Nervous System + Spinal Cord Flashcards
Peripheral Nervous System
general components
Distributed throughout the rest of the body: Visceral organs, muscles, skin, bones
Afferent + efferent neurons, few interneurons
Nerves (have blood vessels and CT)
Ganglia
Nerves definition
Bundles of myelinated axon that carries signals between the PNS + CNS that have blood vessels + dense irregular connective tissue.
Nerves Connective Tissues
- Endoneurium: connective tissue around myelin of a single sheath
- Fascicles: bundle of many axons, nerve makes up many fascicles
- Perineurium: around a fascicle
- Epineurium: around a whole nerve
Spinal nerves - general
- Come out of the spinal cord
- Pairs come out between each pair of vertebrae: 1 to the left + 1 to the right
Cranial nerves
general
- 12 numbered nerves that come out of the brain
- Most come out of the brain stem
- Most go to the head
Ganglia
Clusters of soma of neurons in PNS
Sometimes many synapses
Some have no synapses
3 Branches of the PNS
- Afferent: sensory neurons
- Efferent Nervous System: carries signals out of the CNS that control other parts of the body.
- Enteric Nervous System: Nervous system around the digestive tract controls the glands and smooth muscle, receives sensory signals from the tract, and communicates with the CNS through the efferent + afferent nervous system.
Afferent Nervous System
breakdown
- Gathers info + sends it back to the CNS
- Special Senses: senses with special sensory organs
- Sight, hearing, smell, taste, balance - Somatic Senses: senses of the body
- Of the skin, muscles, + joints - pressure, temp, pain - Visceral Senses: sense of visceral organs + body fluids
- Heart, digestive, reproductive, etc.
- Blood
- Not entirely consciously aware
Efferent Nervous System
definition & components
Definition: Carries signals out of the CNS that control other parts of the body
Associated systems: Autonomic Nervous System & Enteric Nervous System
Somatic Nervous System
Part of the efferent nervous system that controls skeletal muscle.
- Composed of somatic motor neurons + units
- Voluntary
- Controlled by the cerebral cortex - the conscious part of the brain
Autonomic Nervous System:
Part of the efferent nervous system that controls smooth muscle, cardiac muscle, glands, adipose.
- Involuntarily controlled by the hypothalamus
- Sympathetic: “fight or flight” - gets the body ready for action
- Parasympathetic: “rest + digest” - stimulates normal metabolism of the body, works the opposite of the sympathetic
Enteric Nervous System
Part of the efferent nervous system around the digestive tract that controls the glands and smooth muscle, receives sensory signals from the tract, and communicates with the CNS through the efferent + afferent nervous system.
Can act independently of the rest of the nervous system because it has its own interneurons.
Central Nervous System
(CNS) general components
- Located in the dorsal body cavity + inside bones: Spinal cord - in vertebrae, Brain - cranial bones
- Surrounded by meninges = connective tissue membrane that protects the CNS
- Bathes in cerebrospinal fluid
- Lots of interneurons
- Primary information processor of the body
- white & grey matter
White Matter
Fat from the myelinated axons gives it its color that carries info between different parts of the CNS.
In the spinal cord- grey on the outside + white matter around it
In the brain- grey on the outside + inside with white matter in between
Grey Matter
Have lots of synapses for information processing. The cell bodies and unmyelinated axons give it its color.
In the spinal cord- grey on the outside + white matter around it
In the brain- grey on the outside + inside with white matter in between