Summary
OCR Biology A level 5.1.5 Plant and Animal responses summary notes
Summary notes for topic 5.1.5 Plant and Animal responses of OCR Biology A level Module 5. Detailed electronic notes with diagrams.
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Increase in H+ Detected by carotid receptors
Increase in frequency of impulses
Along accelerator nerve
o To diaphragm and intercoastal muscles
Faster breathing
Deeper breating
o To SAN
Heart beats faster
Increased stroke volume
Faster removal of carbon dioxide
Blood CO2 levels fall to norm
Negative feedback
5.1.5 Plant and Animal responses
,Grey matter: consists
White matter: consists of mainly
of mainly nerve cell
myelinated axons and dendrons
bodies and of mainly (myelin makes the long fibres appear
non-myelinated nerve white)
Dorsal root: spinal nerve which carries
impulses from receptors to spinal cord
Ventral root: spinal nerve which
carries impulses from the spinal cord
to the effectors
Central:
- Consists of brain and spinal cord
- Contains intermediate neurones/relay neurones
- Has coordinating role/many synapses
Peripheral:
- Nerves run from sense organs (to CNS)/ muscles or glands (from CNS)
- Contains sensory and motor neurones
- Role in sensing stimuli/controlling effectors (conducting impulses to & from CNS/brain)
- Includes somatic and autonomic nervous system (made up of sympathetic and parasympathetic)
o SOMATIC: controls voluntary/conscious actions
Somatic motor neurones carry impulses from the CNS to skeletal muscles which are
under voluntary control
Have cell bodies in the CNS
Mostly myelinated
o AUTONOMIC: controls unconscious/involuntary actions
, Autonomic motor neurones carry impulses from the CNS to cardiac muscle, smooth
muscle in the gut wall and to glands which are not under voluntary control
Have cell bodies outside the CNS in autonomic ganglia
Mostly unmyelinated
Autonomic:
Preganglionic neurones
o Carry action potentials from the CNS to the
ganglia
2 parts - sympathetic and parasympathetic
STRUCTURE:
o Sympathetic has short pre-ganglionic neurone
and long post-ganglionic neurone
Therefore ganglia nearer spinal cord
o Parasympathetic has long pre-ganglionic
neurone and short post-ganglionic neurone
Therefore ganglia nearer organ
o Sympathetic use noradrenaline
(as a neurotransmitter at the synapse
between neurone and effector)
o Parasympathetic use acetylcholine
(as a neurotransmitter at the synapse between neurone and effector)
ROLES:
o Sympathetic used in stress/fight/flight (gets the body ready for action)
o Parasympathetic used in rest/relaxation/calm
Sympathetic increases and parasympathetic decreases:
- Heart rate/blood pressure
- Speed/rate/depth of breathing
- Airway diameter
o Sympathetic increases blood flow to skeletal muscle
o Parasympathetic increases blood flow to gut (smooth muscle)
Sympathetic involved in orgasm
Parasympathetic involved in sexual arousal
o Sympathetic dilates pupils
o Parasympathetic constricts pupils
Sympathetic makes liver release glucose
Parasympathetic makes liver take up glucose
o Sympathetic reduces peristalsis/digestion
o Parasympathetic allows peristalsis/digestion
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