9 - Diencephalon (Exam 2) Flashcards
What is the diencephalon composed of?
3rd ventricle
Thalamus
Hypothalamus
What is a brief summary of the thalamus?
Gatekeeper to the cortex
Everything goes through the thalamus before it enters or leaves the cerebral cortex (except for smell)
What are the 7 main thalamic nuclei?
- LGN - lateral geniculate nucleus
- MGN - medial geniculate nucleus
- VPL - ventral posterior lateral nucleus
- VPM - ventral posterior medial nucleus
- VA - ventral anterior nucleus
- VL - ventral lateral nucleus
- Pulvinar nucleus
What is the function of the LGN?
Visual pathway
Layers I and II are magno
Layers III, IV, V, and VI are parvo
Ipsilateral temporal retinal fibers - II, III, V
Contralateral nasal retinal fibers - I, IV, VI
What is the function of the MGN?
Auditory pathway
What is the function of the VPL?
Relay all sensory information from the body
What is the function of the VPM?
Relay all sensory information from the face
What are 3 examples of sensory relay nuclei?
- Ventral posterior nucleus (VPL and VPM)
- Medial geniculate nucleus (MGN)
- Lateral geniculate nucleus (LGN)
What is a brief summary of the VA and VL nuclei?
Motor relay nuclei
Input from basal ganglia and cerebellum
Project to primary motor/motor association areas
Under tonic inhibition
What is an example of an association nucleus?
Pulvinar nucleus
What is the function of the pulvinar nuclei?
Vision processing (visual salience, working visual memory) Auditory processing
What 4 association areas do the pulvinar nuclei have connections in?
- Frontal
- Parietal
- Temporal
- Occipital
What is a brief summary of the hypothalamus?
Responsible for body temperature regulation
Links ANS, endocrine system, emotions, and somatic function
Anatomically, what is the hypothalamus a part of?
Diencephalon
Functionally, what is the hypothalamus a part of?
Limbic system
How large is the hypothalamus?
Very small
Only weighs about 4 grams
What are the 4 major regions of hypothalamic nuclei?
- Anterior area
- Lateral nucleus
- Middle area
- Posterior area
Clinically, which is more important for hypothalamic nuclei - general area or specific nuclei?
General area
What is the anterior region responsible for in the hypothalamus?
Heat loss
Sleep
Hormone regulation
Magno/ parvo cells
What is the middle region responsible for in the hypothalamus?
Emotions
Eating and drinking
Hormone regulation
What is the posterior region responsible for in the hypothalamus?
Heat gain
Wakefulness
Memory
What is another name for the pituitary gland?
Hypophysis
How many lobes does the pituitary gland have?
Two lobes
Anterior lobe
Posterior lobe
What is the neural connection between the hypothalamus and the posterior lobe of the pituitary gland called?
Neurohypophysis
What is the vascular connection between the hypothalamus and the anterior lobe of the pituitary gland called?
Adenohypophysis
Feedback systems regulate endocrine function - how are long feedback loops and short feedback loops different?
Long feedback loops involve plasma hormone levels dictating the amount of production and secretion
Short feedback loops have a direct connection between the pituitary gland and hypothalamus
Which region of the hypothalamus is involved with cooling the body down (heat loss mechanisms)?
Anterior hypothalamus
Which region of the hypothalamus is involved with heating the body up (heat gain mechanisms)?
Posterior hypothalamus
Where does each portion of the hypothalamus send signals to regarding “heat loss mechanisms” or “heat gain mechanisms”?
The ANS
Where does each portion of the hypothalamus send signals to regarding a change in clothes, turning the heat on, or opening windows?
The cerebral cortex
How would a lesion to the anterior hypothalamus effect body temperature?
Hyperthermia
A result of loss of “heat loss mechanisms”
How would a lesion to the posterior hypothalamus effect body temperature?
Hypothermia
A result of loss of “heat gain mechanisms”
How would a large, bilateral lesion to the hypothalamus effect body temperature?
Body temperature can’t be regulated
Similar to cold-blooded animals
Which region of the hypothalamus tells the body “I’m hungry!”?
Lateral hypothalamus
Which region of the hypothalamus tells the body “I’m full!”?
Medial hypothalamus
How would a lesion to the lateral hypothalamus effect the body?
Anorexia
Loss of “I’m hungry!” messages
How would a lesion to the lateral hypothalamus effect the body?
Obesity
Loss of “I’m full!” messages
What type of mechanisms help keep the body’s water in balance?
Neural and hormonal mechanisms
What is a neural mechanism example of water balance?
Lateral hypothalamus is stimulated to induce drinking
What is a hormonal mechanism example of water balance?
Increased osmolarity of the blood results in increased ADH and therefore urine retention
Decreased osmolarity of the blood results in decreased ADH and therefore more urination
What would a lesion to the posterior lobe of the pituitary gland present as?
Diabetes insipidus
Inadequate output of ADH therefore excessive urination
What is referred to as the body’s “master clock”?
The suprachiasmal nucleus (SCN)
What is the role of the SCN?
Neurons project to pineal gland
low light stimulates melatonin production
high light inhibits melatonin production
What modulates the activity of the SCN?
Input from the retinhypothalamic tract
How many hours in the rhythm of activity of SCN neurons?
24 hours
