Animal Responses Flashcards
name the two main divisions of the nervous system
central nervous system-brain and spinal cord
peripheral nervous system-all neurones not in CNS
name the two main divisions of the peripheral nervous system
somatic-conscious control
autonomic-not conscious control
name the two main divisions of the autonomic nervous system
sympathetic-stimulates effectors
parasympathetic-inhibits effectors
act antagonistically to regulate response of effectors
describe structure of human brain
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
what is the function of the cerebellum
controls execution of movement
cognition
what is the function of the medulla
autonomous functions
breathing, heart rate
what is the function of the cerebrum
upper part of the brain
organised into lobes that control voluntary actions
what is the function of hypothalamus
thermo and osmoregulation
outline what happens in a simple reflex arc
- receptor detects stimulus
- sensory neuron
- relay neurone in CNS coordinates response
- motor neuron
- response by effector
provides rapid response to stimuli
describe the knee jerk reflex
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
what is the fight or flight response
if brain perceives threat stimulates stress response involving adrenaline triggers physiological response
use the secondary messenger model to explain how adrenaline works
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
describe the three types of muscle tissue
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
describe the structure of skeletal muscles
muscle cells fused together to form bundles of parallel muscle fibres
each bindle surrounded by endomycium- loose connective tissue with many capillaries
describe the microscopic structure of skeletal muscles
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
describe the structure of a myofibril
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
how is muscle contraction stimulated
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
explain the role of calcium ions in muscle contraction
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
outline the sliding filament model
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
how does sliding filament action cause a myofibril to shorten
myosin heads flex in opposite directions-actin filaments pulled towards each other
distance between adjacent sarcomere z lines shortens
explain the role of creatine phosphate in muscle contraction
phosphorylates ADP directly to ATP when oxygen is limited
state the name and location of the 2 nodes involved in heart contraction
sinoatrial node:within the wall of the right atrium
atrioventricular node: near lower end of right atrium in the wall that separates two atria
name the receptors involved in changing heart rate and state their location
baroreceptors detect change in blood pressure
found in carotid body
chemoreceptors detect change in pH found in carotid and aortic body
how does the body respond to an increase in blood pressure
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
how does the body respond to a decrease in blood pressure
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
how does the body respond to an increase in CO2 concentration
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
describe the structure of a neuromuscular junction.
synaptic cleft between a presynaptic and motor neurone and a skeletal muscle cell
acts as end of neural pathway