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
Where is the amygdala found?
Anterior to tip of the hippocampus
What does stimulation of the amygdala cause?
Intense emotions: fear and rage
What is the result of damage to the amygdala?
Calmness
What does stimulation of the nucleus accumbens result in?
Dopaminergic activity
Feeling of wellbeing
How does cocaine work?
Inhibits reuptake of dopamine
Dopamine floods the medial forebrain
How do amphetamines work?
Stimulate dopamine release
What is the motor function of the nucleus accumbens?
Connected to the basal ganglia to cause motor expression of emotion
What is the function of the septal area?
Reward and reinforcement
What does damage to the septal nuclei result in?
Rage
Which components of the limbic system play a role in reward?
Septal nuclei
Nucleus accumbens
Olfactory regions
Brainstem
Which components of the limbic system play a role in punishment?
Thalamus
Amygdala
Hippocampus
What is Wernicke-Korsakoff syndrome caused by?
Alcohol abuse
Affects B1 absorption which affects the limbic system
What are the symptoms of Wernicke encephalopathy?
Confusion and coma
Occular signs
Ataxia
What is ataxia?
Slurred speech, stumbling, incoordination
What are the symptoms of Korsakoff Psychosis?
Memory loss and inability to form new memories after recovery
