the hypothalamus and autonomic control

Question 1

what is a nucleus in the brain?

Answer 1

a group of neurons with similar functions

Question 2

nuclei of the hypothalamus

Answer 2

paraventricular nucleus
suparoptic nucleus
anterior pituitary/adenohypophysis
posterior pituitary/neurohypohpysis

Question 3

what is the difference between adenohypophysis and neurohypophysis?

Answer 3

neurohypophysis derived from neural tube unlike adenohypophysis

Question 4

what happens in the adenohypophysis (anterior pituitary)?

Answer 4

• parvocellular neurons of the hypothalamus release neuro hormones
• bind to receptors to stimulate troph cells
• they release other hormones which enter the rest of the body

Question 5

what happens in the neurohypophysis (posterior pituitary)?

Answer 5

• magnocellular neurons from hypothalamus release neurons directly into systemic circulation

Question 6

how does the hypothalamus control the body?

Answer 6

• controls hormonal system through pituitary gland
• autonomic nervous system

Question 7

what are the two efferent pathways of the ANS?

Answer 7

• sympathetic = fight or flight
• parasympathetic = rest and digest

Question 8

what are the effectors of the ANS?

Answer 8

• smooth muscle
• cardiac muscle
• glands

Question 9

what is the relationship between the different pathways of the ANS?

Answer 9

generally supply the same tissue but have opposing effects

Question 10

how does the ANS function without the hypothalamus?

Answer 10

• sensory (afferent) division, receptors carried via afferent fibers to brainstem nuclei
• produces motor output via efferent fibers to the effectors
• there is sometimes a degree of hypothalamic control

Question 11

what is the general organisation of ANS?

Answer 11

• preganglionic neurons transfer impulses to postganglionic neurons
• via cholinergic synpase which bind to nicotinic acetylcholine receptors
• postganglionic neurons send info to effectors

Question 12

where are preganglionic sympathetic neurons found?

Answer 12

intermediolateral cell column (T1-L3 in spinal cord)

Question 13

organisation of the sympathetic nervous system

Answer 13

• preganglionic neurons originate from spinal cord
• they join the sympathetic chain ganglion
• which is where synapses with postganglionic neuron happen along
• postganglionic fibers pass information to effectors via adrenergic synapse

Question 14

how was the rostral ventrolateral medulla (RVLM) identified experimentally?

Answer 14

• different areas of the medulla were stimulated using an electrode
• response was recorded in spinal cord, quick response was evidence of a direct link

Question 15

what controls sympathetic preganglionic neurons?

Answer 15

rostral ventrolateral medulla (RVLM)

Question 16

what is the organisation of the parasympathetic nervous system?

Answer 16

• preganglionic neurons from intermediate grey
• connect to ganglia near target organs
• cholinergic synapse which activates muscarinic receptor

Question 17

cranial parasympathetic organisation

Answer 17

oculomotor nerve - originates in midbrain, controls pupillary dilation
vagus nerve - originates in medulla, carries out 80% of parasympathetic output