2. COORDINATION AND RESPONSE
1. An organism experiences changes in its internal and
external environments all the time
2. The changes which cause responses in the body are called
stimuli
3. There are two types of stimuli:
a)internal
b)external
4. Mammals detect stimuli through highly specialised sensory
cell called receptor.
5. Effectors in the body carry out the responses to stimuli
3. 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 system
1. 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
cord
b) peripheral nervous system (PNS), consist of cranial nerves
and spinal nerves.
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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 function
1. Contain within the vertebral column
2. It is consist of white matter and grey matter
a) in cross section, grey matter looks like a butterfly
or the letter H
b) consist mainly of cell bodies of neurones
c) surrounded by white matter
d) 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 neurones
Neurones 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 neurones
Interneurones
• 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 function
1. It transmits signal to the CNS for processing
2. 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.
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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 pituitary
b) 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 & LH
Growth
hormones prolactin
Kidney tubules Smooth muscle in the
uterus
Adrenal
cortex Thyroid Ovaries, testes Bones, tissues Mammary
glands
30. • 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 pItuItaRy
Thyroid-stimulating
Hormone, TSH
taRGEt GlaND
Thyroxine
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 kidneys
1. 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 blood
3. 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 cortex
b) 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) Glomerulus
b) Bowman’s capsule
c) Renal tubule
• Renal tubule is made up of the:
a) Proximal convoluted tubule
b) Loop of Henle
c) Distal convoluted tubule
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• Nephron perform three basic process:
1. Ultrafiltration
2. Reabsorption
3. 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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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.
43. Detected by
osmoreseptors in
hypothalamus
Decrease in solute
potential
Normal plasma
osmotic level
Increased in solute
potential
Detected by
osmoreseptors in
hypothalamus
Increased permeability 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.
47. 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
