Chapter 9, Nervous System Flashcards
Central Nervous System
CNS
Peripheral Nervous System
PNS
CNS
Central Nervous System
PNS
Peripheral Nervous System
The CNS contains..
The brain and spinal cord
The PNS contains….
Everything else
The PNS includes
The Somatic Nervous System and the Autonomic Nervous System
The Somatic Nervous System
Is Voluntary
Skeletal Muscle
The Autonomic Nervous System
Involuntary - such as cardiac muscle, smooth muscle, and various glands
Contains 2 parts - the Sympathetic and the ParaSympathetic
Sympatheic
“Fight or flight”
Parasympathetic
“At rest”
Cranial Nerves
12 pairs
Listed by Roman Numerals
Spinal Nerves
31 Pairs
Neurons
Nerve Cells
Nerve Cells
Neurons
Nerve Cells
ARE NOT NERVES
Neurons
Multipolar Bipolar Unipolar Sensory Interneurons Motor Neurons
Neurons
10 Trillion of them in the body!
The brain has about 100 billion!
Parts of a Neuron
Soma (cell body)
Dendrites
Axon
Soma
The cell body
Axon
Sends the impulse AWAY from the cell body
Dendrites
Numerous Extensions
Short branches
RECEIVE the impulse
Nerves
Bundles of axons
Myelin Sheath
Insulating layers of myelin around axons within the brain or spinal cord
Nodes of Ranvier
The narrow gaps on the axon between the myelin
Neuron Cell Membrane
Is selectively permeable
Schwann Cells
In the PNS
Produce Myelin Sheath around axons of myelinated neurons in the PNS
Neuroglia
3 STRUCTURAL types of neurons
Multipolar
Bipolar
Unipolar
Multipolar Neurons
Very common in the CNS
Have many processes - only one process is an axon, the rest are dendrites
Most neurons in the brain and spinal cord are multipolar
Bipolar Neurons
Have only two processes - one axon, one dendrite
Found in the eyes, ears, and nose
Unipolar Neurons
Found in specialized masses of nervous tissues called ganglia
Sensory neurons are unipolar
3 FUNCTIONAL groups of neurons
Sensory
Interneurons
Motor Neurons
Impulse
Can only travel in one direction
Myelin
A lipoprotein that speeds up the impulse
Sensory Neurons
AKA: Afferent Neurons
Afferent Neurons
AKA: Sensory Neurons
Sensory Neurons
Most are unipolar
Travel TO the CNS
Afferent - Travel TOWARD the brain and spinal cord
Have receptors at the end of their dendrites
Afferent
Toward
Interneurons
AKA: Association Neurons
Association Neurons
AKA: Interneurons
Interneurons
Found ONLY in the CNS
Are multipolar
Some aggregate in masses of nervous tissue called nuclei
(nuclei are similar to ganglia, but are in the the CNS) and oh crap I have no idea what that means
Interneurons
Conduct impulses from one part of the brain or spinal cord to another
They may direct incoming sensory impulses to the appropriate part of the CNS for processing and interpretation.
Motor Neurons
AKA: Efferent Neurons
Efferent Neurons
AKA: Motor Neurons
Motor Neurons
Travel AWAY from the CNS to EFFECTORS
Efferent
Away from
Effectors
Muscles, glands, or organs
Something that can change the EFFECT on the body
Neurolimma
Outer layers formed from Schwann Cells on the exterior of some axons
Outside of the myelin sheath
Help to repair damage when nerves are damaged
Neuron Cell body
AKA: Soma
Soma
AKA: Neuron Cell body
Neuron cell body includes
Cytoplasm
Cell membrane
Organelles
Neurofilaments (I have no idea what these are either, or crap, I am going to fail this test)
Soma Organelles
The main players are gogli apparatus, lysomes, and mitochondria
Neurofilaments
Fine, threadlike network which extend from the cell body and are the entire length of an axon
Neurotransmitters
Chemicals that an axon secretes that stimulates or inhibits an effector
Nervous Tissue Including supporting cells is called
Neuroglial cells
Glial
glue
Neuroglial cells
One in the CNS
4 types: Microglial, astrocytes, ependymal, oligodendrites
Neurons CANNOT EXIST
without neuroglial cells
Neuroglial
Outnumber neurons 3 to 1
Microglial
Smallest
Scattered about the CNS
Phagocytic
Help form scars
Oligodendrites
Line up next to nerve fibers
Provide the myelin sheath around the brain and spinal cord
Astrocytes
Are pretty
Astrocytes
Commonly found between neurons and blood vessels
Provide structural support
Join other structures to regulate the content of nutrients and ions within tissue
Also help form scar tissue
Ependymal Cells
Form an epithelial like membrane that covers specialized parts of the brain called choroid plexuses
Form the inner lining that enclose spaces in the brain (ventricles) and in the spinal cord (central canal)
Have a lot to do with CSF
Dorsal Root
Sensory branch of a spinal nerve where it joins the spinal cord
Meninges
3 layer membrane around the brain and spinal cord
For protection
Epidural Space
Between the vertebrae and the spinal cord
Site of an epidural block
Loose connective tissue
Layer 1: Dura Mater
Outermost layer
Tough, white, fibrous tissue
Vascular - many blood vessels and nerves
Attaches to the inside of the cranial cavity
Continues into the vertebral canal and ends at the tip of the cord
Subdural Space
Below the dura mater
Contains loose connective and adipose tissues
Tissues “pad” the spinal cord
Layer 2: Arachnoid Mater
Thin, web-like membrane
No blood vessels
Middle layer
Subarachnoid Space
Contains CSF (CerebroSpinal fluid)
Layer 3: Pia Mater
Very thin
Many nerves and many blood vessels that provide nourishment to the cells of the brain and spinal cord
Closely touches the brain and spinal cord
CSF
CerebroSpinal Fluid
CSF
98% Water
2% Nutrients
CSF
We make it and drain it 2-3 times a day (600-700ml/day)
Fluid should be clear
Housed in the ventricles of the brain
Spinal Cord
Extends from the base of the brain, to the 1-L2 area, then comes to a point
Ends at the Cauda Equina (horse’s tail)
Functions of the Spinal Cord
Conducting impulses to and from the brain
Serves as a center for spinal reflexes
Spinal Cord
About 18 inches long
Spinal Cord
Thickening in the neck region, called the cervical enlargement, gives rise to the upper limbs
Thickening in the lower back, called the lumbar region, gives rise to the lower limbs
Spinal Nerves
31 pairs
Part of the PNS
Branch to various part of the body, then connect them with the CNS
Nerves
Serve the left AND the right side of the body
Have ASCENDING and DESCENDING tracts
Ascending Tracts
Carry sensory information TO the brain
Descending Tracts
Carry motor impulses FROM the brain, down the spinal cord, and out to the muscles and gland
Spinal Cord
Can act independently from the brain (example: reflexes)
Remember, spinal nerves…
DO NOT have the same break down as vertebrae
Cervical Nerves
8 Pairs
Thoracic Nerves
12 Pairs
Lumbar Nerves
5 Pairs
Sacral Nerves
5 Pairs
Coccygeal Nerves
1 Pair
Ventricles
Spaces within the cerebral hemispheres and brainstem
Contain CSF
4 Ventricles
1st and 2nd Ventricles
Are the largest
“Lateral” ventricles
Extend into the cerebral hemispheres and occupy parts of the frontal, temporal, and occipital lobes
3rd Ventricle
Narrow Space
In the mid-brain, beneath the corpus collosum
4th Ventricle
In the brainstem, just in front of the cerebellum
Cerebral Aquaduct connnects the 4th to the 3rd and passes lengthwise through the brainstem
Openings in its “walls” that lead into the subarachnoid space
The brain is composed of…
More than 100 billion multipolar neurons
The brain has 4 major portions
Cerebrum
Diencephalon
Brainstem
Cerebellum
Cerebrum
Has 2 hemispheres - right and left
Longitudinal Fissure separates the right and left
Transverse Fissure separates the cerebrum from the cerebellum
Corpus Callosum
Structure that connects the 2 hemispheres of the brain
Broad, flat bundle of axons
Cerebrum Surface
Has many grooves and fissures to allow for more surface area, for neural tissue
Allows for higher level thinking
Sulcas
The shallow grooves of the cerebrum
Gyri
The ridges of the cerebrum
Fissures
The deep groves of the surface of the cerebrum
Frontal Lobe
Anterior parts of each hemisphere
Where our thinking occurs
Motor cortex - tells muscles to move
Temporal Lobe
Below the frontal and parietal lobes
Separated by the lateral sulcus
Parietal Lobe
Posterior to the frontal lobe and separated by the central sulcas
Receives all sensory information
Occipital Lobe
Posterior part of each hemisphere
Visual
Insula
Deep in the lateral sulcus and covered by parts of the frontal, parietal, and temporal lobes
A circular sulcas separates the insula from the other lobes
Cerebral Cortex
A think layer of gray matter on all lobes of the cerebrum
Outermost part of the cerebrum
Contains nearly 75% of all neuron cells in the nervous system
Function of the cerebrum
Provides higher brain functions Interprets sensory impulses Centers for initiating voluntary muscle movement Stores memory and uses it to reason Intelligence Personality
Functional Areas of the cerebral cortex
Sensory
Association
Motor
Diencephalon
Has the Thalamus and the Hypothalamus
Thalamus
Relay station for sensory impulses arriving to the cerebral cortex from other parts of the nervous system
It receives all the sensory impulses EXCEPT those associated with the sense of smell
Thalamus
Sends sensory impulses to the appropriate regions of the brain for interpretation
All regions of the cerebral cortex can communicate with the Thalamus by means of descending fibers
Hypothalamus
Connected by nerve fibers to the cerebral cortex, thalamus, and other parts of the brain stem
Hypothalamus regulates….
Heart rate and arterial blood pressure Body temperature Water and electrolyte balance Hunger and weight Movements and secretions of the stomach Production of hormones that stimulate the pituitary gland to secrete pituitary hormones Sleep and wakefullness
Limbic Systen
In the diencephalon
Hypothalamus, thalamus, and basal nuclei interconnect with parts of the cerebral cortex
Limbic System
Controls emotional experiences and expressions
Can modify how you act by producing feelings such as fear, anger, pleasure, and sorrow
Recognizes upset in the physical and psychological conditions that may threaten life
Guides behavior that increases chance of survival
Limbic system
Controls:
Emotional experience
Expression
Brain stem
Connects the cerebrum to the spinal cord
Brain stem
Has numerous tracts of nerve fibers and nuclei
The nuclei are masses of gray matter
Brain stem
Midbrain
Pons
Medulla Oblongata
Brain stem
Bundle of nervous tissues
Connects cerebrum to the spinal cord
Numerous tracts of nerve fibers and several nuclei
Consists of midbrain, pons, and medulla oblongata
Midbrain
Contains bundles of myelinated axons that join lower parts of the brain stem and spinal cord with higher parts of the brain
Masses of gray matter that serve as reflex centers
Two are: Vision and auditory reflexes
Pons
Longitudinal parts relay impulses from medulla oblongata and the cerebrum
Pons
Anterior transmits impulses FROM the cerebrum to centers in the cerebellum
Medulla Oblongata
Part of the brain stem between the pons and the spinal cord
Medulla Oblongata
Ina godda davida….
Medulla Oblongata
All ascending and all descending nerve fibers connecting the brain and spinal cord must pass through the medulla oblongata
Medulla Oblongata
Controls visceral activities
Cardiac - regulating heart and heart rate
Vasomotor - regulating blood pressue
Respiratory - regulating breathing
Reticular Formation
Sensory impulses reach the R.F, and respond by activating the cerebral cortex to wakefullness
Reticular Formation
Decreased activity results in sleep
Reticular Formation
Injury to the RF results in a comatose state
Cerebellum
Has 2 hemispheres
Cerebellum location
Located beneath the occipital lobe and posterior to the pons and the medulla oblongata
Cerebellum
Communicates with other parts of the CNS by means of 3 pairs of tracts called cerebral peduncles
Mostly white matter and a think layer of gray matter called the cerebellar cortex
Cerebellum Reflex Center
Not a store
Cerebellum Reflex Center
Integrating sensory information concerning positioning of body parts
Coordinating complex muscle movements
Helps maintain posture
Nitric Oxcide
CNS - may play a role in memory
PNS - vasodilation
Acetylcholine
CNS - controls skeletal muscle actions
PNS - stimulates skeletal muscle contractions at neuromuscular junctions
May excite or inhibit autonomic nervous system actions
Monamines
Group of compounds, which form modified amino acids