Human Body Systems and Nervous System Flashcards

Flashcards about Homeostasis and the Nervous System

Homeostasis

The maintenance of relatively constant internal conditions despite changes in the external environment.

Maintaining Homeostasis

Maintains homeostasis in the body by using feedback inhibition, also known as negative feedback. Any stimulus triggers a response that reduces the stimulus.

Hypothalamus

Monitors the temperature of the skin and organs to help maintain body temperature.

Nervous System

A communication system only found in multicellular organisms (animals specifically) that contains specialized cells to carry messages from one cell to another to ensure efficient communication between body parts. Structures include the brain, spinal cord, and peripheral nerves.

Functions of the Nervous System

Controls and coordinates all activities in the body and responds to internal and external stimuli.

Neurons

Cells of the nervous system that transmit impulses (electrical signals/messages) from the brain to all other parts of the body.

Sensory Neurons

Carry impulses from the sense organ (skin, eyes, nose, ears, mouth) to the spinal cord to the brain.

Motor Neurons

Carry impulses from the brain to the spinal cord to the muscles and glands.

Interneurons

Connect motor neurons and sensory neurons and carries impulses between them.

Cell Body

Largest part of the neuron, contains the nucleus and where most activity occurs.

Dendrites

Short, branched extensions off the cell body that carry impulses from the environment or from other neurons towards the cell body.

Axon

Long extension (fiber) that carries impulses away from the cell body.

Myelin Sheath

Insulating membrane that surrounds the axon of a neuron (though not all axons have one).

Nodes

Gaps in the myelin sheath where the axon is exposed and where the impulse jumps from node to node, increasing its speed.

Resting Neuron

The state of a neuron when it is at rest; the outside of the cell has a positive charge while the inside has a negative charge, creating an electrically charged cell membrane.

Resting Potential

The charge created by the active transport of Na+ and K+ ions when a neuron is at rest, resulting in a slight positive charge on the outside and a slight negative charge on the inside of the cell membrane.

Action Potential

The reversal of charges (from negative to positive) during the transmission of a nerve impulse.

All or None Principle

States that a stimulus will either produce an impulse or not produce an impulse; there is no in between.

Synapse

The location at which a neuron can transfer an impulse to another cell.

Synaptic Cleft

A space that separates the axon terminal from the dendrites of the next neuron; contains tiny vesicles filled with neurotransmitters.

Neurotransmitters

Chemicals used by a neuron to transmit an impulse across a synapse to another cell.