Organisation Of The Nervous System 1 Flashcards
What does the nervous system include?
All neural tissue in the body
Neural tissue contains two kinds of cells, what are they?
- neurons
2. neuroglia (glial cells)
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 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 nervous system(CNS)
2. peripheral nervous system(PNS)
What does the central nervous system consist of?
Consists of the spinal cord and brain and contains neural tissue, connective tissues and blood vessels
What does the peripheral nervous system include?
All me aural tissue outside the CNS
What are the three functions of the CNS?
- 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 and emotion
What are the two primary functions of the brain?
- perform complex integrative functions
- controls both voluntary and autonomic activities
What are the three primary functions of the spinal cord?
- relays information to and from the brain
- performs less-complex integrative functions
- direct many simple involuntary activities
The peripheral nervous system includes all?
Neural tissue outside the CNS
What are the two functions of the PNS?
- deliver sensory information to the CNS
- carry motor commands to peripheral tissues and systems
What is another name for nerves?
Peripheral nerves
What are nerves?
Bundles of axons with connective tissues and blood vessels
What do nerves do?
Carry sensory information and motor commands in the PNS
What do cranial nerves connect to?
The brain
What do spinal nerves attach to?
Spinal cord
What are the three functional divisions of the PNS?
Afferent division, receptors and efferent division
What does the afferent division do?
Carries sensory information from the PNS sensory receptors to CNS
What are receptors and what do they do?
- detect changes or respond to stimuli
- neurons and specialised cells
- complex sensory organs(e.g.,eyes,ears)
What does the efferent division 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
What makes up the efferent division?
Somatic nervous system (SNS) and autonomic nervous system (ANS)
What does the somatic nervous system 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 do the special sensory receptors do?
Monitor smell,taste,vision,balance and hearing
What do the visceral sensory receptors do?
Monitor internal organs
What do the somatic sensory receptors do?
Monitor skeletal muscles,joints and skin surface
What are neurons?
The basic functional units of the nervous system
Describe the structure of neurons
The multipolar neuron Common in the CNS Cell body (soma) Short, branched dendrites Long,single axon
What is the cell body made up of?
Large nucleus and nucleolus
Perikaryon (cytoplasm), surrounding the nucleus
Mitochondria (produce energy)
RER (rough endoplasmic reticulum) and ribosomes (produce neurotransmitters)
What are dendrites?
Highly branched
Dendritic spines: many fine processes, receive information from other neurons and 80-90 percent of neuron surface area
Describe the axon
Long
Carries electrical signal (action potential) to target
Axon structure is critical to function
What is ten synapse?
Area where a neuron communicates with another cell
What are the two cells every synapse involved?
- Pre synaptic cell: neuron that sends message
2. postsynaptic cell: cell that receives message
The communication between cells at a synapse most commonly involves the release of chemicals called?
Neurotransmitters by the synaptic terminal
Discuss neurotransmitters
Are chemical messengers Are released at presynaptic membrane Affect receptors of postsynaptic membrane Are broken down by enzymes Are reassembled at axon terminal
What are the two types of synapses?
Neuromuscular junction and 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 structural classifications of neurons?
Anaxonic neurons
Bipolar neurons
Unipolar neurons
Multipolar neurons
Where are anaxonic neurons found?
In brain and sense organs
Where are bipolar neurons found?
In special sensory organs (sight,smell and 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
Anaxonic neurons are?
Small
All cell process look alike
Found in brain and sense organs
Have more than two processes and they are all dendrites
Bipolar neurons are?
Small
One dendrite, one axon
Found in special sensory organs (sight, smell, hearing)
Have two processes separated by the cell body
Unipolar neurons are?
Also called pseudounipolar neurons Have very long axons Fused dendrites and axon Cell body to one side Found in sensory neurons of PNS
Multipolar neurons are?
Have very long axons
Multiple dendrites, one axon
Common in the CNS
Include all skeletal muscle motor neurons
What are the three functional classifications of neurons?
Sensory neurons : afferent neurons of PNS
Motor neurons:efferent neurons of PNS
Interneurons: association neurons
What is ten function of sensory neurons?
Deliver information from sensory receptors to CNS
What are the three types of sensory receptors?
Interoceptors
Exteroceptors
Proprioceptors
What is the function of interoreceptors?
Monitor internal systems (digestive,respiratory,cardiovascular,urinary,reproductive)
Internal senses(taste,deep pressure, pain)
What is the function of exteroreceptors?
External senses (touch, temperature,pressure)
Distance senses (sight,smell and hearing)
What is the function of proprioreceptors?
Monitor position and movement (skeletal muscles and joints)
What do motor neurons do?
Carry instructions from CNS to peripheral effectors via efferent fibres (axons)
What are the two major efferent systems?
Somatic nervous system SNS
Autonomic nervous system ans
What does the somatic nervous system involve?
Includes all somatic motor neurons that innervate skeletal muscles
What does the autonomic nervous system involve?
Visceral motor neurons innervate all other peripheral effectors
Smooth muscle,cardiac muscle,glands, andipose tissue
Where are inter neurons located?
Most are located in the brain,spinal cord and autonomic ganglia between sensory and motor neurons
What are interneurons responsible for?
Distribution of sensory information
Coordination of motor activity
Are involve in higher functions such as memory,planning and learning
Neurologia is?
Half the volume of the nervous system
Many types of neurologia in CNS and PNS
What are the four types of neurologia in the CNS
Ependymal cells
Astrocytes
Oligodendrocytes
Micrologia
What are ependymal cells?
Cells with highly branched processes;contact neuroglia directly
What are astrocytes?
Large cell bodies with many processes
What are oligodendrocytes?
Smaller cell bodies with fewer processes
What are micrologia?
Smallest and least numerous neuroglia with many fine branched processes
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 and Schwann cells
What are satellite cells?
Also called amphicytes
Surround ganglia
Regulate environment around neuron
What are Schwann cells?
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
Neurons perform?
All communication, information processing and control functions of the nervous system
Neuroglia preserve?
Physical and biochemical structure of neural tissue
Neuroglia are essential to
Survival and function of neurons
Two anatomical divisions of the nervous system are?
The CNS and the PNS
Two functional divisions of the peripheral nervous system and their primary functions are?
The afferent division which brings sensory info to the CNS from receptors in the peripheral tissues and organs and the efferent division which carries motor commands from the CNS to muscles glands and andipose tissue
Two components of the efferent division of the PNS?
Somatic nervous system and the autonomic nervous system
What would the effect of damage to the afferent division of the PNS be?
Would interfere with a persons ability to experience a variety of sensory stimuli
The structural components of a typical neuron are?
Cell body or soma Dendrites An axon Telodendria Nissl bodies Neurofilaments Intermediate neurotubules Neurofibrils Axoplasm Axolemma Initial segment Axon hillock Collaterals
Classify neurons according to their structure
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
