1. List the four biological levels of organization in a human in order from most simple to most complex. Cells, tissues, organs, organ systems
2. Define the term “homeostasis”.
The tendency of the body to maintain a relatively constant internal environment.
3. What does the term “feedback system” refer to with respect to homeostasis? A cycle of events in which a variable, such as body temperature, is continually monitored, assessed, and adjusted.
4. List the three components of a feedback system and describe each briefly. A sensor that detects a change in the internal environment and sends a signal to a control centre A control centre that sets the range of values with which a variable should be maintained, receives information from a sensor, and sends signals to an effector An effector that receives signals from the control centre and responds, resulting in a change to an internal variable
5. Summarize the connection between the integumentary system and the nervous system. The sensory receptors in the integumentary system communicate with the brain and spinal cord via the nerves (the three parts of the nervous system).
6. Using the stomach as an example, illustrate the four biological levels of organization as a human. The stomach is composed of individual cells. Cells of the same type that perform a common function make up tissues, such as those that line the stomach. One or more tissues interact to form more complex structures known as organs, such as the stomach. Several organs, such as the stomach and small intestine, are organized structurally and functionally to form an organ system, such as the digestive system.
7. Explain why the nervous system is critical for maintaining homeostasis. The human nervous system can regulate tens of thousands of activities simultaneously. Its overall function is to collect information about the external conditions in relation to the body’s internal state, analyze it, and initiate appropriate responses to maintain homeostasis.
8. Create a table to identify the different systems in the nervous system and explain the structure and function of each. System
Central nervous system
The spinal cord carries messages from the body to the brain. The brain interprets these messages. The brain then passes response messages through the spinal cord to target structure such as a muscle, gland, or neuron. Peripheral nervous system
Somatic nervous system
Autonomic nervous system
The sympathetic nervous system controls organs in times of stress (fight or flight). The parasympathetic nervous system causes a return to a state of rest and controls organs when the body is at rest.
9. Compare and contrast the basic function of neurons and glial cells. Neurons are the basic structural and functional units of the nervous system. They are specialized to respond to physical and chemical stimuli, to conduct electrochemical signals, and to release chemicals that regulate various body processes. Glial cells support neurons. These cells nourish the neurons, removing their wastes, and defend against infection. Glial cells also provide a supporting framework for all of the nervous-system tissue.
10. Draw a neuron, label its basic structures, and identify their functions. Dendrites – receives impulses from other neurons and conduct impulses to the cell body Cell body – site of the cell’s metabolic reactions and relay gatekeeper for nerve impulses sent down the axon Axon – conducts impulses away from the cell body
Schwann cell – type of glial cell that wraps around the axon to form the myelin sheath, insulating the axon and speeding up impulses Node of Ranvier – spaces between adjacent Schwann cells involved in impulse transmission
11. List three types of neurons based on structure. Explain the differences among these three neurons. Sensory neurons – gather information from sensory receptors and transmit...
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