Chapter 6 - Detecting And Regulating Change

Question 1

What is a receptor?

Answer 1

A receptor is a structure that is able to detect a change in the body’s internal or external environment.

Question 2

What is a sense organ?

Answer 2

When receptor cells of a particular type are grouped together.

Question 3

What are thermoreceptors?

Answer 3

Thermoreceptors are receptor cells that are able to respond to heat and cold.

Question 4

What are skin thermoreceptors and what are their role in the body?

Answer 4

Receptors in the skin that inform the brain of changes in temperature outside the body. They are nerve endings that are sensitive to either heat or cold but not both. They send information to the hypothalamus where it is able to regulate body temp.

Question 5

What is core temperature?

Answer 5

The temperature inside the body. It is monitored by thermoreceptors in the hypothalamus.

Question 6

What are osmoreceptors? And where are they located?

Answer 6

Receptors sensitive to osmotic pressure. They respond to very small changes in osmotic pressure and are able to stimulate the hypothalamus so that the body’s water content is maintained within very narrow limits.
They are located in the hypothalamus.

Question 7

What is osmotic pressure?

Answer 7

Osmotic pressure is determined by the concentration of substances dissolved in the water of the blood plasma.

Question 8

What are touch receptors?

Answer 8

Receptors sensitive to touch.

Question 9

Where can touch receptors be found?

Answer 9

They are found mainly in the skin and just under the skin.

Question 10

What are some examples of touch receptors?

Answer 10

Lips, fingertips, eyelids, external genital organs, hair follicles.
Nerve endings are associated with the base of each hair follicle and responds to any light touch that bends the hair.
Other receptors are located deeper in the skin and are sensitive to pressure and vibrations.

Question 11

What are chemoreceptors?

Answer 11

Receptors stimulated by particular chemicals.

Question 12

What are some examples of chermoreceptors?

Answer 12

• Receptors in our nose and mouth which are sensitive to odours and tastes.
• Receptors sensitive to the composition of body fluids.
• Receptors in certain blood vessels which are sensitive to the pH of the blood and concentration of oxygen and carbon dioxide. These are involved in the regulation of the heartbeat and of breathing.

Question 13

What are pain receptors?

Answer 13

Also known as nociceptors, they are stimulated by damage to tissues. They warn us that damage to tissues is occurring and we need to seek ways to minimise the damage. The pain will continue as long as the pain is present and rarely adapts.

Question 14

What are some examples of pain that are detected by pain receptors?

Answer 14

• damage from a cut or a heavy bump
• poor blood flow to a tissue
• or by excessive stimulation from stimuli such as heat and chemicals.

Question 15

Where are pain receptors found?

Answer 15

They occur in most organs except the brain.

Question 16

What is a reflex?

Answer 16

A reflex is a rapid, automatic response to a change in external or internal environment.

Question 17

What are the four important properties of a reflex?

Answer 17

• A stimulus (required to trigger a reflex).
• involuntary (occurs without conscious thought).
• rapid (only a few neurones are involved).
• Stereotyped (it occurs in the same way each time it happens)

Question 18

What is a spinal reflex?

Answer 18

When a nerve impulse comes into the spinal cord from a receptor and then back out to a effector without going to the brain.

Question 19

Explain the 5 basic components of a reflex arc?

Answer 19

1. A receptor is either the ending of a sensory neuron or a specialised cell associated with the end of a sensory neuron.
2. A sensory neuron carries impulses from the receptor to the CNS.
3. There is at least one synapse
4. A motor neuron carries the nerve impulses to an effector
5. An effective revives the nerve impulses and carries out the appropriate response. Effectors are muscle cells or secretory cells.

Question 20

What are some examples of reflexes?

Answer 20

• blinking
• sneezing or coughing
• constriction of pupil
• secretion of saliva

Question 21

What are acquired reflexes?

Answer 21

Sucking, chewing or following movement with eyes, regaining balance or jamming on the breaks.

Question 22

What is a feedback system?

Answer 22

A feed back system is a circular situation in which the body responds to a change, or stimulus, with the response altering the original stimulus.

Question 23

What are the main components of a feedback loop?

Answer 23

1. A stimulus
2. Receptor
3. Message
4. Modulator
5. Message
6. Effector
7. Response
8. Feedback