autonomic and endocrine systems Flashcards
what kind of effectors does the autonomic nervous system work on?
smooth muscle, cardiac muscle, glands
at does the autonomic nervous system split into and what do they do?
sympathetic - fight or flight, used in exercise, excitement, emergency and embarrassment
can be whole body or organ specific response
parasympathetic = rest and digest, used in digestion, defecation and diuresis, functions in an organ specific manner
describe what happens in different areas of the body due to sympathetic stimulation?
Eyes
Heart
Blood vessels
Lungs
Liver
Reproductive organs
Eyes - dilate to inc. visual field
Heart - beats faster and harder
Blood vessels - dilate where needed like the muscles and heart, constrict where its not needed in an emergency e.g. gut for digestion.
Lungs - widened bronchi to inc, oxygen intake.
Liver - release glucose via gluconeogenesis or glycogenolysis.
Reproductive organs - orgasms
the parasympathetic essentially does the opposite of the sympathetic nervous system, with some exceptions?
only affects atria not ventricles too,
Gastrointestinal tract - peristalsis, enteric nervous system
Bladder - contracts (can have overriding voluntary influences - holding it in).
Reproductive system - maintenance of an erection
most organs have sympathetic and parasympathetic innervation, how are blood vessels different?
blood vessels just use more or less sympathetic innervation, they don’t have any parasympathetic innervation to cause dilation
describe the general pathway/organisation of the autonomic nervous sytem
in the CNS, the preganglionic neuron travels to a ganglion (a bundle of neurons in the periphery in this case) where the postganglionic neuron then goes to the target cell
specifically, describe the pathway and NTs the sympathetic nervous system uses
the preganglionic neuron is short, located in the lumbar and thoracic spinal cord
releases ACh which binds to postganglionic
this postganglionic neuron is long and adrenergic (releases noradrenaline)
specifically describe the pathway and NTs the parasympathetic system uses
preganglionic = longer and in the brainstem and sacral spinal cord, also releases ACh
postganglionic is short (very close to effectors) and binds to muscarinic ACh receptors
when is a postganglionic neuron not used in the autonomic nervous system?
in the adrenal glands, chromaffin cells take the place of postganglionic neurons, they make and release adrenaline
the parasympathetic system is dominated by what?
the vagus nerve - 80% of it actually
what areas of the spinal cord receive and send out info?
dorsal (the back of the spinal cord) receives sensory information
the ventral horn (front) sends out motor information
this mediates any autonomic reflexes, working with medulla
what brain area is key in the autonomic nervous system with examples?
the hypothalamus
circadian rhythm
thermoregulation
sex drive
water balance
reproduction
can you consciously effect autonomic processes?
yes, cortical conscious processes can effect autonomic processes, like anxiety effecting the GI tract, but in the end the visceral afferent input wins, you cannot hold in a wee forever
what does the endocrine system control?
growth, development, reproduction, blood pressure, blood ion concentration, behaviour - when you eat, stress, relationships (oxytocin for example)
there are three kinds of hormones, how is each one synthesised, secreted, what receptors do they use and what is their response time?
peptide:
made from amino acids, secreted using secretory granules and exocytosis, receptors are on the cell surface membrane
responds in seconds to minutes
amino acid derived:
derivatives of tyrosine, requires enzymes to be made, uses vesicles and exocytosis, responds in seconds to minutes
steroids:
metabolites of cholesterol, also requires specific enzymes
they’re lipid soluble so can diffuse across membranes
they bind to intracellular receptors in hours to days
what are the 7 glands of the endocrine system?
pituitary (ant and post)
thyroid
parathyroid
adrenal
ovaries
testes
endocrine pancreas
ofc there are areas in several other organs of endocrine tissue, plus some neuropeptides are kind of hormone kind of NT
explain the structure and function of the thyroid
follicular cells form follicles, which enclose pools of colloid, fluid containing the T3 and T4 thyroid prohormones, made by the follicular cells and diffused away to be stored extracellularly
T3 and T4 are secreted by moving back into the follicular cells then into the blood
the hormones are associated with iodine, which can be used as a tracker
move into target cells by facilitated diffusion to effect nuclear receptors - transcription - growth, metabolism, development
what is the role of the parathyroid glands and what does the hormone they produce do?
synthesises and secretes PTH - parathyroid hormone, a peptide
targets kidneys, bone and GI system
function is to regulate blood levels of calcium and phosphate, by causing kidneys to take in Ca back from tubules, and in the GI tract it assists in the conversion of vitamin D to an active form to help with Ca absorption
in the bones it helps remove a bit of calcium to restock the plasma
what does the cortex of the adrenal gland do?
its the top two zones, releasing mineralocorticoids like the steroid hormone aldosterone, to monitor mineral levels
as well as glucocorticoids - like cortisol which increases glucose concentration
what does the medulla of the adrenal gland do? how are the cortex and medulla linked?
this is where the chromaffin cells are located, secreting adrenaline and noradrenaline
blood vessels pass through the cortex to the medulla and exit via the medullary vein
what doe the testes do hormone-wise?
zoom in on the lobules - seminiferous tubule - this is where the Leydig cells produce testosterone, a steroidal hormone that stimulates protein synthesis and can lead to growth and development
what’s the difference between testosterone and oestradiol?
tiny difference in structure and only one enzymatic reaction between the two
pancreas - insulin and glucagon - what receptor does insulin use?
how are these hormones in such high concentrations upon arriving at the liver?
insulin uses a tyrosine kinase receptor
these hormones go straight into a portal vein so don’t go back to the heart, they go straight to the liver
pituitary - what does the hypothalamus and adenohypophysis do? what does the neurohypophysis do?
the hypothalamus releases releasing hormones from small order neurons, travel via portal vein to the adenohypophysis, stimulate troph cells to release trophic hormones
neurohypophysis releases hormones from large order neurons directly into the systemic circulation
