Lecture 6 Flashcards

1
Q

Diencephalon

A
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2
Q

Diencephalon is deep within the brain, it composes the

A

walls of third ventricle

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3
Q

Diencephalon consists of

A

thalamus, hypothalamus, pituitary gland and pineal gland

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4
Q
A
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5
Q
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6
Q

Thalamus

A

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

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7
Q

Hypothalamus

A

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

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8
Q
A
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9
Q

Hypothalamus input

A

from reticular formation, cerebrum, sensory receptors

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10
Q

hypothalamus output

A

thalamus, multiple effector pathways

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11
Q

Hypothalamus links

A

autonomic nervous system with endocrine system

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12
Q

Hypothalamus controls

A
  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
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13
Q

Upstream endocrine control

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14
Q

Upstream endocrine control: example cortisol

A
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15
Q

Thirst: Δ osmolarity and volume

A
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16
Q

Vasopressin/ADH (antidiuretic hormone)

A

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

17
Q

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

A
18
Q
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19
Q

Neurohypophysis/posterior pituitary:

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downgrowth of hypothalamus

20
Q

Adenohypohysis/anterior pituitary:

A

true endocrine gland

21
Q

Portal System

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

22
Q

Hypothalamus controls pituitary hormone secretion

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23
Q
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24
Q

Hypothalamus synthesises pituitary hormones

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25
Q
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26
Q

Pineal gland

A

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

27
Q
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28
Q

Basal ganglia

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29
Q

Orientation, proximity to III ventricle

A
30
Q

Basal nuclei/basal ganglia

A

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

31
Q

PD

A

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

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33
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34
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35
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