chapter 14: coordination and response

Question 1

how is information sent through the nervous system?

Answer 1

as nerve impulses along neurones

Question 2

describe the mammalian nervous system

Answer 2

• central nervous system: brain and spinal cord
• peripheral nervous system: nerves outside the brain and spinal cord

Question 3

describe the role of the nervous system

Answer 3

for the coordination and regulation of body functions

Question 4

describe the function of a sensory neurone

Answer 4

• carry impulses from sense organs to the CNS

Question 5

describe the function of a relay neurone

Answer 5

• found inside the CNS
• connects the sensory and motor neurones

Question 6

describe the function of the motor neurones

Answer 6

• carries impulses from the CNS to the effectors

Question 7

describe the adaptations of neurones

Answer 7

• axon, a long fibre, to not waste time transferring an impulse from one cell to the next
• axon insulated by fatty sheath with small uninsulated sections called nodes which impulses jump on
• cell body has many extensions called dendrites to connect to many other neurones and receive impulses from them to create a network for easy communication

Question 8

describe a voluntary response

Answer 8

• making a conscious decision to carry out a particular action, starting with the brain

Question 9

describe an reflex action

Answer 9

a means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors

Question 10

describe a simple reflex arc

Answer 10

1. stimulus detected by receptor cell
2. sensory neurone sends impulse to spinal cord
3. impulse passed onto relay neurone in spinal cord
4. relay neurone connects to motor neurone and passes impulse on
5. motor neurone carries impulse to a effector
6. effector carries out response

Question 11

describe a synapse

Answer 11

• a junction between two neurones
• important for the nervous system being a connected network of neurones
• impulses transmitted across them and directed to appropriate route by them
• ensure impulses only travel in one direction as only the first neurone releases neurotransmitters and the second neurone has complementary shapes
• messages are chemical and not electrical, only place where drugs an affect the nervous system

Question 12

describe the events that occur at a synapse

Answer 12

• impulse stimulates the release of neurotransmitters from vesicles
• neurotransmitters diffuse across the synaptic gap
• neurotransmitters bind to the receptor proteins on the next neurone
• impulse stimulated in the next neurone

Question 13

describe sense organs

Answer 13

groups of specialised receptor cells that detect and respond to specific stimuli

Question 14

describe the function of the cornea

Answer 14

transparent covering at the front of the eye that refracts light

Question 15

describe the function of the iris

Answer 15

muscle that controls how much light enters the pupil

Question 16

describe the function of the lens

Answer 16

transparent disc that changes shape to focus light onto the retina

Question 17

describe the function of the retina

Answer 17

layer of light receptor cells that detect light intensity and colour

Question 18

describe the function of the optic nerve

Answer 18

sensory neurone that carries electrical impulses from the eye to the brain

Question 19

describe the pupil reflex

Answer 19

• reflex action controlling the amount of light entering the eye by altering the pupil diameter with the use of iris muscles
• dim light: pupil dilates to let more light in; radial muscles contract, circular muscles relax
• bright light: pupil constricts to let less light so the retina is not damaged; radial muscles relax, circular muscles contract

Question 20

describe eye accomodation

Answer 20

• the way in which the eye focuses on near or distant objects by changing the shape of the lens
• close object: ciliary muscles contract, suspensory ligaments slacken; lens is fatter, so light is refracted more
• far object: ciliary muscles relax, suspensory ligaments tighten; lens is thinner, so light is refracted less

Question 21

describe rod cells

Answer 21

• light receptor, works best in low light and provides night vision and grayscale images

Question 22

describe cone cells

Answer 22

• light receptor that works well in high light, provides colour vision and absorb different wavelengths of light (three types of cones)

Question 23

describe the distribution of rods and cones

Answer 23

• rod cells found all over the retina except blind spot
• cone cells concentrated at fovea, region of eye where light is focused on that allows the brain to form sharo colourec images

Question 24

describe a hormone

Answer 24

a chemical substance produced by a gland of the endocrine system and carried by the blood which alters the activity of one or more specific target organs

Question 25

how does the liver play a role for hormones?

Answer 25

regulates levels of hormones in the blood; transforms or breaks down hormones if there are any in excess

Question 26

why must the endocrine system have a good blood supply

Answer 26

hormones need to get into the bloodstream ASAP to travel around the body to the target organs

Question 27

how do hormones work on the target organ

Answer 27

affects cel with target receptors that the hormone can bind on to, complementary shapes

Question 28

list the 4 endocrine system glands, their hormones, their role and effect

Answer 28

- adrenal gland: adrenaline; fight or flight response; increases heart and breathing rate, increases blood glucose concentration, dilates pupil, diverting blood towards muscles and away from non-essential body parts - pancreas: insulin/glucagon; lowers/increases blood glucose concentration; conversion between glucose and glycogen - testes: testosterone; main sex hormone in males; development of secondary sexual characteristics in males - ovaries: oesteogen; main sex hormone in females; development of secondary sexual characteristics in females

Question 29

compare nervous control and hormone control

Answer 29

- nervous made of nerves brain and spinal cord, endocrine made of glands - nervous use electrical impulse, endocrine use chemical hormone - nervous very fast, endocrine slow - nervous short, endocrine last long

Question 30

describe homeostasis

Answer 30

maintenance of a constant internal environment

Question 31

describe the effects of the adrenal gland in more detail

Answer 31

- increase blood glucose concentration: increased respiration in muscle cells - increased heart and breath rate: glucose and oxygen delivered to muscle cells quicker, carbon dioxide removed quicker - pupils dilate: more info sent to the brain - divert blood towards muscle cells for more glucose and oxygen and less carbon dioxide

Question 32

describe negative feedback

Answer 32

- occurs when conditions change from set point and returns conditions to set point

Question 33

describe the control of blood glucose concentration

Answer 33

- controlled by negative feedback system - pancreas detects change in concentration - high concentration: insulin released, decreases concentration by conversion of glucose to glycogen - low concentration: glucagon released, increases concentration by breakdown of glycogen to glucose

Question 34

outline the treatment of type 1 diabetes

Answer 34

- insulin pump/injections - monitor glucose concentration of the blood or urine - control intake of carbs - exercise after eating

Question 35

describe the maintenance of a constant internal body temperature

Answer 35

- external temperature detected by thermoreceptors - nerve impulses sent via sensory neurones - brain detects a change in temperature - nerve impulses sent to the effectors via motor neurones — - external temperature higher - vasoconstriction - shivering - insulation from fatty tissue — - external temperature lower - vasodilation - sweating

Question 36

describe gravitropism

Answer 36

response in which parts of a plant grow away or towards gravity

Question 37

describe phototropism

Answer 37

response in which parts of a plant grow towards or away from the direction of the light source

Question 38

explain the role of auxin

Answer 38

- made in the shoot tip - diffuses through the plant from the shoot tip - unequally distributed in response to light and gravity - stimulates cell elongation