Lecture 6

Question 1

Diencephalon

Question 2

Diencephalon is deep within the brain, it composes the

Answer 2

walls of third ventricle

Question 3

Diencephalon consists of

Answer 3

thalamus, hypothalamus, pituitary gland and pineal gland

Question 4

Question 5

Question 6

Thalamus

Answer 6

Gateway to sensation
“Relay station and integrating centre” for preliminary processing of sensory afferent signals (what gets through, what doesn’t)
All sensory input (spinal cord, optic tract, cochlear tract) synapses here, are screened out and routed accordingly to cortex
Helps to direct attention to stimuli of interest (aircon noise, street noise etc filtered out)
Crude awareness of sensations (without location or intensity)
Positively reinforcing voluntary motor control

Question 7

Hypothalamus

Answer 7

Collection of specific nuclei and associated fibers (less than 1% of total brain volume)
Integrating centre for homeostasis

Question 8

Question 9

Hypothalamus input

Answer 9

from reticular formation, cerebrum, sensory receptors

Question 10

hypothalamus output

Answer 10

thalamus, multiple effector pathways

Question 11

Hypothalamus links

Answer 11

autonomic nervous system with endocrine system

Question 12

Hypothalamus controls

Answer 12

1. body temperature
2. Thirst and urine output
3. Food intake/hunger
4. Controls anterior pituitary hormone secretion
5. Produces posterior pituitary hormones
6. Directly regulating internal environment (eg shivering, vasoconstriction for heat homeostasis) Controls uterine contraction and milk ejection
7. Autonomic nervous system: Smooth muscle, cardiac muscle, exocrine glands
8. Emotion and behaviour
9. Sleep/wake cycle

Question 13

Upstream endocrine control

Question 14

Upstream endocrine control: example cortisol

Question 15

Thirst: Δ osmolarity and volume

Question 16

Vasopressin/ADH (antidiuretic hormone)

Answer 16

Generated in N supraopticus: increases aquaporins in renal distal tubule and collecting duct
Damage in nucleus: Diabetes insipidus
20 l of urine loss per day

Question 17

Feeding center
Hypophysis tumour infiltrating hypothalamus: affecting hunger/food intake homeostasis (60kg increase in 2 years)

Question 18

Question 19

Neurohypophysis/posterior pituitary:

Answer 19

downgrowth of hypothalamus

Question 20

Adenohypohysis/anterior pituitary:

Answer 20

true endocrine gland

Question 21

Portal System

Answer 21

A vascular channel that begins in one set of capillaries and runs to another without coursing through the heart in between

Question 22

Hypothalamus controls pituitary hormone secretion

Question 23

Question 24

Hypothalamus synthesises pituitary hormones

Question 25

Question 26

Pineal gland

Answer 26

Suprachiasmic nucleus (SCN) neurons in hypothalamus: establish circadian rhythms of neuronal activities

Retinohypothalamic tract –> SCN–> pineal gland –> Δ Melatonin synthesis
Melatonin (“hormone of darkness) synthesis increases 10x at night
Chemical messenger for light dark cycle and biological clock
Powerful antioxidant, decreasing reactive oxygen species

Jetlag-treatment (taken as pill it also induces sleep)
Other functions: effect on ovulation and spermatogenesis

Question 27

Question 28

Basal ganglia

Question 29

Orientation, proximity to III ventricle

Question 30

Basal nuclei/basal ganglia

Answer 30

1 of 3 grey matter structures in cerebrum (cortex, limbic system)
Complex role in controlling movement:
Inhibiting muscle tone
Maintaining purposeful motor activity, supressing unwanted patterns
Monitor and coordinate slow and sustained contractions (posture) eg erector spinae
No direct effect on efferent motorneurons, but modifying pathway activity
Tremendous nr of fibers
Strategic interconnections between: basal nuclei, thalamus, cortex
Thalamus: positive reinforcement of voluntary movements, basal nuclei inhibit it

Question 31

PD

Answer 31

Destruction of dopaminergic neurons projecting into the basal ganglia –> 3 types of motor disturbance:
1. rigidity (increased muscle tone)
2. involuntary, unwanted movements (resting tremor)
3. slowness in initiating, changing and terminating motor behaviour

Question 32

Question 33

Question 34

Question 35