| A | B |
|---|
| Tissues – | groups of similar cells that perform a single function |
| Organs – | group of tissues that work together to perform a complex function |
| Organ Systems – | group of organs that perform closely related functions |
| Homeostasis | Humans contain 11 organ systems that work together to maintain a stable internal environment |
| muscle tissue | Most abundant, Controls the internal movement of materials,Example: pushing food through the digestive system, Controls the external movements of the entire body or parts of the body,Example: typing on a keyboard |
| Epithelial Tissue | Cover the surface of the body and line internal organs |
| Connective Tissue | Holds organs in place and binds different parts of the body together |
| Nervous Tissue | Receives messages from the body’s external and internal environments |
| Feedback Inhibition | Process by which the product of a system shuts down the system or limits its operation, Examples:Furnace in a house,Temperature regulation in the body,Human Menstrual Cycle |
| The nervous system... | controls and coordinates functions throughout the body. The nervous system is one of the body’s communication systems. Without communication, parts of the body could not work together smoothly. |
| Human Nervous System | Function – controls and coordinates functions throughout the body and responds to internal and external stimuli |
| Neurons (Nerve Cells) | Cells that transmit impulses (electrical signals) |
| Types of Neurons | sensory, motor, interneuron |
| Sensory neurons | carry impulses from the sense organs to the spinal cord and brain |
| Motor neurons | carry impulses from the brain and spinal cord to muscles and glands |
| Interneurons (associative neurons) | – connect sensory and motor neurons and carry impulses between them |
| Parts of Neurons | Cell Body, Dendrites, Axon, Myelin Sheath |
| Cell Body | Largest part of a typical neuron,Contains the nucleus and cytoplasm,Most metabolic activity of the cell takes place in the cell body |
| Dendrites | Branched extensions, Carry impulses from the environment or from other neurons toward the cell body |
| Axon | Long fiber that carries impulses away from the cell body, Ends with axon terminals (small swellings) |
| Myelin Sheath | Insulating membrane that surrounds some of the axons, Increases the speed at which the impulse can travel |
| Nerve Impulse | Production depends on the movement of positively charged ions across a cell membrane |
| Resting Potential | Difference in electrical charge across the cell membrane of a resting neuron, Negative charge builds up on the inside of the membrane,Positive charge builds up on the outside of the membrane |
| Action Potential | Reversal of charges, Inside membrane gains a positive charge and the outside gains a negative charge |
| Threshold | Minimum level of a stimulus that is required to activate a neuron |
| Synapse | Location at which a neuron can transfer an impulse to another cell,Gap (small cleft) which separates the axon terminal from the dendrites of the adjacent cell, Terminals contain tiny sacs (vesicles) filled with neurotransmitters |
| Neurotransmitters | Chemicals used by a neuron to transmit an impulse across a synapse to another cell, Diffuse across the gap and attach themselves to receptors on the membrane of the neighboring cell, Examples: Acetylcholine & Norepinephrine |
| Divisions of the Nervous System | Central Nervous System, Peripheral Nervous System |
| Central Nervous System | Relays messages, processes information, and analyzes information, Consists of the brain and the spinal cord,Wrapped in connective tissue (meninges), Cerebrospinal fluid protects the brain and spinal cord and serves as a site for exchange |
| Cerebrum | Site of intelligence, learning, and judgment |
| Cerebellum | Coordinates and balances the actions of the muscles |
| Brain Stem (pons and medulla oblongata) | “switchboard” regulating the flow of information between the brain and the rest of the body |
| Thalamus | Receives messages from the sense organs and relays the information to the proper region of the cerebrum |
| Hypothalamus | Control center for recognition and analysis of hunger, thirst, fatigue, anger, and body temperature |
| Spinal Cord | Pathway that delivers messages to the brain or moves messages from the brain, Responds to stimuli requiring reflex reaction, |
| Peripheral Nervous System | Receives information from the environment and relays commands from the central nervous system to organs and glands, Consists of all of the nerves and associated cells that are not part of the brain and the spinal cord |
| Divisions of the Peripheral Nervous System | sensory and motor |
| Sensory | Transmits impulses from sense organs to the central nervous system |
| Motor | Transmits impulses from the central nervous system to the muscles or glands |
| Motor Division | Somatic Nervous System, Autonomic nervous System |
| Somatic Nervous System | Regulates activities that are under conscious control, Examples: moving skeletal muscles |
| Autonomic nervous System | Regulates activities that are automatic or involuntary, Examples: heartbeat, contraction of smooth muscles in the digestive system |
