33: ADRENAL GLANDS AND PANCREAS Flashcards
adrenal gland
composed of an outer cortex and an inner medulla
secretory activity of the adrenal cortex
is controlled through the renin-angiotensin system and by negative feedback involving the pituitary gland and hypothalamus.
sympathetic nervous system
Hormone release from the medulla is initiated by nerve impulses from the sympathetic nervous system as part of the body’s normal response to stress.
hormonal output of the medulla
About 75% of the hormonal output of the medulla is epinephrine (adrenalin) and 25% is norepinephrine., blood pressure
Epinephrine
increases blood pressure primarily by increasing heart rate and stroke volume, thereby increasing cardiac output
norepinephrine
vasoconstricts blood vessels in all target organs, causing a significant increase in total peripheral resistance and blood pressure.
glycogenolysis
(literally, the lysis of glycogen), Epinephrine also helps to elevate blood glucose by stimulating the conversion of glycogen to glucose in the liver, this process
Mineralocorticoids
help maintain electrolyte balance by increasing the reabsorption of sodium ions from the distal convoluted tubules in renal nephrons.
aldosterone
Themain human mineralocorticoid
glucocorticoids
help to insure the
body has enough available fuel to meet its energy
needs.
glucose
The main fuel of the body
gluconeogenesis
glucocorticoids help provide glucose by mobilizing
fatty acids and amino acids and stimulating the liver
enzymes that then convert them into glucose by the
process of gluconeogenesis (literally, the birth of
new glucose)
cortisol
The primary glucocorticoid in
humans
CRH
(corticotrophin releasing hormone) & ACTH (adrenocorticotropic
hormone)
Release of cortisol is
stimulated by this
androgenic
The sex steroids of the adrenal cortex are
androgenic (male) sex hormones.
Addison’s disease
Hypofunction of the adrenal cortex occurs
in Addison’s disease, characterized by muscular
weakness and fatigue caused by hypoglycemia
related to insufficient cortisol. A more serious
problem is the reduced sodium ion and water
uptake due to lack of aldosterone.
Cushing’s syndrome
Hyperfunction of the adrenal cortex is
called Cushing’s syndrome. Excess amounts of
cortisol cause significant loss of protein to
gluconeogenesis. Muscle wasting, bruising, poor
healing, thinning of the skin and osteoporosis all
result.
pancreas,
an important accessory
organ of the digestive system, is also the source of
the endocrine hormones insulin and glucagon.
blood glucose concentration
80 and 120 mg per 100 ml of blood
islets of Langerhans
Scattered throughout the pancreas are clusters of endocrine cells, these
The two main cell types in the islets
alpha cells that produce the hormone glucagon, and the beta cells that produce insulin.
Insulin
has the effect of lowering blood glucose by increasing the uptake of glucose into liver, muscle and adipose tissue cells. In
glycogen
In liver and muscle, the glucose taken up is converted to this storage molecule
hyperglycemia
The stimulus for insulin release from beta cells is hyperglycemia- high blood glucose.
