| A | B |
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| Nervous system | The communication network and control centre of the body. Involved in maintaining homeostasis |
| CNS | Consists of brain and spinal cord |
| Grey matter | Nerve cell bodies and unmyelinated fibre |
| White matter | Myelinated fibre |
| Protective structures for the brain | Cranium, Meninges (tough and fibrous membrane) and cerebrospinal fluid (between meningeal layers and acts as a shock absorber, also carrying nutrients to the brain) |
| Medulla | Automatically adjusts body functions. Contains cardiac centre (regulates heartbeat), Respiratory centre (breathing rhythm) and vasomotor centre (regulates diameter of blood vessels). Also regulates sneezing, coughing, swallowing and vomiting. |
| Hypothalamus | Controls many body activities, mostly concerned with homeostasis. Includes regulation of heart rate, body temperature, movement of food through the alimentary canal, food and water intake, patterns of waking and sleeping, contraction of the urinary bladder, sexual cycles. Also receives impulses from internal organs, associated with fear and anger, and regulates release of hormones from pituitary gland |
| Cerebellum | Consists of parallel ridges, with the outer fold being grey matter, and the inner fold consisting of white matter. Exercises control over posture and balance and fine co-ordination of voluntary muscle movement. Without it, movement would be spasmodic, jerky and uncontrolled |
| Cerebrum | Largest part of the brain. Cerebral cortex in cerebrum has convolutions which increase surface area. sulci and fissures are the downfolds in the brain. Functions include thinking, reasoning, learning, memory, intelligence, perception of senses and voluntary muscle contraction. |
| Deepest fissure | Longitudinal fiisure, which seperates the cerebrum into two halves called the cerebral hemispheres |
| Tracts | Bundles of nerve fibres within CNS |
| Three functional areas in cortex | Sensory area (interpret impulses from receptors), Motor areas (control muscular movement) and Association areas (concerned with intellectual and emotional processes) |
| Brain | Receiver, analyser, co-ordinator, storer and initiator of nervous impulses (integration and control of bodily functions) |
| Spinal cord | Receives info from sensory nerves, carries impulses to and away from brain and provides a link between sensor/motor/brain. Extends from foramen magnum to second lumbar vertebrae. 44cm in length. |
| Somatic | Part of PNS and is concerned with sensory and motor function of the skin, muscles and skeleton. Mainly voluntary. |
| Autonomic | Part of PNS and is concerned with impulses to organs and glands |
| Sympathetic | Involved in changing your internal environment to conditions suited to greater physical activity |
| Parasympathetic | Involved in changing the internal environment to conditions suited at rest |
| Receptors | Photoreceptor, Thermoreceptor, Chemoreceptor, Mechanoreceptor |
| The four different taste perceptions | Sour, Bitter, Salty and Sweet |
| Function of cornea | Helps to bend light rays as they pass into the eye |
| Function of lens | Helps to focus lights rays onto the retina by bending them |
| Function of iris | Regulates the amount of light entering the ye by changing the size of the pupil. Pigmented and gives the eye colour. |
| Function of pupil | Opening that allows light to enter the eye |
| Function of aqueous humour | Helps bend light, supplies nutrients to lens/cornea, maintains eye shape |
| Conjuctiva | A thin membrane which protects the delicate cornea |
| Suspensory ligaments | Support and holds lens in shape |
| Ciliary body | Changes shape of lens by contracting and relaxing |
| Sclera | White of the eye. Protects the delicate inner structures and helps maintain eyes round shape. Tough and fibrous. |
| Vitreous humour | Maintains shape of eye and keeps retina in contact with choroid |
| Fovea | Area of most acute vision (large conc. of cones) |
| Optic nerve | Carries nerve impulses to the brain |
| Blind spot | No photoreceptors |
| Retina | In it are nerve cells responsible for vision. Contains rods and cones which convert light into nervous impulses |
| Chorios | Absorbs light preventing reflection in the eye |
| Rectus muscle | Helps to move the eyeball |
| Protective structures of the eye | Eye sockets (orbits), Sclera, eyelids, conjuctiva and tear glands |
| Eyelids | Can be closed over the eyes to prevent damage from foreign objects or intense light. Regular blinking keeps the exterior of the eye moist and free of dust |
| Tear gland | Tears contain salts and an enzyme, lysozyme, which kills bacteria. Keeps the surface of the conjuctiva moist, wash away dust and helps prevent bacterial infection. |
| Rods | Cylindrical shaped, highly sensitive to light, can detect the amount of light. More numerous around the side of the retina. |
| Cones | Flask shaped. Three types, each activated by either red light, green light or blue light. Responsible for colour vision. |
| Fight or flight | Sympathetic division |
| Cell body | contains nucleus, cytoplasm and organelles |
| Myelin sheath | Speeds up impulses, insulates and protects axon |
| Node of ranvier | Gaps in sheath that allow the chemical part of the nervous impulses take place |
| Dendrite | carry nervous impulses into the cell body |
| Nucleus | controls the neuron |
| Neurilemma | helps to repair damaged nerve fibres |
| Axon | Carry nervous impulses away from the cell |
| Schwann cell | Regeneration of nerve fibres and production of myelin sheath |
| Filament | Transports impulses to motor end plate |
| Motor end plate | Point at which impulse passes to muscle causing contraction |
| Reflex | Fast, automatic response to a change in the external or internal environment |
| Differences in the two hemispheres of the brain | Left = language ability, right = musical and artistic ability |
| central canal of spinal cord | space in spinal cord that contains cerebrospinal fluid |
| ascending tracts | Sensory axons in spinal cord that carry impulses towards the brain |
| Descending tracts | Motor axons in the spinal cord that conduct impulses down from the brain |
| Afferent/sensory division of PNS | Fibres that carry impulses into the CNS. Has somatic sensory nerve cells that carry impulses into the CNS from receptors in the skin and around the muscles and joints, and visceral sensory nerve cells that take impulses from internal organs into the CNS. |
| Efferent/motor division of PNS | Is subdivided into the somatic and autonomic divisions (which then is subdivided into sympathetic and parasympathetic divisions). SD carries impulses from CNS to skeletal muscles and is under conscious control (voluntary movement). AD carries impulses from CNS to hear muscle, involuntary muscle and glands. |
| Spinal reflex | When a reflex is carried out by the spinal cord alone, meaning the brain is not involved and it is involuntary. |
| Reflex arc | Pathway a nerve impulse follows in travelling from a receptor to an effector |
| Reflex arc components | Receptor, sensory neuron, synapse, motor neuron and effector |
| Protective reflexes | Blinking, sneezing or coughing when something irritates the nose or trachea, constriction of the pupil in response to intense light |
| Receptor | Detect stimuli and as a result generates nerve impulses |
| Sensation | When you become consciously aware of the stimulus. Occurs when nerve impulses conduct from receptor to cerebral cortex. |
| Skin receptors | Touch, pressure, cold, heat and pain. |
| Myopia | Short sightedness. Distant objects are fuzzy because only light rays from close objects can be brought to focus by retina. Can be corrected by concave lenses. |
| Hypermetropia | Long sightedness (can see distant clearly, cant see close objects). Convex lens help. |
| Astigmatism | Curvature of cornea or lens is not uniform. Cylindrical lenses can help. |
| cells | Basic structural and functional units of the body |
| tissue | Group of cells, working together to perform a common function. Cartilage bone, muscle and blood are examples. |
| Organs | Tissues grouped together to form functional units such as heart, liver, kidney and brain |
| System | Organs associated together to form this and carry out one or more vital functions of the body. Eg nervous system, skeletal system, excretory system and circulatory system |
| Cellular respiration | Organic molecules are broken down to make energy available for cell's activities, such as movement of the cell or uptake of minerals from surroundings |
| Synthesis | Involves building up large molecules from simple ones. Some of the energy released by cell respiration can be used for this |
| Growth | Increase in size of cell by synthesis of new structural material |
| Processes cells undertake | Cellular respiration, synthesis and growth |
| Independance of cells | In an organism that consists of only one cell, that cell is completely independant and able to carry out all cellular functions |
| Interdependance | When cells have become specialised for part. functions, the cells and tissues depend on one another to perform essential tasks, to supply them with materials and to remove their wastes |
| Respiratory system | Takes oxygen from the air and releases carbon dioxide to the air |
| Digestive system | Arranged to break down and absorb nutrient materials |
| Circulatory system | Delivers oxygen and nutrients to the cells and carries away the wastes |
| Excretory system | Removes the waste from the body |
| Nervous system | Coordinates the activities of the other systems. Detects when the body is beginning to vary from its normal balanced state and sends messages to the appropriate organs so that change is counteracted |
| Homeostasis | Maintenance of a constant internal environment. All systems of the body contribute to homeostasis |
| Extracellular fluid | Fluid outside body cells. Includes plasma and intercellular/interstitial/tissue fluid (fluid between cells). Contains a high conc. of sodium chloride |
| Intracellular fluid | Fluid occurring inside cells. Low conc of NaCl, mainpositive ions instead are K+ ions, and negative are ions from a variety of organic substances |
| Homeostasis ensures in a fluid environment of the cells | Contains optimum conc. of nutrients, ions, gases and water. Stays at a constant temp (optimum temp for normal cell functioning). Is maintained at the optimum pressure. |
| Steady state | Dynamic equilibrium in which input and output of materials and energy are balanced |
| To maintain homeostasis, what must the body be able to do | Must be able to sense changes in the internal and external environment and must be able to compensate for the changes |
| Feedback system | Circular situation in which the body responds to a change (stimulus), and the response alters the original stimulus |
| Negative feedback system | Response causes the stimulus, or variable, to change in a direction opposite to that of the original change |
| Stimulus | change in the environment that causes the system to operate |
| Receptor | Detects the change |
| Modulator | Control centre responsible for processing information to the effector |
| Effector | Carries out a response counteracting the effect of the stimulus |
| Feedback | Achieved because the original stimulus has been changed by the response |
| Physiological | Internal functioning of the body |
| Behavioural | Do something to help a certain constant |
| Endocrine system | Consists of glands that secrete chemical messages, or hormones, into the blood |
| Neuron | Nerve cell, the basic structural and functional unit of the nervous system |
| Cell body | Part of the neuron that contains the nucleus |
| Dendrites | Short extensions of the cytoplasm of the cell body. Highly branched and carry nervous messages INTO the cell body |
| Axon | Single, long extension of the cytoplasm, that carries messages or nerve impulses AWAY from the cell body |
| Myelin Sheath | Fatty material covering axons. Acts as an insulator, protects the axon from damage and speeds movement of nervous impulses along the axon |
| Nerve fibre | Axon with its associated covering |
| Myelinated fibres | Have myelin sheath |
| Schwann cells | Myelin sheath for outside the brain and spinal cord are formed here, which wrap around the fibre |
| Nodes of Ranvier | Gaps in the myelin sheath |
| Neurilemma | Membrane which surrounds myelin sheath and helps repair injured fibres |
| Neuron types | Sensory (receptor), Motor (effector) or connector |
| Sensory neuron | Carry messages from receptors in the sense organs, or in the skin, to the brain and spinal cord |
| Motor neuron | Carry messages from the brain and spinal cord to the effectors - the muscles and glands |
| Connector neurons | Located in the brain and spinal cord and are the link between the sensory and motor neurons. May also be called association neurons or interneurons |
| Nerve | A bundle of nerve fibres held together by connective tissue |
| Motor end plate | The point where each branch of the motor neuron meets the muscle fibre |
| Synapse | Junction between the branches of adjacent neurons, as nerve impulses must be passed form neuron to neuron (small gap though). Occur between the terminal branches of an axon of one neuron and a dendrite or the cell body of another neuron |
| Neuromuscular junction | Small gap existing where an axon meets a skeletal muscle cell |
| Quickest way body has of maintaining homeostasis | Sending messages in the form of nerve impulses |
| Acetylcholine | Neurotransmitter, acetylcholine activates muscles, and is a major neurotransmitter in the autonomic nervous system. When acetylcholine binds to acetylcholine receptors on skeletal muscle fibers, it opens ligand gated sodium channels in the cell membrane. Sodium ions then enter the muscle cell, stimulating muscle contraction. Acetylcholine, while inducing contraction of skeletal muscles, instead inhibits contraction in cardiac muscle fibers. This distinction is attributed to differences in receptor structure between skeletal and cardiac fibers. Sympathetic response. |
| Adrenaline | Participates in flight or fight response of the sympathetic nervous system. Produced from adrenal glands, it plays a role in short term stress reaction. Increases heart rate etc |
| Curare | 'indian arrow poison' which depress transmissions. Inhibits muscular contraction by preventing acetylcholine from binding with muscle cells at the neuromuscular junction. |
| refraction | bending of light as it passes from one medium to another |
| accomodation | Ability of the lens to change shape and focus light rays |
| rhodopsin | A pigment found in the rods and reddish-purple in colour. Highly sensitive to light, thus allowing rods to enable us to see in dim light |
| presbyopia | Loss of flexibility of lens due to old age. convex lenses needed. |
| Ear | Involved in hearing and the maintenance of the body's equilibrium (balance) |
| outer ear | Collects sound waves and directs them inwards towards rest of ear (invovles the pinna and auditory canal, ending at the tympanic membrane) |
| What does the external opening at the auditory canal secrete, and why? | Glands secrete cerumen (ear wax) which help prevent foreign objects from entering the auditory canal |
| Eustachian tube | Connects the middle ear to the throat. Involved in air presure equalisation. |
| Middle ear tiny bones and function | Auditory ossicles named the malleus, incus and stapes. Are joined together to transfer movment from the tympanic membrane to the oval window. |
| Sound | Produced by vibrating objects. As the objects vibrate it produces regions in which the air molecules are squeezed together (compressions) and a region where the air molecules are further apart (rarefactions). Alternating c and r's are the sound waves that spread out in all directions from a vibrating object, which is then detected by the Organ of Corti in the cochlea of the ear |
| Sequence of events to allow us to hear sound | 1. Sound waves reaching ear are collected by the pinna and directed to the auditory canal. 2. Sound waves travel along the auditory canal to the tympanic membrane. 3. When a compression strikes the tympanic membrane it is pushed in, during the rarefaction that follows, it bulges out again. Thus, the membrane vibrates. 4. Vibration of the tympanic membrane makes the malleus move back and forth. This movement is passed on the incus and stapes, the three bones acting as levers to transmit the movement across the middle ear. Oval window is pushed in and out by the movement of the stapes. 6. Movement of the oval window causes waves of movement in the perilymph to the scalar vestibuli. 7. Movements of the perilymph distort the membranes and bring about movement in the endolymph inside the cochlear duct. 8. Hair cells of the organ of corti are stimulated, and the nerve impulses are transmitted to the brain. 9. At the same time that stimulation of the sensory cells is occuring, movement in the perilymph of the scala vestibuli is transferred to the liquid of the scala tympani. 10. When movement of the perilymph in the scala tympani reaches the round window, the round window moves in the opposite direction. |
| What our ears can do (in terms of sound) | Distinguish different pitches, volumes and the direction the sound is coming from. |
| Neurotransmitter | Special chemicals released from axon endings which diffuse across the gap and attach to the receptors of the next neuron. They are substances that diffuse across the synapse. |
