✅Organisation Of The Nervous System 1 Flashcards
What does the nervous system include?
All neural tissue in the body
How many kinds of cells does neural tissue contain?
Two
What are the two kinds of cells in neural tissue?
- neurons
- neuroglia
What are neurons?
Cells that send and receive signals
What are neuroglia (glial cells)?
Cells that support and protect neurons
What are the organs of the nervous system?
- Brain and spinal cord
• Sensory receptors of sense organs (eyes, ears, etc.) - Nerves connect nervous system with other systems
What are the three main functions of the nervous system?
• Directs immediate responses to stimuli
• Coordinates or moderates activities of other organ systems
• Provides and interprets sensory information about external conditions
What are the two anatomical divisions of the nervous system?
Central (CNS)
Peripheral (PNS)
What is the CNS made up of?
• Consists of the spinal cord and brain
• Contains neural tissue, connective tissues, and blood vessels
What does the PNS consist of?
• Includes all neural tissue outside the CNS
• Functions of the CNS are to process and coordinate what?
• Sensory data from inside and outside body
• Motor commands control activities of peripheral
organs
(e.g., skeletal muscles)
• Higher functions of brain: intelligence, memory,
learning, emotion
What are the primary functions of the brain?
• Perform complex integrative functions.
• Controls both voluntary and autonomic activities.
What are the primary functions of the spinal cord?
- Relays information to and from brain.
• Performs less-complex integrative functions. - Direct many simple involuntary activities.
What are the functions of the PNS?
• Deliver sensory information to the CNS
• Carry motor commands to peripheral tissues and systems
What are nerves? ( also called peripheral nerves)
Bundles of axons with connective tissues and blood vessels
What do nerves do?
Carry sensory information and motor commands in PNS
• Cranial nerves – connect to brain
• Spinal nerves – attach to spinal cord
What does the afferent division of the PNS do?
• Carries sensory information from PNS sensory receptors to CNS.
What do the receptors in the afferent division of the PNS do?
• Detect changes or respond to stimuli
• Neurons and specialized cells
• Complex sensory organs (e.g., eyes, ears)
What does the efferent division of the PNS do?
• Carries motor command from CNS to PNS muscles and glands.
• These target organs, which respond by doing something, are called Effectors.
What do effectors do?
Respond to efferent signals
Cells and organs
How do you distinguish the difference between afferent and efferent?
associate the ”a ” in afferent with the “a” in accessing, and the “e” in efferent with the “e” in exiting.
What are the two sections of the efferent division?
The somatic nervous system (SNS)
The autonomic nervous system (ANS)
What does the SNS do?
• Controls voluntary and involuntary (reflexes) skeletal muscle contractions
What does the autonomic nervous system do?
• Controls subconscious actions, contractions of smooth muscle and
cardiac muscle, and glandular secretions
• Sympathetic division has a stimulating effect • Parasympathetic division has a relaxing effect
What are the basic functional units of the nervous system?
Neurons
Where are the multipolar neuron common?
In the CNS
What are the structure of the multipolar neuron?
Cell body
Short, branches dendrites
Long, single axon
What is the structure of the cell body
• Large nucleus and nucleolus
• Perikaryon (cytoplasm), surrounding the nucleus
• Mitochondria (produce energy)
• RER ”Rough Endoplasmic Reticulum” and ribosomes (produce neurotransmitters)
What is the structure of dendrites?
- Highly branched
- Dendritic spines
• Many fine processes
• Receive information from other neurons - 80–90 percent of neuron surface area
What is the structure of of the axon?
• Is long
• Carries electrical signal (action potential) to target • Axon structure is critical to function
What is the synapse?
• Area where a neuron communicates with another cell
What are the two cells in each synapse?
1- Presynaptic cell
• Neuron that sends message
2- Postsynaptic cell
• Cell that receives message
What does the communication between cells as a synapse mostly involve?
the
release of chemicals call Neurotransmitter by the Synaptic Terminal.
What are neurotransmitters?
Chemical messengers
Where are neurotransmitters released?
At presynaptic membrane
What to neurotransmitters affect?
Receptors of postsynaptic membrane
What are neurotransmitters broken down by?
Enzymes
Where are neurotransmitters reassembled?
Axon terminal
What are the two types of synapses?
Neuromuscular junction
Neuroglandular junction
What is the neuromuscular junction?
Synapse between neuron and muscle
What is the Neuroglandular junction?
Synapse between neuron and gland
What are the four types of neurons?
Anaxonic neurons
Bipolar neurons
Unipolar neurons
Multipolar neurons
Where are Amazonia neurons found?
In brains and sense organs
Where are bipolar neurons found?
Special sensory organs (sight, smell, hearing)
Where are unipolar neurons found?
In sensory neurons of PNS
Where are multipolar neurons found?
Common in CNS
Include all skeletal muscle motor neurons
Describe Anaxonic neurons
• Small
• All cell processes
look alike
• Found in brain and
sense organs
- more than two processes
- all dendrites
Describe bipolar neurons
• Are small
• One dendrite,
one axon
• Found in special
sensory organs (sight, smell, hearing)
- two processes that are separated by cell body
What are the three functional classifications of neurons?
Sensory neurons
Motor neurons
Interneurons
What are sensory neurons
Afferent neurons of PNS
What are motor neurons?
Efferent neurons of PNS
What are Interneurons?
Association neurons
What are the functions of the sensory neurons?
To deliver information from sensory receptors to CNS
What are the three types of sensory receptors?
Interoceptors
Exteroceptors
Proprioceptors
What do interoceptors do?
- Monitor internal systems (digestive, respiratory, cardiovascular, urinary, reproductive)
- Internal senses (taste, deep pressure, pain)
What do exteroceptors do?
- External senses (touch, temperature, pressure)
* Distance senses (sight, smell, hearing)
What do proprioceptors do?
• Monitor position and movement (skeletal muscles and joints)
What do motor neurons do?
• Carry instructions from CNS to peripheral effectors
How do motor neurons Carry instructions from CNS to peripheral effectors?
Via efferent fibres (axons)
What are the two major efferent systems with regards to motor neurons?
SNS and ANS
What does SNS include?
All somatic motor neurons that innervate skeletal muscles
What does ANS involve?
Visceral motor neurons innervate all other peripheral effectors
• Smooth muscle, cardiac muscle, glands, adipose tissue
Where are Interneurons located?
• Most are located in brain, spinal cord, and autonomic ganglia
• Between sensory and motor neurons
What are Interneurons responsible for?
- Distribution of sensory information
* Coordination of motor activity
What higher functions are Interneurons involved in?
Memory, planning, learning
What are half the volume of the nervous system?
Neuroglia
Where are there many types of neuroglia?
In the CNS and PNS
What’s are the four types of neuroglia in the CNS?
Ependymal cells
Astrocytes
Oligodendrocytes
Microglia
What are ependymal cells?
Cells with highly branches processes; contact neuroglia directly and assist in producing, circulating and monitoring cerebrospinal fluid.
What are astrocytes?
Large cell bodies with many processes including:
- maintaining blood-brain barrier
- provide structural support
- regulate concentrations
- absorb and recycle neurotransmitters
- form scar tissue after injury
What are oligodendrocytes?
Smaller cell bodies with fewer processes. They myelinated CNS axons and provide structural framework
What are Microglia?
Smallest and least numerous neuroglia with many fine-branched processes. They remove cell debris,wastes and pathogens by phagocytosis
Describe neuroglia in the PNS
• The cell bodies of neurons in the PNS are clustered in masses called Ganglia.
• Surrounded by neuroglia, found in the PNS
What are the two types of neuroglia in the PNS?
Satellite Cells
Schwann Cells
What are satellite cells also known as?
Amphicytes
What do satellite cells do?
Surround ganglia and regulate environment around neuron
What are schwann cells also known as?
Neurilemma cells
What do schwann cells do?
• Also called neurilemma cells
• Form myelin sheath (neurilemma) around peripheral axons
• One Schwann cell sheaths one segment of axon
• Many Schwann cells sheath entire axon
What do neurons perform?
• All communication, information processing, and control functions of the nervous system
What do neuroglia preserve?
Physical and biochemical structure of neural tissue
What are neuroglia essential for?
Survival and function of neurons
Identify the two anatomical divisions of the nervous system.
The two anatomical divisions of the nervous system are the central nervous system (CNS), consisting of the brain
and spinal cord, and the peripheral nervous system (PNS), consisting of all neural tissue outside the CNS.
Identify the two functional divisions of the peripheral nervous system, and cite their primary
functions.
• The two functional divisions of the peripheral nervous system are the afferent division, which brings sensory information to the CNS from receptors in peripheral tissues and organs, and the efferent division, which carries motor commands from the CNS to muscles, glands, and adipose tissue.
Identify the two components of the efferent division of the PNS.
The two components of the efferent division of the PNS are the somatic nervous system (SNS) and the autonomic
nervous system (ANS).
What would be the effect of damage to the afferent division of the PNS?
Damage to the afferent division of the PNS, which is composed of nerves that carry sensory information to the brain and spinal cord, would interfere with a person’s ability to experience a variety of sensory stimuli.
Name the structural components of a typical neuron.
Structural components of a typical neuron include a cell body or soma (which contains the nucleus and perikaryon), dendrites, an axon, telodendria, Nissl bodies, neurofilaments, intermediate neurotubules, neurofibrils, axoplasm, axolemma, initial segment, axon hillock, and collaterals.
Classify neurons according to their structure.
According to structure, neurons are classified as anaxonic, bipolar, unipolar, and multipolar
Classify neurons according to their function.
According to function, neurons are classified as sensory neurons, motor neurons, and interneurons.
Are unipolar neurons in a tissue sample more likely to function as sensory neurons or motor
neurons?
Because most sensory neurons of the PNS are unipolar, these neurons most likely function as sensory neurons.
Identify the neuroglia of the central nervous system.
Central nervous system neuroglia include ependymal cells, astrocytes, oligodendrocytes, and microglia.
Identify the neuroglia of the peripheral nervous system.
Peripheral nervous system neuroglia include satellite cells (amphicytes) and Schwann cells (neurilemma cells).
