FORM 5CHAPTER 3

COORDINATION AND

RESPONSE

COORDINATION AND RESPONSE1. An organism experiences changes in its internal and

external environments all the time2. The changes which cause responses in the body are called

stimuli3. There are two types of stimuli:

a) internalb)external

4. Mammals detect stimuli through highly specialised sensory cell called receptor.

5. Effectors in the body carry out the responses to stimuli

COORDINATION AND RESPONSE

5. When the stimuli are detected and eventually resort in an appropriate response, it is called coordination

6. The roles of coordination and response are carried out by two different coordinating systems, namely the nervous system and the endocrine system

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The main component and pathway involved in detecting and responding to changes in the external environment

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The main component and pathway involved in detecting and responding to changes in the internal environment

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THE ROLE OF HUMAN NERVOUS SYSTEM

• Organisation of the nervous system1. The human nervous system consist of a giant network of

nerve cells or neurones, and nerve tissues which convey information between the sensory receptors, the organs and effectors.

2. It is divided into main subsystem:a) central nervous system (CNS), consist of brain and spinal cordb) peripheral nervous system (PNS), consist of cranial nerves and spinal nerves.

puteri5578 8Human nervous system

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Cerebrum

• Divided into two halves called the cerebral hemispheres (left and right)• It is responsible for many mental abilities

Cerebellum• Coordinating centre for body movements• Evaluates the information and relays the need for coordinated

movements back to the cerebrum• Then sends appropriate commands to the muscle

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Medulla oblongata• Regulates the internal body processes that do not requires

conscious effort, that is, automatic functions such as the heart beat and breathing.• Reflex centre for vomiting, coughing, sneezing, hiccupping

and swallowing.

Hypothalamus• Important role in homeostatic regulation.• Control centre of the endocrine system

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Pituitary gland• Secretes hormones that influence other glands and body

function• Controls the release of several hormones from the pituitary

gland and thereby serve as important link between the nervous and endocrine system.

Thalamus• Responsible for sorting the incoming and outgoing

information in the cerebral cortex• Integrates the information from the sensory receptor to the

cerebrum by enhancing certain signals blocking others.

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The spinal cord and its function1. Contain within the vertebral column2. It is consist of white matter and grey matter

a) in cross section, grey matter looks like a butterfly or the letter Hb) consist mainly of cell bodies of neuronesc) surrounded by white matterd) the white matter comprises myelin-coated axons of neurones that extend the whole length of the spinal cord

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A cross section of the spinal cord showing the white matter and the grey matter

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The neurones

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

• Neurones transmit nerve impulses to other nerve cells, glands or muscles

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Types of neurones

Neurones afferent (sensory)

• Carry sensory information from receptor cell to the brain and spinal cord.

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Types of neuronesNeurones efferent• carry information

from the brain or spinal cord to the effectors, that is the muscle or gland cells

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Types of neuronesInterneurones• convey nerve impulses

between the various parts of the brain and spinal cord, transmit nerve impulses between afferent and efferent

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The transmission of information across synapses

• Synapse is the site where two neurons, or a neuron and a effector cell communicate.

• The transmission of information across a synapse involve the conversion of electrical signals in the form of neurotransmitter

• The function of synapses include controlling and integrating the nerve impulses transmitted by the stimulated receptors

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Voluntary action and involuntary action

• The PNS has two main function1. It transmits signal to the CNS for processing2. It transmits responses from the CNS to the rest of the

body• Voluntary actions such as walking and talking are

under conscious control• Involuntary actions that involve skeletal muscle

allows immediate action that does not require conscious effort

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• For example, if a finger touch a hot stove, the reaction is to pull the finger immediately without having to think about it

• In such circumstance when the responses to stimuli are involuntary, they are called reflexes.

• The nerve pathway involved in a reflex action is called a reflex arc

• The effectors involved in involuntary action are smooth muscle and cardiac muscle

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Diseases of the nervous system

Parkinson’s disease• Is a progressive disorder of a CNS that typically affect

victims around the age of 60 years onwards.• Parkinson’s disease affect muscular movements, causing

tremors or trembling of the arms, jaws legs and face• Patients also have difficulty in maintaining normal

postures and experience impaired balance and coordination

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Alzheimer's disease• Alzheimer's disease is a neurological disorder which affect

victims around the age of 60yearsonwards, causes the loss of reasoning and the ability to care for oneself.

• Individual of Alzheimer's disease often become confuse, forgetful, and lose their way although they are in place which are familiar to them.

• As their mind continue to deteriorate, patients may lose the ability to read, write, eat, walk and talk.

• the cause of this disease still unknown, but the factors such as genetic, environmental or the aging process itself can lead to Alzheimer's disease

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The role of hormone in human• Endocrine system consists of a number of glands that

secrete hormones.• Hormones are the chemical messenger produce by the

endocrine glands.• Although the hormones travel in the blood of the body, they

affect and influence only the specific target cell.• Once the hormone binds to its target cell, the hormone

cause the cell to respond in the specific manner.

puteri5578 25The transport of hormones to target cells

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1. The endocrine system and nervous system play important roles in maintaining homeostasis.

2. Both this system often works together.

The need for the endocrine system

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The endocrine system• controls involuntary actions• Conveys chemical signal

(hormones)• Messages are conveyed via the

bloodstream• Message are conveyed slowly• Messages are carried from the

source to the various destination• The response or effects are long-

lasting

The nervous system• Control voluntary and

involuntary actions• Conveys electrical signals• Messages are conducted via

neurones.• Messages are conveyed rapidly• Messages are carried between

specific locations• The responses or effect are

temporary

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Regulation of hormones secretion• The pituitary gland is regarded as the master endocrine

gland because it secrete several hormones that control other endocrine gland

• Pituitary gland itself controlled by the hypothalamus.• Pituitary gland consist of two parts:

a) posterior pituitaryb) anterior pituitary

• The posterior pituitary contains the axons and synaptic terminals of the neurosecretory cells that originate in the hypothalamus

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The role of the hypothalamus in regulating the secretion of hormones from the pituitary gland

HypotHalamus

Anterior pituitaryAnterior pituitary

ADH oxytocin

ACTH TSH FSH & LHGrowth

hormones prolactin

Kidney tubules Smooth muscle in the uterus

Adrenal cortex Thyroid Ovaries, testes Bones, tissues Mammary

glands

• ADH and axytocin are synthesised in the neurosecretory cells of the hypothalamus but secrete by the posterior pituitary

• The hypothalamus controls the hormone secretion of the anterior pituitary gland and therefore, affect the secretion of many other endocrine glands indirectly.

• The anterior pituitary controls the secretions of hormones from the thyroid gland, the adrenal gland and gonad. All of which are also endocrine glands.

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HypotHalamus Thyroid-releasing Hormone, TRH

aNtERIoR pItuItaRyThyroid-stimulating

Hormone, TSH

taRGEt GlaNDThyroxine

Stimulates the anterior pituitary to secrete TSH

Stimulates the target gland to secrete Thyroxine

When the thyroxine concentration exceeds a certain level in the blood, its inhibits TRH production in the hypothalamus and TSH

production from the anterior pituitary

Negative feedback

inhibits the release of

TSH

Negative feedback

inhibits the release of

TRH

Negative feedback mechanism in hormone regulation

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HOMEOSTASIS IN HUMAN• Homeostasis is the maintenance of a relatively constant

internal environment.• Physical factor such as body temperature and blood

pressure while chemical factor are sugar level and osmotic pressure such as partial of carbon dioxide and oxygen

The excretory system• Plays an important role in homeostasis• The primary organs of the excretory system are the

kidneys.

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Function of the kidneys1. Helps to regulates the water and salt balance in the body by

excreting more or less salt, and increasing the in take or loss of water.

2. Regulate the osmotic pressure and ionic levels in the blood3. Excrete waste products.4. Regulate the blood pH• Waste products excreted by the kidneys are substances that

are not useful to the body such as waste products from the metabolic reaction (urea, creatinine and uric acid) and foreign substances in the diet (drugs or toxins)

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The human kidney• The kidneys filter the blood and form the urine which

is exits the body through the ureters, urinary bladder and urethra.

• Urine consists of water, urea and other dissolved waste, and some excess nutrients.

• Human kidney has two distinct region:a) Renal cortexb) Renal medulla

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The nephron• The functional unit of the kidney is the nephron.• The human kidney consists of about 1 million nephrons.• A nephron consists of three major parts:a) Glomerulusb) Bowman’s capsulec) Renal tubule• Renal tubule is made up of the:a) Proximal convoluted tubuleb) Loop of Henlec) Distal convoluted tubule

puteri5578 37Nephron

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• Nephron perform three basic process:1. Ultrafiltration2. Reabsorption3. Secretion

Ultrafiltration• When the blood enters the glomerulus, ultrafiltration take place

when the high pressure forces fluid through the filtration membrane into the capsular space

• The fluid that enters into the capsular space is called the glomerular filtrate

• glomerular filtrate contain water, glucose, amino acid, urea, mineral salt and other small molecule. Some composition as blood plasma but not contain red blood cells and plasma protein

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Ultrafiltration in bowman’s capsule

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Reabsorption• Reabsorption take place when the substance moves across

the renal tubule into the capillary network.• In the proximal convoluted tubule, there are abundance of

mitochondria to generate ATP for the process of active transport that used to reabsorb glucose and amino acid.

• Solute concentration in the capillary network is increase, so that water moves into the blood capillary by osmosis

• In the loop of Henle, water, sodium and chloride ions are reabsorbed.

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• At the distal convoluted tubule, more water, sodium and chloride ions are reabsorbed.

• B the time, the filtrate reaches the collecting duct, very little salt left and 99% of water has been reabsorbed into the bloodstream.

• Only 1% of water in the filtrate actually leaves the body as urine.

• Some urea diffuses out into the surrounding fluid and blood because of its small molecular size.

• Finally, about 45% of the original urea remain in the collecting duct to be excrete in the urine.

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Secretion• Not everything is filtered, only 20% of the plasma leaves the blood

vessels and enters the renal tubule. Hence there are waste product in the blood which were not filtered originally.

• Secretion is a process in which waste and excess substances that were not initially filtered are secreted into the renal tubule.

• Secretion take place in the renal tubules and collecting ducts but is especially active at the distal convoluted tubule.

• Secretion occurs by passive diffusion and active transport.

Detected by osmoreseptors in hypothalamus

Decrease in solute potential

Normal plasma osmotic level

Increased in solute potential

Detected by osmoreseptors in hypothalamus

Increased permeabili ty of distal convoluted tubule and collecting duct to water

Greater proportion of water reabsorption in renal tubules

A small volume of concentration urine produced

A large volume of dilute urine produced

smaller proportion of water reabsorption in renal tubules

Decreased permeability of distal convoluted tubule and collecting duct to water

An increased in ADH released from posterior pituitary

A decreased in ADH released from posterior pituitary

Plasma solute potential decreases

Plasma solute potential increases

Increased water intake

Decreased water intake

REGULATION OF ADH PRODUCTION

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Notes about Kidney Dialysis:

The main stages that blood passes through during the dialysis process include:

•Blood enters machine from body (under pressure from radial artery).

•Pump (some diagrams show a roller pump) controls pressure and flow rate.

•Anticoagulant added to prevent clotting. •Blood passes through dialysis membrane (equivalent to

kidney nephrons). •Bubble Trap removes any gas bubbles from blood.

•Blood is filtered then returned to the patient's radial vein.

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BLOOD GLUCOSE LEVEL IN THE BODY

After meal

Rise in blood glucose level

Secretion of more insulin or less glucagon by pancreas

Liver cells absorb glucose from blood to form glycogen

Increase in glucose uptake by body cells

for respiration

Liver cell break down glycogen into

glucose

Decrease in glucose uptake by body cells

for respiration

Drop in blood glucose level

Secretion of less insulin or more glucagon by pancreas

During fasting or after exercise

Blood glucose level returns to normal

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Practising a healthy lifestyle• Drugs can alter brain functions and the rates at

which neurones release neurotransmitters• There are some types of drug and their effects on

the body:

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Stimulants• Increase the activity of the central nervous system• Cocaine, nicotine, amphetamines & caffeine increase the

heart rate and alertness• Hallucinations, LSD perceive things that do not exist

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Depressants• Slow down the activity of the central nervous system• Alcohol, barbiturates & heroin slow down the breathing

rate &lower blood pressure

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Plants hormones• Plants hormones is a chemical substances

which is produced by the plants and influences the growth and development of the plants. Examples auxins and ethylene

Auxins• Auxins controlled the plants respond to

stimuli by growing in a certain direction called tropism.

• Growth of shoots towards sunlight is called +ve phototropism and growth of shoots away from sunlight is called -ve phototropism.

• Auxins promotes the elongation of cells in the shoot

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• The growth movement of a plant is response to gravity is called geotropism.

• Auxins is used to:

a) Increase the stem length by increasing the rate of cell division

b) Stimulate the growth of adventitious roots from the stem

c) Parthenocarpy, produce seedless fruit

d) Promotes growth of plants cells. Delay fruit ripening and prevent fruit from falling off the plant before it is ripe

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Ethylene• Ethylene is a plant hormones which is synthesised during the

ripening of fruits.• The synthesis of ethylene occurs in fruits, leaves and stems• Speedup the ripening of fruits by stimulating the production of

cellulase that used to hydrolyses the cellulose in plants cells walls, making the fruits soft.

• Promotes the breakdown of complex carbohydrates into simple sugar. That is why a ripe fruit tastes sweeter than an unripe fruit

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THE END