WEEK 5 - Topic 11 - Diencephalon

Question 1

What does the diencephalon consist of?

Answer 1

3 paired structures:

• thalamus
• hypothalamus
• epithalamus

Question 2

What is the diencephalon? (Intro)

Answer 2

The diencephalon is the central core of the forebrain, surrounded by the cerebral hemispheres

Question 3

What forms the forebrain?

Answer 3

Cerebral hemispheres

Diencephalon

Question 4

How much of the diencephalon does the thalamus make up?

Answer 4

80%

Question 5

What is the function of the thalamus?

Answer 5

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.

Question 6

What forms the superolateral walls of the third ventricle?

Answer 6

Thalamus

Question 7

What forms the inferolateral walls of the third ventricle?

Answer 7

Hypothalamus

Question 8

What connects the hypothalamus to the pituitary gland?

Answer 8

Infundibulum

Question 9

What is the function of the hypothalamus?

Answer 9

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

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Question 10

What forms the roof of the third ventricle?

Answer 10

Epithalamus

Question 11

The epithalamus is the most ______ portion of the diencephalon

Answer 11

Dorsal

Question 12

What does the epithalamus consist of?

Answer 12

The pineal gland/body

Question 13

What does the pineal gland secrete?

Answer 13

Secretes the hormone melatonin, a sleep-inducing signal.

Question 14

Where is the hypothalamus in relation to the thalamus?

Answer 14

Hypothalamus is anterior and inferior to the thalamus

Question 15

The hypothalamus is ______ to the optic chiasma and ________ to the mammillary bodies.

Answer 15

Dorsal

Superior

Question 16

What are mammillary bodies?

Answer 16

Mammillary bodies are a paired nuclei and they act as relay stations in the olfactory pathways