chapter 11

it is the master control and communication center for the body

sensory receptors monitor changes inside and outside body

the nervous system processes and interprets sensory input and determines what to do

the nervous system activates effector organs to cause a response

brain and spinal cord

integrating and control center

-reflexes

-current condition

-past experience

-spinal nerves

-cranial nerves

-ganglia

communication lines that link all parts of the body to the CNS

Brain

CNS

Spinal Cord

CNS

Cranial Nerves

PNS

Ganglia

PNS

PNS

Spinal Nerves

-somatic sensory fibers convey impulses from the skin, skeletal muscles, and joints

-visceral sensory fibers transmit impulses from the visceral organs

-motor nerve fibers that make up the somatic nervous system and autonomic nervous system

-conducts impulses from the CNS to effectors?

-muscle and glands

-voluntary motor nerve fibers

-conducts impulses from the CNS to skeletal muscles

-involuntary motor nerve fibers that make up the sympathetic and parasympathetic division

-conducts impulses from the CNS to cardiac muscle, smooth muscle, and glands

-mobilizes body systems during an activity

-conserves energy

-promotes housekeeping functions during rest

Supporting cells that surround and wrap around the more delicate neurons

CNS glial cell

-anchors neurons to capillaries

-resorbs leaked potassium ions

-recycles released neurotransmitters

-participates in information processing

CNS glial cell

-monitor the health of neurons

-specialized macrophage that engulfs debris or microorganisms, important because immune cells cannot enter the CNS

CNS glial cell

-line the central cavities of the brain and spinal cord

-cilia helps circulate the cerebrospinal fluid that cushions the brain and spinal cord

CNS glial cell

-line up along the thicker nerve fibers in the CNS

-myelin sheathe of some nerve fibers in the CNS

PNS glial cell

function unknown, but thought to have many of the same functions of astrocytes

PNS glial cell

-forms myelin sheathes around thicker nerve fibers

-vital to the regeneration of damaged peripheral nerve fibers

High Metabolic Rate

Amitotic

Extreme Longevity

Collection of neuron cell bodies in the CNS

Bundle of Axons in the CNS

Collection of neuron cell bodies in the PNS

A bundle of Axons in the PNS

Grey Matter

White Matter

Irritability

-brief reversal of membrane potential with a total amplitude of 100mV (-70mV to +30mV)

-typically only generated in Axons when adequately stimulated

-Does not decay with distance.

-The human body has an equal amount of positive and negative charges, but there are regions where one type of charge predominates.

-any situation in which there are separated electrical charges of the opposite sign

-Measure of potential energy generated by separated electrical charges 

-flow of electrical charge from one point to another 

-used to do work

-amount relies of voltage and resistance 

-hindrance to charge flow provided by 

substances through which a current must pass

-high electrical resistance

-low electrical resistance

-Ions move along chemical concentration gradients from an area of high concentration to an area of lower concentration 

-Ions move toward an area of opposite electrical charge 

-The direction an ion moves, in or out of a cell, depends on the greater of either the concentration gradient or electrical gradient 

yes

-changes in membrane potential

-when the appropriate chemical binds

-measured potential difference between two points in a resting neuron

-decrease in membrane potential 

-inside of the membrane becomes less negative than the resting potential 

-increases probability of producing nerve impulses

-increase in membrane potential

-inside of the membrane becomes more negative 

-reduces probability of producing nerve impulses

-brief, localized changes in membrane potential

-degrade with distance

-initiates action potentials

-when depolarization reaches a critical level between -55 and -50mV

-causes depolarization to become self-generating 

-when a patch of neuron membrane is generating an AP it cannot respond to another stimulus 

-ensures that each AP is a separate all or nothing event

-follows the absolute refractory period

-happens when repolarization is occurring

-elevates threshold for AP generation 

-requires exceptionally strong stimulus to reopen sodium channels

-how fast APs travel

-positive relationship with axon diameter

-positive relationship with the degree of myelination

-occurs in nonmyelinated axons

-voltage-gated channels in the membrane are adjacent to each other

-slow conduction velocity

-occurs in myelinated axons

-myelin blocks sodium and potassium channels

-AP current is maintained and skips to the next myelin sheathe gap where it triggers another AP

-30x faster than continuous conduction 

-high intracellular potassium

-many potassium leakage channels allow for it to diffuse outside the cell

-high extracellular sodium

-few sodium leakage channels

-concentration gradient of both sodium and potassium leaves the membrane potential around -70mV

-sodium and potassium pump compensates for leaking ions and transports 3 sodium ions out and 2 potassium ions in against the concentration gradient

-this keeps the membrane potential at -70mV

the soma can synapse on its own, but the addition of the dendrite processes increases the surface area allowing the neuron to receive more sensory information

Brain and Spinal Cord

integrative and control centers

Cranial Nerves and Spinal Nerves

Communication lines between the CNS and the rest of the body

Motor Nerve Fibers

Conducts impulses from the CNS to effectors

Somatic sensory nerve fibers

Visceral sensory nerve fibers

Conducts impulses from receptors to the CNS

Somatic motor Nerve fibers

Conducts impulses from the CNS to skeletal muscles

Visceral motor nerve fibers

Conducts impulses from the CNS to cardiac muscle, smooth muscle, and glands

mobilizes body system during an activity

conserves energy

promotes housekeeping functions during rest