mod 2: The Endocrine System Flashcards
set point (definition)
“set value”. ideal/optimum conditions
negative feedback (definition)
mechanism where diversion from set point causes return to set point–leads to stability
positive feedback (definition)
mechanism where deviation from set point causes further deviation–leads to instability
hormone (definition, function)
chemical messenger circulating in the blood stream. produced by specialized cells. coordinates various parts of the body by interactive with target cells
target cell (definition)
cells with specialized receptors designed to react only with specific hormones
endocrine gland (definition)
cell, tissue, or organ that produces hormones directly into the blood stream (ductless)
exocrine gland (definition)
cell, tissue, or organ that produces hormones that are moved through ducts or channels
lipid-soluble hormone (definition)
hormone that is chemically identifiable as a lipid or steroid
water-soluble hormone (definition)
hormone that is chemically identifiable as an amino acid or protein
antagonistic hormones (definition)
two hormones that produce opposite effects (ex: insulin and glucagon)
tropic hormone (definition)
hormone that acts on another endocrine gland and causes it to produce another hormone. a hormone whose target cell is another endocrine gland
gonadotropic hormone (definition)
affect reproductive organs (gonads)
hypothalamus (structure, function)
connected to the pituitary gland by a thin stalk and controls the pituitary through “releasing hormones” (this is what they are called) that are carried to the anterior pituitary through a series of blood vessels that go through the stalk. secretes hormones some hormones that it then transfers through neural axons and stores in the posterior pituitary
posterior pituitary (structure, definition, secretions)
the half of the pituitary that faces inwards toward the brain. part of the nervous system. does not produce any hormones itself, only stores hormones produced by the hypothalamus.
SECRETES:
- antidiuretic hormone (ADH) (also called vasopressin)
- oxytocin (OCT)
anterior pituitary (structure, definition, secretions)
the half of the pituitary that faces outwards away from the brain. actually produces hormones SECRETES: - human growth hormone (hGH) - prolactin (PRL) - thyroid-stimulating hormone (TSH) - adrenocorticotropic hormone (ACTH) - follicle-stimulating hormone (FSH) - luteinizing hormone (LH)
diabetes insipidus (definition, cause)
condition where excessive production of very dilute urine occurs. caused by lack of ADH due to hypothalamus failing to produce it or by posterior pituitary failing to release it
releasing hormones (definition, function)
“releasing factors”. hormones produced by neurosecretory cells in the hypothalamus. stimulate or inhibit the secretion of hormones by the anterior pituitary. tropic hormones
hGH (function, effects of abnormal production)
“human growth hormone”
FUNCTION: increases protein synthesis, cell division and growth (especially of cartilage, bone, and muscle), and metabolic breakdown and release of fats stored in fat tissue.
EXCESS: in childhood, causes gigantism. in adults, causes acromegaly
DEFICIENCY: in childhood, causes pituitary dwarfism
gigantism (definition, cause)
a condition where a child will grow extremely quickly and without stopping (reaching a height of 8ft or more. caused by overproduction of hGH during childhood
acromegaly (symptoms/effects, cause)
EFFECTS: bones and soft tissue widen. face widens, ribs thicken, feet and hands enlarge, risk of cardiovascular disease, sugar intolerance, breathing problems, muscle weakness, colon cancer, extreme headache, coarse facial features (prominent forehead, enlarged nose and tongue and lips, widely-spaced teeth), enlarged heart and liver and kidneys, fatigue, excessive perspiration, visual disturbances.
CAUSE: overproduction of hGH in adulthood
pituitary dwarfism (definition, cause)
a condition where a person grows very little in childhood but has normal proportions, caused by insufficient hGH production in childhood
adrenal gland (location, structure)
located on top of the kidneys. made up of an outer layer (the adrenal cortex) and an inner mass (the adrenal medulla), where both parts secrete different hormones and are within the adrenal capsule (outside covering)
adrenal medulla (definition, secretion)
modified nerve tissue of the sympathetic nervous system. not stimulated by hormones from the pituitary, stimulated directly by the hypothalamus though the nervous system so it acts very quickly.
SECRETES:
- epinephrine
- norepinephrine (doubles as a hormone and a neurotransmitter)
in roughly 4:1 ratio
adrenal cortex (definition, secretion)
not nervous tissue. acts slower than the medulla. SECRETES: - glucocorticoids (cortisol) - mineralocorticoids (aldosterone) - gonadocorticoids