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
central
nervous
system
brain
peripheral
nervous
system
spinal cord
neurones carrying impulses
sense organs
to CNS
to effectors
from CNS
somatic
Autonomic
sympathetic
Parasympathetic
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 coordinated 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