Control and Coordination 10th Science Notes PDF

CHAPTER – 7 Control and Coordination Living organisms respond and react to various stimuli like heat, light, cold, touch, pressure etc. Plants and animals both respond to stimuli but in different manner. Example : withdrawl of hand on touching a hot object. Control and Coordination i...

CHAPTER – 7 Control and Coordination Living organisms respond and react to various stimuli like heat, light, cold, touch, pressure etc. Plants and animals both respond to stimuli but in different manner. Example : withdrawl of hand on touching a hot object. Control and Coordination in Animals It is brought about in all animals with the help of two main systems a) Nervous System b) Endocrine System Nervous System : Functions i) To receive the information from environment ii) To receive the information from various body parts. (Stimuli fi Response) iii) To act accordingly through muscles and glands. Stimulus : Any change in environment or within that bring about the reaction eg: touching a hot plate. Response : The reaction of our body to these changes. eg. withdrawal of our hand How do we detect that we are touching a hot object? Receptors : Are specialised tips of some nerve cells that detect the information from the environment. Receptors are Sense Organs Inner Photo receptors Skin Olfactory Gustatory Ear Eyes Receptor Receptor (Nose) (Tongue) Hearing/ Visual Pain Smell Taste Balance of Stimulus Touch Detection Detection the body Heat 63 X-Science  Neuron : Structural and functional unit of nervous system. Neuron (3 main parts) I II III Dendrite Cell body Synapse and Axon Information is Information Part where acquired travels as an electrical signal electrical impulse is converted into chemical message for onward transmission to next neuron by release of neurotransmitters Nucleus Nerve Dendrite ending Axon Cellpody Structure of neuron Fig. 7.1 (a) P 115 Synapse : The point of contact between the terminal branches of axon of one neuron with the dendrite of another neuron is called synapse. Reflex Action A quick, sudden, immediate response of the body to the certain stimuli that involves Spinal cord. eg. (not brain) withdrawal of hand, knee jerk etc. Reflex arc : The pathway through which impulses pass is called reflex arc. 64 X-Science  Stimulus RECEPTOR Sensory Nerves › ORGAN eg. Heat (SKIN) Spinal Cord Response EFFECTOR › ORGAN Motor Nerves eg. Withdrawal (MUSCLE) of Hand Refer to diagram Fig 7.2 Reflex arc Response Responses are of three main types Voluntary : Controlled by fore brain eg. Talking, Writing Involuntary : Controlled by mid and hind brain eg. Heart beat, vomiting, regulation of heartbeat Reflex action : controlled by spinal cord eg. Withdrawl of hand on touching a hot object. Human Nervous System Central Nervous Peripheral Autonomic System Nervous Nervous System System (CNS (PNS) (ANS) Brain Spinal Cranial Spinal Sympathetic Para Cord. Nerves Nerves Nervous Sympathetic System Nervous Fore Brain Arise from Arise from System Mid Brain the brain Spinal Card Hind Brain 65 X-Science  Human Brain Human brain has three major parts or regions a) Forebrain b) Mid Brain c) Hind Brain FOREBRAIN Most complex/specialized part of the brain is CEREBRUM FUNCTIONS : 1. Thinking part of the brain 2. Control the voluntary actions. 3. Store information (Memory) 4. Centre associated with HUNGER 5. Receives sensory impulses from various body parts and integrates it Mid Brain : HYPOTHALAMUS : Chemical co-ordination PITUITARY GLAND : Secretes hormones Hind Brain : CEREBELLUM i) Controls posture and balance ii) Control precision of voluntary actions MEDULLA Controls involuntary actions eg. blood pressure, salivation, vomiting PONS Involuntary action, regulation of respiration Fig 7.3 Human Brain 66 X-Science  PROTECTION OF BRAIN AND SPINAL CORD Brain : Brain is protected by a fluid filled balloon which acts as shock absorber and enclosed in cranium (Brain Box) Spinal Cord : Spinal Cord is enclosed in Vertebral column. Coordination between Nervous and Muscular Tissue Information Central Information [collected by Nervous Processed Nervous tissue] System by (Sensory Nerve) [CNS] [CNS] Action Decesion made [by CNS] Muscle shorten (Motor Nerves) Message Contraction Muscles Passed to [Muscle cell] [Change in shape muscles and arrangement of proteins] Coordination in Plants Movement in Plants Movement dependent Movement independent on growth of growth [immediate response to stimulus] Tropic movements eg. dropping of leaves [directional movements of Touch-me-not in response to stimulus] plant on touching it Phototropism Geotropism Chemotropism Hydrotropism Movement Movement Movement Movement towards light towards gravity towards Chemicals/ towards / growth of pollen water tube towards avule 67 X-Science Plant hormones : Are chemical compounds which help to coordinate growth, development and responses to the environment. Plant hormones : Main plant hormones are : a) Auxin : [Synthesized at shoot tip] Function : – Helps in growth Phototropism : more growth of cells towards light. b) Gibberellin : Helps in the growth of the stem c) Cytokinins : Promotes cell division d) Abscisic acid : Inhibits growth, cause witting of leaves. (Stress hormone) Hormones in Animals Hormones : These are the chemical messengers secreted in very small amounts by specialised tissues called ductless glands. They act on target tissues/organs usually away from their source. Endocrine System helps in control and coordination through chemical compounds called HORMONES 68 X-Science  S. Hormone Endocrine Location Functions No. Gland 1. Thyroxine Thyroid Neck/ Regulation of metabolism Throat of carbohydrates, fats region and proteins. 2. Growth Pituitary Mid Regulates growth and hormone development. 3. Adrenaline Adrenal Above Regulation (increasing) both of blood pressure, heart kidneys heat, carbohydrate metabolism (during emergency) G { 4. Testosterone Testes O Genital/ Changes associated SEX in Males N lower with puberty Hormone A abdomen (Sexual maturity) D estrogen Ovaries S area 5. Insulin Pancreas Below Reduces and regulates stomach blood sugar level IODISED SALT IS NECESSARY BECAUSE : Iodine mineral is essential part of thyronine hormone so it is important that we must consume iodised salt as in turn it is essential for thyroid gland as it controls carbohydrate, proteins and fat metabolism for best balance of growth deficiency of iodine might cause disease called goitre Diabetes : Cause : It is due to deficiency of Insulin hormone secreted by Pancreas that is responsible to lower/control the blood sugar levels. Treatment : Patients have to internally administer injections of insulin hormone fiwhich helps in regulating blood-sugar level. Feedback Mechanism fi makes sure that hormones should be secreted in precise quantities and at right time, which is regulated by feedback mechanism. 69 X-Science  Sugar level in the blood rises SWITCH OFF Feedback sent Detected by cells of Pancreas Synthesis insulin Blood sugar level falls (like a float in watertank) Stop secreting more insulin EXERCISE (Question Bank) Very Short Answers (1 Mark) 1. Where is auxin synthesized in plants? 2. Which gland is known as Master gland? 3. Name the hormone that regulates blood sugar level. 4. What is synapse. 5. What are tropic movements? Give one examples 6. Define hormones 7. Which hormone has inhibiting effect on growth of plants 8. What is phototropism? 9. What are the components of central Nervous System. 10. What happens at synapse between two neurons. Short Answers (2 Marks) 1. Draw diagram of neuron and label cell body, dendrites and axon. 2. What is reflex arc? Explain with the help of a flow-chart. 3. Mention one function of each of the following i) Cerebellum ii) Pons. 4. What is the cause of diabetes? How it can be controlled. 5. Why it is advisable to use iodised salt. 70 X-Science 6. What are the different receptors present in our body? What are their functions. 7. What are plant hormones? Name a plant hormone that promotes growth in plants. 8. What are sensory and motor neurons? Write their functions. Long Answers (5 Marks) 1. What are hormones (in animals) List four characteristics of hormones. Name the hormone required for the following. i) Development of moustache and beard in human male ii) Lowering of blood glucose. 2. Mention the functions of a) Fore brain b) Mid brain c) Hind brain 71 X-Science