Chapter 10: Endocrine System Flashcards
allows cells to communicate with each other to regulate body activities
chemical messengers
4 classes of chemical messengers
- autocrine chemical messengers
- paracrine chemical messengers
- neurotransmitters
- endocrine chemical messengers
- secreted by cells in a local area
- influences the activity of the same cell or cell type from which it was secreted
autocrine CM
- produced by a wide variety of tissues and secreted into extracellular fluid
- has a localized effect on other tissues
paracrine CM
- produced by neurons
- secreted into a synaptic cleft by presynaptic nerve terminals
- travels short distances
- influences postsynaptic cells
neurotransmitters
- secreted into the blood by specialized cells
- travels some distance to target tissues
- results in coordinated regulation of cell function
endocrine CM
10 regulatory functions of the endocrine system
- metabolism
- control of food intake and digestion
- tissue development
- ion regulation
- heart rate and blood pressure regulation
- water balance
- control of blood glucose and other nutrients
- control of reproductive functions
- uterine contractions and milk release
- immune system regulation
composed of endocrine glands and specialized endocrine cells located throughout the body
endocrine system
have ducts that carry their secretions to the outside of the body, or into a hollow organ, such as the stomach or intestines
exocrine glands
- Chemical messengers that are secreted by endocrine glands and cells
- Travel through the general blood circulation to target tissues or effectors
- regulate almost every physiological process in our body
hormones
Specific sites where hormones produce a particular response of the target tissues
target tissues
2 chemical categories of hormones
- lipid-soluble hormones
- water-soluble hormones
- nonpolar
- insoluble in water-based fluids
lipid-soluble hormones
- polar molecules
- can dissolve in blood
water-soluble hormones
3 stimulatory influences on hormone secretion
- control by humoral stimuli
- control by neural stimuli
- control by hormonal stimuli
- blood-borne chemicals that can directly stimulate the release of some hormones
- sensitive to the blood levels of a particular substance
humoral stimuli
chemical messenger hormones made when neurons are stimulated
neuropeptides
occurs when a hormone is secreted that, in turn, stimulates the secretion of other hormones
hormonal stimuli
- hormones that stimulate the secretion of another hormone
- part of a complex process in which a releasing hormone from the hypothalamus stimulates the release of a tropic hormone from the anterior pituitary gland
tropic hormones
3 inhibitory influences on hormone secretion
- inhibition of hormone released by humoral stimuli
- inhibition of hormone release by neural stimuli
- inhibition of hormone release by hormonal stimuli
regulation of hormone levels in the blood can be:
- negative feedback
- positive feedback
- The hormone’s secretion is inhibited by the hormone itself once blood levels have reached a certain point and there is adequate hormone to activate the target cell
- self-limiting system
negative feedback
self-propagated system
positive feedback
Hormones exert their actions by binding to proteins
receptors
portion of each receptor molecule where a hormone binds
receptor site
tendency for each type of hormone to bind to one type of receptor, and not to others
specificity
can also be located in the cytoplasm, but then move to the nucleus when activated
nuclear receptors
proteins that extend across the cell membrane, with their hormone-binding sites exposed on the cell membrane’s outer surface
membrane-bound receptors
- small gland about the size of a pea
- regulates secretion of hormones from other endocrine glands through the hypothalamic-pituitary axis
pituitary gland
made up of two lobes connected by a narrow band called the isthmus
thyroid gland
lies in the upper part of the thoracic cavity
thymus
two small glands located superior to each kidney
adrenal glands
paired, oval organs in the left and right side of the uterus in the lower abdomen
ovaries
a small, pinecone-shaped structure located superior and posterior to the thalamus of the brain
pineal gland
embedded in the posterior wall of the thyroid gland.
parathyroid gland
located inside the abdomen, just behind the stomach, and it’s about the size of a hand
pancreas
- also known as testicles
- lie behind the penis in a pouch of skin called the scrotum
testes
produce neuropeptides and secrete them into the capillary bed in the hypothalamus
neurons of the hypothalamus
capillary beds and veins that transport the releasing and inhibiting hormones
hypothalamic-pituitary portal system
function as either releasing hormones or inhibiting hormones
hypothalamus neuropeptides
stimulates the production and secretion of specific hormones by the anterior pituitary
releasing hormones
reduces the secretion of specific anterior pituitary hormones
inhibiting hormones
produces releasing hormones and inhibiting hormones that travel to the anterior pituitary gland through the hypothalamic-pituitary portal system
hypothalamus
acts on the adrenal cortex, stimulating the secretion of glucocorticoids like cortisol
adrenocorticotropic hormone
helps regulate blood nutrient levels and responds to stress
cortisol
- stimulates milk production (lactation) after childbirth
- has various effects on the reproductive system in both males and females
prolactin
- Increases gene expression, breakdown of lipids, and release of fatty acids from cells
- increases blood glucose levels
growth hormone
- Increases thyroid hormone secretion (thyroxine and triiodothyronine).
thyroid-stimulating hormone
- Increases melanin production in melanocytes to make skin darker in color
melanocyte-stimulating hormone
- also known as vasopressin, is produced in the hypothalamus and released from the posterior pituitary gland
- binds to membrane-bound receptors and increases water reabsorption by kidney tubules. This results in less water lost as urine
antidiuretic hormone
- a hormone produced in the hypothalamus and released from the posterior pituitary gland
- involved in childbirth and lactation
oxytocin
a regulatory mechanism that helps maintain stability and balance, or homeostasis, within a system
negative feedback
____ is when an excess of one or more hormone is secreted from a gland
hypersecretion
____ is when the amount of hormones that are released is too low
hyposecretion
caused by the deficiency of growth hormone
pituitary dwarf
If excess growth hormone is present before bones finish growing in length, exaggerated bone growth occurs
giantism
If excess hormone is secreted after growth in bone length is complete, growth continues in bone diameter only.
acromegaly
______ stimulates ovulation in females while stimulates interstitial cells of the testes
luteinizing hormone
stimulates the development of follicles in the ovaries and sperm cells in the testes
follicle-stimulating hormone
- production of a large amount of dilute urine
- an uncommon problem that causes the fluids in the body to become out of balance
diabetes insipidus
Increase metabolic rates, essential for normal process of growth and maturation
thyroid hormone
elevated rate of thyroid hormone secretion
hyperthyroidism
contains four iodine atoms and is abbreviated T4
thyroxine
contains three iodine atoms and is abbreviated T3
triiodothyronine
- Decreases rate of bone breakdown
- prevents large increase in blood Ca2+ levels following a meal
calcitonin
bones can become soft, deformed, and easily fractured
hyperparathyroidism
nerves and muscles become excitable and produce spontaneous action potentials
hypoparathyroidism
hormones of adrenal medulla
- epinephrine
- norepinephrine
hormone of adrenal cortex
- mineralocorticoids
- glucocorticoids (cortisol)
- Insignificant in males
- increase female sexual drive, growth of pubic and axillary hair
adrenal androgens
results in the release of too much epinephrine and norepinephrine, hormones that control heart rate, metabolism, and blood pressure
pheochromocytoma
a chronic condition in which your adrenal glands don’t produce enough of the hormones cortisol and aldosterone
addison’s disease
disorder that occurs when your body has a high level of the hormone cortisol
cushing syndrome
Increases uptake and use of glucose and amino acids
insulin
Increases breakdown of glycogen and release of glucose into the circulatory system
glucagon
the body’s inability to regulate blood glucose levels within the normal range
diabetes mellitus
occurs when the level of glucose in your blood drops below what is healthy for you
hypoglycemia
Aids in sperm cell production, maintenance of functional reproductive organs, secondary sex characteristics, sexual behavior
testes
Promotes immune system development and function
thymosin
Inhibits secretion of gonadotropin-releasing hormone, thereby inhibiting reproduction
melatonin
- secreted by the right atrium of the heart in response to elevated blood pressure
- inhibits Na+ reabsorption in the kidneys
atrial natriuretic hormone
- secreted by the kidney in response to reduced oxygen levels in the kidney
- acts on bone marrow to increase the production of red blood cells
erythropoietin
secretes human chorionic gonadotropin, estrogen, and progesterone, which are essential to the maintenance of pregnancy
placenta
