BIO201 Lecture Exam 4 (ch. 11 & 12)

Includes: Chapter 11 Nervous Tissue and Nervous System Fundamentals & Chapter 12 CNS

Somatic sensory neurons carry

Afferent information from the skin, joints and muscles

Autonomic motor neurons

Carry efferent information to cardiac muscle, smooth muscle and glands; Are either sympathetic or parasympathetic

sympathetic

fight or flight

parasympathetic

rest and digest

Regarding the organization of the nervous system, _____________ neurons carry information from the skin, muscle and joints to the brain or spinal cord, and _____________ neurons carry information from the retina, the inner ear and cranial nerve I (olfactory nerve) to the brain.

Somatic sensory/special sensory

You just ate a huge meal. Regarding the organization of the nervous system, ___________ neurons would carry information from stretch receptors in your stomach to your brain, and __________ neurons would carry information to your stomach to make it contract and churn during digestion.

Visceral (autonomic) sensory/autonomic motor

The hallmark event of depolarization is

Na+ entering the cell

Repolarization occurs because

Na+ channels close and K+ leaves the cell

Action potential

This is also called a nerve impulse and is transmitted by axons

Relative refractory period

Another action potential can be triggered but the stimulus needs to be much stronger to reach threshold

Absolute refractory period

The neuron cannot respond to another stimulus, no matter what

Depolarization

The inside of the cell becomes less negative, due to an influx of Na+

Repolarization

After becoming more positive due to depolarization, this is the subsequent phase where the inside of the cell becomes more negative due to K+ leaving the cell, allowing the cell to return to its resting membrane potential (RMP)

The all-or-none phrase that refers to action potentials means that as long as the initial stimulus reaches threshold, there will be a large action potential. If threshold is NOT reached, there will just be a small action potential.

True or False

False

Myelination of the axons of neurons in the central nervous system (CNS) is due to

 glial cells called oligodendrocytes.

functions of astrocytes

* To support and connect neurons
* To anchor neurons to blood vessels
* To maintain the optimal chemical environment around the neurons

 the autonomic nervous system (ANS)

motor fibers that conduct nerve impulses from the CNS to control the actions of smooth muscle, cardiac muscle, and glands.

Which glial cells produce and help to circulate cerebral spinal fluid?

Ependymal cells

Which is an excitatory neurotransmitter that is released by motor neurons to stimulate skeletal muscle?

acetylcholine

During depolarization, the inside of an axon will become less negative. True/False

True

In axons that are myelinated, the voltage gated sodium channels are clustered at the nodes of Ranvier, allowing for the action potential to "jump" from node to node. This is called saltatory conduction and it causes the nerve impulse conduction speed to become much slower.

True/False

False

A postsynaptic potential is a graded potential resulting from the actions of a neurotransmitter released to signal another neuron. Postsynaptic potentials can either be inhibitory or excitatory.

True/False

True

True things about neurons include:

* They have high metabolism, causing them to use a lot of glucose to make ATP.


* They are excitable cells that can send electrical impulses.
* They can live a long time.

Which type of channel opens in response to the binding of a neurotransmitter?

A ligand-gated channel

A neuron that connects other neurons and is found mostly in the CNS is known as a(n)

interneuron (association neuron)

When an action potential reaches the axon terminals, it triggers the opening of

voltage-gated calcium channels → the release of neurotransmitter

If bacteria invaded the CNS, microglia can become macrophages to engulf and destroy the bacteria, effectively protecting the CNS.

True/False

True

What affects the speed of action potential conduction?

Both axon diameter AND the amount of myelination on an axon

The resting membrane potential of a cell is negative due to

the sodium-potassium ATP pump that constantly moves 3 Na+ out of the cell and 2 K+ inside the cell

Which neurotransmitter typically gives a feeling of happiness and well-being and shows low levels in patients diagnosed with depression?

Serotonin

Multiple sclerosis is an autoimmune disease where the immune system cells attack and destroy the myelin sheaths surrounding axons. Which leads to…

* decreased speeds of transmission
* lesser coordination
* slower reflexes

The glial cells that fight infections in the CNS are

microglia

The efferent division of the PNS

carries motor commands to muscles and glands and other organs

When Cl- gate channels open on the post-synaptic neuron, this results in a(n)

 IPSP

components of a neuron (nerve cell)…

1) axons

2) myelin

3) axon terminals

5) cell body (soma or perikaryon)

Which of the following statements best describes the membrane situation in the resting state in the neuron?

All of the voltage-gated Na+ and K+ channels are closed

Which of the following type of neuroglia are the most abundant? They wrap around brain capillaries and help form a blood brain barrier.

astrocytes

The autonomic nervous system innervates all of the following…

1\.) cardiac muscle

3) smooth muscle

4) salivary glands

5) blood vessels

NOT SKELETAL MUSCLE

These neuroglia cells line the ventricles of the brain and produce CSF.

ependymal cells

Which membrane potential results in depolarization without a nerve impulse (action potential) being generated

excitatory postsynaptic potential

The part of a neuron that conducts impulses away from its cell body is called a(n) ________.

axon

A threshold stimulus is required to generate an

action potential

Which of the following divisions of the nervous system is also known as the involuntary nervous system?

autonomic nervous system

Multiple sclerosis is an autoimmune disease that leads to the destruction of ___________________ in the CNS.

myelin sheaths

Where in the neuron is an action potential initially generated?

axon hillock

What two systems of the body are crucially dependant on a normal calcium homeostasis?

muscular and nervous

A potential -100 mV on a human neuron would usually be considered to be

hyperpolarized

An IPSP is inhibitory because

it hyperpolarizes the postsynaptic membrane

Visceral motor fibers of the Autonomic Nervous System (ANS) carry information from the

CNS to smooth muscles, cardiac muscles, and glands

__________ has occurred when a neuron is stimulated by more than one axon terminal

spatial summation

The primary site for where a neuron receives signals from other neurons is(are) the

dendrites

This neurotransmitter gives "feel good" feelings and also is the primary neurotransmitter used by our sympathetic nervous system to active our __**"flight or fight"**__ response to increase heart rate (HR) and blood pressure (BP). Increases endogenous opioids → help to block pain sensation

Norepinephrine (NE)

This is a major excitatory neurotransmitter found in the brain and spinal cord. It is important in learning and memory. Excessive release of this neurotransmitter can cause "excitotoxicity". 

Glutamate

This neurotransmitter is released at neuromuscular junctions to excite skeletal muscle. It is also used in the autonomic nervous system.

Acetylcholine (ACh)

This neurotransmitter plays a role in __**sleep cycles, digestive system and appetite regulation**__, and gives feelings of well-being. Many anti-depressant medications work to block the reuptake of this neurotransmitter in order to prolong the effects.

Serotonin (5-HT)

Main inhibitory neurotransmitter of the brain and works by inhibiting CNS activity by opening Cl- channels. Alcohol and certain anti-anxiety drugs such as Valium work to increase this neurotransmitter's effect.

GABA

This neurotransmitter gives feelings of well-being and is often called the __**"feel good" neurotransmitter involved in the happiness that comes from being rewarded**__. It is also involved in motor programs controlling skeletal muscle movement and is decreased in patients with Parkinson's disease.

Dopamine

Define Central Nervous System.

the complex of nerve tissues that controls the activities of the body; brain and spinal cord.

Define Peripheral Nervous System. 

the nervous system outside the brain and spinal cord; spinal nerves and cranial nerves

Define sensory neuron. What is another name for a sensory neuron? 

the nerve cells that are activated by sensory input from the environment; aka __**afferent**__ neurons 

Define motor neuron. What is another name for a motor neuron?

nerve cell forming part of a pathway along which impulses from the brain or spinal cord → muscle or gland; allows for both voluntary and involuntary movement; aka __**efferent**__ neurons

Name the 3 branches of the peripheral nervous system. Which one is voluntary, which are involuntary? Name some effector cells/organs of each branch of the peripheral nervous system.

1. **Somatic nervous system** (voluntary)

* Skeletal muscle


2. **Autonomic nervous system** (involuntary)

* Cardiac muscle, smooth muscle, and glands


3. **Enteric nervous system** (involuntary)

* Part of the GI tract

Name the 2 subdivisions of the autonomic nervous system and  describe what each subdivision is responsible for.

1. **Sympathetic** = mobilizes the body during emergency situations; fight or flight 
2. **Parasympathetic** = promotes non-emergency functions such as glandular activity; rest and digest

Name the 3 major parts of a neuron. Which one receives information from sensory receptors or from another neuron? Which one transmits information to effector cells, or to the next neuron?

1. **Cell body (aka soma)** = contains the nucleus and other organelles; support the chemical processing of the neuron; the most important of which is the production of neurotransmitters
2. **Axon** = transmits information to effector cells, or to the next neuron
3. **Dendrite** = receives information from sensory receptors or from another neuron

What is a myelin sheath? What is it made of? What is its purpose?

a protein and fatty segmented sheath that protects and electrically insulates axons from each other; made of schwann cells in the PNS and oligodendrocytes in the CNS.  

What is the name of the type of conduction that occurs on  myelinated axons? 

Saltatory Conduction

 What is the name of the type of conduction that occurs in unmyelinated axons?

Continuous conduction

What is the difference between gray matter and white matter in the spinal cord?

Gray matter does not contain myelin sheath over the axon, white matter does and the electrical signal is quicker in white matter; The grey matter creates a hornlike structure throughout the inside of the spinal cord whil

Tell me everything you know about M.S. (multiple sclerosis) 

* It is an autoimmune disease, meaning one’s immune system attacks itself rather than invaders; with M.S. specifically the immune system eats away at the protective covering of nerves (aka myelin sheath)


* Myelin sheaths in CNS become damages 
* Inflammation from immune reaction → disruption in neuronal signaling 
* visual disturbances, blindness, muscle weakness and clumsiness, urinary incontinence
* Axon conduction is very slow 

What is the role of calcium at the chemical synapse?

when an action potential reaches the presynaptic terminal, voltage-gated calcium ion channels open and calcium ions enter, the influx of calcium ions causes synaptic vesicles to **release neurotransmitter into the synaptic cleft**; Influx of Ca++ inside axon terminal signals (via 2nd messenger) the release of neurotransmitter by exocytosis

How is the effect of the neurotransmitter terminated at the synapse  once the neurotransmitter has done its job? 

\

1. Degradation of the neurotransmitter by enzymes for the postsynaptic neuron (ex: acetylcholinerase)
2. Removal of the neurotransmitter from synapse by reuptake in presynaptic terminal where it is stored or destroyed (ex: serotonin and SSRIs 
3. Diffusion away from synapse

Acetylcholine role =

excitation of muscles (muscle contraction);  regulating cardiac contractions and blood pressure

Norepinephrine role =

**Increases alertness, arousal and attention; Constricts blood vessels, which helps maintain blood pressure in times of stress**

Dopamine role =

 **allowing you to feel pleasure, satisfaction and motivation**

Serotonin role =

controls your mood and is responsible for happiness. It helps regulate when you sleep and wake, helps you think, maintains your mood, and controls your sexual desire

Endorphins role =

**released when your body feels pain or stress; produced to help relieve pain, reduce stress and improve mood**

GABA role =

**Gamma-aminobutyric acid is an amino acid that functions as the primary inhibitory neurotransmitter for the central nervous system (CNS);  It functions to reduce neuronal excitability by inhibiting nerve transmission**

Glycine role =

acts as neurotransmitter in central nervous system and it has many roles such as antioxidant, anti-inflammatory, cryoprotective, and

**Glutamate role =**

**the most abundant excitatory neurotransmitter in your brain and central nervous system; needed for proper brain function; shapes learning and memory** 

Valium is a drug that acts like GABA (it is a GABA agonist). Therefore valium

Is likely to cause hyperpolarization of the post synaptic neuron

Monamine oxidase is an enzyme that removes dopamine and serotonin from the chemical synapses in the brain. Therefore a monamine oxidase inhibitor could be used to treat…

depression or anxiety

Neuroglia

supporting, non-neuronal cells of the PNS and CNS. (ex: astrocytes)

Nucleus

cluster of unmyelinated nerve cell bodies IN the CNS

Ganglion

group of nerve cell bodies lying \[mostly\] OUTside the CNS. – Exception is basal ganglia inside CNS

Tract

a bundle of myelinated axons of nerve fibers in the CNS

According to most authors, nuclei is to the central nervous system as ___________ is to the peripheral nervous system.

Ganglia

Which of the following is least likely to pass through the blood brain barrier?

Non-lipid hormones (such as protein hormone)

thalamus =

relay for sensory information

The patient speaks with slurred words that cannot be understood. He also is not able to move his right hand. The MRI is most likely to reveal a stroke in which area of the brain?

Left frontal lobe

The cell bodies of somatic motor neurons of the spinal nerves are located in the ventral horn of the spinal cord. True/False

True

frontal lobe

motor speech area (Broca's area)

Area of abstract reasoning, judgement, "seat of intelligence"

primary motor cortex

insula

taste (gustatory) area

parietal lobe

primary somatosensory cortex

occipital lobe

visual area

temporal lobe

auditory area

This brain area recalls experiences and connects them to judgment, conscience, and abstract reasoning and ideas.

Prefrontal cortex

This is a major relay station for all sensory information transmitted to the cerebral cortex.

Thalamus

This is essential to basic survival functions such as breathing, cardiovascular functioning, and reflexes such as sneezing, coughing, and swallowing.

Medulla oblongata

This is crucial for coordination and balance of voluntary movement.

cerebellum

**This is crucial for major homeostatic regulation, including heart rate, blood pressure, thirst, and hunger. It is the connection between the nervous system and endocrine system.**

hypothalamus