Animal Responses OCR A2 Biology

Keywords and quick revision, has pictures :)

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  • Created on: 24-05-12 19:47
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Biology F215
Animal Responses
Key Words
Acetylcholinesterase - An enzyme in the synaptic cleft that breaks down the transmitter substance acetylcholine
Antagonistic - Working against each other in a pair
Association Areas - Regions of the cerebral cortex where the information from sensory areas is made sense of by
comparison with previous experiences
Autonomic Nervous System - The system of motor neurones that controls the non-conscious actions of the body. The
autonomic system controls the actions of involuntary muscles and glands
Central Nervous System - Composed of the brain and spinal cord, it has overall control over the coordination of the nervous
Cardiac Muscle - The muscle of the heart
Cerebellum - The part of the vertebrate brain concerned with the coordination and regulation of muscle tone and balance
Cerebrum - The largest part of the vertebrate brain, consisting of two cerebral hemispheres
Cross-bridge - In voluntary muscle, this is formed by the joining of a myosin head group to an actin thin filament in the
presence of calcium ions, Ca2+
Fight or Flight response - The set of response in an animal that accompany the perception of a threat
Gradation of Response - The amount of motor units - clusters of muscle cells - that are stimulated, the greater the force of
contraction that can be produced
Hypothalamus - A portion of the brain that contains various receptors that monitor the blood, it is also involved in controlling
the Autonomic Nervous System
Medulla oblongata - A portion of the brain - brain stem - that contains the centres for the control of various unconscious bodily
functions via the Autonomic Nervous System
Motor area - An area of the cerebral cortex within which the neurones are responsible for driving motor functions
Muscle fibre - Elongated contractile cells that make up striated muscle
Myofibril - Small fibres that run through each muscle fibre
Myogenic - The contraction of the muscle is generated from within the muscle itself, the term is used to describe the
contraction of the heart, which is controlled by the action of the sinoatrial node
Myosin - The protein that forms the thick filament in muscle cells, this protein has head groups that form the cross-bridges
associated with muscular contraction
Neuromuscular junction - The point where a muscle fibre comes into contact with a motor neurone carrying nerve impulses
from the Central Nervous System
Peripheral Nervous System - The sensory and motor neurones that connect the CNS to the sensors and effectors around the
Power Stroke - The term that describes the action of the myosin head in muscular contraction. The head group attached to the
actin filament tilts backwards, pulling the thick filament to overlap further with the thin filament

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Parasympathetic neurone - Part of the autonomic nervous system, its nerve endings release acetylcholine as a
Sarcolemma - The term for the muscle fibre's plasma membrane
Sarcomere - In voluntary muscle, the span between one Z-line and the next Z-line, the Z line is the central part of the I band
which alternates with the A band.…read more

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The hemispheres are joined together via corpus callosum
The surface area of the cerebral cortex is 2.…read more

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This discovery has resulted from experimental work with monkeys, which has made the
research controversial
But why monkeys?
o Humans and monkeys are both primates and are closely related so share
similar genes due to having a common ancestor.…read more

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The sympathetic nervous system
o Impulses from sympathetic nerves tend to have an excitatory effect
They prepare the body for the `fight or flight' response
Short preganglionic neurones use acetylcholine
o Long postganglionic neurones use noradrenaline at synapse with effector
o Somatic motor neurones carry impulses from the CNS to skeletal muscles which are under voluntary
The parasympathetic nervous system
o Impulses from parasympathetic nerves tend to have the opposite (antagonistic) effect to sympathetic
This is important when body is at rest (`rest…read more

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Out of these which are controlled by the sympathetic (S) or parasympathetic (P)?
How does the brain coordinate responses?
Responses are coordinated via the nervous and endocrine systems, through the action of hypothalamus and its
control of the pituitary gland
o A Fight or Flight response requires a range of coordinated responses to situations of perceived danger
The physiological responses are:
Pupils dilate
o So more light enters eye so more visual information collected
Ventilation rate and depth increases
o Increases removal of carbon dioxide…read more

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The Hypothalamus also releases CRF (corticotropin-releasing factor)
o This stimulates the secretion of ACTH (adreno-corticotropic hormone) from the anterior pituitary gland
Which leads to the release of corticosteroids from adrenal cortex into blood
These help the body
to resist stressors
(stimuli that cause
stress response)
The combined effects of increased sympathetic
nervous system activity and the release of
adrenaline and other hormones into the blood
are responsible for the physiological changes of
the flight or fight response
How are the movements of skeletal muscle around…read more

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o To move the arm down, the triceps contracts to pull on the end of the ulna, this pull pulls the lower arm
down and straightens it, the biceps also relaxes - RIGHT
The movement of many joints requires a wider range of actions and is under the control of group muscles called
What types of muscle are there?
There are three types of muscle
o Smooth muscle - involuntary muscle
Controlled by neurones of the
autonomic nervous system
Not under voluntary control…read more

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Muscle cells form mulitnucleated fibres, surrounded by sarcolemma
o Have a striped (or striated) appearance
What is the structure of a muscle?
Contain many mitochondria Why?
Sarcolemma (plasma membrane) has many infolds called
transverse or T-tubules that spread the depolarisation to all
parts of muscle fibre
Extensive sarcoplasmic reticulum (specialised ER that stores
calcium ions)
Contains myofibrils that are composed of two types of
protein filament and are responsible for contraction
What are fast and slow twitch muscles?
Slow twitch muscles
o They contract slowly…read more

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At the presynaptic neurone
o An action potential arrives at the neuromuscular junction
Ca2+ channels open, allowing Ca2+ to enter presynaptic neurone
Vesicles containing acetylcholine fuse with the presynaptic membrane
o The neurotransmitter acetylcholine is then released into the gap by exocytosis
At the postsynaptic membrane
o Acetylcholine binds with receptors on the muscle fibre membrane (sarcolemma)
Sodium channels open and sodium ions enter, depolarising the sarcolemma
What is the sequence of events in the muscle fibre that lead to contraction?
The depolarisation wave travels…read more



Thanks! These are great - even the other ones you have for F215 :)

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