chapter 3-coordination and response

CHAPTER 3: COORDINATION AND RESPONSE

3.2 THE HUMAN NERVOUS SYSTEM Made up of 1.The central nervous system •Brain •Spinal Cord

2.The peripheral nervous system •Cranial nerve - branch from the brain -connect brain to sensory and effector at the head

•Spinal nerve -branch from the spinal cord -connect the spinal cord to sensory and effector at the thorax, abdomen, limbs

THE HUMAN BRAIN

The brain function as a coordinating and integrating centre:• receive information from receptors •analyse information•integrate information•store information•transmit instruction to effectors

SPINAL CORD

• Continuation of the medulla oblongata • Located in the vertebral column• Consists of a grey matter in the shape of H in

the middle and a white matter around it.

SPINAL CORD

FUNCTIONS OF SPINAL CORD:

1. It connects the peripheral nervous system to the brain.

2. It acts as a minor integrating centre in producing simple reflex responses such as:

-the withdrawal of the hand from a hot object

NEURONE

• The nervous system is made up of millions of nerve cells called neurones.• Neurones transmit nerve

impulses to other nerve cells, glands or muscles.

DENDRITES

CELL BODY

NUCLEUS

MYELIN SHEATH

AFFERENT NEURONECARRY SENSORY

INFORMATION FROM RECEPTOR CELL TO THE BRAIN

AND SPINAL CORD

TRANSMISSION OF INFORMATION ALONG THE NEURONE

• Nerve impulses is carried along the neurones in the form of electrical impulse.

-Travels in one direction from dendrites to axon terminals.

• Begins at the receptors and ends at the effectors.

TRANSMISSION OF INFORMATION ALONG THE NEURONE

1. Receptor detects the stimulus. 2. Nerve impulses are carried by the afferent

neurone to the central nervous system. 3. The central nervous system integrates and

interpret the information. 4. The central nervous system send nerve

impulses – carried by the efferent neurone to the effector.

5. Effector produce response.

• Neurones are not directly connected – there is a gap called synapse.

• Synapse – between axon terminal with the dendrite of another neurone.

- Contains a lot of mitochondria and vesicles containing neurotransmitters (acetylcoline & noradrenaline)

• Nerve impulse arrive at axon terminal (synaptic knob)

• 2. Nerve impulse stimulates the vesicles to release neurotransmitters.

• 3. Neurotransmitters diffuse across the synapse to the subsequent dendrite.

• 4. Energy required is supplied by the mitochondria

• 5. Dendrite is stimulated, and will pass the impulse

VOLUNTARY ACTIONS• Controlled by the cerebrum of the brain. • Involves the process of integration and

interpretation of information to produce response.

• Example : kick a ball • Sight of the ball stimulates the receptor in the

eye – information will be sent to the cerebrum • The information about the ball is interpreted in

the motor area of the brain – sent to the skeletal muscle of the leg to produce a response, that is to kick the ball.

• Automatic action – not controlled by the will of an individual

• Controlled by medulla oblongata -e.g peristalsis, heartbeat, breathing -We are not aware of the responses • Autonomic nervous system – regulates

internal body process

REFLEX ACTION• Reflex Arc – pathway that a nerve impulse travels

from the receptor to the effector • Consists of receptor, afferent neurone,

interneurone in the spinal cord, efferent neurone and effector.

• Examples • Withdrawal of the hand from a hot object;

involves three neurones; afferent neurone, interneurone, efferent neurone

• Knee jerk; involves two neurones; afferent neurone, efferent neurone

WITHDRAWAL OF HAND FROM HOT OBJECT

• When the hand touch a hot object, receptors are stimulated

• Impulses is generated – travels along afferent neurone to the spinal cord

• Impulse travels to an interneurone – then transmitted to another synapse of the efferent neurone.

• Impulse in carried to the muscle. • Also involve other neurones in the brain – enable

the person to feel the sensation of heat and pain

3.3 THE ROLE OF HORMONES IN HUMANS

• Endocrine system – release hormones to regulates physiological process e.g growth, reproduction, metabolism, mentrual cycle, development of secondary sexual characteristics

• Consists of endocrine glands which secretes hormones • Hormones – chemical substances that regulates the

activities of organs and tissues • Endocrine glands do not have ducts – hormones

released into the bloodstream • Blood will carry the hormones throughout the body to

targeted organs, tissues and cells.

REGULATION OF HORMONE SECRETION

1. Secretion of hormone regulated by another hormone •Release of thyroxine is regulated by thyroid- stimulating hormone (TSH) •High level of thyroxine inhibits the release of TSH • Low level of thyroxine stimulates the secretion of TSH and then stimulates the thyroid glands to produce thyroxine

2. Secretion of hormone regulated by the level of certain substances •High level of glucose in blood stimulated pancreas to secretes insulin • Low level of glucose in blood triggers the secretion of glucagon 3. Secretion of hormones regulated by nervous system •Hypothalamus receive nerve impulse from receptors • Then stimulated pituitary glands to release hormone • Adrenal glands are also stimulated by the nervous system

• There are also coordination that involve both nervous and endocrine system e.g when a person is being attacked by a dog

1. Eyes detect stimuli (dog) 2. Nerve impulse in sent to the brain 3. Brain send nerve impulse to adrenal glands 4. Adrenal glands produce adrenaline 5. Adrenaline increase heartbeat rate, breathing rate,

blood pressure, blood glucose level 6. Increase metabolic rate, that produce extra energy to

either “fight” or “flight”

THE USES OF HORMONES IN MEDICINE

1. Growth hormones – treat dwarfism. 2. Insulin – treat patients with diabetes melitus 3. Oestrogen – treat problem related to

development of secondary sexual characteristics, menstrual cycle

4. Progesterone – maintain lining of uterus, prevent miscarriage

• Plays an important role in homeostasis • Kidney is the primary organ • Kidney cortex medulla• Functional unit – nephron Glomerulus Bowman’s capsule Renal Tubule

Structure of Glomerulus

NEPHRON

FORMATION OF URINE

• 1. Ultrafiltration – in the glomerulus• 2. Reabsorption • 3. Secretion

ULTRAFILTRATION

REABSORPTION & SECRETION

NEGATIVE FEEDBACK MECHANISM

• Homeostasis is achieved by negative feedback mechanism

• Negative feedback mechanism- brings a change in a system back to normal

• Positive feedback mechanism- makes a situation more intense

KIDNEY IN HOMEOSTASIS

• Osmoregulation – achieved by regulating the vol. of urine production & excretion from the kidney.

• Hormone: ANTIDIURETIC HORMONE (ADH)• Blood osmotic pressure when a person

sweats too much

REGULATION OF BLOOD OSMOTIC PRESSURE

Blood osmotic

pressure

Osmoreceptors – less stimulated.

Pituitary gland- less stimulated so less ADH is secreted

Adrenal glands- stimulated to

release Adolsterone – DCT absorb more salt

Low ADH causes DST and collecting

duct to be less permeable to

water.

So, less water is reabsorbed from

filtrate into blood. Urine contains

more water (dilute) and lighter

in colour.

This results in an increase in blood

osmotic pressure and return it to normal.

HAEMODIALYSIS

• A process of filtering blood by using an artificial means to replace the function of damaged kidney.

• Takes 6 hours and a patient need to do it 3 times per week.

REGULATION OF BLOOD GLUCOSE LEVEL

• Organ: Pancreas • Islet cells β-cells insulin α- cells Glucagon• Defect in insulin production – DIABETES

MELLITUS

REGULATION OF BODY TEMPERATURE

TYPES OF DRUGS & EFFECTSTYPE OF DRUGS EFFECTS

STIMULANTS • increase CNS activity • Excessive use can cause ecstacy

that soon followed by depression.

DEPRESSANTS • Slow down the activity of CNS• Slow down transmission of nerve

imp. (tranquilisers)

HALLUCINOGENS • Cause a person to hallucinate

NARCOTICS (heroin and morphine) • Induce ecstacy feelings• Block pain signals• Slow down normal brain functions

PLANT HORMONES

• For growth promote cell elongation

development in apical meristem• Hormones auxin used in parthenocarpy

Ethylene synthesised during ripening of fruit speed up ripening of fruits

break down complex carbohydrates

Auxin

• In shoot- Auxin build up in the region of shade & cause cell elongation in the shade region.

• In roots – Auxin inhibit cell elongation.

THE END

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