CO-ORDINATION

all organs and systems in a healthy human body are co-ordinated

co-ordinated means : they co-operate with one another and

work together efficiently

Consider the tennis player about to hit the ball:

Physical activity is one function that requires co-ordination

1 Eyes see ball.

2

3

Information goes to brain & is processed.

Brain sends messages to muscles to hit the ball.

Co-ordination of body functions involves:

NERVOUS CONTROL: THE NERVOUS SYSTEM

Brain & Spinal cord:

the main parts of the NS are called the CNS

Vertebrae protect the spinal cord

Spinal cord

Vertebra

Vertebral column

How is the CNS connected to the various parts of the body?

The Nervous System receives messages from:

Sense organs

CNS

The Nervous System sends messages to:

Muscles Glands Effectors

CNSSalivary glands

IMPULSES

Flow of information

What are ‘stimuli’?

A stimulus is:

a change in the environment that can be detected by a sense organ and brings about a response

Stimuli [stimulus = singular]Cold

Heat

Sound

Chemicals in air

Pain

Neurones and nerves

Neurone = nerve cell

Nerve = a bundle of nerve cells

neurones

Neurones can be very long

Sensory neurones

Motor neurones

Intermediate orRelay neurones

Three types of Neurone

Structure of a sensory neurone

Function of the myelin sheath

to insulate the fibre speeds up the impulses

Myelin sheath:FAT

Direction of impulse along a sensory neurone

Axon carries impulse:

Away from the cell body

Fig. 4 A motor neurone.

[axon terminal]

Direction of impulse

Differences in structure between a:

1. Long axon2. No receptor3. Cell body terminal &

has dendrites4. Many short dendrons

1. Short axon2. Receptor3. Cell body at the side;

no dendrites4. One long dendron

receptor axon

axon

dendron

Sensory neurone

Motor neuroneCNS

CNS

Differences in function between a:

receptor

Sensory neurone

Motor neuroneCNS

CNS

Carries the

impulse towards the CNS

Carries the impulse

away from the CNS

Fig. 5 Connections between a sensory, a relay and a motor neurone.

Neurones DO NOT touch each other

Sensoryneurone

Motorneurone

Relayneurone

A synapse is a tiny gap between neurones

synapse

Impulses travel in direction across a synapse

Sensory neurone

Motor neurone

Relay neurone

Effector

Receptor

How many synapses on one cell body? 1,000 to

10,000!!

Fig. 6 A synapse.

A Reflex Action is a rapid, automatic, involuntary response to a

stimulus

Examples of reflex actions:

Sneezing

Blinking

Coughing

Removing the leg when stepping on a pin

Examples of reflex actions: withdrawing your hand from a hot

object

Why are reflex actions useful to the body?

Question: SEP 2010

1. What is the main function of the nervous system? (2)

The NS contains a network of specialised cells called neurones that coordinate the actions of an animal and transmit signals between different parts of its body.

b. List the stimulus and response for each of the following reflex actions:

i. swallowing; (3)Stimulus: food in mouthResponse: food goes down oesophagus

ii. coughing. (2)Stimulus: foreign particles in tracheaResponse: removal of foreign object from trachea

Question: MAY, 2011 [2B]A student accidentally touches a beaker of hot water. The student pulled her hand away from the hot water very quickly. This is an example of a reflex action.

a) Define the term reflex action. (2)

Question: MAY, 2011 [2B]b) List TWO examples of reflex actions taking

place in newborn babies. (4)

Suckling reflex

Grip reflex

Stepping reflex

Crying reflex

The reflex arc is:

the path along which a nerve impulse travels from the receptor to the effector

e.g. : Knee jerk reflex arc The hand withdrawal reflex arc

The knee jerk is a reflex action

The knee jerk reflex arc

MuscleSpinal cord

Dorsal [back]

TS spinal cord

Ventral [front]

A sensory neurone always enters via the DORSAL ROOT

Dorsal root ganglion is a collection of cell bodies of the sensory

neurones

Fig. 7 The hand withdrawal reflex arc.

Myelin = FAT = whiteGrey matter

White matter

TS spinal cord

Why is the white matter white?

due to nerve fibres covered by myelin

Grey matterWhite matter

due to nuclei present in cell bodies TS spinal cord

Remember nuclei look DARK.

Why is the grey matter grey?

QuestionA transverse section through the spinal cord is examined under the high power of the microscope. Part of it looks like diagram A and part looks like diagram B. Which is grey matter and which is white matter? Give reasons for your decision.

A B

AnswerDiagram A represents nerve fibres cut in cross-section and therefore comes from white matter. Diagram B shows many cell bodies which constitute much of the grey matter.

A B

Label the diagram. Draw arrows to show direction of impulse

A – receptorB – sensory neuroneC – motor neuroneD – synapse

Question: SEP, 2004

6d) The following diagram demonstrates the rapid and automatic removal of a finger from a flame.

i) Complete the diagram by drawing and naming the neurones that bring about this reflex action.

ii) Use arrows to show the pathway of the nerve impulse along the neurones. (4)

e) Some individuals suffer from a motor neurone disease in which the neurones gradually degenerate. How is this likely to interfere with the efficiency of reflex actions? (2)

Reflex actions take longer to occur – they become less efficient.

Label the two neurones. What is the function of each?

Question: SEP 2010

Draw a labelled diagram showing the reflex arc that takes place in a knee jerk reflex. On the diagram indicate clearly the direction of flow of impulses. (You are not expected to draw the muscles involved or the spinal cord).

(6)

Question: MAY, 2011 [2A]A student accidentally touches a beaker of hot boiling water. The student pulled away her hand within a few milliseconds. This is an example of a reflex action.a) Write a brief description about the events leading

to the student pulling away her hand. (5)

b) Draw a diagram showing the reflex arc responsible for producing this reflex action. In your diagram include arrows to show the direction of nerve impulses travelling along the neurones.

(6)

The skull protects the brain

The cerebrum is highly folded

Many neurones can be packed into a small

space.

Two Cerebral hemispheres = cerebrum

The cerebrum controls our:

sensations movements

is responsible for: memory thought intelligence

Cerebrum

The cerebrum contains2. Sensory areas:

for sensation 1. Motor areas: for movement

3. Association areas : for thinking

Parts of the brain:

Cerebrum / cerebral hemisphere

Cerebellum

Medulla oblongata

Pituitary gland

Hypothalamus

Functions of:

releases hormones

homeostasis

Functions of the cerebellum:

controls balance and muscular co-ordination

Functions of the medulla oblongata: controls various automatic processes such as:

the rate of breathing heartbeat

Functions of the cerebrospinal fluid:

1. acts as a shock absorber2. to allow oxygen and

nutrients to diffuse through it to nourish neurones

3. to allow removal of wastes

Meninges are layers of tissue that surround the CNS

Meningitis is an infection of the meninges

Question: SEP 2010

1. List the function of each of the following parts within the central nervous system:

i. cerebrum; (2)ii. cerebellum; (2)iii. medulla oblongata. (2)

2. In humans the cerebrum is very large and

highly folded. Explain why. (2)

HORMONAL CONTROL: THE ENDOCRINE SYSTEM

Glands in the body are:

secrete an enzyme into a duct

secrete hormones have no duct (ductless) have a rich blood supply

Exocrinegland

Endocrine gland

What is a hormone? a chemical which is produced by one part of

the body, travels in the bloodstream and has an effect on the target organ

Fig. 14 Position of the main endocrine glands in the human body.

The main human endocrine glands and their secretions.

Gland Hormone FunctionThyroid Thyroxine Controls the

metabolic rate

Gland Hormone FunctionAdrenals Adrenaline Prepares the

body for action

Kidneys

Adrenal glands

Adrenaline, the emergency hormone

Adrenaline prepares the body for action

Muscles need ENERGY to contract!!

Which process releases energy?

glucose + oxygen carbondioxide

+ water + energy

glucose oxygen

muscle energy

How can MORE glucose + oxygen reach the muscle?

Effects of adrenalineHeart beat increasesBreathing rate

increases

Effects of adrenaline Arteries to muscles widen

What is the effect of this?

5 litres of blood in an adult

If more blood flows to muscles

less must flow to other organs.

Which?

Gut & Skin get less blood As arteries narrow

A person becomes pale when afraid. Why?

Glycogen

Glucose in the blood increases

Glycogen is converted to glucose

Effects of adrenaline

Effects of adrenaline include:

1. Heart beat increases2. Breathing rate increases3. Arteries to gut and skin narrow4. Arteries to muscles widen5. The pupils of the eyes widen6. Glycogen is converted to glucose

Gland Hormone Function

PancreasInsulin Decreases the blood

sugar level

Glucagon Increases the blood sugar level

Control of blood sugar

Question: MAY, 2011

Give a biological explanation for the following situation:A diabetic person received an insulin shot after intake of a meal rich in carbohydrates. (2)

A diabetic person does not produce insulin. The insulin injected helps the person to reduce the sugar level in the blood back to normal.

Gland Hormone Function

Ovaries Female sex hormones e.g. oestrogen

Control sexual development

Testes Male sex hormones e.g. testosterone

Control sexual development

Gland Hormone Function

Pituitary

Growth hormone

Speeds up growth

FSH

Causes follicle to develop into a Graafian follicle

LH Causes ovulation

ADH

Causes kidneys to reabsorb water

Differences between nervous and endocrine co-ordination.

Nervous ChemicalInformation passes as electrical impulses along nerve fibres

Information passes as a chemical substance through the bloodstream

Rapid transmission Slow transmissionResponse is immediate Response is usually slow

e.g. growthResponse is short-lived Response is long-lastingResponse is very exact Response is usually

widespread

Negative feedback control: produces an effect which is the opposite of

what has been happening before e.g. if body temperature rises, sweat is

produced to cool it down is important to keep conditions constant in

the body

Control of blood sugar as an example of:

NORM

Excess

Defic iency

Correc tivemechanism

Correc tivemechanism

NORM

Negativefeedback

Negativefeedback

THE END