose)
increased breakdown of adipose tissue triglyceride (provide a supply of glycerol for gluconeogenesis and of fatty acids for oxidation)
increased cardiac function (increased heart rate)
diversion of blood from viscera to skeletal muscles by vasoconstriction and vasodilation
increased lung ventilation by stimulating brain breathing centers and dilating airways
the hormonal stress response is triggered by _______ inputs to the hypothalamus
activates the ____________ system
neural; CRH/ACTH/cortisol
hormones other than CRH that are released during stress and can also stimulate ACTH secretion
vasopressin and cytokines
chemical signaling agents secreted by immune cells (macrophages and lymphocytes)
link the endocrine stress response to immune system activation
cytokines
basal cortisol levels are required to maintain
regulating blood pressure
cellular concentrations of enzymes required for metabolic homeostasis
systemic anti-inflammatory and anti-immune functions of cortisol
inhibits production of leukotrienes and prostaglandins that promote inflammation
in development, cortisol plays a role in the _________ of many tissues including brain, lungs, intestines
important for maternal stress
differentiation
in stress, cortisol increases _________ _________ of amino acids, glucose, glycerol, and free fatty acids
plasma concentrations
cortisol provides _____ when fasting
amino acids may be converted to glucose or used for ______ ______
fuel; tissue repair
patients who are ill/recovering from surgery catabolize significant amounts of _______ ________
body protein
children subjected to severe stress may exhibit ________ _______
retarded growth
cortisol acts during stress to increase responsiveness of vascular smooth muscle to ___________ to maintain blood pressure
norepinephrine
if cortisol levels are insufficient, a patient may exhibit _________
hypotension
during stress, cortisol inhibits _________ and _________
growth; reproduction
interaction between cortisol and cytokines insures that stress does not cause excessive _________ or _________ reactions
immune; inflammatory
hormones that help maintain blood pressure
aldosterone, vasopressin, glucagon and growth hormones, beta-endorphin
hormone that acts to retain sodium and excrete potassium
aldosterone
hormone that acts to retain water and cause vasoconstriction
vasopressin
hormones that plays roles in mobilization of energy stores
glucagon and growth hormones
hormone who’s release may relate to pain relief
beta-endorphin
prolonged elevation of cortisol may cause reduced _________, __________ of bone and muscle, and __________ immune system function
fertility; deterioration; compromised
prolonged or repeated activation of sympathetic nervous system may contribute to development of __________ and __________
atherosclerosis; hypertension
caused by destruction of adrenal gland tissue by tumors, diseases, and autoimmune attack
destroys multiple cell types in adrenal gland, often decreasing aldosterone levels
imbalances of water, sodium, and potassium in blood leads to hypotension
Addison’s disease
primary adrenal insufficiency
caused by ATCH deficiency
arise from pituitary disease
adrenal cells are normal - disease is not as severe and hypotension does not occur
secondary adrenal insufficiency
diagnosis of secondary adrenal insufficiency
definitive test is measurement of low cortisol levels in the blood
treatment of secondary adrenal insufficiency
replacement of the missing cortisol (daily hydrocortisone tablets), lifelong management
situation of chronically elevated cortisol levels in non-stressed individuals, may be primary or secondary (secondary more common)
Cushing’s syndrome
symptoms of Cushing’s disease
uncontrolled catabolism of protein from bone, muscle, skin, etc.
cortisol-mediated immune suppression
hypertension
most common cause of Cushing’s disease
prolonged clinical use of glucocorticoids to reduce inflammation
treatment of Cushing’s disease
decreasing intake of glucocorticoids or tumor removal
3 factors that influence growth
genetics, environmental factors, endocrine function
bone growth determines _________
height
collagen matrix in which calcium phosphate salts are deposited
bone
structure of immature long bone
ends of bones are called ephysis, the rest is the shaft (diaphysis)
cartilage junction between ends and shafts
epiphyseal growth plate
calcium is stored in the ________ in the form of calcium hydroxyapatite
bones
puts new cartilage down in the interior of the plate
chondrocytes
converts cartilage to bone on the side of the growth plate next to the shaft
osteoblasts
occurs when hormones of puberty convert plates to bone and stop growth
epiphyseal closure
2 rapid periods of growth for height in children
first two years of life and puberty
environmental factors influencing growth
adequate nutrition and freedom from disease
adverse effects of malnutrition on growth are especially evident in _________
early life
maternal malnutrition results in ___________
fetal growth retardation
malnutrition during childhood can inhibit _______ and ____________
growth; intellectual development
hormones/growth factors that influence growth
growth hormone
thyroid hormones
testosterone
estrogen
insulin
cortisol
stimulates postnatal growth
growth hormone
permissive for growth hormones and secretions and actions
permissive for development of the CNS
thyroid hormones
stimulates growth at puberty (stimulates GH effects)
stimulates protein synthesis in males
testosterone
stimulates secretion of growth hormone (GH) at puberty
estrogen
inhibits growth
cortisol
when and how growth hormones influence growth
GH stimulates pre-chondrocytes to differentiate into chondrocytes
chondrocytes secrete IGF-1
IGF-1 acts as autocrine/paracrine agent to cause chondrocytes and osteoblasts to become active
causes of dwarfism
GH or IGf-1 insensitivity
low GH
low IGF-1
short negative feedback loop control of GH release from hypothalamus to anterior pituitary
increase plasma GH leads to increase somatostatin release in hypothalamus and less GHRH
long negative feedback loop control of GH release from hypothalamus to anterior pituitary
increased plasma IGF-1 leads to decreased anterior pituitary GH secretion and increase somatostatin release in hypothalamus and less GHRH
diurnal fluctuations of GH in the blood (diurnal rhythms)
GH elevated when asleep and lower when awake
sex hormones (estrogen and testosterone) relation to growth/GH
cause the pubertal growth spurt
stimulate GH and IGF-I secretion
testosterone also increases protein synthesis (increase muscle mass)
end growth after puberty by “closing” growth plate
insulin’s relation to growth/GH
insulin has general anabolic effects that inhibit protein degradation
also has direct positive effects on fetal growth
thyroid hormone’s relation to growth/GH
thyroid hormone is required for synthesis of GH and growth-promoting effects of GH
prolonged elevation of cortisol in illness/stress or with use of glucocorticoid therapy can _______ _______
inhibit growth
effects of prolonged cortisol elevation in illness/stress or prolonged glucocorticoid therapy
decreased DNA synthesis
stimulated protein catabolism (breakdown of molecules into monomers)
inhibition of bone growth and degradation of existing bone
inhibition of GH secretion
a rapid growth spurt that children may undergo if their normal growth was temporarily inhibited due to malnutrition or illness
compensatory growth
enlargement and broadening of bones and other organs
adulthood overprotection
skeletal thickness, hypertrophy of skin, organomegaly
disproportionate growth
acromegaly
cause of acromegaly
excessive IGF-1 levels after epiphyseal growth plates have closed
abnormally tall height
childhood overproduction
before closure of epiphysis and end of puberty
rapid and proportional growth
gigantism
cause of gigantism
excessive levels of IGF-1 while epiphyseal growth plates are still open
due to slow-growing tumors of anterior pituitary
treatment of gigantism
tumor removal
glucose fate once taken up from the gut in the absorptive state
stored in adipose tissue
needed in almost all tissues
transformed to glycogen in muscle and liver
triglycerides fate once taken up from the gut in the absorptive state
transformed to fatty acids and sent to adipose tissue
amino acids fate once taken up from the gut in the absorptive state
transformed to proteins in muscle
transformed in liver to triglycerides (aka fat)
to maintain glucose for CNS,
glycogenolysis & gluconeogenesis generate ________ _________
while non-neural cells switch to use _____ for fuel rather than glucose (“sparing”)
plasma glucose; fats
breakdown of glycogen to glucose
glycogenolysis
formation of glucose from noncarbohydrate sources
gluconeogenesis
2 most important hormones to play a role in the shifts in energy sources between the absorptive and postabsorptive states
insulin and glucagon
major glucose counter regulatory controls that oppose the action of insulin
GLUCAGON
epinephrine
cortisol
growth hormone
how glucagon inhibits insulin
acts on liver to increase
gluconeogenesis
glycogenolysis
ketone synthesis
glucagon release is governed by ________ ________ _______
plasma glucose levels
major stimulus of glucagon release
decrease in blood glucose
increased glucagon release is a major factor in shift to ____________
the post absorptive period
caused by a lack of insulin production and can result in a state similar to uncontrolled postabsorption
Type 1 diabetes mellitus
caused by a resistance to the effects of insulin and is often a consequence of obesity
Type 2 diabetes mellitus
low blood sugar
caused by excess insulin
and liver disease affecting glycogenolysis and gluconeogenesis
hypoglycemia
symptoms of hypoglycemia from sympathetic nervous system activation
increased heart rate, sweating, anxiety, trembling
symptoms of hypoglycemia from CNS glucose deprivation
headache, confusion, dizziness, slurred speech, lack of coordination, serious convulsions/coma
sources of cholesterol in the body
diet (animal products)
liver and GI tract produce the most cholesterol
almost all cells can synthesize cholesterol
role of the liver in control of cholesterol levels
major regulator of plasma cholesterol by controlling how much cholesterol the liver is producing
saturated fatty acids in diet increase ________
cholesterol
good cholesterol
LDL
bad cholesterol
HDL
LDL:HDL ratio
signifies ones health in relation to cholesterol (aka risk of heart attack)
factors influencing LDL:HDL ratio
smoking
weight
exercise
estrogen
Prohormone
Longer protein or peptide that is cleaved into shorter ones, at least one of which is a peptide protein hormone
Organ most dependent on glucose
Brain
Contraception most likely to happen ____ days before ovulation and ____ days after
5,1
During ovulation, ovum/ova from ovary enters through fallopian tube and travels towards uterus
If fallopian tubes were cut, ova would not reach uterus from ovary
Dominant follicle established
Day 5-7 of menstrual cycle
Day 1-14: follicular phase
Day 14: ovulation
Day 14-28: luteal phase, corpus luteum is formed then degenerates
Follicular phase of ovaries
Menstrual and proliferating phases of uterus
Absence of thyroid hormones in fetal development
Congenital hypothyroidism
Acrosome reaction triggered by
Binding of the heads of sperm to the zona pellucida
Puberty is triggered by
Increased production of GnRH
Peptide vs steroid hormone receptor location
Peptide: binds to receptors on cell membranes
Steroids: binds to intracellular receptors
One hormone must be present for another hormone to have it’s full effect
Permissiveness
Increased prolactin has what effect
Declining levels of estrogen and progesterone will not interfere with plans to lactate because
Secretion of oxytocin and prolactin are more important for lactation
CRH (stress) stimulates release of ACTH
Thyroid hormones stimulate carb absorption from intestine and fatty acid release from adipocytes
Absorptive state
Nutrients enter the blood
Iodine deficiency leads to
low iodine -> low TH ->
negative feedback mediated
increased release of TRH
&TSH
– increased TRH ->TSH
elevation -> stimulation of
thyroid growth -> goiter
Stress response
increased secretion
of the glucocorticoid
hormone cortisol by
adrenal cortex
The hormonal stress
response is triggered by
neural inputs to the
hypothalamus.
• It activates the
CRH/ACTH/cortisol
system
Calcium is the most in the
Bones
GnRH is highest in
Adolesence
Feedback control of GH
secretion from pituitary (Fig.
11-29)
– Hypothalamus secretes GH
releasing factor (GHRH) and
somatostatin (SS).
– GHRH stimulates GH release
from anterior pituitary.
– SS inhibits GH release from
pituitary
Drugs that inhibit vasodilation have what effect on male reproduction
Erection may be inhibited
Hypercalcemia
High amount of calcium
Sertoli cell functions
Form barrier to chemicals in bloodstream
Nourish sperm
Secrete inhibin
Phagocytoses defective sperm
Does not convert estrogens into testosterone
Leydig cells produce
Testosterone
Parturition
Delivery of infant and placenta
Look for ectopic pregnancy in
Fallopian tubes
SRY
Protein normally coded by a gene that is present on the Y chromosome
Antagonist to hCG receptor
Degeneration of corpus luteum and declining levels of estrogen and progesterone
Menstrual cycle
Progesterone is low during first half, then rises to a peak in second half
Luteal phase
Estrogen concentration is high, but progesterone concentration rises even higher
A hormone may be
Inactivated by its target cell
Activated by its target cell
Inactivated by nontarget cells
Excreted before it has a chance to act on a target cell
Hormones that influence secretion of other hormones
Tropic
If the adrenal glands were removed from a patient, his plasma cortisol levels would
______, secretion of
CRH by the ______ would
______, and
secretion of ACTH by the _____ would _______
decrease; hypothalamus; increase; adenohypophysis;
increase
What can you find in the blood when you’re extremely stressed out
Increased secretion of corticotropin from the anterior pituitary
Result of hypersecretion of growth hormone
Acromegaly
If pituitary gland is removed from a human
The adrenal gland will atrophy and plasma cortisol levels will be reduced
