Lesson 8: Organization of the Nervous System

What part of the neuron generates an outgoing impulse on the axon?

cell body

What part of the neuron receives signals and send to the cell body?

dendrite

What are the Node's of Ranvier?

small gaps between myelin sheaths on the axon

• help to speed up the transmission of the signal

What is the purpose of a myelin sheath?

insulates, adds strength and speed of electric impulse

What type of cells form myelin sheaths on axon?

Schwann cells(PNS) or oligodendrocytes (CNS)

What forms the white matter of the brain and spinal cord?

myelinated axons

What forms the gray matter of the brain?

unmyelinated axons

• folds of the brain mainly consist of grey matter

What forms myelin?

cell membrane of neuroglia cell

What is contained in the peripheral nervous system?

Sensory neurons, motor neurons

• carry impulses from receptors to CNS

• carry impulses from CNS to effectors

What is in the Central Nervous System?

Brain and Spinal Cord

• interneurons

What is the purpose of interneurons and where are they located?

pass signals from the sensory neurons in the PNS to motor neurons in the PNS (connect neurons and integrate signals)

What is the direction of conduction of a signal in the nervous system?

sensory receptor(PNS) →sensory neurons (PNS) → Interneuron (CNS) → motor neuron (PNS) → effector (PNS)

What nervous system uses muscles as effectors (skeletal muscle) and uses voluntary control?

somatic nervous system

What category of the nervous system controls heart rate, digestion, etc using involuntary muscles and glands?

Autonomic nervous system

What are the two categories of the autonomic nervous system?

sympathetic and parasympathetic

What is the function of the sympathetic nervous system?

stress situations

• triggering sight or flight response

• located in autonomic nervous system

What is the purpose of the parasympathetic nervous system?

Conserve energy

• “rest and repose”

• located in Autonomic Nervous System

What are the characteristics of the cerebrum in humans?

• right and left hemispheres

• Corpus callosum

• specific association and processing areas

What is the purpose of the corpus callosum?

connects the two hemispheres of the brain

What lobe is responsible for speech, higher order thinking, planning, and problem solving ?

Frontal lobe (oral/written)

What lobe is responsible for spatial analysis and perception?

Parietal Lobe

What lobe of the brain regulates the visual recognition of objects?

occipital lobe

Which lobe interprets auditory information and speech?

temporal lobe

What part of the CNS is described as a “Cable of Neurons”

Spinal Cord

What encloses and protects the spinal cord?

vertebral column and meninges (connective tissue membranes, cover spinal cord and protect brain)

Where is gray matter located in the spinal cord?

inner zone

• contains motor neurons and interneurons

Where is the white matter contained in the spinal cord?

outer zone

• myelinated axons of sensory and motor neurons

What is the function of the spinal cord?

carry messages from the body to the brain, vice versa

What is a reflex?

rapid motor response to a stimulus

Why are reflexes so quick?

the sensory neuron passes info to a motor neuron in the spinal cord without higher processing in the brain

What is a monosynaptic reflex?

reflex where only two neurons are involved with only one synapse between them

Most reflex are not __________, and involve an interneuron

monosynaptic

• cross more than 1 synapse in grey matter

What is the point of a reflex?

allows the body to react before pain

What are the nerves of the peripheral nervous system?

clustered axons

What are the ganglia of the PNS

cell bodies, outside of the CNS

In the PNS where are sensory neurons in the spinal cord?

dorsal surface - dorsal root

cell bodies in dorsal root ganglia

In the PNS where are the motor neurons in the spinal cord?

exit ventral surface - ventral roots

Somatic motor neuron cell bodies in spinal cord

Where are the autonomic motor neuron cell bodies?

spinal cord

Describe an autonomic neural path

Use of two motor neurons, signaled transferred to a nerve ganglion outside of CNS, effector is either stimulated or inhibited

What is a preganglionic neuron?

cell body in spinal cord

What is a post ganglionic neuron?

cell body in nerve ganglion outside of CNS

• transmits to effector

What nervous system response to conscious control and reflexes?

Somatic Nervous System (SNS)

What nervous system has motor neuron cell bodies in the CNS and axons extend from CNS to effector?

Somatic Nervous System

What nervous system has heavily myelinated axons?

Somatic Nervous System

What nervous system has stimulatory effect on effectors?

Somatic Nervous System

What nervous system has skeletal muscle effectors?

Somatic Nervous System

What nervous system controls unconscious/involuntary, and some internal reflexes?

Autonomic Nervous System

What nervous system uses 2 neurons to reach effector (pre and post-ganglionic)

Autonomic Nervous System

What nervous system has little to no myelin on the axons?

Autonomic Nervous System

What nervous system has stimulatory or inhibitory effect on effectors?

Autonomic Nervous System

What nervous system uses cardiac and smooth muscles, and gland effectors?

Autonomic Nervous System

Where are the sympathetic nerves in the sympathetic nervous system?

nerves exit CNS from middle ganglia

• in long chain

Parasympathetic v. Sympathetic: which nervous system uses energy?

Sympathetic

• dilate eyes

• speed up heartbeat

• delaying emptying of the bladder

Parasympathetic v. Sympathetic: which nervous system conserves energy?

Parasympathetic

• constrict eyes

• secrete saliva

• empty colon

Where are the parasympathetic nerves in the parasympathetic nervous system?

nerve fibers origin is base of brainstem

• ganglia are close to effectors

What part of the autonomic nervous system triggers “fight or flight” response?

Sympathetic

What part of the autonomic nervous system has nerves originate in the middle portion of the spinal cord?

Sympathetic

What part of the autonomic nervous system has long postganglionic neurons?

sympathetic

What part of the autonomic nervous system has ganglia located just outside spinal cord?

sympathetic

What part of the autonomic nervous system keeps body energy use as low as possible?

Parasympathetic

What part of the autonomic nervous system has most of the nerves originating in the brain stem or sacral regions of spinal cord?

parasympathetic

What part of the autonomic nervous system has long preganglionic neurons?

parasympathetic

What part of the autonomic nervous system has ganglia near effector organ?

parasympathetic

How does the nervous system maintain homeostasis in the integumentary system?

• receptors detect temperature changes

• ANS regulates sweat glands and blood vessels to dissipate or conserve heat

How does the nervous system maintain homeostasis in the muscular system?

Skeletal muscles can be stimulated to shiver to generate heat

How does the nervous system maintain homeostasis in the cardiovascular system?

ANS (autonomic nervous system) monitors blood pressure, heart-rate and even blood volume

How does the nervous system maintain homeostasis in the respiratory system?

nervous system regulates breathing depth and rhythm while also monitoring O2 and pH levels

What is the axon terminal?

end of an axon, specialized region that contains finger-like projections

What part of the neuron is considered presynaptic (carries messages)?

axon

• 1 axon per neuron with many dendrites

What part of the neuron is post-synaptic?

Dendrite

Synaptic terminal is synonymous with…

axon terminal

In the brain, ____ cells outnumber neurons

glial

What are the features of the brain?

white matter, grey matter, stroma, blood vessels

What is the purpose of white matter in the brain?

they are bundles that connect different parts of grey matter

What is the largest part of the brain?

Cerebrum

What part of the brain is responsible for conscious thoughts and actions?

Cerebrum

Where do dendrites receive messages at?

Synapses