Grade 9 Biology Unit 1 PDF

Unit 1 Grade 9 Nervous system 1  Study Subject Grade Date Block week Unit/Lesson/Topic...

Unit 1 Grade 9 Nervous system 1  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 1 1.2.15. conduct simple experiments to deduce the stimulus-response pathway that controls a person's response to a stimulus, and depict it diagrammatically, with reference to sense organs and effector organs (muscles and glands). Learning 1.2.16. describe the human central nervous system (brain and spinal Outcome cord as areas of coordination) and the peripheral nervous system, which /Objective: together serve to coordinate and regulate body functions Objectives: Identify that in humans and other vertebrates the central nervous system (CNS) is made up of the spinal cord and brain. Show understanding for somatic and autonomic nervous system Student ………………………………………………………………………………………………………………………. Class 8A Name: 2  Nervous system The human nervous system consists of: the central nervous system (CNS) – the brain and spinal cord the peripheral nervous system – nerve cells that carry information to or from the CNS The human nervous system is divided into two subdivisions: 1- The first is the central nervous system (CNS) and 2- The second is the peripheral nervous system (PNS). The central nervous system with its two components (Brain and spinal cord) represents the center of processing and taking decisions and they are located at the center of the body, separating the human body into two symmetric halves (mirror image). From the CNS parts emerge a network of nerves (PNS) that connect and communicate the CNS to the rest of the body organs (the sensory organs and the effector organs). 3 The Nervous System The human nervous system consists of the: o central nervous system (CNS) – the brain and the spinal cord o peripheral nervous system (PNS) – all of the nerves in the body It allows us to make sense of our surroundings and respond to them and to coordinate and regulate body functions Information is sent through the nervous system as nerve impulses – electrical signals that pass along nerve cells known as neurons A bundle of neurons is known as a nerve Function of Nervous system: The nervous system processes and interprets sensory input and decides what actions should be taken. The nervous system activates effector organs such as muscles and glands to cause a response called motor output. At a more integrative level, the primary function of the nervous system is to control and communicate information throughout the body. It does this by extracting information from the environment using sensory receptors. This sensory input is sent to the central nervous system, which determines an appropriate response. Control (processing and taking decision) Connect and communicate the parts of the nervous system. 4  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 1 1.2.16. describe the human central nervous system (brain and spinal cord as areas of coordination) and the peripheral nervous system, which together serve to coordinate and regulate body functions. 1.2.19. Classify sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals 1.2.15.conduct simple experiments to deduce the stimulus-response pathway that controls a person's response to a stimulus, and depict it Learning diagrammatically, with reference to sense organs and effector organs Outcome (muscles and glands) /Objective: Objectives: Show understanding for somatic and autonomic nervous system. Student ………………………………………………………………………………………………………………………. Class 8A Name: 5 The peripheral nervous system (PNS) consists of the nerves that branch out from the brain and spinal cord. These nerves form the communication network between the CNS and the body parts. The peripheral nervous system is further subdivided into the somatic nervous system and the autonomic nervous system. 6  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 2 1.2.17.investigate a variety of simple reflexes, and explain the significance of a simple reflex arc (including sensory, relay and motor neurons) as a means of automatically and rapidly integrating and coordinating stimuli with responses, modelling transmission at a synapse. 1.2.18. Compare and contrast the way in which different sense organs enable an individual to respond to the environment. 1.2.16. Describe the human central nervous system (brain and spinal cord as areas of coordination) and the peripheral nervous system, which together serve to coordinate and regulate body functions Objectives: Identify that nervous systems are made up of neurons (nerve cells) linking receptor cells (e.g., in eyes, ears and skin) to effector cells (in Learning muscles/glands). Outcome Identify that nervous systems are made up of neurons (nerve cells) /Objective: linking receptor cells (e.g., in eyes, ears and skin) to effector cells (in muscles/glands). Recall that in the mammalian nervous system the CNS (brain and spinal cord) is connected to the body via the peripheral nervous system (pns) (sensory and motor neurons. Explain how the CNS coordinates an animal’s responses via : ▪ sensory neurons carrying impulses from receptors to the CNS. ▪ motor neurons carrying impulses from the CNS to effectors Differentiate between the structure of relay, sensory and motor neurons Describe that within the CNS, impulses are passed from sensory neurons to motor neurons through relay neurons. Student ………………………………………………………………………………………………………………………. Class 8A Name: 8 Nerve cells - The smallest Building unit of the human body is the cell. - The functional unit of the nervous system is the Nerve cell (Neuron). - Their shape is adapted to perform a specific function which is to carry electrical impulses from one place to another: - They have a long fiber (axon) which is insulated by a fatty sheath (myelin sheath) - They have tiny branches (dendrons) which branch further as dendrites at each end - Dendrites These are branch-like structures that receive messages from other neurons (at the terminals) and allow the transmission of messages to the cell body forming a Synapse. - Cell Body Each neuron has a cell body with a nucleus, Golgi body, endoplasmic reticulum, mitochondria and other components. - Axon Axon is a tube-like structure that carries electrical impulse from the cell body to the axon terminals that pass the impulse to another neuron. - Synapse It is the chemical junction between the terminal of one neuron and the dendrites of another neuron. 9  Types of Neurons There are three main types of neurons: sensory, relay and motor o Sensory neurons carry impulses from sense organs to the CNS (brain or spinal cord) o Relay neurons are found inside the CNS which connects sensory and motor neurons o Motor neurons carry impulses from the CNS to effectors (muscles or glands) Neurons have a long fiber (axon) This means that less time is wasted transferring the impulse from one cell to another The axon is insulated by a fatty sheath with small uninsulated sections along it (called nodes) This means that the electrical impulse does not travel down the whole axon, but jumps from one node to the next Their cell body contains many extensions called dendrites This means they can connect to many other neurons and receive impulses from them, forming a network for easy communication. Identifying the types of neurons: Sensory neurons are long and have a cell body branching off the middle of the axon Relay neurons are short and have a small cell body at one end with many dendrites branching off it Motor neurons are long and have a large cell body at one end with long dendrites branching off it 10  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 2 1.2.15. Conduct simple experiments to deduce the stimulus-response pathway that controls a person's response to a stimulus, and depict it diagrammatically, with reference to sense organs and effector organs (muscles and glands). 1.2.16.describe the human central nervous system (brain and spinal cord as areas of coordination) and the peripheral nervous system, which together serve to coordinate and regulate body functions Objectives: recall that a stimulus is a change in the environment of an organism. Learning state that simple reflexes produce rapid involuntary responses Outcome to stimuli. /Objective: Identify reflex as automatic nervous reaction that cannot be concisely controlled. Recall examples of simple reflexes in humans, to include new- born reflexes (e.g., stepping, grasping, sucking), pupil reflex, knee jerk and dropping a hot object. Identify that nervous co-ordination, including simple reflexes, requires: O Receptors to detect stimuli o Effectors to produce the response. Identify that reflexes have a protection function Student ………………………………………………………………………………………………………………………. Class 8A Name: 11 The stimulus response pathway The stimulus response pathway is the route starting from the stimulus that is detected by the receptor cells in the sense organ to the response produced by a part of the body called an effector organ. This pathway is controlled by the central nervous system (CNS) as shown in the diagram below. When you hear a phone ring you go to pick up the call. Do you know how this reaction happens? Your ear detects the sound, then send a message to the brain which recognize that this sound is of the phone ring and take the decision that you need to go pick up the call. Well, how exactly your ear did so? There are specialized cells in your ear that detects the sound these cells are called the receptor cells and the sound here is called the stimulus. These receptor cells send the sound (stimulus) in a form of a signal to the brain. The brain recognize the sound, it is the phone ring and tell you through another signal that you should go pick the phone call (the response) The signals that are sent by the receptors and rece ived b y t he eff ectors should be carried b y certa in signal ca rriers which are the nerves (we will ref er to them here as neurons). There are three t ypes of neurons that take part in this path wa y: 12  The sensor y neuron: Carries the signa l from the receptors (sense organs) to the central nervous us system (CNS). The motor neuron: Carries the signal from the CNS to the eff ector organ (muscle or glands). The rela y neuron : also kno wn as the interneuron, are found in the CNS, they connect the sensory and motor neurons. Th e compon ents of the sti mul us – respo nse pathw ay The stimulus: A change in the surrounding environment. Receptors: Specialized cells in the sense organ (ex: ear) that detect the stimulus. Central nervous system: The center of processing and taking decision (the brain or the spinal cord). The effector: The organ that produces the response, it is either a muscle or a gland. The neurons: Carry the signals from and to the components of the pathway (Sensory, Relay and Motor). 13  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 2 1.2.18. compare and contrast the way in which different sense organs enable an individual to respond to the environment. 1.2.19.classify sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals Objectives: investigate skin sensitivity to single and double stimuli as an example for nervous response. Learning Describe how the tongue through taste buds detect different chemical Outcome /Objective: stimuli Research the parts of the ear and describing how the ear detects sound Describe how sense organs detect chemical stimuli and send to the brain. Student ………………………………………………………………………………………………………………………. Class 8A Name: 14  The diagram summarizes how information flows from receptors to effectors in the nervous system. Receptors Receptors are groups of specialized cells. They can detect a change in the environment (stimulus) and produce electrical impulses in response. Sense organs contain groups of receptors that respond to specific stimuli.. Sense uli Sense Stimulus Receptor cells organ Sight Eye Light Rods and cons Hearing Ear Sound Corti g Tasting Tongue Chemicals in food Taste buds Smell Nose Chemicals in air Olfactory receptors Touch Skin Pain, temperature, Several specialized pressure, receptors etc. Effectors Effectors are parts of the body - such as muscles and glands - that produce a response to a detected stimulus. For example: a muscle contracting to move an arm muscle squeezing saliva from the salivary gland a gland releasing a hormone into the blood This diagram summarizes how information flows from receptors to effectors in the nervous system. 15  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 3 1.2.15. Conduct simple experiments to deduce the stimulus-response pathway that controls a person's response to a stimulus, and depict it diagrammatically, with reference to sense organs and effector organs (muscles and glands). 1.2.17. Investigate a variety of simple reflexes, and explain the significance of a simple reflex arc (including sensory, relay and motor neurons) as a means of automatically and rapidly integrating and coordinating stimuli with responses, modelling transmission at a synapse Objectives: Learning state that simple reflexes produce rapid involuntary responses Outcome to stimuli. /Objective: Identify reflex as automatic nervous reaction that cannot be concisely controlled. Define the simple reflex arc Recall examples of simple reflexes in humans, to include new- born reflexes (e.g., stepping, grasping, sucking), pupil reflex, knee jerk and dropping a hot object. Describe the nervous pathway of a spinal reflex arc to include receptor, sensory neuron, relay neuron, spinal cord, motor neuron and effector. Identify that reflexes have a protection function Student ………………………………………………………………………………………………………………………. Class 8A Name: 16  Reflex Action: A reflex action is a way for the body to automatically and rapidly respond to a stimulus to minimize any further damage to the body. It follows this general sequence and does not involve the brain: Stimulus → receptor → sensory neuron → relay neuron → motor neuron → effector → response The nerve pathway followed by a reflex action is called a reflex arc. For example, a simple reflex arc happens if we accidentally touch something hot. 1. Receptor in the skin detects a stimulus (the change in temperature). 2. Sensory neuron sends impulses to relay neuron 3. Motor neuron sends impulses to effector. 4. Effector produces a response (muscle contracts to move hand away). Sensory Neuron Relay Neuron Motor Neuron 17  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 3 1.2.17. Investigate a variety of simple reflexes, and explain the significance of a simple reflex arc (including sensory, relay and motor neurons) as a means of automatically and rapidly integrating and coordinating stimuli with responses, modelling transmission at a synapse 1.2.18.compare and contrast the way in which different sense organs Learning enable an individual to respond to the environment. Outcome Objectives: /Objective: Define synapse. Identify parts of the synapse. Describe how synapse transmits an impulse from one neuron to another. State that nervous systems use electrical impulses for fast, short- lived responses including simple reflexes. Student ………………………………………………………………………………………………………………………. Class 8A Name:. 18 - The synapse: A synapse is a junction between two neurons across which electrical signals pass. The human body contains up to 500 trillion synapses. When a nerve impulse arrives at the end of one neuron it triggers the release of neurotransmitter molecules from synaptic vesicles The neurotransmitters diffuse across the synaptic cleft and bind with receptors on the next neuron, triggering another impulse. Main steps of synapse: 1-Axon (1st neuron A ) carrying electrical impulse 2- Neurotransmitters enclosed in vesicles in the presynaptic membrane will be stimulated by the electrical impulse 3- The vesicle will open and neurotransmitters will be released in the synaptic cleft 4- Postsynaptic membrane receive the neurotransmitters by certain receptors 5-Axon ( 2nd neuron ) will be having an electrical impulse exactly similar to the previous one. 19 Parts of Synapse: A: Neuron (Presynaptic) B: Neuron (Postsynaptic) 1. Mitochondria 2. Synaptic vesicle full of neurotransmitter 3. Auto receptor 4. Synaptic cleft 5. Neurotransmitter receptor 6. Calcium Channel 7. Fused vesicle releasing neurotransmitter 8. Neurotransmitter re- uptake pump 20  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 4 and 5 1.2.20. Apply knowledge of the structure and function of the eye to explain changes in the eye in response to light levels (pupil reflex), and close and distant 1.2.21. Investigate how the blind spot affects vision and describe the function and distribution of rods and cones. Objectives: Describe the structure if the eye Describe the function of the parts of the eye Learning Explain the pupil reflex Outcome Explain the accommodation of the eye to view near and distant /Objective: objects State the distribution of rods and cons in the retina of a human Describe the function of rods and cons demonstrate that images that fall on the blind spot are not seen and the brain fills in the gap using information from rods and cones on either side of the blind spot. Investigate how the blind spot affects vision. Investigate the pupil reflex Student ………………………………………………………………………………………………………………………. Class 8A Name: 21 The eye The eye is a sense organ that responds to light Structure Function Cornea Refracts light - bends it as it enters the eye Iris Controls how much light enters the pupil Lens Focuses light onto the retina Retina Contains the light receptors Optic nerve Carries impulses between the eye and the brain The Eyelid: protect the eye The sclera, or white part of the eye, protects the eyeball. The iris Pigmented (decides the color of your eyes). The pupil, or ( black dot at the center of the eye), is a hole through which light can enter the eye. 22  The main parts of the eye are: 1- Cornea 2- Iris 3- Lens 4- Retina 5- Optic nerve 1- Cornea: Front part of the tough outer coat, the sclera. It is convex and transparent. It refracts light - bends it as it enters the eye. 2- Iris: Pigmented - decides the color of your eyes – so light cannot pass through. Its muscles contract and relax to alter the size of its central hole or pupil. 3-lens: Transparent, Bi-convex, Flexible disc behind the iris attached by the suspensory ligaments to the ciliary muscles. Focuses light onto the retina. 4-The retina: Light passes through the eyeball to the retina. Contains the receptor cells. There are two types of receptor cells (Rods and Cones) Rods are more sensitive to light than cones. There are three different types of cone cells which produce color vision. A photograph of a human retina seen through the eye. 23  Rods Cones Number in the retina 120 million 7 million Where concentrated Outer edges of the retina The fovea Work best in Dim light Bright light 24 Fovea The part of the retina that has many more cones than rods The blind spot An area in the retina that contains no receptor cells (Rods and Cones) and found at the beginning of the optic nerve. There is no image detection in this spot. 5- Optic nerve: Bundle of sensory neurons at back of eye. Carries impulses from the eye to the brain. The pupil reflex The amount of light entering the eye is controlled by a reflex action. The size of the pupil changes in response to bright or dim light. This is controlled by the muscles of the iris. It is contraction and relaxation of the muscles of the iris (circular and radial). 13 25 In bright light: 1. Radial muscles of the iris relax. 2. Circular muscles of the iris contract. 3. Less light enters the eye through the contracted pupil. In dim li ght : Radial muscles of the iris contract. Circular muscles of the iris relax. More light enters the eye through the dilated pupil. 14 26 Pathway of light For the light to be focused on the retina, it should be refracted (the rays should be bent) by the cornea and the lens. Accommodation The ability of the lens to change its shape to focus near and distant objects is called accommodation. Accommodation = Adjustment It is the adjustment of the eye to see objects at various distances. 15 27 There are two parts of the eye muscles involved in the lens accommodation: Ciliary muscles Suspensory ligaments Changes during accommodation: (A) contraction of ciliary muscles; (B), approximation of ciliary muscles to lens; (C), relaxation of suspensory ligament; (D), increased curvature of anterior surface of lens. The following diagram shows the changes that occur to the ciliary muscles, suspensory ligaments and consequently the lens. Judging distance Your brain gets information from the eyes about how much they are pointing toward each other. Using that information, the brain can tell how far away any object is, whether it is a baseball or a paper clip. Position of Ciliary Suspensory Muscle tension Lens object muscles ligaments on lens shape Near Contract Slackened Low Fat Distant Relax Stretched High Thin 28  Study Subject Grade Date Block week Unit/Lesson/Topic sheet Science 9 1 6 1.2.17.investigate a variety of simple reflexes, and explain the significance of a simple reflex arc (including sensory, relay and motor neurons) as a means of automatically and rapidly integrating and coordinating stimuli with responses, modelling transmission at a synapses. Objectives: Learning Investigate response times by catching a ruler dropped between Outcome their fingers explaining the difference in response time. /Objective: Student ………………………………………………………………………………………………………………………. Class 8A Name: 29 Test Your reaction time: Reaction time is the time taken for a person to respond to a stimulus. For example if you touch something very cold, there is a slight delay between you touching it and moving your hand away, because it takes time for the information to travel from your hand, to your brain where it is processed and then a response started. Material: 30 Cm ruler Stop watch Friends Steps: Hold the top of the ruler with your arm stretched out. Your fingers should be on the highest measurement. Ask a friend to put their thumb and index finger slightly open at the bottom of the ruler, with the ruler between their fingers. Drop the ruler and record the measurement on the ruler where the other persons fingers are. Repeat for all participants. Let each person have three attempts and record the average value. The person with the fastest reaction time is the one who catches the ruler at the lowest measurement, as the sooner the ruler is caught the less time it has had to fall. 30