week 8 - hypothalamus

Question 1

Name the four lobes of the brain

Answer 1

frontal
parietal
occipital
temporal

Question 2

Where is the hypothalamus located in relation to the thalamus?

Answer 2

ventral and anterior

Question 3

What is the hypothalamus

Answer 3

paired small nucleus - weight 4g in relation to brain w 1.4 kg

Question 4

What are nuclei?

Answer 4

cluster of neurons in CNS, neurons in one nucleus usually have roughly similar connections and functions

Question 5

Name the boundaries of the hypothalamus

Answer 5

superior: hypothalamic sulcus separating it form the thalamus
inferior: optic chasm, tuber cinereum, mammillary bodies
anterior: lamina terminals
posterior: tegmenjtum of midbrain
medial: third ventricle
lateral: internal capsule

Question 6

define the hypothalamus?

Answer 6

primary regulator of autonomic and endocrine functions
produces hormones that regulate different behaviours

Question 7

give an example of an endocrine control of the hypothalamus

Answer 7

oxytocin release controls feeding behaviours

Question 8

give an example of an autonomic control of the hypothalamus

Answer 8

thermoregulation

Question 9

What are the functions of the hypothalamus

Answer 9

• stress reaction via hypothalamic-pituitary-adrenal axis
• fighting, fleeing, feeding, mating

Question 10

Give examples of homeostatic processes controlled by the hypothalamus

Answer 10

• respiration
• circulation
• food-water intake
• digestion
• metabolism
• body temp

Question 11

Why is a functional hypothalamus important?

Answer 11

harmonious growth of the body, differentiation of sexual characteristics, sexual and reproductive activities

Question 12

Name the three regional subdivisions of the hypothalamus visible int he sagittal plane

Answer 12

anterior (subraoptic), middle (tuberal), posterior (mammillary)

Question 13

name the three regional subdivisions of the hypothalamus in the coronal plane

Answer 13

lateral, medial, periventricular

Question 14

name the location and function of the suprachiasmatic nuclei

Answer 14

medial, anterior
biological rhythms such as sleep

Question 15

name the location and function of the ventromedial nuclei

Answer 15

medial, tuberal
appetite, body weight insulin regulation

Question 16

name the location and function of the lateral nuclei

Answer 16

lateral, tuberal
appetite and body weight control

Question 17

define the term afferent

Answer 17

conduct inwards or towards something eg. nerves, CNS, blood vessels, organ

Question 18

define the term efferent

Answer 18

conduct outwards, away from something eg. nerves, CNS, blood vessels, organ
-> efferent neurons carry impulse outwards to effector organs

Question 19

Describe the afferent connections of the hypothalamus

Answer 19

formic - fibre track going from hippocampus to hypothalamus
stria terminalis - fibre track from amygdala
olfactory bulb
retina
spinal cord

Question 20

name the four types of afferent connection

Answer 20

1. somatic and visceral
2. visual
3. Olfaction
4. auditory
5. corticohypothalamic fibres
6. hippocampo-hypothalamic fibres
7. amygdala-hypothalamic fibres
8. thalami-hypothalamic fibres
9. tegmental fibres

Question 21

describe the route of somatic and visceral afferents

Answer 21

• general somatic, gustatory and visceral sensations reach the hypothalamus through collateral branches of the lemniascal afferent fibres and the tracts solitaries and through the reticular formation

Question 22

describe the route of visual afferents

Answer 22

leave optic chaise and pass to the suprachiasmatic nucleus

Question 23

describe the route of olfactory afferents

Answer 23

travel through the medial forebrain bundle

Question 24

describe the route of the auditory afferents

Answer 24

have not been identified, but since auditory stimuli can influence activities of hypothalamus, they must exist

Question 25

describe the route of the corticohypothalamic fibres

Answer 25

arise form the frontal lobe of the cerebral Cortex and pass directly to the hypothalamus

Question 26

describe the route of the hippocampo-hypothalamic fibres

Answer 26

pass form hippocampus through fornix to the mammilary body

Question 27

describe the route of the amygdala-hypothalamic fibres

Answer 27

pass through amygdaloid complex to hypothalamus through stria terminals by a route that passes inferior to lentiform nucleus

Question 28

describe the route of the thalami hypothalamic fibres

Answer 28

arise form dorsomedial and midline thalamic nuclei

Question 29

Where do tefmental fibres arise from?

Answer 29

midbrain

Question 30

What connections has the forinx?

Answer 30

afferent and efferent connections between the hippocampus and hypothalamus

Question 31

what connections has the stria terminalis?

Answer 31

afferent and efferent connections between amygdala and hypothalamus

Question 32

Describe the efferent connections of the hypothalamus

Answer 32

1. descending fibres to brainstem and spinal cord 2. mammilothalmic tract 3. mammillotegmental tract 4. multiple pathways to limbic system

Question 33

describe the course of the descending fibres to the brainstem and spinal cord

Answer 33

- descending fibres to brainstem and spinal cord influence the peripheral neurons of ANS - descend through series of enurons in reticular formation - connected to parasympathetic nuclei of CN3, CN7, CN9, CN10 - reticulospinal fibres connect hypothalamus with sympathetic cells of origin in lateral grey horns of first thoracic segment to second lumbar segment of spinal cord and sacral parasympathetic outflow at level of second, third, fourth sacral segments of spinal cord

Question 34

describe the course of the mammillothalimc tract

Answer 34

arises in maxillary body, terminates in anterior nucleus of thalamus, pathway relayed to cingulate gyrus

Question 35

describe the course of the mammillotegmental tract

Answer 35

arises form mammilary body and terminates in cells of reticular formation in tegmenjtum of the midbrain

Question 36

Explain afferent and efferent connections of the mammillary nucleus

Answer 36

- hypothalamus = output of limbic system - mammilary body receiving nucleus form hippocampus via fornix - mammillary body is an efferent connection to thalamus, from thalamus there is an efferent connection to cingulate cortex - lots o limbic system integration occurs in cingulate cortex

Question 37

what is the function of the hypothalamus in terms of lesions?

Answer 37

temperature regulation food intake sleep-wake cycle emotions water balance

Question 38

What does an anterior lesion of the hypothalamus lead to?

Answer 38

hyperthermia insomnia diabetes insipidus

Question 39

what does a posterior lesion of the hypothalamus lead to?

Answer 39

hypothermia hypersomnia

Question 40

what does a ventromedial nucleus lesion of the hypothalamus lead to?

Answer 40

excessive eating - hyperphagia emotions - rage

Question 41

What does the lateral lesion of the hypothalamus lead to?

Answer 41

reducing eating - hypophagia

Question 42

describe the circadian regulation if melatonin production

Answer 42

- suprachiasmatic nucleus = pacemaker involving intermediolateral nuclei in spinal cord, superior cervical ganglion and input form eye - control production and release of melatonin in pineal gland - SCN sets pace and release hormones