SBI4U: Introduction to the Nervous System

The human brain • 3-pound (1.4-kilogram)

mass of jelly-like fats and tissues • Up to _____________________

work together and coordinatethe ____________________and mental processes that set humans apart from other species.

What are Nerve Cells?• Neurons are similar to other __________________

– Surrounded by __________________________– Have a _____________________ that contains genes– Contain _____________________________________________– Carry out basic cellular processes such as _______________ and _____________

• Neurons are different by– Specialized extensions called _________________ and _______________– Communicate with each other by ________________________________– Contain some specialized structures (____________________) and chemicals

(__________________________)• Most _______________ consist of a _______________ and extensions called _________

and ______________.• Cell Body contains the __________________• _______________ carry impulses towards cell body• _____________ carry impulses away from the cell body

Types of Neurons• Sensory neurons

– Carry nerve impulses from _________________– Have ________ dendrites and _________ axons

• Motor neurons– Carry nerve impulses from _________________

_____________________ (ex. muscle or gland)– Have ________ dendrites and _________ axons

• Interneurons– Found ________________________________– Provide a link within the CNS between ________

neurons and _______________ neurons– Have short dendrites and long or short axons

Reflex Arc• Simplest nerve pathway• Occurs __________________

_______________________• Five components

– ___________________ – ___________________ – ___________________ – ___________________ – ___________________

Nerves• Consist of many fibers

(neurons) wrapped in _________________• 3 Types of nerves

– Sensory nerves contain only the long dendrites of ________________________ ______________________________• Carry impulses __________________________

– Motor nerves contain only the long axons of ____________________ wrapped in myelin• Carry impulses __________________________

– Mixed nerves contain both the long dendrites of ___________________ and the long axons of ____________________ wrapped in myelin• Conduct impulses __________________________

Central Nervous System• Contains the nerves of the _____________ and _________________

– Function = __________________________________________• Brain is found in the __________________________ as overall control center for the

nervous system• Spinal Cord is _________________________________ and extends down the back of

the neck, thorax and abdomen– Center of ______________________– Provides a ______________________________________

• Both are enclosed in 3 protective membranes called the ___________________• Space between ________________ contains ___________________________ which

protects and cushions the CNS

Peripheral Nervous System• All parts of the nervous system ____________________________________• The sensory and motor neurons that connect to the CNS

– Function = _______________________________________

Somatic and Autonomic Nerves• ______________________ control skeletal muscle, bones, skin that a person can control

– ___________________ which relay info about environment to CNS– ___________________ which initiate appropriate response

• ___________________________ control the muscles of the glands and internal organs which we can’t control– _____________________ & _____________________ components

Autonomic NervesSympathetic component _______________________ [neurotransmitter used=norepinephrine]• ________________ from internal organs ___________________________________

Parasympathetic ________________________________ [neurotransmitter used=acetylcholine]• Work in conjunction/opposition to each other

– Ex. “on” / “off” switches

Adrenalin• Sympathetic nervous system also stimulates secretion of _________________________

________________________ from the medulla of the adrenal glands• Prepares body for ___________________________________• “Epi-pen” given in allergic reactions as it _____________________________