Chapter 14: Nervous Tissue Flashcards
Neurology
A study of the normal functioning and disorders of the nervous system
The human nervous system consists of:
-The brain and cranial nerves
-spinal cord and spinal nerves
- ganglia
-enteric plexuses and sensory receptor
Nerve
Bundle of axons
Ganglia
Swelling/knot
- are masses of nervous tissue (cell neuron bodies) outside the brain and spinal cord
Enteric plexuses
Are networks of neurons located in the walls of the GI tract organs; help regulate digestive system activities
- “Brian of the gut”
What are Sensory Receptors
Are specialized nerve endings
The CNS consists of the
Brian and spinal cord
PNS
Cranial nerves (12)
Spinal nerves (31)
Functions of motor and sensory neurons
- collect information: receptors detect changes in environment and goes to CNS
- process and evaluate information: CNS determines required response
- initiate response: initiates impulses that PNS Carrie’s to effectors
Somatic sensory nervous system
Conscious
Touch, pain, pressure, vibration, proprioceptiom
Visceral sensory nervous system
Generally Unconscious of
Impulses form blood vessels and viscera
Somatic Motor Nervous system
Voluntary
Conducts impulses that cause the contraction of skeletal muscles
Autonomic Motor nervous system
Involuntary
Conducts impulses that regulate smooth muscle, cardiac muscle, and glands
Sensory receptors function
- Detect stimuli in the internal and external environments
- transmitted by affrent neurons to the brain and spinal cord
Interneurons
- Analyze information and provide perception
- stores some of it
- makes decisions regarding appropriate behaviour
Motor neurons
- efferent
- respond to integration decisions by initiating effectors ( including muscle fibres and gland at cells)
Somatic sensory neurons
Convey information from sensory receptors in the skin, skeletal muscles, joints, and for special senses ( vision, hearing, taste, smell) to the CNS
Somatic Motor Neurons
Convey information from the CNS to skeletal muscles only
- output of information that results in muscular contraction
Autonomic sensory neurons
(visceral)
- conveys information mainly from visceral organs( smooth muscle, organs in the thorax, abdomen, and pelvis) to the CNS
Autonomic Motor Neurons
Convey information from the CNS to smooth muscle, cardiac muscle, and glands
Branches of Autonomic Nervous system
- sympathetic
- parasympathetic
Sympathetic neurons
Fight or flight
- increase heart rate
Support excessive or emergency action
Parasympathetic Neurons
Rest and digest
- slow it down
- “ takes care of” activities
ENS sensory neurons
- monitors chemical changes within the GI tract and the stretching of the walls
ENS Motor Neurons
- govern contraction of the GI tract smooth muscle and secretions of acid from the stomach, and endocrine cells.
Nervous tissue
Vascular
Compromised of two cells
- neurons
- neuroglia
Neurons
- highly specialized
- cannot go under meotic division
- electrically excitable: initiate, transmit, and receive nerve impulses
Glial Cells
- non excitable
- Support, nourish, protects neurons, and maintains interstitial fluid
- Continue to divide
Found in both the CNS and PNS
** tumours are more likely to be deprived from glial cells then a neurons
Neuron Special Characteristics
- high metabolic rate
- extreme longevity
- nonmiotic
- excitable
- conductive
Neuron structure
Contain:
- cell body (soma)
- nucleus and nucleolus
- Chromatophilic substance
- Dendrites
- Axon
- mitochondria
Chromatophilic Substance
Free ribosomes and rough endoplasmic reticulum
Dendrites
Receive signals and transfer them to the cell body
Axon
Transmit nerve impulses away from the cell body and towards other cells
Region where axon connects to the cell body
Hillock
Axon collaterals
Side branches of the main axon
Terminal arborizations
Extensions at the end of the axon
Synaptic knobs
Expanded regions at the tip of the axon
Perikaryon
Cytoplasm within the cell body
Neurofilaments
Intermediate filaments that form neurofibrils, which help support cell extensions
Cell bodies
Protein synthesis
Dendrite
Recovering / input zone
Axon
Output zone
Examples of neurotransmitters
- acetylcholine
- aspartame
- glycine
- dopamine
- endorphins
- glutamate
- GABA
- norepinephrine
- seratonin
- nitric oxide
Neuron classification
Depends on a number of processes extending from the cell body
Include:
- unipolar
- bipolar
- multipolar
Unipolar
- single, short process branches like a T from the cell body
- the process is an axon with peripheral and central process
Bipolar
- two process, one dendrite and one axon
Multipolar
- many dendrites and a single axon
- most common type of neuron
Glial cells of the CNS
- astrocytes
- oligodendrocytes
- microglia
- ependymal cells
Glial Cells: PNS
- Schwann cells
- satellite cells
Astrocytes
- processes of astrocytes make contact with blood capillaries, neurons, and the Pina mater
Two types: - photoplasnic ( grey matter)
- fibrous (white matter)
Functions of astrocytes
- help form the BB
- regulate tissue fluid composition
- form a structural network
- replace damaged neurons
- assist neuronal development
- help regulate synaptic transmission
- change synapse numbers
Ependymal cells
- collated cuboidal epithelial cells
- line the ventricles of the brain and the central canal of the spinal cord
- help produce cerebral spinal fluid
Help form choroid plexus
Microglia
- originate in the red bone marrow and migrate to the CNS as it developed
- function and phagocytes: remove cellular debris, microbes, and damaged nervous tissue
Oligodendrocytes
- only CNS
- wrap themselves around the axons
- produce myelin (insulator of electrical activity)
Satellite cells
- surround cell bodies of neurons of 5e PNS
- regulate fluid around neuron cell bodies in the PNS
Neurolemmocytes / Schwann cells
- encircle axons in the PNS and for the myelin sheath
- participate in axon regeneration
