Anatomy Nervous System Test

The nervous system is divided into

Central Nervous System and Peripheral Nervous System

Function of the Nervous System

Master control center for the body, detects impulses from the center

Central Nervous System

Brain and spinal cord

Peripheral Nervous System

Cranial Nerves and Spinal Nerves not in brain/spinal cord

Cranial Nerves

Originate in the brain, 12 to help control body

Spinal Nerves

Originate in the spinal cord

Peripheral Nervous System is divided into

Sensory (Afferent) Division and Motor (Efferent) Division

Sensory (Afferent) Division

Sends impulses from the senses AT the CNS

Motor (Efferent) Division

Sends impulses from the CNS to the muscles and glands (EXITS)

The Motor division divides into the

Autonomic and Somatic Nervous System

Autonomic Nervous System

Involuntary muscle control like digestion, urination, heart pumping

Somatic Nervous System

Voluntary muscle control like muscular skeletal movements

The Autonomic Nervous System is divided into the

Sympathetic and Parasympathetic Divisions

Sympathetic Division

Used in emergency situations, fight or flight response

Parasympathetic Division

Reduces the sympathetic response, provides resting functions such as digestion and urination.

Effects of an activated Sympathetic/fight or flight

Heart rate and breathing rate increase, blood pumped to the extremities for physical activities and is diverted from organs

What system does the nervous system work with?

The Endocrine System

For the nervous system to do its job it uses

Sensory input, integration, and response

Sensory input

Detects changes/stimuli inside and outside of the body

Integration

Processing and interpreting the information

Response

Activation of muscles (motor output) or glands

The 2 major types of nerve cells are

Neurons and neuroglia

Neurons

Conduct impulses around the body, make up 10% of nerve cells

Neuroglia

Act as nerve glue & support, insulate, and protect neurons, make up 90% of nerve cells

What do all neurons have in common?

A main cell body and processes extending outward.

The cell body contains the

Nucleus, cytoplasm, organelles

Processes of a neuron are divided into

Dendrites and Axons

Dendrites

Bring impulses TOWARDS the cell body

Axons

Send impulses AWAY from the cell body

What do processes end with?

Axon terminals

Axon terminals

Release neurotransmitters to pass the impulse to the next neuron

MS disease

Myelin sheath degenerates, motor function issue

Neurons are classified by

number of processes extending from the cell body and their function

One process

Unipolar neurons

Two processes

Bipolar neurons

many processes

Multipolar neurons

Afferent neurons

Carry impulses AT the CNS

Efferent neurons

Carry impulses away from the CNS (EXITS)

Interneurons

Connect afferent and efferent neurons.

What are axons wrapped in?

Myelin, which is like a waxy insulation.

How is myelin formed?

Schwann cells (type of neuroglia) wrap itself around the axon, like a coil, helping it move faster with support and protection.

Neurilemma

Outer layers of the Schwann cell

What does myelin do?

Helps the nerve impulses to travel more quickly.

Myelin sheath

All of the myelin wrappings collectively.

Nodes of Ranvier

Gaps formed because the myelin sheath has many Schwann cells.

Where are Neuroglial cells found

In both the CNS and PNS.

Neuroglial cells in the CNS

Astrocytes, Microglia, Ependymal cells, oligodendrocytes

Astrocytes

Support and ANCHOR neurons to surrounding capillaries, giving blood to surrounding tissues

Microglia

Provide immune response to to CNS

Meningitis

Meninges infection, microglia help

Ependymal cells

Secrete and circulate cerebrospinal fluid

Oligodendrocytes

Provide myelin insulation to neurons in the Central Nervous System.

Neuroglial cells in the Peripheral Nervous System

Satellite cells, Schwann cells

Satellite cells

SUPPORT and anchor neurons in the PNS.

Schwann cells

Provide myelin insulation to neurons in the PNS.

What is a nerve impulse

An electrical signal that travels along a neuron

How do nerve impulses arise

It arises from a movement of ions causing a change in electrical charges.

How is intracellular space charged?

Negatively charged (resting potential)

How is extracellular space charged?

Positively charged (resting potential)

What happens when a neuron is stimulated by the environment or another neuron?

Sodium rushes into the neuron, and quickly reverses the charges (Depolarization), this process quickly moves down the length of a neuron.

What is depolarization known as?

Action potential

What happens as the impulse passes?

Potassium diffuses out of the neuron (Repolarization)

Refractory period

Spike down caused by ions moving back to original spots

What does sodium potassium pump do after repolarization?

Restores ion concentrations to normal, resting potential returns. (All or Nothing event) → Homeostasis

What are some problems with the Na K pump if it doesn’t work?

Congestive heart failure

Synapse

Where two neurons meet

Synaptic cleft

The space between the two neurons at a synapse because the neurons don’t touch.

What happens when an impulse reaches the axon terminal?

It can’t cross the gap between the two neurons, so it stimulates vesicles to release neurotransmitters across the synaptic cleft.

How do neurotransmitters open the next neuron?

They cause channels to open, continuing the action potential from one neuron to the next.

What is an example that uses this process?

When you take drugs that cause hormones to be released like Caffiene.

What chemical helps impulses travel?

Calcium ions

What are the 3 layers of connective tissue that protect the brain and spinal cord called? (blood-brain barrier)

Meninges

Layers of meninges from top to bottom

Skin, Periosteum, Bone, Dura Mater, Arachnoid Membrane, Pia Mater

Dura mater

Thick, tough layer

Arachnoid membrane

Thin, cobweb-like layer

Pia Mater

Thin layer containing lots of blood vessels

What is between the Arachnoid layer and the pia mater?

Cerebrospinal Fluid (CSF)

What does the cerebrospinal fluid do

Protects the brain by preventing it from contacting the skull & maintains the blood brain barrier.

What does the blood brain barrier do?

Controls homeostasis for the brain and prevents infection.

Where is CSF produced

Spaces within the brain called ventricles

What are the four ventricles?

Lateral (Right and Left), 3rd and 4th ventricles.

How are the lateral ventricles connected to the third ventricle?

The thin interventricular (inter= between ventricles) foramen → Foramen of Monro (hole)

What are choroid plexuses

Clusters of capillaries in the ventricles that secrete CSF, causing it to flow around the ventricles, then be absorbed by arachnoid granulations in the blood.

What is CSF constantly doing in the ventricles?

Being produced, circulated, and reabsorbed. (Continuously and closed)

Cerebrum

Largest part of the brain, divided into two hemispheres (right and left)

How are the two hemispheres of the brain connected?

A bundle of nerve fibers called the corpus callosum.

What is the surface of the cerebrum covered with?

Ridges (gyri) and grooves (sulci)

What are the deep grooves that divide portions of the brain?

Fissures

What are the brain’s 3 major layers from superficial to deep?

Cerebral cortex, cerebral medulla, basal nuclei

Cerebral cortex

Gray matter, made of cell bodies and dendrites

Cerebral medulla

White matter, made of myelinated axons.

Basal nuclei

Islands of gray matter

How is the cerebrum divided?

It is divided into 4 lobes based on their functions, and are named for parts of the skull protecting them.

Frontal lobe

Controls voluntary movements like walking, reasoning + decision making. memory, predicting consequences. planning, verbal communication in Broca’s area

How is the frontal lobe separated from the parietal lobe?

The central sulcus

Parietal lobe

Sensations like pain, temperature, and touch, visual spatial processing and body position.

Occipital lobe

Visual processing, vision and memory of objects.

How is the temporal lobe separated from the frontal lobe?

Lateral sulcus

Temporal lobe

Controls memory, comprehension and pronunciation of words. smell and sound, emotional association of memories.

Diencephalon

Small nondescript region within the cerebrum