Topic 11 - Coordination and response

Question 1

What is Homeostasis?

Answer 1

Homeostasis is the maintenance of the body’s internal environment within tolerable limits around an optimum value. e.g. temperature: 37°C is the optimum temperature for the enzymes that control metabolism.

Question 2

Which organs and tissues in the human body are involved in homeostasis?

Answer 2

All of them

Question 3

In greenhouses, when sensors detect changes in what 2 things?

Answer 3

In greenhouses, when sensors detect changes in temperate and light intensity, corrective measures are triggered.

Question 4

When sensors detect a change from normal conditions and trigger an appropriate response? (what is this called)

Answer 4

this is called negative feedback.

Question 5

Water content is controlled at a what level?

Answer 5

Water content is controlled at a cellular level.

Question 6

Excess heat is lost from the human body by…

Answer 6

sweating

Question 7

When excess heat damages enzymes they are…

Answer 7

denatured

Question 8

Sugar content in the body is controlled by? (2)

Answer 8

• The release of the hormone insulin
• The activation of enzymes

Question 9

Water is being controlled by what organ?

Answer 9

Kidney

Question 10

Salt being controlled by what organ?

Answer 10

Kidney

Question 11

Temperature being controlled by what organ?

Answer 11

Skin

Question 12

Sugar being controlled by what organ?

Answer 12

Pancreas

Question 13

Carbon dioxide being controlled by what organ?

Answer 13

Lungs

Question 14

Urea being controlled by what organ?

Answer 14

Kidney

Question 15

What is the stimulus of skin?

Answer 15

Temperature

Question 16

What is the stimulus of tounge?

Answer 16

Chemical taste (in food and drink)

Question 17

What is the stimulus of nose?

Answer 17

Chemical smells (in the air)

Question 18

What is the stimulus of eyes?

Answer 18

Light

Question 19

What is the stimulus of ear?

Answer 19

Sound

Question 20

What is a receptor?

Answer 20

the thing that detect the signals

Question 21

What is a stimulus?

Answer 21

a chemical or physical change that triggers the receptor

Question 22

3 types of effectors? (3)

Answer 22

• a muscle contracting to move an arm
• a muscle contracting to alter pupil diameter in the eye
• a gland releasing ainto the blood hormone

Question 23

What is the order of reflex action?

Answer 23

stimulus → receptor →sensory neurone→relay neurone→ motor neurone → effector → response

Question 24

Step by step reflex action when a hand is over a candle? (5)

Answer 24

1. Receptor cells in the skin detect a stimulus (the heat from the candle).
2. Sensory neurone sends impulses to relay neurone in the spinal cord.
3. The relay neurone connects to the motor neurone (and also sends a message to the brain).
4. Motor neuronesends impulses to effector.
5. Effectorproduces a response (muscle contracts to move hand away).

Question 25

What happens when you are too hot? (sweating)

Answer 25

Sweat glands in the skin release more sweat. The sweat evaporates, transferring heat energy from the skin to the environment.

Question 26

What happens when you are too hot? (blood vessel)

Answer 26

Blood vessels leading to the skin capillaries become wider - they dilate - allowing more blood to flow through the skin, and more heat to be lost to the environment. This is called vasodilation.

Question 27

What happens when you are too cold? (hairs)

Answer 27

Skeletal muscles  rapidly and we shiver. These contractions need energy from , and some of this is released as heat

Question 28

What happens when you are too cold? (blood vessels)

Answer 28

Blood vessels, which lead to the skin capillaries, become narrower - they constrict – which allows less blood to flow through the skin and conserve the core body temperature. This is called vasoconstriction.

Question 29

What are the 7 parts of the eye? (7)

Answer 29

1. Cornea 2. Iris 3. Lens 4. Retina 5. Optic nerve 5. Pupil 6. Ciliary muscle 7. Suspensory ligaments

Question 30

What is the function of the cornea?

Answer 30

Refracts light - bends it as it enters the eye

Question 31

What is the function of the lens?

Answer 31

Further refracts light to focus it onto the retina

Question 32

What is the function of the retina?

Answer 32

Contains the light receptors

Question 33

What is the function of the optic nerve?

Answer 33

Carries impulses between the eye and the brain

Question 34

What is the function of the pupil?

Answer 34

Space in the iris that allows light into the eye

Question 35

What is the function of the ciliary muscles?

Answer 35

A ring of muscle that contracts and relaxes to change the shape of the lens

Question 36

What is the function of the sensory ligament?

Answer 36

Ligaments that connect the ciliary muscle to the lens

Question 37

What is the function of the iris?

Answer 37

Controls how much light enters the pupil

Question 38

What is positive tropism?

Answer 38

Positive tropism is when a plant grows towards the stimulus.

Question 39

What does a stem respond to?

Answer 39

Stem response to light is positive phototropism (grows towards the light).

Question 40

What does a root respond to?

Answer 40

Root response to gravity is positive geotropism (grows in the direction of the force of gravity).

Question 41

What are auxin?

Answer 41

Auxin is a family of plant hormones. They are mostly made in the tips of the growing stems and roots, which are the meristems. They can diffuse to other parts of the stems or roots. Auxin change the rate of elongation in plant cells, controlling their length.

Question 42

How do stems and roots respond differently to high concentrations of auxin? (2)

Answer 42

- cells in stems grow more - cells in roots grow less

Question 43

What is Phototropisms?

Answer 43

In a stem, the shaded side contains more auxin and grows longer – causing the stem to bend towards the light.

Question 44

Hormones vs Nerves