Hypothalamus Flashcards
What are the higher centers of the brain?
- Basal Ganglia
- Cerebellum
- Cerebrum (including Cortex of the brain, & limbic System)
What are the higher centers of the brain involved in?
- Voluntary control
- Planning
- Imitation
Name the lower centers of the brain
- Brain stem (medulla oblongata, Pons and Mid Brain)
- Thalamus
- Hypothalamus
What are the functions of the lower centres of the brain?
- Simple reflexes
- autonomic control
Label the main areas of the brain
Where is the hypothalamus located?
- 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
The hypothalamus has a crucial role in the endocrine system in three ways:
- As an endocrine organ that controls the anterior pituitary (AP; major function)
- Via nerve fibres that innervate the posterior pituitary (PP)
- Via autonomic innervations of more distant glands (adrenal medulla, pineal, kidney parathyroid, pancreatic islets)
Label the:
- Corpus callosum
- Optic chiasm
- Cerebrum
- Hypothalmus
- Thalamus
- Pineal gland
Show the relation of pituitary gland to hypothalamus and rest of brain
Label an enlargement of pituitary gland and its connection to hypothalamus
Label the Hypothalamic nuclei
What is the main function of the hypothalamus?
Homeostasis→or maintaining the status quo of the body
List the homeostatic functions of the hypothalamus
- 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.
Direct Hypothalamic Regulation of Endocrine Glands: The Adrenal medulla (AM)
- AM is made up of postganglionic neurons without axons.
- These cells are stimulated by sympathetic acetylcholine (ACh) which stimulates catecholamine release (adrenaline and noradrenaline)
Direct Hypothalamic Regulation of Endocrine Glands: The kidneys
Sympathetic fibres release noradrenaline which increases renin release by the juxtaglomerular apparatus (JGA)
Direct Hypothalamic Regulation of Endocrine Glands: The Parathyroid glands
Sympathetic fibres stimulate PTH release via β-adrenergic receptors.
Direct Hypothalamic Regulation of Endocrine Glands: Pancreatic islets
Several effects from sympathetic fibres, depending upon cell type; decrease insulin, increase glucagon
Direct Hypothalamic Regulation of Endocrine Glands: Pineal gland
During darkness, impulses pass from hypothalamus to spinal cord to pineal gland to stimulate N-acetyltransferase which leads to production and release of melatonin.
TRUE or FALSE: The higher centres of the brain control the hypothalamus
TRUE
Why is the hypothalamus is ideally situated for sensing changes in blood chemistry?
- 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.
TRUE or FALSE: The hypothalamus is thought to be a key regulator of ageing
TRUE
•Via IKK-β, NF-κB and Gonadotropin-releasing hormon (GnRH)
