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CLASS 10 NOTES SCIENCE Control And Coordination The nervous system is like the contro! center of our bodies. It’s made up of special tissues called nervous tissue. The worker in this system is the nerve cell or neuron, The nervous system is mainly in charge of managing and coordinating things in complex animals. Functions of the nervous system: * The nervous system gets information from the world around us. ri he \ a) + It collects information from different parts of our body. " ree) * It helps us to make decisions and control our muscles and glands. fos, Nevron and Nerve cells , was Neurons are the basic structural and functional units of the nervous system. Neuron is a highly specialized cell which is responsible for the transmission of nerve impulses. Nucleus Structure of a neuron: A neuron has four main parts: eaees Cell Body (Soma): * Contains the nucleus and other organelles. * Maintains the cell's functions. Aven Nerve Dendrites: oon © Tree-like structures that extend from the cell body. « Receive signals fram other neurons and conduct these signals toward the cell body. Axon: * Along, thread-like structure that carries impulses away from the cell body. « It ends in axon terminals, which transmit signals to other neurons, muscles, or glands. * The axon may be covered with a myelin sheath, which insulates it and speeds up the transmission of nerve impulses. Nerve endings: They are like tiny branches at the ends of neurons, and they send electrical signals to other neurons. Working of a nevron: aia: * Stimulus Received: The neuron receives a stimulus, which initiates an electrical signal called an action potential. * Impulse Generation: The action potential is generated at the cell body and travels along the axon. * Impulse Propagation: The nerve impulse moves down the axon towards the axon terminals. * Synapse Transmission: At the synapse, neurotransmitters are released, transmitting the signal to the next neuron or target cell, * Response: The signal leads to a response, such as muscle contraction or hormone release. Midbrain: The inclusion of the hypothalamus defines its composition. Hypothalamus: * It lies at the base of the cerebrum. * It also controls the urges for eating and drinking. * It controls sleep and wake cycle of the body. Hindbrain: Serving as the link between the spinal cord and the rest of the brain, it consists of three distinct parts. Human Srain Anatomy 1. Cerebellum: It's under the balanced and does three main things: = = * helps you move * keeps you balanced = * manages things you do on purpose 2. Medulla: It's the brain stem, found at the bottom of the brain and stretching into the spinal cord. It handles things our body does automatically, like hearing, heartbeats, breathing, and actions like salivating and vomiting. 3, Pons: * It also controls involuntary actions. * It regulates respiration Spinal Cord: It manages quick reflex actions and sends messages between the body and the brain. Peripheral Nervous System fe) The peripheral nervous system includes cranial nerves and spinal nerves. We have 12 pairs of cranial nerves that extend from the brain to the head's organs. Additionally, there are 31 pairs of spinal nerves that come out of the spinal cord and connect to organs below the head. 1,Cranial Nerves: Originate from the brain and extend throughout the head. 2, Spinal Nerves: Arise from the spinal cord and extend throughout the body, excluding the head. 3. Visceral Nerves: Emerge from the spinal cord and establish connections with internal organs. Reflex Action: A rapid, sudden, and immediate bodily response to a stimulus. Examples include the knee jerk and withdrawing the hand upon touching an object. Reflex Arc: The route traveled by nerve impulses during a reflex action is known as a reflex arc. (Stimulus) (Skin) (Muscles) (Hand Withdrawal) Messaye to train Spinal cond cas Figure 6.2 Reflex are Three Types Of Responses: 1. Voluntary Actions: Governed by the forebrain. Examples include talking and writing. 2. Involuntary Actions: Regulated by the mid and hind brain. Examples encompass heartbeat, vomiting, and respiration. 3.Reflex Actions: Orchestrated by the spinal cord. An instance is the withdrawal of a hand upon touching a hot object. Coordination in Plants: Control and coordination in plants are carried out by hormones. Auxin- Helps in the growth of plant tissues tokinin Promotes cell division, delays ageing of cells ogeing Facilitates stem growth, triggers seed germination, stimulates Gibberellins flowering, supports cell division, and fosters seed development post-germination. Suppresses growth, induces wilting of leaves, pore sees encourages bud and seed dormancy. Ethylene This is a. gas hormone responsible for fruit ripening. 5, Thigmotropism: Movement of plant parts in response to touch is called as thigmotropism. Positive thigmotropism involves movement towards touch, while negative thigmotropism entails movement away from touch. The movement of tendrils around a support is an example of positive thigmotropism. The Endocrine System: Qates miciu: alain « Exocrine Glands: Exocrine glands release their secretions through ducts that open onto an epithelial surface, « Endocrine Glands: Endocrine glands are ductless glands that release hormones directly. into the bloodstream in humans. In the human body, notable endocrine glands include the pituitary, thyroid, adrenal, pineal, pancreas, ovary (female), testis (male), and others. Now, let's delve into each gland to learn more. Pitvitavy Gland: « Pea-sized gland situated at the base of the Pituitary brain « Functionsas- the master gland, overseeing Thyroid the secretions of all other endocrine glands « Produces Growth Hormone (GH), LH, FSH. « Insufficient GH Secretion results in Dwarfism « Excessive GH secretion leads to Gigantism Adrenals in children. « Excessive GH in adylts causes ‘Acromegaly’ Thyroid Gland: * Butterfly-shaped gland i in the throat - * Secretes the hormone ‘Thyroxine,’ which regulates body metabolism * Requires iodine for thyroxine synthesis i in the body * Todine deficiency results in under-secretion of thyroxine « Under-secretion of thyroxine causes goitre *—— Pancreas zo. Ovaries,’ Uterus Prostete/ Testes ——») Paricreas: Leaf-like gland located behind the stomach in the abdomen Functions as both an endocrine and exocrine gland Endocrine furiction involves the production of two hormones: Insulin and glucagon “Insulin andiglucagon act antagonistically to requiate blood sugar levels Exocrine function includes the secretion of enzymes to break down proteins, lipids, carbohydrates, and nucleic acids in food « Insufficient insulin production from the pancreas results in diabetes Adrenal Gland: « Present in pairs above each kidney « Size decreases with age * Secretes adrenaline, a hormone facilitating the flight and fight response * Additionally secretes noradrenaline er | l Gonads: « Gonads are gamete-producing organs: testes in males, ovaries in females * Testes produce androgen (testosterone and other male hormones), while ovaries produce estrogen and progesterone (female hormones) * Androgen and estrogen contribute to gamete production and influence the sexual characteristics of males and females, respectively « Progesterone serves as the pregnancy hormone. IMPORTANT QUESTIONS & 1) What are hormones? Hormones are the chemical substances secreted in trace amounts by specialised tissue called endocrine glands. 2) Trace the sequences of events through a reflex arc which occur when a bright light is focused on your eyes. Photo receptors (EYE) ———=} Sensory neuron ———=} Spinal cord ¥v Effector, ———=- Muscles in Eye (blinking = Motor neuron 3) (a) What is reflex arc? (b) What are the components of reflex arc? (c) How do muscle cells move? a. The process of detecting the signal or the input and responding to it by an output action might be completed quickly. Such a connection is commonly called reflex arc. b. Stimulus " Receptors" Sensory neurons " Spinal cord" Motor neurons “ Effector. c. Muscle cells have special proteins that change their shape and arrangement in the cell in response to electrical impulse, This leads the muscle cells shortening. 4) What are hormones? Name the hormone produced by thyroid gland and state its function. Chemical coordination in animals occurs through chemicals called hormones which are secreted by endocrine glands. Thyroxin hormone. It regulates metabolism of carbohydrates, fats and proteins. It is advisable to consume iodized salt in our food as iodine is required by our thyroid gland to produce thyroxin hormone. If it lacks in our body goiter may occur due to enlargement of thyroid in the neck region. 
