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