nervous system Flashcards
what is the nervous system responsible for?
1) much like a computer but far more complex; the nervous system CONTROLS and ADJUSTS the activites of other systems
what nervous system controls the brain and spinal cord?
the central nervous system
what is the Central Nervous System responsible for?
1) integrating, processsing and coordinating sensory input and motor output 2) intelligence, memory, learning and emotion all stem from the Central Nervous System
what does the peripheral nervous system include?
1) All the Neural tissue outside the CNS.
what is the main function of the peripheral Nervous System?
1) provides sensory information to the CNS and carries motor commands from the CNS to peripheral tissues and systems.
what are the 2 subdivisions within the peripheral nervous system and what are their function?
1) afferent division A) brings sensory information to CNS 2)Efferent division A) CARRIES motor commands to muscles and glands
what do receptors within the afferent division do?
1) monitor specific characteristics of environment 2) a receptor can be a dendrite, a specialized cell, cluster of cells, or a complex sense organ like the eye
where does the efferent division end?
1) at the EFFECTOR: which is a muscle cell, gland cell, or another cell specialized to perform very specific functions
what do the somatic and visceral sensory receptors within the afferent device do?
1) somatic sensory receptors A) monitor skeletal muscles, joints and skin 2) Visceral Sensory receptors- A)monitor internal structures like smooth muscle, cardiac muscle, glands and respiratory and digestive organs.
which division is responsible for delivering information to special sense organs, such as eye and ear
AFFERENT DIVISION
which division includes somatic nervous system and autonomic nervous system and what do they do?
1)Somatic Nervous system A) controls musclular contactions 2) Autonomic Nervous system A)regulates smooth muscle, cardiac muscle and glandular activity
the somatic nervous system activities may be
voluntary: muscle contractions are controlled voluntarily involuntary: outside your awareness. ex you touch something hot it will withdraw immediately.
what is a Neuron?
basic functional unit of nervous system. HIGHLY speicialized cell.
what is a sensory Neuron and what does it do ?
1) A neutron whose axon carries sensory information from PNS to CNS
what does a Motor Neuron do?
1) a neutron whose axon carries motor commands from CNS towards effectors
what is a neuroglia or glial cell ?
1)suppporting cells interact with neurons and regulate extracellular environment. 2) Defend Pathogens and perform repairs in neural tissue
Within Neural tissue there are two distinct cells; Neurons and Neuroglia. What is the function of a Neuron and Neuroglia?
1) A Neuron is what transmits and processes information in the nervous system 2)A Neuroglia or glial cell support the neurons. They A)act as phagocytes, B)provide a supportive framework and C)maintain the intercellular environment * around 100 billion glial cells. approximately 5 times the number of neurons
what is the function of a Soma in a neuron?
1) Cell body- contains nucleus, mitochondria,ribosomes and other organelles 2) biosynthesizes organic molecules such as enzymes
What is the function of Dendrites within a Neuron?
1) stimulated by environmental changes or actvities of other cells
what is the function of an Axon within a Neuron?
1) conducts nerve impulses ( action potential) towards synaptic terminals
What is the synaptic Terminal and what does it do?
1) It is where the neuron communicates with another cell
What are the 4 kinds of GLIAL or NEUROGLIA cells found within the central nervous system ?
1) Astrocytes 2)Oligodendrocytes 3) Microglia 4) Ependymal cells
What are the significant functions of the Astrocytes?
1) Controls Interstitial environment A)increase surface area of cell B)allows scavenging of ions, neurotransmitters or metabolic by-products that accumulate in microenvironment. C)This enables astrocytes to control chemical content of interstitial environment within CNS D) Therefore they isolate neurons from changes in chemical composition of interstitial space within CNS 2)Maintain blood brain barrier A)Neural tissue must be biochemically and physically isolated from general circulation because of hormones or chemicals in blood would be harmful to neuron function. B)Chemicals secreted by asctrocytes are CRUCIAL for the maintenance of blood-brain barrier 3)provides mechanical and structural strength. supports neurons of brain and spinal cord. 4) repair damaged sites within neural tissue. A) make structural repairs stabilize tissue prevent injury by producing scar tissue 5) Direct growth and interconnnection of developing neurons through secretion chemicals known as NEUROTROPIC FACTORS
what are the main functions of Oligodendrocytes?
* similar to astrocytes however have smaller cell bodies and less cytoplasmic processes 1) improve functional performance of Neurons by wrapping axons in MYELIN which INSULATES neurons 2)Internodes- large areas wrapped in myelin 3) Myelin sheath gaps- small gaps between myelin sheaths 4) white matter- regions in CNS dominated by myleninated axons 5)Gray areas- regions dominated by neuron cell bodies, dendrites and unmyelinated axons
What is the function of Microglia?
*smallest of glial cells 1) first appear in embryonic stem cells through division of mesodermal stem cells 2) Stem cells that create Microglia originate in bone marrow and are related to those that make macrophages and monocytes of blood. 3) migrate to CNS and are the police force. A) Phagocytic- engulfing cellular debris and waste products. B) protect CNS by phagocytosing viruses, microorganisms and tumor cells * only 5 percent of glial cells microglial. but multiply dramatically during infection or injury
What are the function of Ependymal Cells?
1) line ventricels of brain and central canal of spinal cord 2)filled with cerebrospinal fluid. this fluid provides a protective cushion and transports dissolved gases, nutrients, wastes and other materials. * cuboidal to columnar in shape 3) act as receptors that monitor composition of CSF 4) free surfaces of ependymal cells covered with cilia. ciliated ependymal cells assist circulation CSF. 5) specialized ependymal cells participate secretion of cerebrospinal fluid
what are the Neuroglia of the peripheral nervous system?
1) satellite cells 2) schwann cells
what are ganglia
cell bodies in PNS clustered together
what are peripheral nerves?
1) axons bundled together wrapped in connective tissue.
what is the function of satellite cells?
1) regulate exchange nutrients and waste products between neuron cell body and extracellular fluid. 2) Isolate neuron from stimuli and those provided at synapses
What are the function of Schwann Cells?
1) Shield axons from intersitial fluids. A) axon that is wrapped in myelin is myelinated B) Myelin improves speed of action potential or nerve impulse is propagated along axon.
Outline the steps of Axon myelination in PNS?
1) the Schwann cell encloses axon within groove of cytoplasm. 2)Schwann cell begins to rotate 3)As the schwann cell rotates, inner membranous layers compress and cytoplasm forced into more superficial layers. the myelin sheath consists phospholipid bilayer of cell membrane; with schwann cell nucleus and cytoplasm at surface.
Explain what a node and internode does?
1)Each Schwann cell can myelinate only 1 mm of an axon; many schwann cells are needed to myelinate an entire axon. the narrow opening between 2 schwann cells is the NODE. the INTERNODES are areas myilenated by individual schwann cells ?
what is the perikaryon within a Neuron?
1) surrounding cytoplasm within a neuron cell 2) contains organelles that provide energy and perform bio-synthetic activities
what is a neurofilament and neurotubles?
1) cytoskeleton of perikaryons contain neurofilaments and neurotubules. bundles of neurofilaments are called neurotubules
What are Nissl bodies?
ribosomal clusters which synthesize pepties and proteins
what is significant about neurons lacking a centrosome?
- Neurons lose centrioles during differentiation and are incapable of undergoing cell division.
- If a Neuron is lost to injury or disease they can not be replaced
What is the one of the primary functions of glial cells?
limit number of types of stimuli affecting individual neruons.
What is the function of an axon?
1) also called a Nerve Fiber. it is capable of producing action potential
What is the specialized region within a multipolar Neuron Called?
Axon hillock. it connects the initial segment of the axon to the soma
What is axoplasmic transport within an axon?
a complex process where organelles,nutrients, synthesized molecules and waste products move between cell body and syapctic terminals.
what is the synapse?
a specialized site where the neuron communicates with another cell
what is a terminal bouton?
where one neruon synapses another
what are Neurotransmitters?
release of specific chemicals taht is triggered by arrival of nerve impulse.
what does an anaxonic Neuron do
- small neurons.
- no anatomical clues to distinguish dendrites from axons
What do bipolar neurons do
- many fine dendrites fuse to form one single dendrite
- relatively rare important relaying sensory information concerning sight,smell and hearing
- axons not myelinated
What is structural classification of Pseudounipolar Neurons?
- continuous dendritic and axonal processes
- sensory neurons of peripheral nervous system usually pseudounipolar and axons may be myelinated
what is the structural classification of Multipolar Neurons?
- several dendrites and single axon may have one or two more branches.
- most common type of Neuron in CNS.
- all motor neurons control skeletal muscles and are multipolar with myelinated axons
What are the 3 functional classifications of Neurons ?
- Sensory Neurons
- Motor Neurons
- Interneurons
what is the function of Sensory Neurons?
- Almost all are pseudouniplar neurons
- form afferent division of PNS. main function deliver information to CNS.
3.
What do are the axons of sensory neurons called and what is their function?
- Afferent Fibers
- extend between sensory receptor at spinal cord or brain.
1.
What do somatic Sensory Neurons do?
- Transmit information about outside world and our position within it
What do visceral Sensory Neurons do?
Transmit information about internal conditions** and **status** of other **organ system
What are receptors ?
processes of specialized sensory neurons or cells monitored by sensory neurons
What are the function of Exteroceptors?
- provide information about touch, temperature, pressure sensations and complex special senses like sight, smell and hearing
What is the function of proprioceptors
monitor position** and **movement** of **skeletal muscles** and **joints
What is the function of Interoceptors?
monitor digestive, respiratory, cardiovascular, urinary, reproductive systems** and provide sensations deep pressure and **pain** as well as **taste, another special sense
What is the function of motor Neurons?
*efferent division
stimulate** activity of **peripheral tissue, organ, or organ system.
What is white matter?
myelinated axons. have action potential
What is grey matter
unmyelinated axons ( cell dendrites, neuroglia) integrative functions
What is significant about myelinated axons?
- myelinated** are **faster
- speed afftected by thickness of myelin sheath
- lipid acts as insulaters forcing myelin to jump from node to node.
What are type A nerve Fibers
- myelinated
- conduct at 15-120 m/s
- supply skeletal** and most sensory **neurons
Where is a type B Nerve fiber found ?
- operates 3-15 m/s
- lightly myelinated. Part of Autonomic Nervous System
3.
What Is a Type C Nerve Fiber ?
- small, unmyelinated
- operate 2m/s or less.
- Autonomic Nervous System
The autonomic nervous system is voluntary? T or F
False. The autonomic nervous system is involuntary
What are the divisons of the autonomic system? is it one neruon system or 2
- * 2 neuron system. the somatic is 1
Sympathetic-prepares body for physical activity. fight** or **flight
parasympathetic-vegetative functions such as emptying food or urinary bladder
Enteric-plexuses within wall of digestive tract. operates independantly of CNS**. ex **Gut feeling.
What are the 3 structures of peripheral nerves?
- epineurium- surrounds entire nerve
- perineurium- surrounds axons forms fascicles
- epineurium-surrounds entire nerve
The c1-c4 is which plexus within the ventral rami?
cervical plexus
The c5-t1 is which plexus within the ventral rami?
brachial plexus
the L1-L4 is which plexus within ventral rami?
Lumbar Plexus
The L4 to S4 is wihch plexus within ventral rami?
Sacral plexus
The S4-S5 is which plexus
coccygeal plexus
