Motivated Behaviour: Role of the Hypothalamus NOT FINISHED

Question 1

What are the functions of the hypothalamus?

Answer 1

Homeostasis and Survival 
--> set point 
--> motivated behaviours
Integration of somaticc and autonomic responses 
- cardiovascular system
- blood composition and volume 
- food/water intake 
- temperature control 
- circadian rhythm 
- reproductive behaviours 
- emotional behaviour

Question 2

What is the triad of things that the hypothalamus affects?

Answer 2

ANS
endocrine systems
behaviour

Question 3

What are the hypothalamic inputs?

Answer 3

limbic regions, olfactory regions, retina, hippocampus

sensory receptors, in hypothalamus and in the viscera via BS, circumventricular organs

Question 4

What are the hypothalamic outputs?

Answer 4

1. pituitary –> hormones
2. brain stem –> ANS, coordination of behaviour
3. limic –> emotion, coordination of behaviour

Question 5

Describe the structure of the hypothalamus in terms of the anterior-posterior axis

Answer 5

Anterior 
- preoptic area , close to optic chiasm 
- suprachiastmic nucleus (circadian rhythms)
- nuclei concerned with 'set points' 
Posterior
- mamillary body x2
- emotional processing?
- Korsakoff's syndrome

Question 6

Describe the structure of the hypothalamus in terms of the medial lateral axis

Answer 6

3 x zones
Periventricular zone (forms cap of 3rd ventricle)
- anterior pituitary regulation –> SCN, arcuate nucleus (feeding)
Medial zone
- paraventricular
Lateral zone
- lateral hypothalamic area (feeding)
- supraoptic nuclei (release hormones to p. pituitary)

Question 7

ANS control
What are the inputs and outputs?
What is the evidence for this?

Answer 7

Inputs 
- exteroreceptors 
- interoreceptors 
Output
- to brainstem nuclei 
- paraventricular nucleus +++
- origins of preganglionic SNS/PNS 
Evidence
- stimulations/lesions of the hypothalamus 
- cannot control BP and HR, + gut and other ANS function

Question 8

Describe the endocrine role of the hypothalamus

Answer 8

The hypothalamus is connected

• indirectly to the anterior pituitary
• parvocellular secretory cells - very small
• hypophysiotrophic hormones –> capillaries
• directly to posterior pituitary –> magnocellular neurosecretory cells
• oxytocin and ADH

Question 9

Describe the hypothalamic role in food intake

short and long term regulation

Answer 9

• glucose + brain –> constant demand, intermittent supply, storage
• intake regulation is complex
• setpoint disruption in obesity and starvation
  Short term regulation
  –> hypothalamic inputs -> glucose and ghrelin
  —> hypothalamic glucose receptors
  Long term regulation
  –> fat stores –> leptin –> hypothalamus
  ….. NOT FINISHED

Question 10

Describe the hypothalamic role in temperature control

Answer 10

Hypothalamic thermoreceptors
NB pyrexia –> change of set point
Anterior hypothalamic nuclei - heat disappoint
Posterior hypothalamic nuclei - heat rendition
- integrated response
ANS –> blood vessels
Endocrine –> metabolism
Behaviour –> shivering, painting, seek warmth/shade

Question 11

Describe the hypothalamic role in reproductive behaviour

Answer 11

Anatomical differences in XY and XX - sexual dimorphism
Preoptic area –> different in XX XY, + sex hormone receptors in many nuclei
- Endocrine –> sexual organs, puberty, cyclical
- ANS –> sexual organs
- Behavioural –> courtship

Question 12

What are the clinical correlations?

Answer 12

• brain injury is rare due to anatomical location
• bilaterally so need to damage both
  Tumours
• diverse symptoms
• progressive changes
• locations –> inoperability