Hypothalamus

Question 1

What are the higher centers of the brain?

Answer 1

• Basal Ganglia
• Cerebellum
• Cerebrum (including Cortex of the brain, & limbic System)

Question 2

What are the higher centers of the brain involved in?

Answer 2

• Voluntary control
• Planning
• Imitation

Question 3

Name the lower centers of the brain

Answer 3

• Brain stem (medulla oblongata, Pons and Mid Brain)
• Thalamus
• Hypothalamus

Question 4

What are the functions of the lower centres of the brain?

Answer 4

• Simple reflexes
• autonomic control

Question 5

Label the main areas of the brain

Answer 5

Question 6

Where is the hypothalamus located?

Answer 6

• Region below the thalamus in brain (ie part of brain, but not behind blood-brain barrier-BBB)
• Composed of discrete groups of neurones called ‘nuclei’ or ‘areas’
• E.g. arcuate nucleus, paraventricular nucleus

Question 7

The hypothalamus has a crucial role in the endocrine system in three ways:

Answer 7

1. As an endocrine organ that controls the anterior pituitary (AP; major function)
2. Via nerve fibres that innervate the posterior pituitary (PP)
3. Via autonomic innervations of more distant glands (adrenal medulla, pineal, kidney parathyroid, pancreatic islets)

Question 8

Label the:

• Corpus callosum
• Optic chiasm
• Cerebrum
• Hypothalmus
• Thalamus
• Pineal gland

Answer 8

Question 9

Show the relation of pituitary gland to hypothalamus and rest of brain

Answer 9

Question 10

Label an enlargement of pituitary gland and its connection to hypothalamus

Answer 10

Question 11

Label the Hypothalamic nuclei

Answer 11

Question 12

What is the main function of the hypothalamus?

Answer 12

Homeostasis→or maintaining the status quo of the body

Question 13

List the homeostatic functions of the hypothalamus

Answer 13

• Blood pressure
• Temperature
• Fluid and electrolyte balance
• Body weight
• Sleep

These factors are regulated at what is known as the ‘hypothalamic set point’.This point can migrate over time but is relatively fixed.

Question 14

Direct Hypothalamic Regulation of Endocrine Glands: The Adrenal medulla (AM)

Answer 14

• AM is made up of postganglionic neurons without axons.
• These cells are stimulated by sympathetic acetylcholine (ACh) which stimulates catecholamine release (adrenaline and noradrenaline)

Question 15

Direct Hypothalamic Regulation of Endocrine Glands: The kidneys

Answer 15

Sympathetic fibres release noradrenaline which increases renin release by the juxtaglomerular apparatus (JGA)

Question 16

Direct Hypothalamic Regulation of Endocrine Glands: The Parathyroid glands

Answer 16

Sympathetic fibres stimulate PTH release via β-adrenergic receptors.

Question 17

Direct Hypothalamic Regulation of Endocrine Glands: Pancreatic islets

Answer 17

Several effects from sympathetic fibres, depending upon cell type; decrease insulin, increase glucagon

Question 18

Direct Hypothalamic Regulation of Endocrine Glands: Pineal gland

Answer 18

During darkness, impulses pass from hypothalamus to spinal cord to pineal gland to stimulate N-acetyltransferase which leads to production and release of melatonin.

Question 19

TRUE or FALSE: The higher centres of the brain control the hypothalamus

Answer 19

TRUE

Question 20

Why is the hypothalamus is ideally situated for sensing changes in blood chemistry?

Answer 20

• The hypothalamus is ideally situated for sensing changes in blood chemistry as parts of it sit outside the blood-brain barrier.
• Some areas of the hypothalamus also contain ‘fenestrated’ blood vessels which are highly permeable
• The hypothalamus can then pass this information on neurally. As peptides are less lipophilic than steroids, this is an important aspect of peptide feedback.

Question 21

TRUE or FALSE: The hypothalamus is thought to be a key regulator of ageing

Answer 21

TRUE

•Via IKK-β, NF-κB and Gonadotropin-releasing hormon (GnRH)