Lab Week 10 Nervous tissue, spinal cord, and reflexes

Two divisions of the nervous system

Central nervous system and Peripheral nervous system

Central nervous system

Brain and spinal cord

Peripheral nervous system

Sensory receptors and nerves

Sensory versus motor

Sensory: bring information into the brain

Motor: convey info from CNS to muscles and glands, converts plan into action

Three parts of a neuron (nerve cell)

Neuron cell body or soma

Dendrites

Axon

Identify the parts of a multipolar neuron

dendrites, neuron cell body, nucleus, axon hillock, axon, Schwann cell, Node of Ranvier, myelin sheath, presynaptic terminals and collateral axon

Dendrites (general definition for this and these next few terms)

Cell extensions of the cell body that receive information from other neurons or sensory receptors; conduct currents toward the cell body

Neuron cell body

Or soma, typical cell functions such as protein synthesis and housekeeping

Nucleus

Part of the neuron cell body

Axon hillock

The triangular region of the neuron cell body that is devoid of Nissl bodies, it leads to the axon that exits the neuron cell body

Axon

Arises from axon hillock of the cell body then becomes the initial segment; part of trigger zone where action potentials are generated; ends at presynaptic terminal

Schwann cell

Or neurolemmocytes, the common glia of the peripheral nervous system

Node of Ranvier

The Schwann cells wrap around axon, leaving thin regions between successive cells called this

Myelin sheath

Most long nerve fibers of CNS & PNS are covered by a layer of white fatty material

•protects & insulates

•fibers covered are said to be myelinated

Presynaptic terminals

Neurons transmit information electrochemically along the length of the axon to this

Collateral axon

Branch off of the main axon

Three functional types of neurons

•Sensory or afferent: action potentials toward C N S.

•Motor or efferent: action potentials away from C N S.

•Interneurons: within C N S from one neuron to another.

Another word for neuroglia

Glia

Describe and identify an oligodendrocyte (a type of neuroglia)

Essentially a Schwann cell, but in the CNS, so produces myelin

Describe and identify a microglia (a type of neuroglia)

An immunity cell

Describe and identify an astrocyte (a type of neuroglia)

Blood brain barrier

Describe and identify an ependymal cell (a type of neuroglia)

Produce cerebral spinal fluid

Identify enlargements of the spinal cord

Cervical and lumbar

Identify the roots of spinal nerves, spinal cord, conus medullaris, cauda equina, filum terminale

Identify and describe the structure of a nerve including the different coverings

Explain the clinical significance of cauda equina

A bundle of nerves and nerve roots at the lower end of the spinal cord, Cauda Equina Syndrome is when these nerves are compressed resulting in mainly pain in the lower back

Identify and label structures of a cross section of a spinal cord

Identify the direction of action potentials through the various structures on the cross section of the spinal cord

pg 236

Identify the parts of the meninges of the spinal cord

bold

What is the number of each type of spinal nerve

Cervical - 8

Thoracic - 12

Lumbar - 5

Sacral - 5

Coccygeal - 1

Identify (or match) the four major plexuses of the body, the specific spinal nerves contributing to each plexus and the major nerves arising from each plexus

Cervical - C1-4 - Phrenic

Brachial - C5-T1 - Radial, median, ulnar, musculocutaneous, axillary

Lumbar - L1-4 - Femoral, obturator

Sacral - L4-S4 - Sciatic (tibial and common fibular)

Definition of plexus

Interwoven

Which extremity does the axillary nerve connect to

Shoulder

Which extremity does the radial nerve connect to

Arm, writs and hand

Which extremity does the musculocutaneous nerve connect to

Arm

Which extremity does the ulnar nerve connect to

Forearm and hand

Which extremity does the median nerve connect to

Arm and hand

Which extremity does the obturator nerve connect to

Thigh

Which extremity does the femoral nerve connect to

Thigh

Which extremity does the tibial nerve connect to

Leg

Which extremity does the fibular nerve connect to

Leg and foot

List the five structures involved in a reflex arc

1. Sensory receptor

2. Sensory neuron

3. Interneuron

4. Motor neuron

5. Effector organ

Difference between a stretch, golgi tendon, and withdrawal reflex

Stretch: muscle stretch

Golgi tendon: excessive tension

Withdrawal reflex: pain/damage threat

Match the patellar reflex with its description and know it’s corresponding nerve that is being tested

It occurs when the patellar tendon is tapped, stretching the quadriceps muscle

Femoral nerve

Triceps brachii

When tapped, it extends the elbow

Radial nerve

Biceps brachii

Tap on the biceps brachii causes the elbow to flex

Musculocutaneous nerve

Calcaneal tendon

When tapped, causes plantarflexion

Tibial nerve

Eye (blink and corneal)

When light is shined into one eye, the pupil constricts in both eyes

Optic nerve and oculomotor nerve

Normal

Movement of an inch or two

Hyporeflexic

Showing less than average response

Hyperreflexic

Showing an exaggerated response

What are the three different neuron shapes

Multipolar neuron: many dendrites and an axon

Bipolar neuron: has a dendrite and an axon

Pseudo-unipolar neuron: has an axon and no dendrites

Which neuron shapes are motor and which are sensory?

Motor: multipolar neuron

Sensory: bipolar and pseudo-unipolar neuron

Which neuron shape is for special senses and which is for general senses

Special senses: bipolar neuron

General senses: pseudo-unipolar neuron