| A | B |
|---|
| 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 funtional 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 | Coordiantes 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 occuring 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 bood |
| 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, whcih wrap areound 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 maintaing homeostasis | Sending messages in the form of nerve impulses |
| Positive and negative electrical charges | Two charges the same - repel, unlike charges attract. When unlike are separated, an electrical force tend to draw them together |
