Directed Objectives: Exam V Flashcards
Job of the nervous system (Functions)
Pg. 366
- Maintaining homeostasis
- Cells must work together to maintain homeostasis.
- Can stimulate or inhibit activities to help maintain this. - Receiving sensory input
- Monitor numerous external and internal stimulus - Integrating Information
- Brain and spinal cord are major organs for processing sensory input and initiating responses.
- The put may produce an immediate response, be stored as memory or ignored. - Controlling muscles and glands.
- Controls the secretions of many glands, including sweat glands, salivary glands, and glands of the digestive tract. - Establishing and maintaining mental activity.
- The brain is the center of mental activities, including consciousness, thinking, memory, and emotions.
PNS VS. CNS
Pg. 366
Peripheral Nervous System (PNS)- Consists of the nervous tissue outside the CNS (nerves and ganglia)
-Carries information about the different tissues of the body to the CNS and carries commands from the CNS that alter body activities.
Central Nervous System(CNS)- Consists of the brain and spinal cord.
Subdivisions of the PNS
Pg. 367
Two subdivisions:
- Sensory division
- Transmits electrical signals, called action potentials, from sensory receptors in the body to the CNS.
- Cells bodies located near the spinal cord by ganglia.
- Also known as Afferent Division
- Motor division
- Transmits action potentials from the CNS to effector organs, such as muscles and glands.
- Also known as Efferent Division
S A M E E F O F N F T F S E O E O R R R R E E Y N N T T
Subdivisions of the Motor Division
Pg. 368
- Somatic
- Voluntary (conscious)
- Bodily
- Autonomic
- Involuntary (unconscious)
- Self-governing
-Example: The somatic nervous system allows you to decide to move your skeletal muscles, as when you raise your hand.
Trigger Zone Pg. 369
The combination of the axon hillock and the initial segment.
-Where action potentials are generated.
Nissel bodies Pg. 369
- Rough Endoplasmic Reticulum
- Located primarily in the cell body and dendrites.
- Primary sites of protein synthesis in neurons.
Astrocytes Pg. 370
Glial cells that are star-shaped because cytoplasmic processes extend from the cell body.
- Support & Regulate Ions
- Exchange of materials between neurons and capillaries
- Help regulate the composition of extracellular brain fluid. They do this by releasing chemicals that promote the formation of tight junctions between the endothelial cells of the capillaries.
-Nourish neurons and provide a blood brain
barrier between nervous tissue and the blood.
Blood brain barrier Pg. 370
The endothelial cells with their tight junctions form the blood brain barrier.
-Determines what substances can pass from the blood into the nervous tissue of the brain and spinal cord.
-Protects neurons from toxic substances in the blood.
Allows the exchange of nutrients and waste products between the neurons and the blood, and prevents fluctuations in the blood composition from affecting blood functions.
Ependymal Cells Pg. 371
Line the ventricles (cavities) of the brain and the central canal of the spinal cord.
-Frequently have patches of cilia that help circulate cerebrospinal fluid through the brain cavities.
Oligodendrocytes Pg. 371
Have cytoplasmic extensions that can surround axons. If the cytoplasmic extensions wrap many times around the axons, they form an insulating material a myelin sheath.
- One oligodendrocyte can form myelin sheaths around axons of multiple neurons.
- Produce myelin in the CNS
- Often wrap around several neurons.
Neurotransmitters Pg. 369
The presynaptic terminals store many secretory vesicles that contain signal modules.
Axon Pg. 369
Main central process of a neuron that normally conducts action potentials away from the neuron cell body.
Soma Pg. 369
- Also known as the neuron cell body.
- Enlarged portion of the neuron containing the nucleus and other organelles.
- The source of information for protein synthesis.
Microglial Cells Pg. 370
The CNS-specific immune cells.
-They phagocytize necrotic tissue, microorganisms, and other foreign substances that invade the CNS.
Gray Matter VS. White Matter Pg. 374
- Gray Matter
- Consist of groups of neuron cell bodies and their dendrites, where there is little myelin, these areas are darker in appearance.
- In the CNS, the cortex consists of gray matter in the surface of the brain. Nuclei are clusters of gray matter located deeper within the brain.
- In the PNS, gray matter consists of clusters of neuron cell bodies, each of which is called ganglion (pl. ganglia: a swelling or knot).
*White Matter
-Consist of bundles of parallel myelinated axons, they are whitish in color.
-White matter of the CNS forms nerve tracts, or conduction pathways, which propagate action potentials from one area of the CNS to another.
In the CNS, bundles of axons and their connective tissue sheaths are called nerves.
Schwann Cell Pg. 371
- Glial cell of the PNS
- Form myelin sheaths.
- Each Schwann cell forms a portion of the myelin sheath around only one axon.
Nodes of Ranvier: Gaps in the myelin sheath.
Ganglion (Singular) Pg. 374
Ganglia (Plural)
Any groups of nerve cell bodies in the peripheral nervous system.
Voltage-Gated Ion Channels Pg. 378
Open and close in response to a specific, small voltage change across the plasma membrane.
-The movement of ions into and out of the cell changes the charge difference across the plasma membrane, which, in turn, can cause voltage-gated open channels to open and close.
Resting Membrane Potential Pg. 376
Electric charge difference inside a plasma membrane, measured relative to just outside the plasma membrane.
Depolarization Pg. 378
Occurs when the membrane potential becomes more positive and is the movement of the membrane potential closer to zero.
All Or Nothing Response Pg. 382
When a stimulus is applied to a cell, an action potential is either produced or not. In the muscle cells, the cell either contracts to the maximum extent possible, (for a given condition) or does not contract.
Synaptic Vesicle Pg. 389
Secretory vesicle in the presynaptic terminal containing neurotransmitter substances.
Acetycholinesterase Pg. 390
Enzyme found in synaptic cleft that causes the breakdown of acetylcholine to acetic acid and choline, thus limiting the stimulatory effect of acetylcholine.
EPSP- Excitatory
Postsynaptic Potential Pg. 391
Depolarization in the postsynaptic membrane that brings the membrane potential close to the threshold.
Acetycholine Pg. 390
Neurotransmitter substance releases from motor neurons of the parasympathetic and sympathetic divisions, all postganglionic neurons of the parasympathetic division, and some central nervous system neurons.