Bio Ch 40 Flashcards
Endocrine System
organ system involved in the coordination of body activities; uses hormones as chemical signals secreted into the bloodstream
Hormones
chemical messenger produced in one part of the body that controls the activities of other parts
Exocrine glands
secrete their products into ducts, which take them to the lumens of other organs or outside the body
Endocrine glands
secrete their products into the bloodstream, which delivers them throughout the body
Chemical signals
means of communication between cells, between body parts, and even between individuals
Pheromones
chemical signals that influence the behavior of other individuals
Peptide hormones
most endocrine glands secrete these hormones - peptides, proteins, glycoproteins, and modified amino acids
Steroid hormones
all have the same molecular complex of 4 carbon rings because they are all derived from cholesterol
Cyclic adenosine monophosphate (cAMP)
immediate result of epinephrine binding is the formation of this; contains 1 phosphate group attached to adenosine at 2 locations
First messenger
chemical signal such as a peptide hormone that binds to a plasma membrane receptor protein and alters the metabolism of a cell because a second messenger is activated
Second messenger
chemical signal such as cyclic AMP that causes the cell to respond to the 1st messenger - a hormone bound to plasma membrane receptor protein
Hypothalamus
helps to regulate the internal environment of the body; influences heartbeat, blood pressure, appetite, body temperature, and water balance through the autonomic nervous system; also controls the glandular secretions of the pituitary gland
Pituitary gland
small gland that lies just inferior to the hypothalamus; consists of the anterior and posterior ____, both of which produce hormones
Antidiuretic hormone (ADH)
neurons in the hypothalamus (neurosecretory cells) produce this hormone as well as oxytocin
Posterior pituitary
portion of the pituitary gland that stores and secretes oxytocin and antidiuretic hormone produced by the hypothalamus
Negative feedback
effect of the hormone acts to shut down the release of the hormone; maintains stable conditions and homeostasis
Oxytocin
2nd hormone made in the hypothalamus; causes uterine contractions during childbirth and milk letdown when a baby is nursing
Positive feedback
the stimulus continues to bring about an effect that ever increases in intensity
Hypothalamic-releasing hormones
one of many hormones produced by the hypothalamus that stimulates secretion of an anterior pituitary hormone
Hypothalamic-inhibiting hormones
one of many hormones produced by the hypothalamus that inhibits the secretion of an anterior pituitary hormone
Anterior pituitary
portion of the pituitary gland that is controlled by the hypothalamus and produces 6 types of hormones, some of which control other endocrine glands
Gonadotropic hormones
stimulate the gonads (testes, ovaries) to produce gametes and sex hormones
Adrenocorticotropic hormone (ACTH)
stimulates the adrenal cortex to produce cortisol
Thyroid-stimulating hormone (TSH)
stimulates the thyroid to produce thyroxine (T4) and triiodothyronine (T3)
Prolactin (PRL)
produced in quantity only after childbirth; causes the mammary glands in the breasts to develop and produce milk; also plays a role in carb and fat metabolism
Melanocyte-stimulating hormone (MSH)
causes skin color changes in many fishes, amphibians, and reptiles having melanophores (special skin cells that produce color variations)
Growth hormone (GH)
AKA somatropic hormone; promotes skeletal and muscular growth; increases the rate at which amino acids enter cells and protein synthesis occurs; also promotes fat metabolism as opposed to glucose metabolism
Thyroid gland
attached to the trachea just below the larynx; weighs 20 grams; composed of a large number of follicles, each a small spherical structure made of thyroid cells that produce the hormones triiodothyronine (T3) , which contains 3 iodine atoms, and thyroxine (T4), which contains 4 iodine atoms
Thyroxine
hormone secreted from the thyroid gland that promotes growth and development; in general, it increases the metabolic rate in cells
Hypothyroidism
immune system produces antibodies that destroy the thyroid gland
Hyperthyroidism
results from oversecretion of T3 or T4; Graves disease is the most common cause of this in children and adolescents
Exophthalmos (exophthalmia)
excessive protrusion of the eyes due to edema in eye socket tissues and inflammation of the muscles that move the eyes
Calcitonin
hormone secreted by the thyroid gland when the blood calcium level rises; primary effect is to bring about the deposit of calcium in the bones
Parathyroid hormone (PTH)
produced by the parathyroid glands; causes the blood calcium level to increase and the blood phosphate level (HPO4 2-) level to decrease); promotes the activity of osteoclasts, releasing calcium from the bones;also promotes the reabsorption of calcium by the kidneys, lessening its excretion; in the kidneys, also brings about activation of vitamin D
Parathyroid glands
gland embedded in the posterior surface of the thyroid gland; produces parathyroid hormone
Adrenal glands
sit atop the kidneys; each is about 5cm long and 3cm wide; weighs about 5 g; consist of inner and outer portion; two functionally distinct endocrine glands; stress prompts the hypothalamus to stimulate both portions of this
Adrenal medulla
inner portion of the adrenal gland; secretes the hormones epinephrine and norepinephrine
Adrenal cortex
outer portion of the adrenal gland; secretes mineralocorticoids, such as aldosterone, and glucocorticoids, such as cortisol
Epinephrine
adrenaline; secreted by the adrenal medulla
Norepinephrine
noradrenaline; secreted by the adrenal medulla
Cortisol
most important glucocorticoid produced by the human adrenal cortex; raises blood glucose level by promoting the breakdown of muscle proteins to amino acids, which are taken up by the liver from the bloodstream and converted into glucose; also promotes the catabolism of fatty acids rather than carbs (spares glucose)
Glucocorticoid
type of hormone secreted by the adrenal cortex that influences carbohydrate, fat, and protein metabolism
Mineralocorticoids
produced by the adrenal cortex; regulates salt and water balance, leading to increases in blood volume and blood pressure
Aldosterone
most important of the mineralocorticoids; primarily targets the kidneys; promotes renal absorption of sodium and renal excretion of potassium and thereby helps regulate blood volume and blood pressure
Atrial natriuretic hormone (ANH)
when the atria of the heart are stretched due to increased blood volume, cardiac cells release a hormone called this, which inhibits the secretion of aldosterone from the adrenal cortex
Renin
when the blood sodium level and therefore blood pressure is low, the kidneys secrete this enzyme that converts the plasma protein angiotensinogen to angiotensin I, which is changed to angiotensin II by an enyzme in lung capillaries
Pancreas
slender, fish-shaped organ that stretches across the abdomen behind the stomach and near the duodenum of the small intestine; 6 inches long, weighs 80 grams; composed of 2 types of tissue
Pancreatic islets (islets of Langerhans)
endocrine tissue that produces and secretes the hormones insulin and glucagon directly into the blood
Insulin
secreted when there is a high blood glucose level, which usually occurs just after eating
Glucagon
secreted from the pancreas, usually in between meals, when blood glucose is low; major target tissues are the liver and adipose tissue; it stimulates the liver to break down glycogen to glucose and to use fat and protein in preference to glucose as energy sources; adipose tissue cells break down fat to glycerol and fatty acids
Testes
male sex organs; located in the scrotum
Ovaries
female sex organs; located in the pelvic cavity
Androgen
example = testosterone; testes produce these male sex hormones
Estrogens & progesterone
ovaries produces these female sex hormones
Anabolic steroids
testosterone or related chemicals with dangerous side effects
Pineal gland
epiphysis; located deep in the human brain; produces melatonin
Melatonin
involved in our daily sleep-wake cycle
Circadian rhythms
daily 24-hour cycles controlled by an internal timing mechanism called a biological clock
Thymus gland
lies just beneath the sternum; organ reaches its largest size and is most active during childhood; gets smaller and fatty with age
Leptin
peptide hormone produced by adipose tissue throughout the body; acts on the hypothalamus, where it signals satiety (fullness)
Prostaglandins
potent chemical signals produced within cells from arachidonate, a fatty acid; not distributed in the blood; act locally, quite close to where they were produced; implicated in the pain and discomfort of menstruation in women; mediate the effect of pyrogens, chemicals believed to reset the temperature regulatory center in the braine
