A.2 The Human Brain

Question 1

Metabolism of the Brain

Answer 1

The energy demands of the brain are high: they account for at least 20% of a human adult’s energy consumption
- ATP is used for the synthesis of neurotransmitters
- ATP is used to carry out the active transport needed to maintain resting potential

Question 2

List the 5 parts and functions of the brain

Answer 2

• pituitary gland:Produces and secreted hormones (ex: ADH)
• hypothalamus: Maintains homeostasis via coordination of the nervous and endocrine systems
• cerebellum: Controls balance and coordination
• medulla oblongata: Controls involuntary responses (ex: swallowing, digestion)
• cerebral hemisphere: centre for highly complex functions (ex: learning, memory and emotion)

Question 3

Outline the autonomic nervous system

Answer 3

• controls unconscious processes using the medulla oblongata
• consists of sympathetic & parasympathetic

Question 4

Outline the differences between the sympathetic and parasympathetic

Answer 4

Parasympathetic nerves cause an increase in blood flow to the gut (increases salivary release, lowers ventilation rate + reduces heart rate)

Sympathetic nerves cause a decrease in blood flow to the gut (decrease salivary release + increases ventilation rate + increases heart rate)

Question 5

Outline the importance of the pupil reflex

Answer 5

• Failure of the pupil reflex indicates the damage to medulla oblongata
• used to test for brain death

Question 6

What happens to the eye when it is bright

Answer 6

• circular muscles contract
• pupil constricts
• radial muscle relax

Question 7

What happens to the eye when it is dim

Answer 7

• radial muscles contract
• pupil dilates
• circular muscle relax

Question 8

What is the relationship between the enlargement and folding of the cerebral cortex

Answer 8

The folds in the cortex enabling a large increase in surface area without increasing the size of the cranium
- the folding has become more extensive in the number of neurons present in the cortex controlling complex behaviour

Question 9

What is the correlation between body size and brain size

Answer 9

• There is a positive correlation between body size and brain size but this relationship is not directly proportional
  causes: the larger the animal the larger the brain required to monitor and control its processes, brain size is limited by the metabolism of the animal

Question 10

Left and right cerebral hemisphere functions

Answer 10

• The left side of the brain controls movement, muscle contraction on the right side of the body (and vice-versa)
• The right side of the brain receives stimuli from the left side of the body (and vice-versa)

Question 11

What are the localised functions of the cerebral hemispheres

Answer 11

visual cortex: processes stimuli received by light sensitive rod and cone cells in the retina
broca’s area: language comprehension & language comprehension
nucleus accumbens: pleasure and reward centres (ex: dopamine)

Question 12

What can be observed in fMRI

Answer 12

measures changes in blood flow through the brain. This can indicate which regions of the brain are most active

Question 13

What can be observed in lesions

Answer 13

They are abnormal areas of brain tissue which can indicate the effect of the loss of a brain area