Detecting and regulating change

Question 1

What are receptors?

Answer 1

• Detect changes in the bodies internal or external environment
• Some are simple nerve endings, while others are receptor cells grouped together to form sense organs EG. The eye

Question 2

Types of receptors

Answer 2

• Thermoreceptors
• Osmoreceptors
• Chemoreceptors
• Touch receptors
• Pain receptors

Question 3

Thermoreceptors

Answer 3

respond to heat and cold

Question 4

Osmoreceptors

Answer 4

Are sensitive to osmotic pressure, which is the concentration of substances dissolved in the water of blood plasma. Located in the hypothalamus

Question 5

Chemoreceptors

Answer 5

stimulated by particular chemicals

Question 6

Touch receptors

Answer 6

sensitive to very light touches. They are mainly found in the surface of the skin

Question 7

Pain receptors

Answer 7

stimulated by damage to tissues. They are mainly found in skin and mucous. They warn us that damage to tissue is occurring and for this they don’t adapt

Question 8

Protective reflexes

Answer 8

Present from birth

Question 9

Acquired reflexes

Answer 9

Complex motor patterns that are learned

Question 10

All reflexes…

Answer 10

• Require a stimulus
• Are involuntary
• Are rapid
• Are stereotyped (occur in the same way each time)

Question 11

All reflexes consist of….

Answer 11

• A stimulus
• A receptor
• A sensory neuron
• At least one synapse
• A motor neuron
• An effector

Question 12

What is homeostasis?

Answer 12

The process of keeping the environment inside the body fairly constant

Question 13

What is the purpose of homeostasis

Answer 13

To help us stay independent of our external enviroment

Question 14

It is important that the body regulates…

Answer 14

Core body temperature

pH and concentrations of dissolved

substances in the body fluids
concentration of glucose in the blood

concentration of oxygen and carbon dioxide in the blood and other body fluids

blood pressure

concentration of metabolic rates

Question 15

What is a feedback system?

Answer 15

Circular system in which the body responds to a change with the response altering the original stimulus

Question 16

Negative feedback system

Answer 16

The response causes the stimulus to change in a direction opposite to that of the original change

Question 17

Common features of a negative feedback system

Answer 17

• The stimulus is the change in the environment that causes the system to operate
• The receptor detects this change
• The modulator is a control centre responsible for processing information received from the receptor and for sending information to the effector
• The effector carries out a response counteracting the effect of the stimulus
• Feedback is achieved because the original stimulus has been changed by the response

Question 18

Positive feedback

Answer 18

When positive feedback occurs, the response to the stimulus reinforces and intensifies the stimulus
- This does not contribute to homeostasis

Question 19

Example of positive feedback

Answer 19

An example is during child birth

• Labour is initiated by the secretion of oxytocin
• Causing contractions of the uterus
• The contractions push the baby’s head against the cervix, sending impulses to the brain
• The brain responds by instructing the pituitary to secrete more oxytocin
• Intensifying the uterus contractions