co ordination
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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