Endocrine system Flashcards
endocrine glands are ______ glands composed of glandular epithelium
ductless
the endocrine and nervous systems function to achieve and maintain ______.
homeostasis
glands of the endocrine system are widely scattered throughout the body. The effects of hormones work more ____ and last ____ than those of neurotansmitters
slowly, longer
both nervous system and endocrine mediators create their effects by binding to receptors on or in _____.
target cells
responsible for secreting hormones directly into the blood
endocrine glands
hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid glands, thymus, adrenal glands, pancreatic islets, ovaries, testes, and placenta are all_____.
major endocrine glands
hormones that target other endocrine glands and stimulate their growth and secretion
tropic hormones
hormones that target reproductive tissues
sex hormones
hormones that stimulate anabolism in target cells
anabolic hormones
hormones where molecules are manufactured by endocrine cells from cholesterol and are lipid soluble
steroid hormones
hormones that are synthesized primarily from amino acids:
- protein hormones
- glycoprotein hormones
- peptide hormones
nonsteroid hormone molecules
_____ hormones cna easily pass through the phospholipid plasma membrane of target cells
steroid hormones
hormones signal a cell by binding to the target cell’s _____ in a “lock and key” mechanism
specific receptors
Different hormone-receptor interactions produce different regulatory changes within the target cell through chemical reactions
Combines hormone actions (3):
- synergism
- permissiveness
- antagonism
_______:
- diffuse into the blood and are transported to almost every point in body
- a given hormone affects only specific target cells
- effects work more slowly and last longer than neurotransmitters
how hormones work
hormones directly regulate target cells
primary effect
hormones influence or modulate other regulatory mechanisms in target cells
secondary effects
hormone passes into the nucleus, where it binds to a mobile receptor and activates a certain gene sequence to begin the transcription of messenger riboneucleic acid
mobile-receptor model
nonsteroid hormone delivers chemical message to fixed receptor on target cell’s plasma membrane. message is passed into the cell
first messenger
picks up message passed into cell by first messenger. triggers appropriate celllular changes
second messenger
amplifies effects of the hormone. doesn’t take a lot of nonsteroid hormone to produce a huge effect
is faster than steroid mechanism
second messenger mechanism
hormone secretion is regulated by:
- signals from the nervous system
- chemical changes in the blood
- other hormones
most hormonal regulatory systems are ________.
negative feedback loops
tend to reverse any deviation of the internal environment away from its stable point
responses that result from operation of feedback loops within the endocrine system are called
endocrine reflexes
an endocrine gland is sensitive to the physiological changes produced by its _______.
target cells
endocrine gland secretion may also be regulated by a hormone produce by ______.
another gland
endocrine gland secretions may be influenced by input from _______.
nervous system
sensitivity of target cell to any particular hormone depends in part on the number of _____ it has
receptors
the more receptors there are, the more sensitive the target cell.
if the synthesis of new receptors occurs faster than degradation of old receptors, the target cell will have ____ receptors and thus be more _____ to the hormone.
more, sensitive
increased number of hormone receptors increases sensitivity
up-regulation
decreased number of hormone receptors decreases sensitivity
down-regulation
major link between the nervous and endocrine systems. cells from here synthesize at least 9 different hormones
hypothalamus
The _________ secretes 7 different hormones and is driven by the hypothalamus
pituitary gland
hypothalamus and pituitary together regulate virtually all aspects of _____, _______, ____, and _____.
- growth
- development
- metabolism
- homeostasis
influence carbohydrate metabolism by decreasing glucose uptake, which decreases use of glucose for ATP production in cells.
Insulinlike Growth Factors (IGFs)
____ and ____ may stimulate liver cells to release glucose into the blood
IGFs and Growth hormone
stimulates hypothalamus to secrete growth hormone releasing hormone (GRGH) –>
GRGH goes to pituitary gland and stimulates release of GH –>
GH stimulates secretion of IGFs=speed breakdown of liver glycogen into glucose –>
Blood glucose increases above normal levels and inhibits release of GHRH
Hypoglycemia
- stimulates hypothalamus secrete Growth hormone-inhibiting hormone (GHIH) –>
GHIH goes to pituitary gland and inhibits secretion of GH –>
low levels of GH and IGFs slows breakdown of glycogen in the liver and blood glucose levels decrease –>
Decreased blood glucose levels below normal inhibits release of GHIH
hyperglycemia
- located just inferior to the larynx
- only endocrine gland that stores secretory product in large quantities (100 day supply)
thyroid gland
4 actions of thyroid hormones
- increase metabolic rate
- stimulate synthesis of additional sodium-potassium pumps
- stimulate protein synthesis and increase use of glucose and fatty acids for ATP production
- with GH and insulin, accelerate body growth of nervous and skeletal systems
______ is an endocrine gland and an exocrine gland and is the first part of the small intestine
the pancreas
endocratic tissue of the pancreas is called:
pancreatic islets
the _________ controls glucagon and insulin.
_____:
low blood sugar stimulates secretion of glucagon from alpha cells
- glucagon acts on liver cells to accelerate conversion of glcogen to glucose and promotes formation of glucose from lactic acid and certain amino acids (gluconeogensis)
- hepatocytes (liver cells) then release glucose into the blood=rise in blood glucose levels
pancreatic islets,
hypoglycemia
the ____ controls glucagon and insulin.
_____:
- stimulates secretion of insulin by beta cells to lower blood glucose levels
- insulin acts on cells body to accelerate facilitated diffusion of glucose into cells
- insulin speeds conversion of glucose into glycogen, increase uptake of amino acids, increase protein synthesis, speeds up synthesis of fatty acids, slows conversion of glycogen to glucose, slow formation fo glucose from lactic and amino acids
pancreatic islets,
hyperglycemia
increased activity of the sympathetic nervous system stimulates ____ secretion.
glucagon
