Chapter 3 Coordination and Movement

3.1 Movement and Coordination

1. Humans, animals and plants are always exposed to changes in the external and internal environment. Change in the environment is known as stimulus.

2. Examples of external stimuli are temperature, light, sound, taste, touch and pressure.

3. Examples of internal stimuli are such as temperature, osmotic pressure and blood sugar levels.

4. Organisms response to stimuli. Organisms respond to changes in external and internal environments to protect themselves from injury and ensure the survival of the organism.

5. Receptors are specialized cells that can detect changes in the internal and external environment. Example of receptors: skin, eye, nose, ear and hypothalamus.

6. Receptors receive and transmit stimuli to the integration center (central nervous system), where the information is processed and sent to the effector.

7. Information is transmitted as electrical impulses.

8. Effector is an organ that responds to stimuli presented by the central nervous system. Examples of effector: muscle or gland.

9. Impulses are transmitted from the receptors to the central nervous system via afferent pathway.

10. Impulses of the central nervous system to effectors are delivered via the efferent pathway.

11. Internal environment is controlled by negative feedback mechanism. When a change is detected, the correction mechanism applies to remedy the situation back to normal

1

For example, if our body temperature increases or decreases, the correction mechanism will occur in the body to restore it back to normal temperature.

12. Body coordination is the process of different parts of the body working together to get a proper response. Nervous system and the endocrine system coordinate all these activities.

3.2 Role of the Human Nervous System

1. Human nervous system consists of the central nervous system and peripheral nervous system.

2. The central nervous system is the central body integration. They deliver, integrate, compare and analyze information and coordinate response.

3. The central nervous system consists of the brain and spinal cord.

4. Peripheral nervous system extends from the central nervous system. Peripheral nervous system includes the autonomic nervous system and the somatic nervous system.

5. Cranial nerves projecting from the brain, while the spinal nerves extends from the spinal cord.

Brain

2

1. The brain is the main organ in central coordination.

2. Brain is confined in the skull that protects the brain from injury.

3. The exterior of the brain consists of gray matter while the inside consists of white matter.

4. Gray matter contains cell bodies of neurons, while white matter consists of axons only.

The spinal cord

1. The spinal cord is the main route between the brain and peripheral nervous system.

2. These nerves send impulses to the brain and from the brain, and control the reflex action.

Human spinal cord

3. The exterior of the spinal cord consists of white matter, while the inside consists of gray matter.

4 Dorsal root and ventral root stretch from the spinal cord together to form the spinal nerve.

5. Dorsal root axons contain afferent neurons or sensory neuron axons while the ventral root contains axons of eferen neurons or axons of motor neurons.

6. Dorsal ganglion contains sensory neuron cell bodies located in the dorsal root.

Neurons

1. Nerve cells that make up the nervous system are called neurons.

3

2. Each neuron consists of a cell body containing the nucleus and fine cytoplasm processes known as nerve terminals.

3. The function of various parts of the eferen neuron.

Structure FunctionAxons The long fibers that conduct impulses from the cell bodyDendron Short fibers that receive and transmit impulses toward the cell bodyDendritic Terminal branches that are at the end of axons and dendron, which

receive or transmit impulses.Myelin sheath Fatty substance around axons or dendron, which serves as

insulation layerRanvier nodes Part along the axons that are not coated with myelin coating; help

accelerate the rate of impulse transmission

4 There are three types of neurons: a) motor neurons

b) sensory neurons

4

c) intermediate neuron (interneuron).

Transmission of information from receptor to effector

1. The information in the nervous system delivered in the form of electrical impulses produced when there is a difference between the electrical charge inside and outside of the cell membrane of neurons.

2. When a receptor receives a stimulus, nerve impulses transmitted through sensory neurons to interneuron in the spinal cord.

3. lnterneuron will send impulses to other interneuron, which finally forward the impulses to the central nervous system for the integration and translation.

4. From the central nervous system, motor neurons transmit nerve impulses to the effector, which results in a respond.

Synapses

1. Synapse is the space where the axons of the neurons are close to the dendrites of other neurons.

5

2. Mitochondria and vesicles containing neurotransmitters found in abundance in the synaptic knob. Examples of neurotransmitters are acetylcholine and noradrenalin.

3. When the impulse reaches the synaptic knob, the vesicles fuse with the pre-synaptic membrane to release neurotransmitters into the synaptic space.

4. Neurotransmitters diffuse across the synaptic space to the post-synaptic membrane.

5. In the post-synaptic membrane, the neurotransmitters bind to receptors and stimulate new impulses which then pass along the neurons.

6. Impulse transmission at synapses allow neurons interact with other neurons at the same time, and thus produce a double response.

7. Since neurotransmitter release from pre-synaptic membrane, impulse transmission at synapses is one way.

Controlled and uncontrolled actions

1. Voluntary action is the action under control and done in consciousness.Example: reading, writing, and raising your hand.

2. Involuntary actions controlled by the autonomic nervous system in the body. It is not under the control of the brain. It is controlled by the medulla oblongata and spinal cord. Examples of actions that occur in our bodies that are not conscious include heartbeat, peristalsis and secretion of digestive juices.

Reflex action

1. Reflex is an involuntary action that happens automatically.

2. Reflex action is necessary to protect our body from injury.

3. Route of impulse transmission from receptor to effector is named the reflex arc.

4. Reflex arc consists of receptors, sensory neurons, spinal cord, motor neurons and effector.

5. When a receptor receives a stimulus, impulses transmitted along sensory neurons to the interneuron in the spinal cord.

6. Interneuron then sends impulses to the motor neurons, which send impulses to the effector. Example: When the hand accidentally touches a hot object or when stepping on a nail.

6

7. In a knee-jerk response, impulse sent directly to the motor neuron without interneuron.

Disease and nervous system

1. A people with Parkinson's disease experience trembling hands and feet, muscle stiffness in certain parts of the body is due to insufficient production of a neurotransmitter, dopamine in the brain.

2. Multiple sclerosis is caused by damage to the myelin coating of neurons. People with this disease moves slowly.

7

3. Epilepsy (or fits) is characterized by the sudden release of the electrical charge of the neuron.

4. Alzheimer's disease is caused by degeneration of brain neurons during old age. People with this disease have intellectual disorders, memory loss and confusion.

5. Poliomyelitis is caused by a viral infection of the central nervous system.

Question

1. Which of the following is not a stimulus of the internal environment?A temperatureB osmotic pressureC level of the blood sugarD Light

2. The figure below shows the longitudinal section of the human brain.

Of the following actions, which are not controlled by the brain labeledW, X, Y and Z?

Part Brain FunctionA W MemoryB X HeartbeatC Y BalanceD Z Peristaltic

3. The following diagram shows the structure of the synapse hump.

What is the function of P?A increase speed of impulseB Produce energy to transmit impulses across synapsesC help impulse to cross the synapseD Secretes neurotransmitters

8

3.3 The Role of Hormones in Human

1. Hormone is a protein that is secreted from the endocrine glands in our body.

2. Hormones are chemical messengers that are secreted directly into the blood, and carried to target organs that are found in other parts of the body.

3. Hormones are produced in small quantities.

4. Hormones are specific in terms of action, and only act on specific target organs.

5. Hormone action is slow but the effect lasts longer.

Human Endocrine System

1. Endocrine system consists of endocrine glands that secrete hormones to coordinate body activities and response to stimuli from the environment.

2. Endocrine glands do not have ducts. Hormones are secreted through ducts, but are secreted directly into the blood stream that carries hormones throughout the body.

9

Endocrine Hormone FunctionPituitary gland Antidiuretic hormone Control of water balance

Leutinising hormone Stimulates ovulationOxytocin Stimulate uterine muscle

contractions during childbirth

Prolactin Stimulate the secretion of milk by the mammary gland

Growth hormone Stimulate growthAdrenocorticotropic hormone

Stimulates the adrenal cortexto produce hormones

Thyroid-stimulating hormone

Stimulates the thyroid gland to produce thyroxine

Stimulating hormonefollicular

Stimulate the ovaries to produce estrogen

Thyroid gland Thyroxine Control the rate of bodymetabolism

Adrenal Glands(Medulla)

Epinephrine Prepares the body for emergency by increasing metabolism, increase heart rate which increases the blood flow to vital organs, increase blood glucose concentration and dilation of the pupil

Adrenal Glands(Cortex)

Aldosterone Controls the concentration of sodiumand potassium in the blood

Pancreas Insulin Lowers blood glucose concentration

Glucagon Increase the concentration of glucose in the blood

Ovary(Girls only)

Estrogen Controls the development of female secondary sexual characteristics

Progesterone Prepare the uterus for embryo implantation

Testes(Men only)

Testosterone Controls the development of male secondary sexual characteristics

Effects of hormonal imbalances

10

1 hormone imbalance caused by excessive production of hormones or deficiency of certain hormones.

2 As the endocrine system coordinates long-term change or response in our body, the imbalance in hormone production will affect our health.

Hormone Overuse LackGrowth hormone Gigantism (children)

Acromegali (adult)Stunted growth

Thyroxine Increased metabolic rate and size of the thyroid gland (goiter)

Stunted physical and mental development of children (Cretinism)Lack of energy for adults(Myxedema)

Insulin Low blood glucose level (Hypoglycemia)

High level of glucose in blood and urine (diabetes mellitus)

Estrogen Early Puberty Late PubertyProgesterone Loss of embryo Testosterone Early Puberty Late Puberty

3.4 Homeostasis in human

1. Internal environment of an organism refers to the interstitial fluid that moistens tissue cells and tissues, along with the circulatory system.

2. Internal environment must be maintained at a constant level, or at least between certain limits, to ensure that the cells are maintained in optimal physical and chemical properties in the internal environment.

3. Physical factors that need to be kept constant include the body temperature and blood pressure.

4. Internal factors include the partial pressure of oxygen and carbon dioxide, osmotic pressure and blood sugar levels.

5. Homeostasis is the maintenance of the constant internal environment through regulatory mechanisms in the body.

6. Homeostasis is achieved through a negative feedback mechanism.

7. Negative feedback mechanism consists of three important parts:(A) sensory organs or receptors to detect changes in the internal environment.(B) The control center (brain) initiate appropriate corrective action.(C) response or effector organs that perform corrective actions to restore normal internal environment.

8. When deviations from the norm occur, corrective mechanisms act to restore internal environment to the original level (negative feedback mechanism).

11

Formation of urine

1. Kidneys are part of the excretory system.

2. Longitudinal section of the kidney showing the cortex (outside), medulla, and pelvis.

3. Kidney consists of millions of nephrons (functional units).

4. Each nephrons consists of Bowman capsule, proximal convolutedtubules, loop of Henle, distal convoluted tubules and collecting duct.

12

4. Renal arteries carry blood into the kidneys while the renal vein carries blood out of the kidney.

5. Urine formation involves the process of ultrafiltration, reabsorption andsecretion.(A) ultrafiltration occurs in Bowman capsule. Blood from the glomerulus are forced into Bowman's capsule by high pressure generated by the afferent arterioles. Red blood cells and blood proteins are too large and can not penetrate the pores of the glomerular wall and Bowman's capsule. Glucose, amino acids, urea, water and mineral salts that form the glomerular filtrate flows into the proximal convoluted tubules.(B) In the promixal convoluted tubule, the absorption of glucose and amino acids occurs through active transport process while the water is absorbed by osmosis. In loop of Henle, water, sodium and chloride ions reabsorbed.(C) In the distal convoluted tubule, hydrogen ions, potassium ions, ammonium ions, urea and toxins or drugs secreted either actively or passively and removed.

6. When the filtrate reaches the collecting duct, most of the water and mineral salts

13

needed by the body have been reabsorbed. Only the urea and excess water and mineral salts are left in the fluid in filtrate. Liquid is removed as urine through the collecting duct.

Osmoregulation mechanism

1. Osmoregulation is the regulation of blood osmotic pressure.

2. This process is controlled by negative feedback mechanism involving the control of water and mineral salts in the distal convoluted tubule and collecting duct.

3. When the osmotic pressure in the body increases due to the intake of little water, excessive sweating or high salt intake, osmoreseptor in the hypothalamus is stimulated.

4. Nerve impulses are generated and sent to the pituitary gland to increase hormone production of antidiuretic hormone (ADH), and adrenal glands to reduce aldosterone production.

5. ADH increases the permeability of the distal convoluted tubule wall and collecting duct to absorb the water into the blood by osmosis.

6. Aldosterone causes a decrease the absorption of sodium chloride.

7. This decreases the volume of urine but increases the mineral salt content of the urine. Small amount of urine is produced.

8. When the osmotic pressure of the blood decreases due to high water intake, the production of antidiuretic hormone (ADH) is reduced, and aldosterone production increased.

9. The wall of distal convoluted tubule and collecting duct becomes less permeable to water. More sodium chloride reabsorbed due to high level of aldosterone.

10. Large volume of dilute urine produced.

14

Defective renal function

1. Renal damage caused by poison, kidney disease, high blood pressure or high blood glucose levels.

2. Prolonged kidney damage can result in kidney failure.

3. Kidney failure occurs when the nephrons are destroyed.

4. Unfiltered blood can not be allowed to accumulate because it would be toxic at higher concentrations.

5. The waste in the blood can be removed by using a machine that serves as the artificial kidney.

6. Patients can also opt for a kidney transplant.

7. The machine has a semi-permeable membrane that alows small molecules from the blood to diffuse through it into the dialysate. This process is called hemodialysis.

8. During hemodialysis, the patient's blood taken from the artery, fed into a semi-permeable dialysis tubing, and inserted into the dialysis fluid.

9. Dialysis fluid contains the amount of mineral salts and glucose, with the same composition as in blood plasma (without nitrogenous material).

10. A concentration gradient exists between nitrogenous waste, nutrients and other toxins seeping out of the patient's blood into the dialysis fluid.

11. After a few hours, and clean filtered blood returned to the patient through a vein in the same hand.

15

12. Dialysis fluid is often changed to eliminate wastage and to maintain a diffusion gradient between the blood of patients and dialysis fluid.

13. Patients with kidney failure must undergo dialysis for life.

14. Kidney transplant involves replacing a damaged kidney from a donor kidney.

Regulation of sugar levels (glucose), blood

1. When blood glucose levels are above normal levels, beta cells in islets of Langerhans in the pancreas secrete the hormone insulin into the blood.

2. Insulin converts any excess glucose to glycogen which is not soluble, andstored in the liver and muscles.

3. Level of the glucose in the blood is decreased and thus returned to normal.

4. When glucose levels are less than normal, α cells in islets of langerhans in the pancreas secretes a hormone, glucagon, into the blood, which converts glycogen back into glucose. This restores blood glucose to normal levels.

16

Regulation of body temperature

1 Body temperature is regulated by the heat generated through metabolism with the heat lost from the body.

3.5 Adopting a Healthy Lifestyle

1. Drug abuse is an overdose of drugs without a doctor's prescription.

2. Drug abuse can lead to high blood pressure, heart problems, liver damage and weaken the immune system.

3. Drugs also cause brain damage and mental problems.

4. Alcohol is a tranquilizer.

5. Excessive consumption of alcohol can cause vomiting and breathing problems.

3.6 Plant Hormone

1. Plant hormones are organic compounds that act as messengers that promote or inhibit the growth and development of plants.

2. Examples of plant hormones are auxin, giberelin, cyotokinin, abscicic acid and ethylene (a gas).

17

Hormone FunctionsAuxin This hormone promotes cell growth and the start of root growth.

They work with cytokinins, another major group of plant hormones, to promote growth of roots and stems.

Ethylene Promotes fruit ripening.Gibberellin Stimulates the germination of the seed and flowering.Abscisic acid Promotes the closing of stomata in order to maintain water

levels. It also inhibits shoot growth and controls the dormancy of the seed.

Cytokinin The ratio of auxin to cytokinin level affects cell division and differentiation. They also delay the aging of the plant tissue.

3. Auxin stimulates elongation of the meristematic cells.

4. Auxin produced continuously at the end of the shoot and the root.

5. Auxins affect the growth response of roots and stems.

6. High concentration of auxin stimulates cell elongation in shoots and encourages shoot growth but inhibit root cell elongation and root growth.

7. Light causes an uneven distribution of auxin in the shoot tip and thus regulates fototropisme and geotropisme.

8. Shoots usually grow towards the light while roots grow away from light.

9. Shoots respond negativly to gravity and grow towards the top, while the roots respond positively to gravity and grow downwards.

Hormone use in agriculture

1. Auxins are widely used in agriculture and biotechnology to modify the growth and development of plants.

2. Auxin is also used to promote the production of fruits without seeds (Parthenocarpy).

18

3. Auxin applied as a powder to stimulate root formation in stem cuttings.

4. Auxins are used as herbicides.

5. Auxin together with ethylene used to accelerate ripening of fruit.

19