Unit A - Introduction to the Nervous System

homeostasis

A state of stability the human body always tries to reach and maintain

nervous system

sends and receives electrical impulses that regulate body structures and processes to achieve this despite changes in the internal and external environment.

Photoreceptors

sensitive to light / sense of vision

Mechanoreceptors

sensitive to vibrations / sense of sound, balance, body position, touch, pressure, and pain

Chemoreceptors

sensitive to chemicals / sense of taste and smell

Central Nervous System (CNS

integrates and processes electrochemical info sent by nerves

• Brain

• Spinal cord

Peripheral Nervous System (PNS)

includes nerves that carry sensory messages to and from the CNS. It is further divided into two sections.

Somatic Nervous System (SNS)

voluntary portion of the PNS which controls the skeletal muscles

Autonomic Nervous System (ANS)

provides involuntary control of glandular/cardiac muscle, part of PNS

Sympathetic Nervous System

arouses body to expend energy (e.g. fight or flight), part of ANS

Parasympathetic Nervous System

calms body and conserves and maintains energy (e.g. rest and digest, para-dormir), part of ANS

What is the difference between the nervous system and hormones?

	Nervous System	Hormones
Function	Coordinating rapid, precise responsens, and is especially important in mediating interactions with the external environment.	Regulation that requires duration rather than speed like: organic metabolism and H20 electrolyte balance inducing adaptive changes to help the body cope with stress controlling reproduction regulating red blood cell production along with ANS controls and integrates circulation and digestion
Size of Effect	Single muscle or cell	All cells they reach with the correct receptor
Speed of Action	100 m/s	Seconds, Minutes, +

basically:

neurons = fast, precise response mainly to the external environment, reaches single muscle or cell

hormones: duration, balance in internal environment, faster reach, takes longer

Thermoreceptors

sensitive to temperature / sense of hot and cold