Homeostasis And The Nervous System

Question 1

What is homeostasis?

Answer 1

The regulation of conditions inside the body to maintain a stable environment in response to both internal and external conditions

Question 2

What three conditions does homeostasis control?

Answer 2

Blood glucose concentration
Body temperature
Water levels

Question 3

How does automatic control work in homeostasis?

Answer 3

Receptors detect a change, coordination centres interpret the change and effectors carry out the change

Question 4

How are signals sent in the body?

Answer 4

By the nervous system or the endocrine system.

Question 5

What are the main three differences between the two response systems?

Answer 5

The nervous system is more precise whereas the endocrine system is more genera.
The nervous system responds quickly whereas the endocrine system is slower and long lasting
The nervous system sends electrical impulses but the endocrine systems sends hormones

Question 6

How does automatic control work?

Answer 6

Negative feedback

Question 7

What is negative feedback?

Answer 7

When internal condition is too high it is decreased to normal, if decreased too much negative feedback will increase it. It will fluctuate internal conditions by small amounts.

Question 8

What is a reflex action or reflex arc?

Answer 8

A automatic and rapid response in the unconscious part of the brain

Question 9

What is the nervous system?

Answer 9

The nervous system is a way of allowing humans to react to their surroundings

Question 10

What is the CNS made of?

Answer 10

Neurons .

Question 11

What is the general structure of a neuron?

Answer 11

Long, thin, small, lots of different types

Question 12

What is a synapse?

Answer 12

A synapse is the gap between neurones. It releases chemicals to another neuron which continues to transmit an electrical signal

Question 13

What is the CNS made from?

Answer 13

Brain and spinal chord - where the thinking takes place

Question 14

What is the structure of a reflex arc?

Answer 14

Stimulus picked up at receptor
Transferred down sensory neurons to CNS
CNS interprets the interprets the signal
CNS transfers signal down motor neurons to effectors
Effectors are muscles or glands

Question 15

What is the name of the neuron in the CNS?

Answer 15

Relay neuron

Question 16

What is the name of the largest part of the brain and what does it do?

Answer 16

Cerebral cortex - responsible for consciousness, intelligence, memory

Question 17

What is the name of the back part of the brain and what does it do?

Answer 17

Cerebellum - responsible for muscle coordination and balance

Question 18

What is the name of the last on the brain stem?

Answer 18

Medulla - controls unconscious activities like breathing and heart beat

Question 19

What is the name of the centre part of the brain?

Answer 19

Hypothalamus - controls body temp and sends signals to pituitary

Question 20

What are the three ways of studying the brain?

Answer 20

Studying people with brain damage
Electrically stimulating brain
Scanning the brain with CT/MRI

Question 21

Why is treating the brain difficult?

Answer 21

Could cause trauma, mental health problems and infection
Location in skull and fragile tissue makes it difficult to fix
Complexity and small understanding of brain makes it hard to fix

Question 22

What is the front part of the eye called and what is it for?

Answer 22

Cornea - refracts light towards centre

Question 23

What are the small arms inside the eye and what are they for?

Answer 23

Iris - allows light to pass through to lense - creates pupil

Question 24

What is the name of the lights focus point in the eye?

Answer 24

The retina

Question 25

Explain the iris reflex.

Answer 25

Bright light can cause damage to the eye so the iris constricts by contracting circular muscles and relaxing radial muscles in bright light to let less in the eye dilates by contracting radial muscles and relaxing circular muscles in dark light to let more in.

Question 26

Explain accommodation.

Answer 26

Accommodation is a reflex that changes the refractive power of the lens so they light focuses on the retina

Question 27

What two parts control accommodation?

Answer 27

Ciliary muscles - connected to eye wall Suspensory ligaments - connect to lens

Question 28

How does accommodation work with a close object?

Answer 28

Object is wide so requires a lot of refraction This causes the lens to be short and fat by contracting the ciliary muscles toward the lens which slacken the suspensory ligaments

Question 29

How does accommodation work with a far object?

Answer 29

The object is far and light travels nearly parallel so it requires a small amount of refraction. This is done by making the lens long and thin by relaxing the ciliary muscles which cause the ligaments to go taught.

Question 30

Explain how glasses fix long sighted vision.

Answer 30

Can’t refract enough Image focus behind retina Unable to focus on close objects Convex lens is necessary to focus light

Question 31

Explain how glasses fix short sighted vision.

Answer 31

Light refracts light too much Distant objects are blurry Image focused before retina Concave lenses will fix this

Question 32

What are the medical names for long and short sightedness

Answer 32

Long - hyperopia Short - myopia

Question 33

What is thermoregulation?

Answer 33

The control of internal body temperature

Question 34

What is a thermoregulatory centre?

Answer 34

A small centre in the hypothalamus that is the bodies thermostat

Question 35

What two places detect temperature?

Answer 35

Thermoregulatory receptors detect temp of blood Skin also contains temp receptors that signals the brain

Question 36

What happens if body temp is too high?

Answer 36

Bloods vessels dilate and sweat is produced to transfer energy from the skin to the environment

Question 37

What happens if body temp is too low?

Answer 37

Blood vessels near skin constrict Erector muscles stick up hairs to trap a layer of insulating air Shivering contacts muscles which creates more need for energy, heating the body up