CH7 - Nervous System Flashcards
CNS Functions
- Integration
- Interpret incoming sensory information
- Issues outgoing instructions
CNS Organs
- Brain
- Spinal Cord
PNS Organs
- Spinal Nerves
- Cranial Nerves
Carry impulses to and from spinal cord
Spinal nerves
Carry impulses to and from brain
Cranial nerves
PNS Functions
- Cranial and spinal nerves link CNS and rest of body
- Perform motor and sensory function
Carries general sensory signals from muscles, bones, joints, skin and special sense organs
Somatic sensory division
Carries signals from organs
Visceral Sensory division
Carry impulses from the sensory receptors to the CNS
Sensory (afferent) division
- Afferent Arrives at brain
Nerve fibers that carry information away from the CNS
Motor (efferent) division
- efferent exits brain
Carries signals to skeletal muscles
Somatic Motor Division
“Fight or flight” division
Sympathetic
“E” division
“Rest and digest” division
Parasympathetic
“D” division
Nervous tissue is made of 2 types of cells
- Neurons
- Neuroglia
Conduct nerve impulses
Neurons
Don’t conduct nerve impulses
Neuroglia
Anchor neurons to blood capillaries as barrier against harmful substances
Astrocytes
Phagocytes that monitor neuron health and dispose of debris or bacteria
Microglia
Cilia circulate cerebrospinal fluid through CNS brain and spinal cord as protective cushion
Ependymal Cells
Produce myelin sheaths around CNS
Oligodendrocytes
Produce myelin sheaths around PNS
Schwann Cells
Protect neuron cell bodies in PNS
Satellite Cells
Metabolic center, contains nucleus, cytoplasm, and all organelles except centrioles
Cell Body
Conduct impulses toward cell body
Dendrites
Conducts impulses away from cell body, connected at axon hillock
Axon
Allow communication to flow from one neuron to the next
Axon Terminals
Protects, insulates, and speeds up nerve impulses, with gaps between Schwann cell production areas called Nodes of Ranvier
Myelin Sheaths
Gray Matter
No Myelin
White Matter
Myelin
Carry impulses from the central nervous system to viscera and muscles and glands
Motor (efferent) neurons
Cell bodies located in CNS; connect sensory and motor neurons
Interneurons
Many extensions from the cell body
Multipolar neurons
One dendrite and one axon
Bipolar neurons
Short single process leaving cell body
Unipolar neurons
Sensory Receptors of Skin
- Pain
- Temperature
- Light touch
- Deep pressure
- Proprioception
Clusters of cell bodies in the CNS
Nuclei
Collections of cell bodies outside the CNS in the PNS
Ganglia
Bundles of nerve fibers in CNS
Tracts
Bundles of nerve fibres in PNS
Nerves
Resting membrane is polarized
Action Potential 1: Neuron at Rest
Stimulus initiates local depolarization
Action Potential 2: Stimulus
Depolarization and generation of an action potential
Action Potential 3: Depolarization
Propagation of the action potential
Action Potential 4: Propagation
Restoring the inside of the membrane to a negative charge
Action Potential 5: Repolarization
Initial ionic conditions restored
Action Potential 6: Reset to Rest
When the action potential reaches the axon terminal…
the electrical charge opens calcium channels
Somatic Reflexes
- Reflexes that stimulate the skeletal muscles
- Involuntary; skeletal muscle is normally under voluntary control
Autonomic Reflexes
Regulate the activity of smooth muscles, the heart, and glands
Simple Reflex Arcs
- Receptor picks up stimulus
- Sensory afferent neuron sends info
- Interneuron acts as integration center
- Sends motor neuron to effector
- Effector is usually muscle
4 Brain Divisions
- Cerebral hemispheres (Cerebrum)
- Diencephalon
- Brain stem
- Cerebellum
Gyri and Sulci
Ridges and Grooves
3 basic parts of Cerebrum
- Cortex of gray matter
- Internal area of white matter
- Basal nuclei
Outer layer in the cerebral cortex composed mostly of neuron cell bodies
Gray Matter
Fiber tracts deep to the gray matter
White Matter
Executive functions (critical thinking, reasoning)
Frontal Lobe
- Sends impulses to skeletal muscles
Primary somatic sensory area
Parietal Lobe
- Receives impulses from the body’s sensory receptors
Interprets visual information
Occipital Lobe
Interprets auditory and olfactory information
Temporal Lobe
3 Structures of Diencephalon
- Thalamus
- Hypothalamus
- Epithalamus
Hypothalamus
- Helps regulate body temperature
- Controls water balance
- Regulates metabolism
Parts of Brain Stem
- Midbrain
- Pons
- Medulla oblongata
Protection of CNS
- Scalp and skin
- Skull and vertebral column
- Meninges
- Cerebrospinal fluid (CSF)
- Blood-brain barrier
Tough outermost layer
Dura Mater
Middle layer
Arachnoid layer
Internal Layer
Pia Mater
Cerebrospinal Fluid (CSF)
Formed by the choroid plexus (capillaries in the ventricles of the brain)
Blood-brain barrier is useless against
- Respiratory gases
- Alcohol
- Anesthesia
How many PNS cranial nerves
12 pairs
How many PNS spinal nerves
31 pairs