14. endocrine system Flashcards
nervous sys vs endocrine sys
nervous:
fast, delivers to individual cells, effects resolve quickly, faster AP
endocrine:
slower, longer lasting effects, widespread, longer AP
describe 4 charcteristics of a hormone
- produced and released by an endocrine or neuroendocrine cell
- exert regulatory influence on the function of distant cells
- be effective at very low concentrations (nanomolar (10-9) - picomolar 10-12range)
- be carried via the bloodstream to its target cells
the processes that the endocrine system control is?
- produced and released by an endocrine or neuroendocrine cell
- exert regulatory influence on the function of distant cells
- be effective at very low concentrations (nanomolar (10-9) - picomolar 10-12range)
- be carried via the bloodstream to its target cells
paracrine
signal nearby (neighbor) cells
autocrine
signal the same cell that they belong to
why are autocrine and paracrine not considered hormones?
they do not enter the bloodstream
why is carbon dioxide not considered a hormone?
although this gas is carried through the bloodstream, it is not produced by endocrine cells
haemocoel
The cavity, between the organs of arthropods and molluscs, through which the blood etc. circulates.
open circulatory sys
Endocrine chemical signals diffuse from their cell of production into
capillaries (closed circulatory systems)
haemocoel (open circulatory systems)
Further delay in endocrine response can occur because some hormones
- –are produced only upon stimulation of the cells that make them.
- –Time required for synthesis delays hormonal effect.
- –are transcription factors.
- –Time required for translation delays hormonal effect.
hydrophobic hormones example
they are lipid soluble and are bound hormones bc they need plasma transporters in blood like albumin to help them
ex: steroid and thyroid
hydrophilic hormone example
free hormones bc they can go directly in plasma blood which is mostly water
ex: monoamine and peptide
free fraction
percentage of hormone that is unbound (free) at any given time
3 benefits of blood transport proteins:
— help protect hormones from being broken down by enzymes
— prevent kidneys from filter hormones
— prolong half time of hormones they are transporting so that it can stay in blood for hours days or weeks
Endocrine cells are commonly divided into two major classes:
epithelial (nonneural) cells
neurosecretory cells
Epithelial cells
may be dispersed in epithelia
may comprise discrete epithelial glands.
typically are activated by hormones from other sources
may also receive neural input
example: β cells of the pancreas
Neurosecretory Cells
–synthesize neurohormones in their cell bodies
–release neurohormones into the bloodstream, not the synaptic cleft
are signaled to secrete neurohormones by typical neurons
–convert neural signals into chemical (neurohormone) signals.
have cell bodies in the CNS, axons outside the CNS
–may communicate directly with nearby target cells OR
–may form a neurohemal organ
neurohemal organ
- -is a cluster of highly vascularized neurosecretory axon terminals
- -transports neurohormones to distant cells
gland
one or more cells that produce and secrete a particular product
define exocrine
(product is secreted onto skin or into body cavities)
give 6 ex of an exocrine gland secretion
milk oil sweat bile mucus digestive enzymes
exocrine vs endocrine
although both are involved in secretions, endocrine secretes into body tissues directly through the blood stream
exocrine secretes through ducts onto the body or surface of body cavities BUT NEVER EXACTLY INSIDE
define endocrine
(product (hormone) is secreted inside the body)
name 5 types of endocrine cells
unicellular multicellular discrete diffuse intermediate
discrete
endocrine cells grouped and adhered together (e.g., thyroid)
diffuse
scattered among non-endocrine cells (e.g., intestinal epithelium)
intermediate
between discrete and diffuse (e.g., Islets of Langerhans)
give 8 examples of endocrine gland
pituitary pineal pancreas gonads (ovaries, testes) thyroid gland parathyroid hypothalamus adrenal
where is the pituitary gland located?
pea-sized gland housed
within a saddle-shaped extension of the skull’s sphenoid bone,
(((((the sella turcica (Latin: “Turkish saddle”) at the base of the brain))))
why is the pituitary gland also called the master gland?
The pituitary controls the function of most other endocrine glands.
roles of the hypothalamus
–links the afferent nervous system
to the endocrine system via the pituitary gland.
controlling body temperature thirst hunger other homeostatic systems reproductive cycles sleep
amino acid vs lipid derivative hormones
amino acid-based (water soluble) - enter cells via membrane channels
lipid derivatives (fat soluble) - enter cells through the plasma membrane
steroid hormones
are synthesized from cholesterol (a lipid coming from animal fat or we synthesize ourselves)
are lipid-soluble
can enter cell through plasma membrane or be endocytotically transported
act on receptor molecules inside their target cells
examples of steroid hormones
hormones of the gonads and adrenal cortex
hormones produced in skin
placental hormones
insect molting hormones
