B10 - the human nervous system fact test

Question 1

what is homeostasis

Answer 1

homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes

Question 2

what are some examples of what homeostasis controls

Answer 2

• blood glucose concentration
• body temperature
• water levels

Question 3

what do all control systems include

Answer 3

• cells called receptors which detect stimuli
• coordination centres that receive and process information about receptors
• effectors (muscles contract and glands secrete hormones) which bring about responses to restore optimum levels

Question 4

what does the nervous system allow

Answer 4

humans to respond to stimuli and coordinate their behaviour

Question 5

how does the nervous system respond to a stimulus

Answer 5

• stimulus (change in environment)
• receptor (detects a nucleus)
• coordinator (CNS: brain/spinal chord coordinate response)
• effector (muscle or gland causes response)
• response (muscle contracts or gland secretes hormones

Question 6

what is a voluntary action

Answer 6

a response that involves conscious thought (thinking time)

Question 7

what is a reflex action

Answer 7

a response that does not require conscious thought (thinking time) and happens very quickly to avoid unnecessary damage to the body

Question 8

how does the axon of a nerve cell help it be adapted to its function

Answer 8

the axon is a long fibre which is insulated by a fatty (myelin) sheath

they are strong so can carry messages up and down the body

the insulation means that the impulses can travel faster

Question 9

how do the dendrones of a nerve cell help it be adapted to its function

Answer 9

tiny branches branch further as dendrites at each end. they receive incoming impulses from other neurons

there are many branches allowing each neurons to connect to many other neurons

Question 10

what is a synapse

Answer 10

a synapse is the small gap between 2 neurons where nerve impulses are relayed by a neurotransmitter

Question 11

how does an electrical impulse travel through a synapse

Answer 11

• the impulse reaches the end of the neuron
• the impulse causes the release of chemicals known as neurotransmitters
• chemical diffuses across the space between the neurons known as the synapse
• chemical reaches the neuron and joins to the receptors on the end of the neuron
• this triggers an impulse down this neuron

Question 12

what does the cerebral cortex control

Answer 12

intelligence, personality, conscious thought and high level functions such as language and verbal memory

Question 13

what does the cerebellum control

Answer 13

balance, coordination of movement and muscular activity

Question 14

what does the medulla control

Answer 14

unconscious activity such as heart and breathing rate

Question 14

what is the function of the hypothalamus

Answer 14

regulating centre for temperature and water balance between the body, links the nervous system to the hormonal system via the pituitary gland

Question 15

why is the brain hard to study and treat

Answer 15

due to its complexity and delicacy

Question 16

how have neuroscientists mapped regions of the brain to their functions

Answer 16

• studying patients with brain damage
• electrically stimulating parts of the brain
• using fMRI scanning (functional MRI measures brain activity whilst completing tasks)

Question 17

what is the retina

Answer 17

layer of light sensitive cells found at the back of the eye. when light hits this, the cells are stimulated. impulses are sent to the brain which interprets the information to create an image

Question 18

what is the optic nerve

Answer 18

a nerve that leaves the eye and leads to the brain. it carries the impulses from the retina to the brain to create an image

Question 19

what is the sclera

Answer 19

white outer layer which supports the structures inside the eye, it is strong to prevent damage to the eye

Question 20

what is the cornea

Answer 20

the see-through layer at the front of the eye, allows light through and the curved surface bends and focuses light onto the retina

Question 21

what is the iris

Answer 21

muscles that surround the pupil

Question 22

what do the ciliary muscles and suspensory ligaments do

Answer 22

hold the lens in place, control its shape

Question 23

what is it called when the focus of the eye changes

Answer 23

accommodation

Question 24

how does the eye focus on a near object

Answer 24

• ciliary muscles contract so they have a smaller diameter
• suspensory ligaments loosen so lens gets thicker/more curved
• ticker lens is more convergent - light rays are refracted inwards more
• light rays focus on the retina

Question 25

how does the eye focus on a distant object

Answer 25

• ciliary muscles relax so they have a larger diameter
• suspensory ligaments tighten so lens gets thinner/less curved
• thinner lens is less convergent - light rays are refracted inwards less
• light rays focus on the retina

Question 26

how does the pupil adjust to bright light

Answer 26

the circular muscles contract and radial muscles relax to make the pupil smaller, avoiding damage to the retina

Question 27

how does the pupil adjust to dim light

Answer 27

the circular muscles relax and radial muscles contract to make the pupil larger so more light can enter to create a better image