Adrenal Gland
what is secreted in the adrenal medulla
epinephrine and norepinephrine are secreted whenever the sympathetic nervous system is activated
gonadocorticoids include both
estrogens (female sex hormones) and androgens (male sex hormones)
epinephrine and fat breakdown
fat breakdown is increased, skeletal muscles are tensed, and renin secretion from the kidney is increased
cortisol is considered as a
glucocorticoid
cortisol
glucocorticoids- produced by zona fasciculate, the middle layer, and the zona reticularis, the deep layer
epinephrine increases
heart rate, coronary blood flow, blood pressure, and respiration rate (improving cardiac function)
principle action of glucocorticoids
help promote normal metabolism, resistance to stress and counter inflammatory response
effect of cortisol
helps to keep blood glucose concentration within a normal range between meals
used for the relief of itching and inflammation caused by a wide variety of skin conditions (eg. insect bites, allergic reactions, and eczema)
hydrocortisone cream
cushing's disease
hyperfunction of the adrenal cortex
negative feedback by cortisol is on both the
pituitary and hypothalamus
adrenal medulla is stimulated by
preganglionic neurons directly, so controlled by the hypothalamus as if part of the autonomic nervous system, NOT by tropic hormones from pituitary
what is the precursor to all corticosteroid
prenenolone
secondary hypersecretion due to pituitary problem
CRH low ACTH high Cortisol high
testoserone
androgens- also produced by zona fasciculate and zona reticularis
adrenal medulla hormones
epinephrine norepinephrine
three initiating reasons different reasons need to be treated using different methods
1. secondary hypersecretion due to hypothalamic problem 2. secondary hypersecretion due to pituitary problem 3. primary hypersecretion due to problem with adrenal cortex
cortical hormone action has a lag time of at least
30 minutes
how much do adrenal glands weigh?
4 grams
secretion of cortisol is controlled almost entirely by
ACTH from the anterior pituitary
glucocorticoid control of secretion
ACTH is released in response to stress and low blood levels of glucocorticoids
primary hypersecretion due to problem with adrenal cortex
CRH low ACTH low Cortisol high
secretion of ACTH is controlled by
CRH from the hypothalamus
secondary hypersection due to hypothalamic problem
CRH levels high ACTH levels high Cortisol levels high
long term stress response
Mineralcorticoids: retention of sodium and water by kidney increase blood vol and BP Glucocorticoids proteins and fats converted to glucose or broken down for energy increased blood sugar suppression of immune system
the adrenal medulla acts like
a part of the sympathetic nervous system
the adrenal medulla secretes which hormones?
epinephrine and norepinephrine (Catecholamines) in response to sympathetic stimulation
the kidney is the target organ for what?
aldosterone
cortex three layers
aldosterone (mineralcorticoids) cortisol glucocorticoids) testosterone (androgens)
why is cortisol secreted?
almost any type of stress will cause an immediate and marked increase in CRH secretion by hypothalamus and ACTH secretion by the anterior pituitary gland, followed by greatly increased adrenocortical secretion of cortisol
tumors of the adrenal cortex cause an overproduction of
androgen hormones that produce secondary sexual character, for example, the appearance of heavy facial hair on a woman.
The two adrenal glands lie where
at the superior poles of the kidneys
mechanisms of reabsorption of sodium by kidney
basolateral membrane and luminal membrane
epinephrine does what with the sphincter?
causes contraction in the digestive system and urinary systems (slow down the functions of these two systems)
corticosteroid are all formed from the basic unit of
cholesterol
principle action of gonadocorticoids
concentrations secreted by adults are very low
aldosterone acts on the kidney to
decrease sodium excretion decrease water excretion increase potassium excretion
mineralcorticoid control of secretion
decreased blood volume or sodium level initiate renin-angiotensin pathway to stimulate aldosterone secretion; increased blood levels of potassium stimulate aldosterone secretion. ACTH has a minor effect in promoting aldosterone secretion
when aldosterone acts on the kidney to decrease sodium excretion, decrease water excretion, and increase potassium it results in
decreases plasma levels of potassium increase effective circulating volume increase extracellular fluid volume increase blood pressure
too much cortisol will induce
diabetes
cushing's disease 10-15 million of every million people
hyperfunction of the adrenal cortex-hypersecretion of cortisol too much of a good thing: upper body obesity, "central obesity"; rounded face, "moon face"; increased fat around the neck, "buffalo hump" thinning arms and legs; weakened skin; severe fatigue; weak muscle; high blood pressure and high blood glucose
addison's disease 1 in 100,00 people
hypofunction- of the adrenal cortex-hyposecretion of cortisol and sometimes aldosterone: weight loss; muscle weakness; fatigue; low blood pressure
short term stress --- from diagram
hypothalamus --> nerve impulses---> spinal cord --> preganglionic sympathetic fibers --> adrenal medulla ---> catecholamines (epi and norepinephrine)
combat stress
increase availability nutrients for energy increase susceptibility of blood vessels to constriction reduce inflammation
principal action of mineralcorticoids
increase plasma levels of sodium and water and decrease plasma levels of potassium
action of aldosterone on the renal tubule
increase the formation of Na+ -K+ -ATPase at the basolateral membranes of the renal tubular cells increase the formation of sodium channels at the luminal membranes of the renal tubular cells
short term stress response
increased heart rate increased blood pressure liver converts glycogen to glucose and releases glucose to blood dilation of bronchioles changes in blood flow patterns leading to increased alertness and decreased digestive and kidney activity increased metabolic rate
cortisol increases amino acid concentration in the blood by
inhibiting protein synthesis in select tissues
adrenal cortex is essential for
life-- if removed or damaged severely, death occurs unless hormones are replaced artificially
what does aldosterone do?
maintains blood volume by regulating renal sodium reabsoprtion in the kidney. Aldosterone also regulates renal potassium excretion
aldosterone is necessary to maintain
mineral balance for sodium and potassium
aldosterone
mineralcorticoids -- produced by zona glomerulosa, the outermost layer
adrenal cortex hormones
mineralocorticoids (aldosterone) glucocorticoids (cortisol) gonadocorticoids (androgen)
adrenal medullae are actually
modified sympathetic ganglia
is the adrenal medulla required for survival?
no- as long as the rest of the sympathetic nervous system is intact.
adrenal medulla secretes two amines
norepinephrine 20% epinephrine 80%
All the target organs of sympathetic nerve can receive the control of
norepinephrine from adrenal medulla
adrenal androgens mediate some changes which occur in
puberty, but for the most part the secretion of adrenal sex hormones are insignificantly small compared to the amounts produced from the ovaries or testes
long term stress-- from diagram
releasing hormone --> cortricotrope cells of anterior pituitary --> adrenal cortex--> mineralocorticoids or glucocorticoids
epinephrine decreases
skin blood flow - (blood redistribution)
the adrenal medulla neurotransmitters and target receptors:
somatic nervous system: acteylcholine (N1) receptor parasympathetic nervous system: acetylcholine (M) receptor sympathetic nervous system: norepinephrine (alpha and beta receptors) adrenal medulla: epinephrine and norepinephrine (alpha and beta receptors)
all of the hormones synthesized by the adrenal cortex are from
steroid cholesterol, and they all have similar chemical formulas.
anti inflammatory
suppresses immune system function
epinephrine control of secretion
sympathetic nervous system SNA
norepinephrine control of secretion
sympathetic nervous system SNS
principle action of norepinephrine
sympathomimetic that is, produces effects that mimic those of SNS during stress
principle actions of epinephrine
sympathomimetic that is, produces effects that mimic those of SNS during stress
the hormones secreted by the adrenal medulla are
sympathomimetic- that is, the actions of adrenal medulla hormones "mimic" sympathetic nervous system activation
at the luminal membrane of the renal tubular cells what happens?
the Na+ diffuses from distal tubular urine into the cytoplasm via the Na+ channels. The K+ permeates from the cytoplasm into the distal tubular urine.
aldosterone is produced by
the adrenal cortex -- zona glomerulosa
each adrenal gland is composed of two distinct parts
the adrenal medulla, and the adrenal cortex
adrenal medulla
the central 20% of the gland, is functionally related to the sympathetic nervous system.
cortisol stimulates
the liver to sythesize glucose (not from carbs, but from amino acids and glycerol) called gluconeogenesis.
during a stressful situation which hormones released take effect in seconds?
the medullary hormones
adrenal cortex
the peripheral 80% of the gland, secretes entirely different group of steroid hormones, called corticosteriods.
aldosterone is secreted in response to
the renin angiotensin pathway stimulates aldosterone secretion (renin angiotensin aldosterone system) ACTH has a effect in promoting aldosterone secretion increased plasma potassium (major effect) decreased blood plasma (also for ADH) decreased plasma sodium
at the basolateral membranes of the renal tubular cells what happens?
the sodium potassium adenosine triphosphatase (Na+ -K+ -ATpase) pump the Na+ from cytoplasm into the blood, at the same time the K+ from blood into cytoplasm
if you're a smoker what does nicotine stimulate?
the sympathetic nervous system and causes a slight increase in epinephrine release. This increase dulls the hunger sensation
the adrenal cortex is divided into three layers and manufactures
three kinds of steroid hormones (corticosteroids)
T/F in response to stress, the cortex and medulla are often both activated
true
cortisol promotes
use of fat for energy production in our bodies (rather than glucose)
symptoms of cushing's disease
weight gain, buffalo hump, central obesity, moon face, purple striae, infection