WEEK 5 - Topic 11 - Diencephalon Flashcards
What does the diencephalon consist of?
3 paired structures:
- thalamus
- hypothalamus
- epithalamus
What is the diencephalon? (Intro)
The diencephalon is the central core of the forebrain, surrounded by the cerebral hemispheres
What forms the forebrain?
Cerebral hemispheres
Diencephalon
How much of the diencephalon does the thalamus make up?
80%
What is the function of the thalamus?
The thalamus is the relay station for info entering the cerebral cortex.
- It consists of many specialised nuclei and afferent impulses from all senses and all parts of the body synapse with at least one of its nuclei.
- Within the thalamus, the “crude” sensory info is sorted out and edited and sent to the cerebral cortex for specific stimulus localisation and discrimination.
- Overall, the thalamus mediates sensation, motor activity, cortical arousal, learning and memory.
What forms the superolateral walls of the third ventricle?
Thalamus
What forms the inferolateral walls of the third ventricle?
Hypothalamus
What connects the hypothalamus to the pituitary gland?
Infundibulum
What is the function of the hypothalamus?
Controls body homeostasis
- Controls the ANS: Influences blood pressure, rate and force of heartbeat, digestive tract motility, eye pupil size)
- Initiates physical responses to emotions: The hypothalamus is part of the limbic system and it contains nuclei involved in perceiving pleasure, fear, rage and sex drive.
- Regulates body temperature: Monitors blood temperature and initiates shivering/sweating.
- Regulates food intake: Monitors blood levels of glucose and amino acids and regulates feelings of hunger and satiety.
- Regulates water balance and thirst by receiving input from osmoreceptors
- Regulates sleep-wake cycles: Its suprachiasmatic nucleus sets the timing of the sleep cycle in response to daylight and darkness.
- Controls endocrine system functions: Controls releasing and inhibiting hormones which controls the secretion of hormones by the anterior pituitary
-
What forms the roof of the third ventricle?
Epithalamus
The epithalamus is the most ______ portion of the diencephalon
Dorsal
What does the epithalamus consist of?
The pineal gland/body
What does the pineal gland secrete?
Secretes the hormone melatonin, a sleep-inducing signal.
Where is the hypothalamus in relation to the thalamus?
Hypothalamus is anterior and inferior to the thalamus
The hypothalamus is ______ to the optic chiasma and ________ to the mammillary bodies.
Dorsal
Superior