E5 The Human Brain Flashcards

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1
Q

Outline the function of the medulla oblongata

A

Controls automatic and homeostatic activities, such as swallowing, digestion and vomiting, and breathing and heart rate

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2
Q

Outline the function of the cerebellum

A

Coordinates unconscious functions, such as movement and balance

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3
Q

Outline the function of the hypothalamus

A

Maintains homeostasis via coordination of the nervous and endocrine systems, produces hormones secreted by posterior pituitary

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4
Q

Outline the function of the pituitary gland

A

Produces and secretes hormones regulating many body functions

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5
Q

Outline the function of the cerebral hemispheres

A

Act as the integration centre for highly complex functions, such as learning, memory and emotion

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6
Q

Explain how animal experiments can be used in the identification of the brain part involved in specific functions

A
  • One method of investigating the function of specific brain regions is to either stimulate the region with electrodes or remove the region (lobotomy) and assess the physical effect
    • Because such procedures are highly invasive and potentially damaging, animal models are frequently used
    • Such studies may be limited by the fact that animal brains may be dissimilar to human brains, so valid comparisons can be hard to make
    • The best comparisons are made with primates, however ethical considerations are of greater concern with these models
    • Animal experimentation using rats and mice have been used to understand and develop drug treatments for brain diseases such as MS
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7
Q

Explain how lesions can be used in the identification of the brain part involved in specific functions

A
  • Lesions are abnormal areas in brain tissue (either from accidents or congenital) which can indicate the effect of the loss of an area
    • Such studies may be limited by the fact that many functions involve multiple brain areas, making complex effects difficult to interpret
    • The brain also has the ability to re-learn skills by re-routing the function through another part of the brain (plasticity)
    • Split brain patients have been used to identify the functional roles of the left and right hemispheres
    • Individuals with aphasia (impairment to use or understand language) often have damage to specific regions of the left hemisphere
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8
Q

Explain how fMRI scanning can be used in the identification of the brain part involved in specific functions

A
  • fMRI records changes in blood flow and can indicate active regions of the brain via an increase in blood flow
    • Oxygenated haemoglobin (oxyhaemoglobin) responds differently to a magnetic field than deoxygenated haemoglobin
    • These differences in oxygenation (reflecting level of brain activity) can be represented visually by different colours
    • When a subject is given a stimulus designed to stimulate specific brain activity, fMRI can be used to localise regions involved
    • Temporal activities can also be recorded to allow identification of sequential collaboration between brain parts
    • While this procedure is non-invasive and can be performed on healthy subjects, not all brain activity is detected by fMRI
    • fMRI studies have been used to diagnose ADHD and dyslexia, in addition to being used to monitor recovery from strokes
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9
Q

Explain sympathetic control of the heart rate, movement of the iris and flow of blood to the gut

A
  • Involved in processes that prepare the body for action (‘fight or flight’ responses)
    • The sympathetic nervous system releases noradrenaline (adrenergic) via sympathetic nerves
    • Heart rate will increase to improve blood flow (via release of adrenaline)
    • Pupils will dilate to improve vision (via contraction of radial muscles)
    • Blood flow to gut will decrease (due to vasoconstriction of blood vessels by smooth muscles)
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10
Q

Explain parasympathetic control of the heart rate, movement of the iris and flow of blood to the gut

A
  • Involved in processes that occur when the body is relaxed (‘rest and digest’ or ‘feed and breed’ responses)
    • The parasympathetic nervous system releases acetylcholine (cholinergic) via parasympathetic nerves
    • Heart rate will decrease to reduce blood flow (via stimulation by vagus nerve)
    • Pupils will constrict to restrict light and potential retinal damage (via contraction of circular muscles)
    • Blood flow to gut will increase to facilitate digestion (due to vasodilation of blood vessels by smooth muscles)
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11
Q

Explain the pupil reflex

A
  • The pupil reflex is a cranial reflex originating at the brainstem and under the control of the autonomic nervous system
    • Bright light can overstimulate photoreceptors and potentially damage the retina
    • In changing levels of light, the iris will automatically resize to regulate the amount of light that reaches the retina

In dim light conditions:
• Relay neurons stimulate thesympatheticnervous system, causingradial musclesto contract and the pupil todilate

In bright light conditions:
• Relay neurons stimulate theparasympatheticnervous system, causingcircular musclesto contract and the pupil toconstrict

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12
Q

Discuss the concept of brain death

A
  • Whole brain death is the loss of measureable activity in the brain stem and cerebrum
    • Failure of the pupil to response to light indicates brain stem death
    • Without brain stem function, life cannot continue
    • Cerebrum involves higher order brain function
    • Non-functioning cerebrum with functioning brain stem is vegetative state
    • Some would argue that this is the death of the person, although brain stem function alone may be able to maintain homeostasis
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13
Q

Outline how pain is perceived and how endorphins can act as painkillers

A
  • Pain is perceived when impulses pass from pain receptors to sensory areas of the cerebral cortex
    • Endorphins are released by the pituitary gland during stress, injury or exercise, and act as painkillers by blocking pain perception
    • They do this by blocking the release of neurotransmitters at the synapses involved in pain signal transmission
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