12. Limbic System and Hypothalamus Flashcards
What does the hypothalamus control?
Fluid and electrolyte balance Food ingestion Thermoregulation Reproduction Immune responses Circadian rhythm
What inputs are brought to the hypothalamus via the blood?
Hormones: growth, catecholamines, sex hormones
Chemical: pH, glucose
Physical: temperature, osmolarity
What are the neural inputs to the hypothalamus?
Nucleus solitarius in the medulla: barorecptors, chemoreceptors
Reticular formation in pons and medulla: alertness and arousal
What hypothalamic outputs are in the blood?
Direct hormone release (ADH, oxytocin)
Stimulation of pituitary (hypophyseal portal system)
What neural outputs does the hypothalamus have?
Autonomic effects
Limbic system
Which hypothalamic nuclei are in contact with the posterior pituitary?
Supraoptic
Paraventricular
What is produced in supraoptic nuclei?
ADH
What are supraoptic nuclei stimulated by?
Increased osmolarity
What do paraventricular nuclei produce?
Oxytocin
Which hypothalamic nuclei releases trophic hormones for the anterior pituitary?
Median eminence
What is Cushing’s syndrome?
Excess cortisol
What is Addison’s disease?
Adrenal insufficiency
What can the pressure of a hypothalamic/pituitary tumour cause?
Compression of the optic chiasma Bilateral hemianopsia (visual field loss)
What part of the embryonic brain is the hypothalamus part of?
Diencephalon
What part of the embryonic brain is the limbic system from?
Junction of the diencephalon and telencephalon
What structures are contained in the limbic system?
Cingulate gyrus Mammillary bodies Fornix Hippocampus Amygdala Septal nuclei
Where are the mammillary bodies found?
Inferior surface of hypothalamus
Between brainstem and cerebrum
What is the function of the mammillary bodies?
Short term memory
Smell
Direction
What does the fornix connect?
Mammillary bodies to the hippocampus
Where does decussation occur in the fornix?
Crus
Where is the hippocampus?
Temporal lobe
Under inferior horn of the lateral ventricle
What is the function of the hippocampus?
Making new memories
What is the name for the 3 layers of cells in the hippocampus?
Allocortex
What is Alzheimer’s caused by?
Cortical degeneration, especially in the hippocampus