autonomic and endocrine systems

Question 1

what kind of effectors does the autonomic nervous system work on?

Answer 1

smooth muscle, cardiac muscle, glands

Question 2

at does the autonomic nervous system split into and what do they do?

Answer 2

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

Question 3

describe what happens in different areas of the body due to sympathetic stimulation?
Eyes
Heart
Blood vessels
Lungs
Liver
Reproductive organs

Answer 3

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

Question 4

the parasympathetic essentially does the opposite of the sympathetic nervous system, with some exceptions?

Answer 4

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

Question 5

most organs have sympathetic and parasympathetic innervation, how are blood vessels different?

Answer 5

blood vessels just use more or less sympathetic innervation, they don’t have any parasympathetic innervation to cause dilation

Question 6

describe the general pathway/organisation of the autonomic nervous sytem

Answer 6

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

Question 7

specifically, describe the pathway and NTs the sympathetic nervous system uses

Answer 7

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)

Question 8

specifically describe the pathway and NTs the parasympathetic system uses

Answer 8

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

Question 9

when is a postganglionic neuron not used in the autonomic nervous system?

Answer 9

in the adrenal glands, chromaffin cells take the place of postganglionic neurons, they make and release adrenaline

Question 10

the parasympathetic system is dominated by what?

Answer 10

the vagus nerve - 80% of it actually

Question 11

what areas of the spinal cord receive and send out info?

Answer 11

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

Question 12

what brain area is key in the autonomic nervous system with examples?

Answer 12

the hypothalamus
circadian rhythm
thermoregulation
sex drive
water balance
reproduction

Question 13

can you consciously effect autonomic processes?

Answer 13

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

Question 14

what does the endocrine system control?

Answer 14

growth, development, reproduction, blood pressure, blood ion concentration, behaviour - when you eat, stress, relationships (oxytocin for example)

Question 15

there are three kinds of hormones, how is each one synthesised, secreted, what receptors do they use and what is their response time?

Answer 15

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

Question 16

what are the 7 glands of the endocrine system?

Answer 16

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

Question 17

explain the structure and function of the thyroid

Answer 17

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

Question 18

what is the role of the parathyroid glands and what does the hormone they produce do?

Answer 18

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

Question 19

what does the cortex of the adrenal gland do?

Answer 19

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

Question 20

what does the medulla of the adrenal gland do? how are the cortex and medulla linked?

Answer 20

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

Question 21

what doe the testes do hormone-wise?

Answer 21

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

Question 22

what’s the difference between testosterone and oestradiol?

Answer 22

tiny difference in structure and only one enzymatic reaction between the two

Question 23

pancreas - insulin and glucagon - what receptor does insulin use?
how are these hormones in such high concentrations upon arriving at the liver?

Answer 23

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

Question 24

pituitary - what does the hypothalamus and adenohypophysis do? what does the neurohypophysis do?

Answer 24

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

Question 25

how are some of these hormones regulated?

Answer 25

simple feedback loop - like with PTH if Ca levels are detected as too high, less PTH is secreted, like insulin and glucose as well

in a chain of hormones, the final hormone often influences production of the earlier ones

Question 26

what is an exception to the sympathetic system using NA in postganglionic neurons?

Answer 26

sweat glands use ACh

Question 27

muscarinic ACh receptors have 5 subtypes, M1, 3 and 5 use the same G protein, what are their locations and effects?

Answer 27

M1, 3 and 5 use Gq
M1 = typically cause smooth muscle contraction, and increased secretion at the salivary, lacrimal and gastric glands

M3 = endothelial cells of blood vessels, activation causes release of NO which causes relaxation
Excretion in salivary glands, gastrointestinal motility, bronchoconstriction, bladder voiding, mucus secretion in bronchioles - be aware when considering drugs and people with asthma

M5 = who knows

Question 28

M2 and M4 muscarinic ACh receptors use Gi alpha subunits - how are they inhibitory?

Answer 28

result in less adenylyl cyclase - less cyclic cAMP, more GIRK receptors open, K+ moves out (and decreases Ca2+ movement too) so hyperpolarises the cell

Question 29

M2 and M4 muscarinic ACh receptors use Gi alpha subunits - what effects do they have when activated and where?

Answer 29

M2 - cardiac receptor
found in the atria and nodal tissue, reduces contraction frequency
it also causes a reduce in Ca2+, meaning smaller/fewer cardiac action potentials, reducing contraction strength

Question 30

as a drug, what would muscarine do?

Answer 30

muscarine - an agonist of muscarinic receptors, would overstimulate all of these in the body = too much mucus in airways, heart rate too slow, abdominal pain as smooth muscle contracts too much etc…

Question 31

pilocarpine is a non-selective agonist of muscarinic receptors - how is it used to treat glaucoma and why only applied topically?

Answer 31

glaucoma - too much fluid in eye - pilocarpine causes contraction of iris muscles allowing space for drainage

only applied topically as ingestion would = too many receptors being effected

Question 32

Cevimeline is an M3 selective agonist - what can it be used to treat?

Answer 32

dry mouth and eyes by increasing secretion

Question 33

why is it hard to find selective drugs?

Answer 33

ligand binding site of these muscarinic receptors are very similar

Question 34

what are anticholinesterases?

Answer 34

prevent breakdown of ACh so are deemed as cholinomimetic as they mimic affects of ACh