Module 2: Section 4

Question 1

Brain stem components

Answer 1

• Midbrain
• Pons
• Medulla oblongata

Question 2

Brain stem function overview

Answer 2

Provides link between the spinal cord and the higher brain centres

Question 3

5 major functions of brain stem

Answer 3

1. Housing the cranial nerves
2. Vegetative functions
3. Posture reflexes
4. Reticular activating system
5. Sleep

Question 4

Housing the cranial nerves

Answer 4

• Supply sensory and motor fibres in the head and neck
• Control hearing, eye movement, facial sensations, taste, swallowing, and movement of the face, neck, shoulder and tongue muscles

Question 5

Vegetative functions

Answer 5

Contains clusters of neurons that control the vegetative functions of the cardiovascular, respiratory and digestive systems

Question 6

Vegetative functions of cardiovascular and respiratory system

Answer 6

• Medulla oblongata detects CO2 and O2 levels in the blood and determines what changes need to occur in the body
• Ex: Low O2 levels would result in increased respiration

Question 7

Posture reflexes

Answer 7

• Muscle reflexes involved in posture and equilibrium come from brain stem
• Functions to maintain the body in an upright, balanced position and provide a stable background for voluntary activity

Question 8

Reticular activating system - Location and purpose

Answer 8

• Located in the brain stem and extends to the thalamus
• It monitors incoming sensory input (except smell) and filters what reaches conscious awareness

Question 9

What do ascending fibres from the reticular formation do?

Answer 9

They pass selected sensory information to the cortex, forming the reticular activating system (RAS)

Question 10

Can the cortex affect the RAS?

Answer 10

Yes, descending fibres from the cortex can also activate the RAS

Question 11

Sleep

Answer 11

The brain stem produces neurotransmitters that act on the brain to control sleep and wake states

Question 12

What determines if we are awake or asleep?

Answer 12

The balance between sleep-promoting and wake-promoting neurotransmitters

Question 13

What is the major inhibitory neurotransmitter in sleep?

Answer 13

GABA, which is heavily present during sleep

Question 14

What is the diencephalon?

Answer 14

• Consists of the thalamus, hypothalamus, epithalamus, and subthalamus
• Located at upper end of brain stem

Question 15

Functions of the diencephalon

Answer 15

• Relay sensory information between brain regions
• Controls autonomic functions
• Connects nerves and endocrine system
• Controls emotion in conjunction with the limbic system

Question 16

Thalamus

Answer 16

• Located deep in the brain
• It’s an integrating centre for all sensory input on its way to the cortex
• Conducts preliminary processing
• Also amplifies the importance for signals of specific interests

Question 17

What is preliminary processing?

Answer 17

The thalamus filters signals by removing weaker ones and sending stronger, more important impulses to the cortex

Question 18

Hypothalamus

Answer 18

• It’s an integration centre for homeostatic functions
• Serves as link between the autonomic nervous system and the endocrine system

Question 19

8 main roles of the hypothalamus

Answer 19

1. Controls production and secretion of pituitary hormones
2. Plays role in sleep-wake cycle
3. Is an autonomic nervous system coordinating centre
4. Controls uterine contraction and milk ejection
5. Controls fluid uptake
6. Influences urine output and thirst
7. Involved in emotion and behaviour
8. Controls body temperature

Question 20

What role does the hypothalamus play in negative feedback?

Answer 20

It maintains homeostasis by detecting body changes and triggering responses that reverse them, keeping conditions stable

Question 21

How does the hypothalamus respond when the body gets cold?

Answer 21

• It triggers heat production (shivering) and reduces heat loss (shunts blood from skin)
• It also influences behaviours like putting on warm clothes or starting a fire

Question 22

Cerebral cortex

Answer 22

• Composed of grey matter
• Divided into the right and left hemispheres that are connected by the corpus callosum
• Consists of 6 defined layers that are interconnected to form the cortical microcircuits

Question 23

Grey matter

Answer 23

Area that contains neuron cell bodies with their dendrites and glial cells and interneurons

Question 24

4 lobes of the cerebral cortex

Answer 24

1. Frontal lobe
2. Parietal lobe
3. Occipital lobe
4. Temporal lobe

Question 25

Frontal lobe

Answer 25

- Located at front of head - Responsible for voluntary motor activity, speech, and elaboration of thought

Question 26

Parietal lobe

Answer 26

- Located between frontal and occipital lobes - Responsible for receiving and processing sensory input

Question 27

Occipital lobe

Answer 27

- Located at back of head - Does initial processing for vision input

Question 28

Temporal lobe

Answer 28

- Located on side of head - Involved in vision and hearing

Question 29

Somatosensation

Answer 29

- The parietal lobe processes physical sensations - The somatosensory cortex (front of parietal lobe) receives input from the peripheral nervous system - It processes somaesthetic input (touch, pressure, temperature, pain) and proprioceptive input (body position) - This info is then sent to higher brain areas for further interpretation

Question 30

Somatosensory Cortex

Answer 30

- Each region of the somatosensory cortex processes somaesthetic and proprioceptive input from specific body parts - Cortex on one side of brain receives input from the opposite side of body (crossing pathways in spinal cord)

Question 31

Sensory Homunculus

Answer 31

Physical representation of human sensory perception, located within the brain

Question 32

Primary motor cortex

Answer 32

- Inside frontal lobe - Contains pyramidal neurons that send axons down the spinal cord and synapse with the alpha-motor neurons of skeletal muscles

Question 33

What does the primary motor cortex work in conjunction with?

Answer 33

Th premotor cortex

Question 34

Motor homunculus

Answer 34

Depicts the relative output of the primary motor cortex to different parts of the body

Question 35

3 parts of the celebellum

Answer 35

1. Vestibulocerebellum 2. Spinocerebellum 3. Cerebrocerebellum

Question 36

Vestibulocerebellum

Answer 36

Important for balance, spatial orientation and control of eye movement

Question 37

Spinocerebellum

Answer 37

- Regulates skilled voluntary movements - Receives proprioceptive input to allow continuous fine-tuning of movement

Question 38

Cerebrocerebellum

Answer 38

- Receives all its input from the cerebral cortex - Involved in planning voluntary movement as well as the evolution of sensory information

Question 39

Basal Ganglia – Location

Answer 39

Consists of masses of grey matter located within the cerebral white matter

Question 40

Basal Ganglia – Functions

Answer 40

Controls motor activity, cognition, emotions, and learning

Question 41

What regions of the brain is the basal ganglia connected to and influences?

Answer 41

1. Cerebral cortex 2. The thalamus 3. Brain stem

Question 42

Basal Ganglia – 4 Structures

Answer 42

1. caudate nucleus 2. putamen 3. globus pallidus 4. claustrum

Question 43

Basal ganglia main function 1

Answer 43

Inhibiting muscle tone throughout the body

Question 44

Basal ganglia main function 2

Answer 44

Permitting purposeful motor activity while suppressing unwanted movements

Question 45

Basal ganglia main function 3

Answer 45

Helping monitor and coordinate sustained contractions like the ones related to posture

Question 46

What regions of the brain are included in the limbic system?

Answer 46

- Lobes of the cerebral cortex - The basal ganglia - The thalamus - The hypothalamus

Question 47

What does the limbic system help regulate?

Answer 47

- Learning - Motivation - Behaviour - Emotions

Question 48

Hypothalamus role in behaviour

Answer 48

- It controls the involuntary internal responses in preparation for action

Question 49

The nature of motivated behaviours

Answer 49

- Can be homeostatic - Can also be non-homeostatic, these involve the reward and punishment centres

Question 49

Cortex role in behaviour

Answer 49

- Provides neural mechanisms necessary for regulating skeletal muscle responses needed for behaviours

Question 50

Phineas Gage

Answer 50

- Accident drove iron rod through frontal lobe - survived but had major personality/behavior changes - Showed link between brain damage, personality, and localized brain functions