Animal Responses

Question 1

name the two main divisions of the nervous system

Answer 1

central nervous system-brain and spinal cord
peripheral nervous system-all neurones not in CNS

Question 2

name the two main divisions of the peripheral nervous system

Answer 2

somatic-conscious control
autonomic-not conscious control

Question 3

name the two main divisions of the autonomic nervous system

Answer 3

sympathetic-stimulates effectors
parasympathetic-inhibits effectors
act antagonistically to regulate response of effectors

Question 4

describe structure of human brain

Answer 4

parietal lobe-top of brain
movement and orientation
memory and recognition

occipital lobe-back of the brain
visual cortex-processes signal from eye

temporal lobe-beneath temples
processes auditory signals

Question 5

what is the function of the cerebellum

Answer 5

controls execution of movement
cognition

Question 6

what is the function of the medulla

Answer 6

autonomous functions
breathing, heart rate

Question 7

what is the function of the cerebrum

Answer 7

upper part of the brain
organised into lobes that control voluntary actions

Question 8

what is the function of hypothalamus

Answer 8

thermo and osmoregulation

Question 9

outline what happens in a simple reflex arc

Answer 9

1. receptor detects stimulus
2. sensory neuron
3. relay neurone in CNS coordinates response
4. motor neuron
5. response by effector
   provides rapid response to stimuli

Question 10

describe the knee jerk reflex

Answer 10

tapping patellar tendon stimulates stretch mediated receptors
impulse travels from sensory to motor neurone
Quadriceps contract -inhibits antagonistic hamstring contraction

diagnostic-multiple kicks= cerebellar disease
lack of reflex=nervous problem

Question 11

what is the fight or flight response

Answer 11

if brain perceives threat stimulates stress response involving adrenaline triggers physiological response

Question 12

use the secondary messenger model to explain how adrenaline works

Answer 12

adrenaline first messenger-hormone receptor complex forms
conformational change to receptor activates G-protein
activates adenylate cyclase-converts ATP to cAMP
cAMP second messenger-activates protein kinase A pathway
results in glycogenolysis

Question 13

describe the three types of muscle tissue

Answer 13

striated skeletal muscle- multi-nucleated cells
antagonistic muscle pairs allow movement
smooth involuntary muscle-enables walls of blood vessels and intestines to contract
cardiac muscle-branched unnucleated cells
Myogenic contraction-heartbeat

Question 14

describe the structure of skeletal muscles

Answer 14

muscle cells fused together to form bundles of parallel muscle fibres
each bindle surrounded by endomycium- loose connective tissue with many capillaries

Question 15

describe the microscopic structure of skeletal muscles

Answer 15

myofibrils:site of contraction
sarcoplasm:shared nuclei and cytoplasm with lots of mitochondria and endoplasmic reticulum
sarcolemma:folds inwards towards sarcoplasm to form transverse tubules

Question 16

describe the structure of a myofibril

Answer 16

z line: boundary between sarcomeres
i band:only actin (appears light under microscope)
a band: overlap of actin and myosin (appears dark under microscope)
h zone: only myosin

Question 17

how is muscle contraction stimulated

Answer 17

neuromuscular junction: action potential causes voltage gated calcium channels to open
vesicles move and fuse with presynaptic membrane
exocytosis of acetylcholine diffuses across synaptic cleft
binds to receptors on sodium channel proteins on skeletal muscle cell membrane
influx of sodium=depolarisation

Question 18

explain the role of calcium ions in muscle contraction

Answer 18

action potential moves through T tubules in sarcoplasm-causes calcium channels in sarcoplasmic reticulum to open
calcium binds to troponin causing conformational change in tropomyosin
exposes binding sites on actin filaments so actinmyosin bridges form

Question 19

outline the sliding filament model

Answer 19

myosin head with ADP forms cross bridge with actin
power stroke: myosin head changes shape and loses ADP pulling actin over myosin
ATP attaches to myosin head causing it to detach from actin
ATPase hydrolyses ATP so myosin head can return to original position
myosin head reattaches to actin further along filament

Question 19

how does sliding filament action cause a myofibril to shorten

Answer 19

myosin heads flex in opposite directions-actin filaments pulled towards each other
distance between adjacent sarcomere z lines shortens

Question 20

explain the role of creatine phosphate in muscle contraction

Answer 20

phosphorylates ADP directly to ATP when oxygen is limited

Question 21

state the name and location of the 2 nodes involved in heart contraction

Answer 21

sinoatrial node:within the wall of the right atrium
atrioventricular node: near lower end of right atrium in the wall that separates two atria

Question 22

name the receptors involved in changing heart rate and state their location

Answer 22

baroreceptors detect change in blood pressure
found in carotid body
chemoreceptors detect change in pH found in carotid and aortic body

Question 23

how does the body respond to an increase in blood pressure

Answer 23

baroreceptors send impulses to cardioinhibitory centre in medulla
more impulses to SAN down vagus nerve via parasympathetic nervous system
stimulates release of acetyl choline, decreasing blood pressure

Question 24

how does the body respond to a decrease in blood pressure

Answer 24

baroreceptors send more impulses to cardioacceleratory centre in medulla more impulses to SAN via sympathetic nervous system
Stimulates release of noradrenaline increasing heart rate and strength of contraction

Question 25

how does the body respond to an increase in CO2 concentration

Answer 25

chemoreceptors detect pH decrease and send more impulses to cardioacceleratory centre
more impulses to SAN via sympathetic nervous system
heart rate increases so rate of blood flow to lungs increases

Question 26

describe the structure of a neuromuscular junction.

Answer 26

synaptic cleft between a presynaptic and motor neurone and a skeletal muscle cell
acts as end of neural pathway