The Nervous System OCR Mammalian Physiology and Behaviour A2 Revision.
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Transcript of The Nervous System OCR Mammalian Physiology and Behaviour A2 Revision.
The Nervous System
OCR Mammalian Physiology and Behaviour
A2 Revision
The Nervous System
Describe the organisation of the nervous system
Outline organisation of autonomic nervous system
Outline the role of the autonomic nervous system in
digestive system, heart action and the size of the pupil
in the eye
Structure of the human brain
Functions of the cerebrum, hypothalamus, cerebellum,
medulla oblongata
Symptoms and causes of Alzheimer's disease
Human Nervous System
Neurones
– Cell body
– Nerve fibres
– 3 types– Motor, intermediate (relay), sensory
Glial cells
– Schwann cells
– Myelin sheath (node of ranvier)
Organisation of human nervous system
– Central nervous system
– Peripheral nervous system
Human Nervous System
br ain spinal cor d
cent r alner voussyst em
sense or ganst o CN S
somat ic
sympat het ic Par asympat het ic
A ut onomic
t o eff ect or sf r om CN S
neur ones car r ying impulses
per ipher alner voussyst em
Central Nervous System
Neurones receive and integrate information arriving via
synapses
Excitatory and inhibitory synapses
Action potential (CC)
– Energy from stimulus causes temporary and local reversal
of the resting potential (depolarised)
Central Nervous System
Brain
Spinal cord
– Grey and white matter
– Cerebrospinal fluid
Meninges
Spinal Cord, showing Neurones in a Reflex Arc
Peripheral Nervous System
Sensory neurones
Motor neurones
Spinal nerves
Cranial nerves
Somatic and autonomic nervous system
Somatic nervous system
Autonomic Nervous System
Includes all motor neurones that take information to
viscera, controlling
– Activity of all smooth muscle
– Beating of cardiac muscles
– Activity of endocrine glands
Sympathetic Nervous System“Fight or Flight”
Cell bodies on motor neurones in autonomic ganglion
Axons pass to all organs in the body
Synapse with smooth and cardiac muscle
Noradrenaline (epinephrine)
Some use acetylcholine
Parasympathetic Nervous System“Rest and Digest”
All nerve pathways begin in the brain, or spinal cord
Carry impulse to inside the wall of the organ
Synapse with effector organ
Vagus nerve carries information to all of organs in
thorax and abdomen
Acetyl choline
Examples of control by Autonomic Nervous system
The digestive system walls of digestive system have
nervous ending from SNS and PSNS
– SNS• Reduce peristalsis, sphincters close
– PSNS• Sphincter muscles open, smooth muscle contracts• Increase secretions
Action of heart
– Cardiac muscles are myogenic
– SAN
– SNS increases rate and force of contraction
Examples of control by Autonomic Nervous system
Pupil in the eye
– Stimulation SNS• Radial muscles contract• Widening pupil
– Stimulation PSNS• Circular muscles contract• Narrow pupil
The Brain
How do we perceive, think, learn and remember?
What exactly is consciousness?
How does brain control behaviour such as walking and
talking, our emotions?
Study of brain
– Broca
– Study of people with damaged brains
The Brain (continued)
Effects of drugs on the brain
Brain scans
– Computer Assisted Tomography
– Positron emission tomography
– Magnetic resonance imaging
The structure of the brain
Brain – in situ
Brain and association areas
Functions of cerebrum
Higher order processes
Cerebral cortex receives sensory information and
processes this information
Two hemispheres receive information from different
sides of body
Primary sensory areas
Association areas
– Parietal, temporal and occipital lobes
– Prefrontal association
Functions of hypothalamus
Receives and integrates information
Brings about responses through Autonomic nervous
system or secretions of the pituitary gland
Control of body temperature
Control of hormones from endocrine glands
– Secretions from posterior pituitary gland
– Secretions from anterior pituitary glands
Functions of cerebellum
Control and co-ordination of movement and posture
Involved in learning of tasks requiring carefully co-
ordinated movements
Functions of medulla oblongata
Control of breathing
– Rhythmic patterns of impulses
– Conscious controls of breathing patterns
– CO2 receptor cells in Med. Ob. increase frequency of
nerve impulses
Heart rate and blood pressure
– Impulses from M.Ob. to SAN
– PSNS (vagus nerve) – SAN beats more slowly
– SNS – SAN beats faster
Alzheimer’s Disease
Dementia
Alzheimer's
– Tissues in cerebral cortex looks abnormal
– “tangles”
– “plaques”
Diagnosis
– Changing pattern of behaviour
Alzheimer’s Disease
Causes
– Tau
– Beta amyloid
– APP
– “familial” Alzheimer’s
– Environmental factors
Prevention and treatment
– Symptoms temporarily reduced by drugs
– Development of inhibitors
– Vaccines
– Advice