5.1.5 - animal responses Flashcards
central nervous system (CNS)
this consists of the brain and the spinal cord
peripheral nervous system (PNS)
this consists of all the neurones that connect the CNS to the rest of the body - sensory neurones and the motor neurones
somatic nervous system
this system is under conscious control - when you voluntary decide to do something
autonomic nervous system
works constantly; under subconscious control and is used when the body does something automatically without you deciding to do it - it is involuntary
how is the autonomic nervous system split?
sympathetic and parasympathetic
sympathetic nervous system
increasing activity
parasympathetic nervous system
decreasing activity
role of the brain
processing all the information collected by receptor cells about changes in the internal and external environment
role of the cerebrum
receives sensory information, interprets it and sends impulses along motor neurones to effectors to produce a response
structure of the cerebrum
highly convoluted, increasing its surface area and its capacity for complex activity
split into two hemispheres
role of cerebellum
concerned with the control of muscular movement, body posture and balance - does not initiate it, but coordinates.
role of the medulla oblongata
contains regulatory centres of the autonomic nervous system, controlling reflex activities
role of the hypothalamus
main controlling region for the autonomous nervous system:
- controlling complex patterns of behaviour
- monitoring the composition of blood plasma
- producing hormones
where is the pituitary gland found
base of the hypothalamus
anterior pituitary
produces 6 hormones including FSH
posterior pituitary
stores and releases hormones produced by the hypothalamus, such as ADH
reflex action
the body responding to situations without concsious thought, causing a faster response, preventing or minimising damage to the body
steps of the reflex arc
- receptor - detects and creates an action potential in sensory neurone
- sensory neurone - carries impulse to spinal cord
- relay neurone - connects the sensory neurone to motor within spinal cord
- motor neurone - carries impulse to effector
the spinal cord
column of nervous tissue running up the back. it is surrounded by the spine for protection
knee jerk reflex
leg is tapped just below the kneecap and stretches the tendon acting as a stimulus
this causes a reflex arc that causes the thigh to contract at the same time as the leg kicking
absence of knee jerk reflex
nervous problems
blinking reflex - corneal
if the cornea is stimulated it will blink to keep it safe from damage
optical reflex
blinking as a reflex to over bright light.
cranial reflex
occurs in the brain
how to reflexes increase the chance of survival
- being involuntary - prevents brain from being overloaded
- not having to be learnt - present at birth
- extremely fast - normally involves only one or two synapses
skeletal muscle
make up the bulk of body muscle tissue. the cells repsonsible for muscle
cardiac muscle
found only in the heart, and are myogenic meaning they contract without the need for a nervous stimuli
involuntary muscle (smooth muscle)
many parts of the body
sarcolemma
the plasma membrane in the muscle fibres
structure of muscle fibres
contain a number of nuclei and are much longer than normal cells making the muscle stronger
lots of mitochondria to provide the ATP that is needed for muscle contraction
myofibrils
long cylindrical organelles made of protein and specialised for contraction, lined up to provide maximum force when contracting
actin
thinner filament - consists of two strands twisted around each other
myosin
the thicker filament - consists of long rod shaped fibres with blubous heads that project to one side
I bands
region where there is only actin - light bands
A bands
the length of the myosin bands - dark
z line
line found at the centre of each i band
sarcomere
distance between adjacent Z lines
H zone
only myosin filaments
what happens to the actin and myosin during contraction?
- light band becomes narrower
- Z lines move closer together, shortening the sarcomere
- H zone become narrower
motor unit
all the muscle fibres supplied by a single motor neurone
what happens when an action potential reaches a neuromuscular junction?
stimulates calcium ion channels to open
what happens when the sarcolemma is depolarised?
travels deep into the muscle fibres by spreading through the T tubles - causing the sarcoplasmic reticulum to release calcium, causing sarcoplasm to be flooded with calcium ions
role of troponin
calcium ions bind to it, causing a change of shape, pulling on the tropomyosin moving it away from the actin-myosin bindinhg sites on actin filament.
describe the sliding filament theory
- myosin and actin filaments slide over eachother to make the saromeres contract
- simultaneous contraction means myofibrils and muscle fibres contract
- sarcomeres return to original length
what happens when the muscle stops being stimulated?
- calcium ions leave binding sites and are moved back into SR by AT
- troponin molecules return to original shape
- tropomyosin molecules block actin myosin bidning sites again
- actin filaments slide back to relaxed position
what is a neuromuscular junction
synapse between a motor neurone and a muscle cell
how do you monitor muscle fatigue
monitor electrical signals
muscles contract in response to electrical signals which can be detected by electrons onnected to a computer
this is called electromyography
how is energy supplied for muscle contraction
- aerobic respiration
- anaerobic (very little)
- creatine phosphate
fight or flight response
instinct that all mammals possess - when a potentially dangerous situation is detected, the body automatically triggers a series of physical responses; help mammals survive
what is the cause of the flight or flight response
shift in the balance of stimulation to increase activity of the sympathetic nervous system and decrease in activity of the parasympathetic nervous system
how is the fight or flight response coordinated
hypothalamus activates sympathetic nervous system and adrenal system by releasing CRF
sympathetic nerbous system activates adrenal medulla releasing adrenaline and noredrenaline.
pituitary gland releases ACTH leading to adrenal cortex releasing hormones
hormones released by adrenal cortex in fight or flight response and roles
cortisol - regulate BP and metabolism
corticosterone - regulates immune response
chain reaction triggered by adrenaline
- adrenaline binds to its receptor, activating adenylyl cyclase
- adenylyl cylase triggers conversion of ATP to cAMP
- increase in cAMP levels activate protein kinases, triggering conversion of gylcogen into glucose
how is the nervous system involved in increasing heart rate?
centre in medulla oblongata which increases heart rate sends impulses through sympathetic nervous system in accelerator nerve to SAN
how is the nervous system involved in decreasing heart rate?
centre in the medulla iblongata which decreases HR sends impulses along the parasympathetic nervous system in the vagus nerve to the SAN
baroreceptors
pressure receptors - detect changes in blood pressure (if blood pressure is too low, it will have to increase the HR)
chemoreceptors
chemical receptors - detect changes in levels of C02 e.g.
if chemoreceptors detect high co2 what happens?
decreases the pH which is detected and a response is triggered to increase heart rate.
effects of hormones on heart rate
adrenaline and noradrenaline increase heart rate, imcrease the frequency of impulses produced by the SAN
