we did a lot of notes today....NERVOUS SYSTEM!
Neuron- nerve cell specialized for carrying signals from one part of the body to another.
Nerve- the communication line made from bundles of neuron fibers wrapped in connective tissue.
The nervous system has two MAIN parts. The CNS (Central Nervous System) and the PNS (Peripheral Nervous System)
The functions of the N.S. are sensory output, Integration/Association interneurons, and Motor Output.
- has nucleus and other organelles
- Dendrites- branched, short, and recieve message from other cells
- Axon- long fiber that conducts signal toward another neuron or effector.
- Supporting cells- protect, insulate, reinforce
- Myelin sheath- chain of beadlike supporting cells
- Nodes of Ranview- spaces in myelin where impulse is transmitted
- synaptic knob- relays signals to other neurons
The signals move through the neuron in a weird way. In rest, the INSIDE IS NEGATIVE AND THE OUTSIDE IS POSITIVE. A stimulus is something that causes a nerve signal to start. Action potential is self-propagating change in voltage across plasma membrane.
How does the impulse move from neuron to cell?
- Electrical Synapse
- action potential jumps from cell to cell
- heart and digestive track
- Chemical synapse
- synaptic cleft- narrow gap seperating 2 cells.
- most other organs, skeletal muscle and CNS
Neurotransmitter- chemical carrying info from neuron to another type of cell that will react
- Action Potential arrives at the synaptic knob
- Neurotransmitter vessicals fuse with membranes
- neurotransmitters are released into cleft
- neurotransmitter diffuse across gap and binds to receptor proteins on receiving neurons
- Ion channels open and ions trigger action potential.
- Neurotransmitter are broken down and returned to sending neoron for recycling
- brain and spinal cord
- Cephalization- concentration of nervous system at the head end.
- Centralization- presence of CNS saparate from PNS
- spinal cord- bundle of nerve fibers in spinal column (Central communication between brain and body)
- Brain- Master control center (Homeostasis center, sensory center, emotion, intellect
- Brain as cerebrospinal fluid - liquid that cushions the CNS and helps supply it with nutrients, WBC, and hormones.
- Has Meninges- layers of connective tissue for protection
- white matter- mainly axons (with myelin sheath)
- gray matter- mainly nerve cell bodies and dendrites (Cerebral Cortex)
- Has a couple of divisions.
- Sensory Division
- brings info to CNS from outside environment
- Info into CNS from body itself (internal environment)
- Motor Division
- Somatic Nervous System- carrys signals to Skeletal muscles (voluntary, concious control)
- Autonomic Nervous System- controls smooth and cardiac muscle, organs, glands, digestive, circulatory, excretory, and endocrine (2 branches and involuntary)
Yep! Thats all folks!
- Study for finals
- UP pg. 81-84
- study for test Mon.
- Crossword puzzle