B10-homeostasis and response

Question 1

Homeostasis is

Answer 1

about maintaining an optimum internal environment in the body which needs to happen in response to internal and external changes

Question 2

What sorts of things need to be regulated

Answer 2

Bodily fluids
Volume of blood
Carbon dioxide levels 
pH
Body temperature

Question 3

The coordination and control of the internal environment involved two systems:

Answer 3

• the nervous system

- the hormonal system

Question 4

There are 4key features to a good control system:

In order:

Answer 4

• stimulus
• receptors
• coordination centre
• effectors

Question 5

Pathway through the nervous system

Answer 5

Stimulus->receptor cell(convert the message to an electrical impulse)->sensory neurone->coordinator(brain and spinal cord)->motor neurone->effector(muscles and glands)

Question 6

The receptor cells in our sense organs

Answer 6

Convert various stimuli into electrical impulses these are then transmitted through the nervous system

Question 7

A reflex action

Answer 7

is a rapid response to a stimulus usually protecting the body from harm like moving a body part away from a hot object

Question 8

What are synapses

Answer 8

are physical gaps between the neurones which the electrical impulses have to cross.

Question 9

What is the difference between the structure of the sensory and motor neurone

Answer 9

The nucleus is to the left motor neurone whereas the nucleus is in the in the centre or the sensory neurone. The motor neurones endings are on muscles whereas the sensory neurone ends in the central nervous system.

Question 10

Sense organs examples

Answer 10

Nose (olfactory cells), skin (thermoreceptor cells or baro-receptor cells), eye(photoreceptor cells),ear(sound wave detecting cells(vibrations)

Question 11

Coordinators examples

Answer 11

Spinal cord, brain

Question 12

Effectors examples

Answer 12

Salivary glands, skeletal muscles, pancreas

Question 13

Reflex actions examples

Answer 13

moving a body part away from a hot object or sharp object, the iris pupil reflex depending on how bright it is, coughing and sneezing, maintaining balance while moving and changes in rate of breathing

Question 14

2 differences in reflex actions

Answer 14

The response is automatic and rapid as it doesn’t involve the conscious part of your brain and are important to avoid danger or harm and take care of your basic body functions. They often involve just 3types of neurones:an electrical impulse passes from the receptor along the sensory neurone to the CNS it then passes along a relay neurone and straight back along the motor neurone and them arrives at the effector organ this pathway is called a reflex arc.

Question 15

Look at

Answer 15

Labelled diagrams of neurones etc

Question 16

Flow chart for reflex arc

Answer 16

Stimulus->receptor->sensory neurone->relay neurone->motor neurone->effector->reponse

Question 17

Reflex arc example

Answer 17

Bright light->light sensitive cells in the eye->sensory neurone->relay neurone->motor neurone->muscles around the pupil->pupil shrinks

Question 18

Reflex arc example stress

Answer 18

Stress->receptors->motor neurone->release of a hormone from a gland near the kidneys->release of adrenaline

Question 19

Why is it important for adrenaline to be released in a stressful situation

Answer 19

To produce the fight or flight response

Question 20

How does the impulse cross the gap between neurones[synapses] (you
must include the following words: neurotransmitter, vesicles,
receptors)

Answer 20

The nerve impulses cause the vesicles to move to the edge of the synaptic space, the neurotransmitters are releases into the synaptic space where they diffuse across and bind to the receptors in the dendrite of the next nerve cell,the receptors generate a new nerve impulse which travels on to the next synapse and the bound neurotransmitters are released from the receptors some of which are broken down by enzymes and some return to the axon terminal where the vesicles are formed.(look at diagram as well)