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