Anaphy - Review for midterms - (White matter & Grey Matter, CNS & PNS)

White matter consists primarily of?

myelinated axons of many neurons

Gray matter consists of?

• neuron cell bodies

• dendrites

• unmyelinated axons

• axon terminals

• neuroglia

connect the brain to the periphery

cranial nerves

connect the spinal cord to the periphery

spinal nerves

• bundle of axons located in the CNS

• interconnect neurons in the spinal cord and the brain

tract

what gives the whitish appearance of white matter?

white matter is primarily composed of myelinated axons and the whitish appearance of myelin is the reason of it’s color

what gives the gray appearance of gray matter?

• the Nissl bodies impart a gray color

• little to no myelin presence

how does the gray and white matter look like in the spinal cord?

• white matter surrounds an inner core of grey matter

• shaped like a butterfly or letter H

how does the gray matter look like in the brain?

a thin shell of gray matter covers the surface of the largest portions of the brain (cerebrum & cerebellum)

where do nerve impulses generate from?

CNS

divisions of the PNS

• somatic nervous system

• autonomic nervous system

• enteric nervous system

what comprises the somatic nervous system?

• sensory neurons that convey information from somatic receptors

• motor neurons that conduct impulses from CNS to skeletal muscles only. (voluntary)

what comprises the autonomic nervous system?

• sensory neurons that convey information from autonomic sensory receptors

• motor neurons that conduct impulses to smooth muscles, cardiac muscles and glands (involuntary)

where are autonomic sensory receptors located?

visceral organs, such as lungs and stomach

2 branches of the motor part of the autonomic nervous system

• sympathetic division

• parasympathetic division

what are neurons that increase the heart rate? On the other hand, what slows it down?

• Sympathetic neurons increase the heart rate

• Parasympathetic neurons slow it down

These are the neurons that take care of the fight-or-flight response (exercise / emergency actions)

Sympathetic Neurons

These are neurons that take care of the rest-and-digest activities

Parasympathetic Neurons

• brain of the gut

• it’s function is involuntary

• consists approximately of 100 million neurons in enteric plexuses

Enteric Nervous System

how does the ENS communicate with the CNS?

via sympathetic and parasympathetic neurons

These neurons monitor and regulate the activities happening within the GI tract

Sensory neurons of the ENS

What are examples of activities happening in the GI tract?

• stretching of walls in GI tract

• contraction of GI tract smooth muscle to propel food through the GI tract

• GI tract secretions

• GI tract endocrine cells, which secrete hormones

process of nerve impulse in the Somatic Nervous System

(1) Somatic and special sensory receptors and somatic neurons → (2) CNS → (3) somatic motor neurons (voluntary) → (4) skeletal muscle

process of nerve impulse in the Autonomic Nervous System

(1) Autonomic sensory receptors and autonomic sensory neurons → (2) CNS → (3) Autonomic motor neurons (involuntary) : Sympathetic & Parasympathetic) → (4) smooth muscle, cardiac muscle & glands

process of nerve impulse in the Enteric Nervous System

(1) Enteric sensory receptors and Enteric sensory neurons in the GI tract and Enteric Plexuses → (2) CNS → (3) Enteric motor neurons (involuntary) → (4) smooth muscles, glands, and endocrine cells of the GI tract

Neurons communicate using 2 types of electrical signals, what are these?

• graded potentials

• action potentials

used for short - distance communication only

graded potentials

allow communication over long distances within the body

action potentials

an action potential within a muscle fiber

muscle action potential

an action potential that occurs in a neuron

nerve action potential or nerve impulse