PHYL 141 Exam 3

CNS (Central Nervous System)

Consists of the brain and spinal cord, which primarily interpret incoming sensory information and issue instructions based on that information and on past experience

PNS (Peripheral Nervous System)

Consists of the cranial and spinal nerves, ganglia, and sensory receptors

Neuron (Nerve cells)

The basic functional units of nervous tissue. Highly specialized to transmit messages from one part of the body to another in the form of nerve impulses

Ganglia

In the PNS, clusters of neuron cell bodies

Neuroglia

Glial cells, of the CNS include astrocytes, oligodendrocytes, microglial cells, and ependymal cells. Found in the PNS is Shwann cells, also known as neurolemmocytes, and satellite cells.

Astrocytes

are the most abundant CNS neuroglia

Oligodendrocytes

Have processes that form myelin sheaths around CNS axons

Microglial cells

are defensive cells in the CNS

Ependymal cell

Line cerebrospinal fluid filled cavities

Schwann cells/ Satellite cells

Which form myelin, surround neurons in the PNS

Unipolar Neurons

One very short process, divides into peripheral and Central Processes

Pseudo unipolar neurons

derived from bipolar neurons

Bipolar neurons

two processes attached to the cell body, quite rare

Multipolar neurons

Processes from cell body that are classified as dendrites, carries impulses away from CNS (neurons un brain and spinal cord)

Afferent (Sensory) neurons

Neurons carrying impulses from sensory receptors in viscera to the CNS (towards the Brain)

Efferent (motor) neurons

Neurons carrying impulses from the CNS to the viscera and/or body muscles and glands (away from brain)

Sensory

Contains nerve fibers that conduct impulses from sensory receptors TOWARD CNS

Motor

Contains nerve fibers that conduct impulses AWAY FROM CNS

Interneurons

Which are situated between and contribute to pathways that connect sensory and motor neurons

Mixed nerves

Most nerves of the body, including all spinal nerves, are mixed nerves

Neural tube

The embryonic structure that ultimately forms the brain and spinal cord

Autonomic Reflex (Visceral)

Mediated through the Autonomic nervous system (ANS)

Somatic

Stimulate skeletal muscles by the somatic divisions

5 components of reflex arc

1. Receptor
2. Sensory Neuron
3. Integration Center
4. Motor Neuron
5. Effector

Stretch reflexes

Deep tendons

Reciprocal Inhibition

Causes them to relax and prevents them from resisting (or reversing) the contraction of the stretched muscle

Monosynaptic Reflex and Polysynaptic Reflex

The integration center is in the spinal cord, and in each example the receptor and effector are in the same limb. The patellar reflex, a two neuron monosynaptic reflex. A flexor reflex, an example of a polysynaptic reflex

Extrinsic eye muscles

Lateral Rectus
Medial Rectus
Superior Rectus
Inferior Rectus
Inferior Oblique
Superior Oblique

Lateral Rectus

Moves eye laterally

Medial Rectus

Moves eye medially

Superior Rectus

Elevates eye and turns it medially

Inferior Rectus

Depresses eye and turns it laterally

Inferior Oblique

elevates eye and turns it laterally

Superior Oblique

Depresses eye and turns it laterally

Optic Disc (Blind spot)

Site where there are no photoreceptors at fundus

Rods

Specialized photoreceptors for dim light

Cones

Color photoreceptors that operate in high lighting for visual acuity

Optic nerve

Axons leave the retina in the tight bundle of fibers

Sensory Receptors

Respond to outside stimuli

Special Senses

Vision, hearing, Equilibrium, steel and taste

general Senses

React to touch, pressure, pain, heat, cold, stretch, vibration, and changes in body position and are distributed throughout the body

Exteroceptors

React to stimuli in the external environment (EX. cutaneous receptors in skin, receptors in eye)

Interoceptors (Visceroceptors)

Respond to stimuli arising in the body ( EX. Stretch receptors internal organs, chemoreceptors)

Proprioceptors

Respond to internal stimuli from skeletal muscles, joints, and ligaments/tissues covering bones and muscles (similar to interoceptors)

External and middle ear

Sense of hearing

Internal ear

Sense of balance/equilibrium

Mesencephalon

2

Rhombencephalon

Frontal lobe

Parietal Lobe

Occipital Lobe

Temporal Lobe

Gyrus

Sulcus

Fissure (a Deep sulcus)

Motor Areas

Primary motor cortex
Premotor cortex
Frontal eye field
Brocas area (outlined by dashes)

Prefrontal cortex

Working memory for spatial tasks
Executive area for task management
Working memory for object recall tasks
Solving complex, multitask problems

Central Sulcus

3

Sensory areas and related association areas

Primary somatosensory cortex
Somatosensory association cortex
Gustatory cortex (in Insula)

Midbrain

Pons

Medulla oblongata

Thalamus

Pineal gland

Hypothalamus

Dura meter

Arachnoid mater
-Periosteal
-Meningeal

Pia mater

D
A
P

Dura mater
Arachnoid mater
Pia mater

Arachnoid villus

J

Right Lateral Ventricle (Deep to Cut)

O

Circulatory Pattern of Cerebrospinal Fluid

START
Lateral Ventricle
Interventricular foramen
Third ventricle
Fourth Ventricle
Subarachnoid space
END
Returns via Arachnoid Villus

Olfactory Bulb (Sheep brain)

Optic nerve (II) (Sheep Brain)

Infundibulum (Sheep Brain)

Mammillary body (Sheep Brain)

Cerebral Peduncle (Sheep Brain)

Pons (sheep brain)

Trigeminal nerve (V) (Sheep brain)

Abducens Nerve (VI) (Sheep Brain)

Medulla Oblongata (Sheep Brain)

5 Steps of Reflex Arc

Superior Oblique Muscle

Trochlea

Superior Oblique Tendon

C

Superior rectus muscles

Lateral rectus muscle in eye

Inferior oblique muscle in eye

Inferior rectus muscle in eye

Ciliary body

B

Ciliary Zonule

Cornea

Iris internal eye

Pupil internal eye

space between the iris

anterior Segment (contains aqueous humor)

G

Lens (internal eye)

Scleral venous sinus

Posterior Segment (Contains vitreous humor)

Sclera (Internal eye)

Choroid (Internal eye)