Nervous System: Unit D & E: Mechanism of body control chapter 11

• - Any self regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival
• - Balance is the main job of the nervous system

-The glands and organs that produces hormones an release them directly into the blood so they can travel through tissues and organs all over the body

a system (along with the endocrine system that controls all activities in the body

• - the brain
• - the spinal cord
• - the nerve
• - the senses

• 1) Sensory Input - Monitor both internal and external environment (gather info)
• 2) integration - process the information and often integrate (/combine) with stored information (process the info) 
• 3) Motor Output - if necessary signal effector organs to make an appropriate response (can be conscious or unconscious) (/act on info)

Central Nervous System (CNS) - Brain and spinal cord that coordinate (/bring together) incoming and outgoing information

• Peripheral Nervous System (PNS) - Carries information between organ effectors and CNS
• - All portions of the body outside of the spinal cord and brain

An organ or cell that acts in response to a stimulus (signal)

Permits the body’s voluntary action (eg writing your name)

Permits the body’s involuntary action, for example, functioning of blood vessels, gland, the bladder, stomach and heart

• - any of the cell that hold nerve cells in place and help them work the way they should. 
• - another term for glia/glial

Glial cells (neuroglial) and Neurons

• - hold neurons in place 
• - provide neurons with nutrients
• - insulate neurons
• - Remove cellular debris when neurons die
• defends against infection.

Are information messengers, transmit information throughout the nervous system

• Sensory neurons - relay information about environment from sensory receptors to the CNS 
• Interneurons - link neurons with other neurons (such as neurons only found in the CNS: brain and spinal cord)
• Motor Neurons - carry impulses from the CNS to the effectors (muscles, glands, organs) to produce a response.

• - Bundles of fibres that transmit impulses of sensation to te brain or spinal cord. 
• - Group of neurons forms a nerve

A organ or cell able to respond to light, heat or other external stimulus (/signal) and transmit a signal to a sensory nerve

• - Dendrites
• - Nucleus
• - Cell body
• - Axon hillock
• - Axon
• - Myelin Sheath 
• - Synaptic terminal/ axon terminal/ terminal branches

Functional portion of the neuron (keeps neurons alive), when in groups outside of CNS called ganglion

(Tree like structure) short extensions tat receives signals from other neurons or environment

Long extensions that transmits impulses away to other neurons or effectors

• - the white insulation around the axon is called the myelin sheath. 
• - Myelin sheathing acts as an insulator preventing loss of charged ions from the axon and allows conduction of faster impulses 

• - Schwann cell forms the myelin sheath
• - Areas between the myelin sheath are called the nodes of Ranvier

Membrane surrounding the axon, that promotes regeneration.

(Use somatic NS) involuntary response that initially bypasses interpretation of the brain.

An autonomic response controlled primarily the spinal cord. 

Stimulus -> receptor -> sensory neuron -> interneurons -> motor neurons -> effector organ -> response

Divide or cause to divide into two sharply contrasting groups

• 1) Resting Potential 
• - A neuron is at rest when it is not sending an electrical signal
• - charge inside of nerve is -70mV
• - polarized cell

• 2) Resting Potential 
• - Occurs when the neurons sends information down the axon, away from the cell body
• - charge inside neuron jumps to +40mV
• - it is a depolarized nerve

- sodium potassium pumps use atp (active transport) to pump 3 sodiums ions out and 2 potassium ions in the neuron. this unequal distribution of ions leads to a polarized membrane.

• 1) Resting Potential
• - charge inside is -70mV 
• - sodium-potassium pumps is active and pumps 3 Na+ out and 2 K+ in (3:2 ratio)
• - K leaks out through k+ channel

• 2) Depolarization 
• - Na+ gates opens
• - Na/K pump becomes inactive 
• - (-70mV) jumps to (+40mV)

• 3) Repolarization
• - Na+ gates closes
• - K+ gate opens 
• - K+ gate then closes slowly, this results to some K+ escaping the neuron causing hyperpolarization 

• 4) Refractory period 
• - recovery time required before a neuron can return to resting potential

Minimum level of stimulus required to produce a response (>2mV)

It is the space between neurons, divides neurons

release transmitters into the synapse

Receives neurotransmitters from the synapse

Once an action potential reaches the end plate of a neuron the “message” needs to be converted to a chemical to bridge the gap between to cells called synapse

Once the action potential reaches the end plate of the neuron

• 1) Presynaptic membrane is depolarized (with the aid of Ca2+) 
• 2) synaptic vesicles releases neurotransmitters (acetylcholine) from axon bulb (axon terminal)
• 3) Neurotransmitters bind to receptors on postsynaptic dendrite (Causing the postsynaptic to open their channels)
• 4) postsynaptic membrane opens either io channels
•  - Na+ flows in = excitatory
•  - K+ flows out = inhibitory 
• 5) Neurotransmitters are broken down by an enzyme (cholinesterase) Ion gates close 
• 6) Neurotransmitters are reabsorbed by pre-synaptic neuron for rebuilding 

(Synaptic Transmission cause the action potential of the postsynaptic neuron)

Alzheimer’s Disease is inhibitory (decrease production of neurotransmitters in the brain) 

Parkinson's disease is excitatory