Homeostasis & Autonomic Nervous System L1

Question 1

define homeostasis

Answer 1

maintenance of stable internal environment
- Maintenance of equilibrium (through compensation)
- Maintenance of variables (e.g. blood pressure) within -
limited ranges
- involves integrated function of different organ systems

Question 2

what is the result if homeostasis is not maintained

Answer 2

disease

Question 3

what are the steps of homeostatic control

Answer 3

stimulus - sensor (monitoring) - controller (coordination) - effector (response) - effect
minimises disturbances

Question 4

describe process of negative feedback

Answer 4

effector leads to reduction in stimulus
- blood pressure, plasma osmolarity, pupil diameter

Question 5

how does the pupil respond to light

Answer 5

changes in diameter to adjust levels of light reaching retina
ganglia within retina detect light changes and send message to iris muscles via autonomic nervous system

Question 6

what are the iris muscles that are involved in iris dilation

Answer 6

1. the sphincter pupillae
   - circular, constrictor,
2. dilator pupillae.
   - radial, dilator,

Question 7

what are the three control mechanisms

Answer 7

1. nervous system
2. endocrine system
3. paracrine system

Question 8

what is an important division of nervous system and what is it important for

Answer 8

autonomic nervous system
- important in maintaining homeostasis

Question 9

what are the 3 main components of autonomic nervous system

Answer 9

1. sensory afferent nerve fibres
   - blood pressure via baroreceptors
2. control centres
3. efferent pathways

Question 10

what are the 3 control centres of ANS

Answer 10

1. hypothalamus
2. brain stem
3. spinal cord

Question 11

what are the 2 efferent pathways of the ANS

Answer 11

1. parasympathetic
   - brings processes back to normal rate
2. sympathetic
   - prepares body for flight or fight

Question 12

what do sympathetic and parasympathetic NS have in common

Answer 12

1. both have 2 neurons in series
   - the preganglionic neurone originating from CNS
   - postganglionic neurone originating from autonomic ganglion

Question 13

what feature of PSNS and SNS allows signal to be amplified

Answer 13

one preganglionic neurone can synapse with many post ganglion neurones

Question 14

what are the distinct features of the PSNS

Answer 14

1. long preganglionic neurone
2. short postganglionic neurone

Question 15

what is the origins of the preganglionic nerve in PSNS

Answer 15

1. cranial nerve
   - III: oculomotor (eye)
   - VII: facial (lacrimal, nasal, submandibular)
   - IX: glossopharyngeal (parotid)
   - X: vagus (thorax and abdomen)- important
2. pelvic nerve
   - rectum, bladder

Question 16

what is the origins of the postganglionic nerve in PSNS

Answer 16

autonomic ganglia near or on target tissue

Question 17

what are the distinct features of the SNS

Answer 17

1. short preganglionic neurone
2. long postganglionic neurone
3. adrenal medulla

Question 18

what is the origins of the preganglionic nerve in SNS

Answer 18

Thoracic 1 (T1) - Lumbar 2/3 (L2/3)

Question 19

what is the origins of the postganglionic nerve in SNS

Answer 19

autonomic ganglia
2 Paravertebral sympathetic chains- chains that run down spinal cord

Question 20

how is the adrenal medulla involved in SNS

Answer 20

Preganglionic neurones goes directly into it stimulating it to release adrenaline and noradrenaline into blood stream

Question 21

what are the 4 types of neurotransmitters involved in ANS

Answer 21

1. ACH
2. noradrenaline
3. adrenaline
4. Non-Adrenergic, Non-Cholinergic (NANC) neurotransmitters

Question 22

what are the two kinds of receptors involved in ANS

Answer 22

1. Cholinergic
   - Nicotinic or muscarinic
2. Adrenergic
   - a or b

Question 23

where are nicotinic cholinergic receptors used

Answer 23

they are on the autonomic ganglia between CNS and preganglionic neurone in both SNS and PSNS

Question 24

which cholinergic receptor is used in the SNS and PSNS on autonomic ganglion

Answer 24

nicotinic
blocked by curare

Question 25

what neurotransmitter binds to nicotinic cholinergic receptors in the SNS and PSNS

Answer 25

acetylcholine

Question 26

what cholinergic receptor is used on target organs between postganglionic neurone and target organs

Answer 26

muscarinic
blocked by atropine

Question 27

what neurotransmitter binds to muscarinic cholinergic receptors in the PSNS
(postganglionic neurone)

Answer 27

acetylcholine

Question 28

what kind of receptor is muscarinic and what ion does it effect when it is active

Answer 28

G protein coupled receptor
causes K+ to leave target organ

Question 29

what type of Adrenergic receptor is found in the SNS in postganglionic neurone

Answer 29

A- adrenoceptors
blocked by phentolamine
B-adrenoceptors
- blocked by propranolol

Question 30

what are the types of A- adrenoceptors, where are they found, what neurotransmitter do they respond to and what is the effect

Answer 30

A1: postsynaptic, noradrenaline
- vasoconstriction and smooth muscle contraction
A2: presynaptic, noradrenaline
- Reduction in adrenergic and cholinergic transmission

Question 31

what are the type types of B- adrenoceptors, where are they found, what neurotransmitter do they respond to and what is the effect

Answer 31

B1: heart, noradrenaline and adrenaline
-Increase in heart rate and force of contraction
B2: heart, adrenaline
- Vasodilation and smooth muscle relaxation