Lesson 3 - Endocrine Pt 1 Flashcards
gap junctions
pores in cells membranes that allow signaling molecules, nutrients, and electrolytes to move from cell to cell
neurotransmitters
released from neurons to travel across the synaptic cleft to a second cell
paracines
secreted into tissue fluids to affect nearby cells
hormones
chemical messengers that travel in the bloodstream to stimulate physiological responses in other tissues and organs
endocrine system
glands, tissues, and cells that secrete hormones
endocrinology
the study of the endocrine system and the diagnosis and treatment of its disorders
endocrine glands
organs that are sources of hormones
exocrine glands
have ducts that carry secretion to an epithelial surface or the mucosa of the digestive tract: “external secretions”
examples of exocrine glands
sweat glands
endocrine glands
no ducts; contain dense, fenestrated capillary networks which allow easy uptake of hormones into the bloodstream: “internal secretions”
what kind of effects do endocrine glands produce?
intracellular effects such as altering target cell metabolism
speed and persistence of response: nervous
reacts quickly (msec timescale) and stops quickly
speed and persistence of response: endocrine
reactly slowly (seconds or days), effects may continue for days or longer
adaptation to long-term stimuli: nervous
response declines, adapts quickly
adaptation to long-term stimuli: endorcine
responses persist, adapts slowly
area of effect: nervous
targets and specific (one organ)
area of effect: endocrine
general, widespread effects (many organs)
True or False: Chemicals can only act as hormones or neurotransmitters, not both
false, several function as BOTH hormones and neurotransmitters
examples of chemicals that are both hormones and neurotransmitters (3)
norepinephrine, dopamine, and antidiuretic hormone
both the nervous and endocrine system can have similar effects on target cells (example)
both norepinephrine and glucagon cause glycogen hydrolysis in the liver
an example of how the nervous system and endocrine system can regulate each other
neurotransmitters can affect glands and hormones can affect neurons
cells that share characteristics with both the nervous and endocrine system are called
neuroendrocine cells; neuron-like cells that secrete oxytocin into the blood
target organs/cells
those organs or cells that hve receptors for a hormone and can respond to it
what do some target cells posses?
enzymes that convert a circulating hormone to its more active forms
three chemical classes of hormones
steroid, monoamines, and peptides
lipid-derived hormones
derived from fats like sex steroids from gonads and corticosteroids from adrenal glands
monoamines (biogenic amines)
made from amino acids, like tyrosine used to produce the catecholamines and thyroid hormone
catecholamines (3)
dopamine, epinephrine, and norepinephrine
peptide hormones
created from chains of amino acids
examples of peptide hormones (4)
thyroid-stimulating hormone, luteinizing hormone, follicle-stimulating hormone, insulin
prohormones
inactive molecules that are converted to the active hormones before or after they are secreted; many peptide hormones are synthesized as these
steroids
derived from cholesterols
leukotrienes
have secondary roles as hormones causing inflammation during allergic reactions
prostaglandins
involved in coordinating local cellular activities and can be converted to thromboxanes (vasoconstrictor) or prostacyclins (vasodilator)
eicosanoids
derived from arachidonic acid (a 20-carbon fatty acid)
steroids released by reproductive organs: testes
androgens
steroids released by reproductive organs: ovaries (2)
estrogens and progestins
steroids released by reproductive organs: cortex of adrenal glands
corticosteroids
steroids released by reproductive organs: kidneys
calcitriol
proinsulin
a prohormone, has a middle portion called a connecting peptide that is removed to form the active form of insulin (two peptide chains connected by disulfide bridges)
melatonin is synthesized from
amino acid tryptophanh
what are some monoamines synthesized from?
tyrosine
don’t forget slide 19, you don’t understand it
hormone secretion fluctuates on…(5)
- the circadian rhythm
- a woman’s monthly cycle
- under the influence of neural, hormonal, or humoral stimuli
stimuli for hormone secretion: neural stimulation
nerve fibers supply some endocrine glands and elicit the release of their hormone
examples of neural stimuli for hormone secretion (2)
- the sympathetic nervous system stimulates the adrenal medulla to secrete epinephrine and norepinephrine in situations of stress
- in childbirth, the positive feedback loop of oxytocin
stimuli for hormone secretion: hormonal stimuli
hormones from the hypothalamus regulate secretion by the anterior pituitary gland
examples of hormonal stimuli for hormone secretion
pituitary hormones stimulate other endocrine glands to release thyroid hormone, sex hormones, and cortisol
stimuli for hormone secretion: humoral stimuli
refers to blood-borne stimuli; rising blood glucose concentration stimulates the release of insulin
rising blood glucose concentration stimulates the release of _____
insulin
low blood osmolarity stimulates the secretion of _____
aldosterone
low blood calcium level stimulates the secretion of _____
parathyroid hormone