Comparative Vertebrate Anatomy - Exam 3 Review

Central Nervous System (CNS)

The integrating and command center of the body.

Where is the CNS located?

The cranium and the vertebral canal

What does the CNS consist of?

• Brain

• Spinal Cord

Peripheral Nervous System (PNS)

Carries information to and from the CNS.

Somatic Sensory

Sensory innervation of the outer portions of the soma (the body)

Special Somatic Senses

Senses whose receptors are concentrated in a small, specialized area.

General Somatic Senses

Senses whose receptors are spread widely throughout the “outer” body.

Visceral Sensory

Sensory innervation of the inner body, the viscera, the heart, lungs, G.I. tract, etc.

General Visceral Senses

Senses whose receptors are widely distributed throughout inner body, the viscera.

Special Visceral Senses

Senses whose receptors are concentrated in a small, specialized area.

Somatic Motor (aka Voluntary Nervous System)

Motor innervation of most of the skeletal muscles

(excepting the pharyngeal arch muscles), can not be subdivided.

Visceral Motor

Motor innervation of the inner body, the viscera, can be subdivided.

General Visceral Motor (aka Automatic/Involuntary Nervous System)

Controls the cardiac and smooth muscles.

Special Visceral Motor

It controls the pharyngeal arch musculature, a special group of skeletal muscles.

Sensory/Afferent Division

carries sensory information to the CNS from the sense receptors.

Motor/Efferent Division

Carries motor information from the CNS from the sense receptors, can be further divided.

Sensory Input

Using millions of sensory receptors to monitor stimuli in both the external and internal environments.

Integration

The processing and interpretation of the sensory input.

Motor Output

The activation of “effector organs” to respond to stimuli.

Nervous Tissue

Main component of the nervous system

Neurons

The cells which send the nerve impulses.

Neuroglia

The supporting cells of the nervous system.

Dendrites

Serve as receptive sites

Axons

Serve as distributive sites, anchoring on they perikaryon.

Telodendria

Many branches occurring at the terminal end of the axon.

Axon Terminals

Knob-like endings of the telodendria.

Epineurium

Ensheathes the entire nerve organ, outermost sheath.

Perineurium

Ensheathes a nerve fascicle.

Endoneurium

Ensheathes a single nerve fiber, innermost sheath.

Multipolar Neurons

Neurons having three or more radiating processes

What neurons do multipolar neurons account for?

• Sensory

• Motor

• Interneuron

Bipolar Neurons

Neurons having two radiating processes, one axon and one dendrite.

Unipolar Neurons

Neurons having only one radiating process that serves as both an axon and a dendrite.

What neurons do both unipolar and bipolar neurons account for?

• Senses

Neurotransmitters

Chemicals found in chemical synapse

Synapse

Neurons communicate with one another and with other cells at a certain point.

Glial Cells

Neuroglia of the CNS

Astrocytes

Most abundant of the gilal

Astrocytes functions:

• Regulate the ionic balance around the neurons

• Recycle neurotransmitters

• Memory format information

Microglia

Small type & least abundant of the glial cells.

Microglia functions:

• Defend the CNS from foreign invaders

• Consume dead neurons

Ependymal Cells

• Simple, cuboidal, ciliated epithelium gilal cells

• Forms a lining in the hollow spaces of the brain and spinal cord.

Ependymal functions:

• Circulation of cerebrospinal fluid

• Diffusion into the tissues of the CNS

Oligodendrocytes

Insulate CNS neurons

What is the insulating material in Oligodendrocytes?

Myelin

Ventricular Zone/Germinal Layer

Innermost layer and is the layer lining the neurocoel, highly miotic.

Marginal Zone

Outermost layer, low cell content.

Intermediate Zone/Mantle Layer

Middle layer and surrounds the

ventricular zone.

Neuroblasts

Develops into neurons.

Neuroglial Stem cells

Develop into the neuroglia.

Sulcus Limitans

Two plates of developing nervous tissue form one above and one below an invagination in the midpoint of the neurocoel

Alar Plate

The plate dorsal of the sulcus limitans, containing sensory neurons.

Basal Plate

The plate ventral of the sulcus limitans, containing motor neurons.

Menix Primitiva

Most primitive, found in most fishes, a delicate c.t. membrane.

Nonmammalian Vertebrates Meningeal Sheath

• Dura Mater

• Leptomenix

Dura Matar

Tough, outer layer of c.t.

Leptomenix

Inner layer of a vascular membrane in nonmammalian

Meningeal Layers in Mammals

• Dura Mater

• Arachnoid Mater

• Pia Mater

Arachnoid Mater

Middle layer in mammals, many collagen bundles to make a spider-web look.

Pia Mater

Innermost layer in mammals

Where does the spinal cord begin?

Foramen Magmum

Conus Medullaris

Ending of the spinal cord.

Cauda Equina

Spinal nerves arising from the conus medullaris

Dorsal Horns

Composed of interneurons receiving sensory information from the PNS.

Ventral Horns

Process motor information.

Lateral Horn

Processes sympatic motor information, located in the thoracic region of the spinal cord.

Gray Commissure

Connects the two halves of gray matter

Ascending Tracts

Carry sensory information from the receptors to the brain.

Descending Tracts

Carry motor information from the brain to the effector organs.

Commissural Tracts

Carry information from one side of the spinal cord to the other.

Spinal nerves

Communication of sensory and motor information between the spinal cord and the body.

Ventral Roots

Carry motor information from the spinal to the body.

Dorsal Roots

Carry sensory information into the spinal cord from receptor organs.

Dorsal Root Ganglion

Swollen structure in the dorsal root

Which group possess the primitive conditions of the spinal nerve cords?

Agnathans

Lampeys

The dorsal and ventral roots do not join together

Dorsal Ramus

Carries motor and sensory information to and from the dorsal body; the epaxial muscles and dorsal integument.

Ventral ramus

Both sensory and motor, will innervate the ventral body and also the lateral body wall.

What are the four plexuses?

• Cervical

• Brachial

• Lumbar

• Sacral

Prosencephalon

Anteriormost vesicle and will give rise to the forebrain.

Mesencephalon

Middle vesicle and will give rise to the midbrain.

Rhombencephalon

Posteriormost vesicle

Rhombencephalon gives rise to which portion of the brain?

The hindbrain.

Prosencephalon gave rise to what?

• Telencephalon (aka; Cerebrum)

• Diencephalon

Rhombencephalon gave rise to what?

• Metencephalon (cerebellum and pons)

• Myelencephalon (medullanoblongata)

Ventricles

Cavities within the brain lined with ependymal cells and are filled with cerebrospinal fluid.

Lateral Ventricles (First & Second ventricles)

C-shaped ventricles located within the cerebral hemispheres of the telencephalon.

Third Ventricles

located in the diencephalon.

Fourth Ventricles

located in the “hind” brain between the cerebellum and the brain stem.

Which region of the brain has all our nuclei and a portion of the reticular formation?

Medulla

Hypothalamus

Main visceral control center of the body

Epithalamus

Tiny group of nuclei and the unpaired Pineal Gland.

Relay Nuclei

12 major nuclei in the thalamus.

Cerebrum in Fishes:

• Pallium

• Globus Pallidus

Pallium

Primitive sensory and association area.

Globus Pallidus

Motor area located below the pallium

What is left of the Globus Pallidus?

Hippocampus

Dorsal Ventricular Ridge

A factor increasing the size of the reptilian cerebrum

Avian Ridge

Only found in birds

Gyrus

Term for a cortical elevation.