5.5.6: The brain Flashcards Preview

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Flashcards in 5.5.6: The brain Deck (25)
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1
Q

What are the four main parts of the brain and outline their main roles?

A
  • The cerebrum (largest part, organises higher thought processes).
  • The cerebellum (coordinates movement and balance).
  • The hypothalamus and pituitary complex (organises homeostatic responses and controls physiological responses).
  • The medulla oblongata (coordinates many of the autonomic responses).
2
Q

What is the structure of the cerebrum?

A
  • The cerebrum has two cerebral hemispheres, which are connected via a bundle of nerve fibres called the corpus callosum.
  • The outermost layer of the cerebrum consists of a thin layer of nerve cell bodies called the cerebral cortex.
3
Q

What do the ‘higher brain’ functions include?

A
  • conscious thought
  • conscious actions (including the ability to override some reflexes)
  • emotional responses
  • intelligence, reasoning, judgement & decision making
  • factual memory
4
Q

What is the sensory area of the cerebral cortex responsible for?

A

-Sensory areas receive action potentials indirectly from the sensory receptors.

5
Q

What do the association areas in the cerebral cortex do?

A

-They compare sensory inputs with previous experience, interpret what the input means and judge an appropriate response.

6
Q

What do the motor areas of the cerebral cortex do?

A

-Motor areas send action potentials to various effectors (muscles and glands).

7
Q

How do the sizes of the regions in the sensory areas of the cerebral cortex vary?

A

-The sizes of the regions allocated to receive input from different receptors are related to the sensitivity of the area that inputs are received from

8
Q

How do the sizes of the regions in the motor areas of the cerebral cortex vary?

A

-The sizes of the regions allocated to deal with different effectors are related to the complexity of the movements needed in parts of the body.

9
Q

The cerebellum is involved with balance and fine coordination of movement. To do this, what must it do?

A

-It must receive information from many sensory receptors and process information accurately.

10
Q

What do the sensory receptors that supply information to the cerebellum include?

A
  • The retina
  • The balance organs in the inner ear
  • The spindle fibres in the muscles which give information about muscle length and joints.
11
Q

Where is the conscious decision to contract voluntary muscles initiated?

A
  • In the cerebral cortex

- However, the cerebral cortex does not supply the complex signals required to coordinate complex movements.

12
Q

The cerebellum coordinates the fine control of muscular movements such as:

A
  • Maintaining body position and balance e.g. riding a bike.
  • Judging the position of objects and limbs while moving and playing a sport.
  • Tensioning muscles in order to use tools and play musical instruments effectively.
  • Coordinating contraction and relaxation of antagonistic skeletal muscles when walking and running.
13
Q

How does complex activity become ‘programmed’ into the cerebellum?

A
  • Fine control of muscular movements often requires learning.
  • Once learnt, such activities may become second nature and involve much unconscious thought.
  • This coordination requires complex nervous pathways that are strengthened in practice.
14
Q

How does the cerebellum control coordination (in terms of neurones and action potentials)?

A

-Neurones from the cerebellum conduct action potentials to the motor areas so that the motor output to the effectors can be finely controlled.

15
Q

How are the cerebrum and cerebellum connected?

A

By the pons.

16
Q

What does the hypothalamus control?

A

Homeostatic mechanisms in the body.

-It contains its own sensory receptors and acts by negative feedback to maintain a constant internal environment.

17
Q

How does the hypothalamus control temperature?

A
  • Detects changes in core body temperature.
  • Also receives sensory output from temperature receptors in skin.
  • It will initiate responses to temperature change that regulate body temperature within a narrow range.
  • Responses may be mediated by the nervous system or hormonal system (via the pituitary gland)
18
Q

How is the hypothalamus involved in osmoregulation?

A
  • Contains osmoreceptors that monitor the water potential in the blood.
  • When the water potential changes, the osmoregulatory centre initiates responses that bring about a reversal of this change.
  • The response is mediated by the hormonal system via the pituitary gland.
19
Q

How does the hypothalamus work with the posterior lobe of the pituitary gland?

A
  • Posterior lobe is linked to the hypothalamus by specialised neurosecretory cells.
  • Hormones (e.g. ADH) that are manufactured in the hypothalamus, pass down the neurosecretory cells and are released into the blood from the pituitary gland.
20
Q

What does the anterior lobe of the pituitary gland do?

A

-Produces its own hormones which are released into the blood in response to releasing factors produced by the hypothalamus.

21
Q

What are releasing factors?

A

Hormones that need to be transported only a short distance from the hypothalamus to the pituitary.

22
Q

What do the hormones from the anterior pituitary control?

A

A number of physiological processes in the body, including response to stress, growth, reproduction, and lactation.

23
Q

What does the medulla oblongata control?

A

-The non-skeletal muscles (the cardiac muscles and involuntary smooth muscles).

24
Q

How does the medulla oblongata control the non-skeletal muscles?

A

By sending action potentials through the autonomic nervous system.

25
Q

The medulla oblongata contains centres for regulating several vital processes. What do these vital processes include?

A
  • The cardiac centre, which regulates heart rate.
  • The vasomotor centre, which regulates circulation and blood pressure.
  • The respiratory centre, which controls rate and depth of breathing