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 _____________________________