Biology(3) Neurons

Neuron / Nerve cell

• basic unit of the nervous system

• carries impulses to the nervous system

Parts of neuron

dendrites, nucleus, cell body, axon, nodes of Ranvier, myelin sheath cells, axon terminal

Classification of Neurons

1. Sensory or affective

2. Motor or effective

3. Associative neurons

Sensory / affective

carry impulses from the sense organs to the brain and spinal cord.

Motor / effective

carry impulses from the brain and spinal cord to the muscles.

Associative neurons

located in the CNS, analyze and interpret the data or impulses.

Stimulus

triggered the information sent to the central nervous system

Response

reaction to the stimulus _____ happened

Nerve impulse

wave of a chemical reaction and electrochemical change

Neurotransmitters

• When a nerve impulse reaches the axon terminal, ________are released

• which send the information across the synapse

Action potential

information transmitted

reaction time

happens in the length of time between the activation of the stimulus up to its recognition

Homeostasis

is the condition wherein the human body system is maintained in balance despite the changing factors outside.

Stimulus

The variable that is being regulated.

Sensor

It monitors the value of the variable and sends the message to the control center

Control center

It matches the data to the normal values

Effector

The organ, gland, muscle or other body parts that act on the

message from the control center to move back to the set point to regulate

the body.

Negative feedback

• can control the body temperature and even the glucose level.

• To maintain the values in normal range,____________ happens in a loop that includes the stimulus, sensor, control center and effector.

Positive feedback

This type of feedback serves to intensify a response until endpoint is reached