SLHS 566 Exam 1

What are non-speech functions of the airway system?

• transport something into/out of the body

  • air

  • liquids

  • solids

What is anatomy?

study of structures of organisms and relation to their parts

What is physiology?

science dealing with functions of living organisms or their parts

Describe the following anatomical position: Anterior

closer to the front of the body

Describe the following anatomical position: Posterior

closer to the back of the body

Describe the following anatomical position: Rostral

closer to the head of the body

Describe the following anatomical position: Caudal

closer to the tail/feet, away from head

Describe the following anatomical position: superior

upper (NOT superficial)

Describe the following anatomical position: inferior

lower (NOT deep)

Describe the following anatomical position: superficial

closer to the surface of the body

Describe the following anatomical position: deep

away from the surface of the body

Describe the following anatomical position: medial

closer to the middle of the body

Describe the following anatomical position: lateral

closer to the side of the body

Describe the following anatomical position: proximal

closer to the trunk/start of an extremity

Describe the following anatomical position: distal

away from the trunk/away from the start of an extremity

Describe the following anatomical position: central

related to the center

Describe the following anatomical position: Caudal

related to the periphery

What anatomical direction describes A?

Posterior

What anatomical direction describes B?

Anterior

What anatomical direction describes A?

rostral

What anatomical direction describes B?

caudal

What anatomical direction describes C? ***This is referring to the brain!

rostral

What anatomical direction describes D? This is referring to the brain!

caudal

What anatomical direction describes A?

Superior

What anatomical direction describes B?

inferior

What anatomical direction describes A?

medial

What anatomical direction describes B?

lateral

What anatomical direction describes A?

proximal

What anatomical direction describes B?

distal

What are the three anatomical planes? How do they divide the body and cortex?

• sagittal

  • divides right from left

• coronal

  • divides front from back

• transverse

  • divides up from down

Which anatomical plane describes A?

Coronal

Which anatomical plane describes B?

transverse (horizontal)

Which anatomical plane describes C?

sagittal

What are the two main nervous systems in the body and what components make them up?

• Central Nervous System

  • Brain and Spinal Cord

• Peripheral Nervous System

  • Cranial Nerves and Spinal Nerves

What two main nervous systems make up the peripheral nervous system? What functions do they govern?

• Somatic Nervous System

  • voluntary body movements

  • conscious perception/integration of sensory stimuli

• Autonomic Nervous System

  • involuntary body control

  • breaks down into 3 divisions

The autonomic nervous system breaks down into 3 divisions, identify them and describe their individual functions.

• enteric NS

  • everything related to the GI track

• sympathetic NS

  • fight or flight responses

• parasympathetic NS

  • rest and digest responses

What are the 6 types of glial cells? Where are they found and what is their main function?

• Microglia

  • CNS

  • Clean up crew

• Ependymal Cells

  • CNS

  • CSF production + balance

• Oligodendrocytes

  • CNS

  • produce myelin

• Astrocytes

  • CNS

  • maintain the blood brain barrier

• Satellite Cells

  • PNS

  • Repair muscle and are the astrocytes of the PNS

• Schwann Cells

  • PNS

  • produce Myelin

What are the two types of neurons?

• motor neurons

• sensory neurons

What are motor neurons?

• neurons located in the brain/brain stem/spinal cord (Upper motor neurons)

• axon extends to muscle fiber (lower motor neurons)

• discharges electrochemical signal to cause muscle contraction

What are sensory neurons?

• neurons located throughout the body that transmit info from body back to CNS

What are the two types of motor neurons?

• upper motor neurons (UMN)

• lower motor neurons (LMN)

Discuss how an upper motor neuron functions

• axons of UMN are entirely contained in CNS and never exit the neuraxis (brain + spinal cord)

• cell bodies of these neurons sit in the cerebral cortex

• Wherever the UNM ends in the spinal cord is where a LMN originates — at the point of communication

Discuss how a lower motor neuron functions

• LMN send motor axons outside of the neuraxis to a muscle

• it is what ultimately moves a structure

The corticospinal tract is a major neuronal pathway for motor movement. Outline from the point where an upper motor neuron starts its way to where it connects with a lower motor neuron.

1. upper motor neurons start in the primary motor cortex. the cell bodies of these neurons reside in the PMC.

2. at the internal capsule, all of the axons from the UMN’s in the OMC meet and congregate, creating a bundle of axons called a tract

3. this tract travels down the cortex to the brainstem. It passes through the midbrain and the pons

4. at the level of the medulla, this tract made of pyramids (axons) crosses over to the other side of the medulla, moving contralaterally. This is known as the DECUSSATION OF PYRAMIDS. 90% of the fibers will do this but a small group will remain ipsilateral.

5. past the medulla the tract reaches the spinal cord where cell bodies of lower motor neurons (LMN) live. Axons from this tract will send electrical signals to LMNs causing the LMNs to send signals to our muscles to contract.

In general what are the two main functions of neurons?

• send signals

  • to other neurons (UMN)

  • to muscles (LMN)

• receive signals

  • from other neurons

  • from the environment → sensory neurons

What are the main parts of a neuron?

1. dendrites

2. soma/cell body

3. axon hillock

4. nodes of ranvier

5. myelin sheath

6. axon

7. axon terminal

What are dendrites and what is their function?

• extend from the cell body (soma)

• receive electrochemical signals from other neurons or sensory receptors

What is an axon and what is its function?

• one long, thin process

• sends electrochemical signals to other neurons (which will be received by dendrites!)

What is a process?

anything that hangs off the cell body

What is the difference between a unipolar, bipolar, pseudounipolar, and multipolar neuron? How can we determine this?

We can determine what kind of neuron it is by looking at how many processes are hanging off of the cell body!

• unipolar

  • only one process

• bipolar

  • two processes

• pseudounipolar

  • only one process off of the cell body but that process bifurcates into two

• multipolar

  • many processes!

    • we have one axon BUT dendrites are processes two which is what makes it multipolar

What is the myelin sheath?

myelin is a fatty (lipid), white-ish substance that wraps around portions of the axon. Insulates the axon and aids in the conduction of the electrical signal.

What are nodes of ranvier?

Gaps in the myelin sheath with a high concentration of ion channels that maintain the electrical signal throughout the axon.

What are the two types of conduction and what kind is used with myelinated axons?

• continuous and saltatory

• Neurons with myelinated axons function via saltatory conduction

  • this is much more efficient than continuous conduction because instead of all ion channels having to be open along the axon, only some of the ion channels open at a time at the nodes of ranvier.

What happens at the axon hillock?

decides if the input coming from the dendrites is enough to send an action potential down the axon

• if not strong enough to reach threshold - an AP will not go off

What happens in the axon terminal that leads to the synapse between the presynaptic and postsynaptic neuron?

1. When the action potential arrives at the axon terminal, it reaches voltage-gated Ca2+ channels

2. The voltage of the action potential opens up these calcium ion channels

3. Ca2+ then enters the presynaptic neuron which sends a signal to vesicles filled with neurotransmitters

4. these neurotransmitter vesicles move to the membrane of the presynaptic neuron and dock on the membrane via a docking protein

5. Neurotransmitters are then released via exocytosis. Exocytosis is an active transport process where a cell moves large molecules, proteins, or waste out of the cell by fusing a small sac (vesicle) with the outer cell membrane.

6. Now these neurotransmitters are in the SYNAPTIC CLEFT where they will bind to receptors located on the dendrites of the postsynaptic neuron.

7. Once the NTs bind to the receptors, a signal is initiated in the postsynaptic cell and is sent to the axon hillock to determine if an action potential will be sent down the axon.

What happens to the NT in the synaptic cleft?

The NT doesn’t just disappear on its own. If there were no “clean up” mechanisms they would remain in the cleft and continuously stimulate the postsynaptic neuron.

Enzymes go to the NT and bring it back into the neuron where its recycled or repackaged

What is a refractory period?

period after an action potential before a neuron can fire again

• during this period an action potential cannot go off

What are the four types of gated-channels? What opens and closes them?

• Mechanical gated ion channels

  • opens and closes in response to touch, stretch, force

• Leakage gated ion channels

  • always passively open and lets specific ions to move passively across the membrane → help maintain the balance

• Voltage-gated ion channels

  • opens and closes in response to voltage

• Ligand gated ion channels

  • opens and closes in response to chemical substances like Neurotransmitters

Where do neurons eventually connect to? Where does this occur?

Neurons eventually connect to the muscle at the neuromuscular junction

What are the three types of muscle?

• Striated Muscles (aka skeletal muscle)

  • voluntary muscle

• Smooth Muscles (non-striated)

  • involuntary muscle

  • organs like our stomach

• Cardiac Muscle

  • no control

  • heart muscle

Cardiac muscle is also striated. What makes it different than skeletal muscle?

• cardiac muscle is also striated but it is a different subset.

• It is different because

  • cardiac muscle is involuntary and skeletal muscle is voluntary

  • cardiac muscle has 1 or 2 nuclei while skeletal muscle has many nuclei

  • cardiac muscle does not regenerate but skeletal muscle does

What kind of muscle is pictured here?

cardiac muscle

What kind of muscle is pictured here?

skeletal/striated muscle

What kind of muscle is pictured here?

smooth muscle

How many striated muscles do we have? Are they all paired?

• we have ~329 striated muscles

• all of them are pared except the procerus and diaphragm

Muscles have 4 properties. What are they?

• excitability: respond to a stimuli

• contractibility: can contract

• extensibility: can be stretched without tearing

• elasticity: return to normal shape

What is the outermost protective layer of a muscle called?

epimysium

Explain the Russian nesting dolls of a muscle.

• Epimysium

  • Muscle

• Perimysium

  • Fascicle

• Endomysium

  • muscle fiber

    • Myofibril

      • filaments containing actin and myosin

In what part of the muscle does contraction actually occur?

contraction occurs at the level of the myofibrils in the muscle fiber. The actin and myosin are involved in contraction.

What part of the muscle is labeled A?

tendon

What part of the muscle is labeled B?

epimysium

What part of the muscle is labeled C?

muscle fiber

What part of the muscle is labeled D?

endomysium (between fibers)

What part of the muscle is labeled E?

blood vessel

What part of the muscle is labeled F?

fascicle

What part of the muscle is labeled G?

perimysium (wraps around each fascicle)

What part of the muscle fiber is labeled A?

striations

What part of the muscle fiber is labeled B?

nucleus

What part of the muscle fiber is labeled C?

myofibrils

What part of the muscle fiber is labeled D?

Filaments containing actin and myosin

What is the difference between the sarcolemma and the endomysium of the muscle fiber?

the sarcolemma is the cell membrane of a muscle fiber, while the endomysium is the layer of connective tissue that wraps around that membrane

What is the smallest functional unit of striated muscle?

the muscle fiber

What are properties of a muscle fiber?

• multinucleated

• made up of many myofibrils

• endomysium separates muscle fivers from one another

Each myofibril contains:

• filaments of MYOSIN protein molecules

  • these are thick!

• filaments of ACTIN protein molecules

  • these are long and thin!

What two components are important for muscle contraction?

myosin and actin are important for muscle contraction

What is a sarcomere?

• contractile unit

• smallest unit in a muscle that can contract

• a repeated sequence of actin and myosin along the length of the myofibril

What is represented between the Z lines?

the sarcomere is the unit represented between 2 Z-lines

What is the sliding filament theory of muscle contraction?

1. When an electrical signal is sent from a lower motor neuron to a muscle, Acetylcholine is released which causes calcium to be released.

2. The calcium is what allows myosin to bind to the actin filament. When the filaments bind together they form a crossbridge.

3. Energy being released from ATP allows myosin to then pull the actin filaments inward which shortens the sarcomere and leads to muscle contraction.

What is a motor unit?

Has 2 parts

• a single lower motor neuron.

• all of the muscle fibers innervated by LMN axon

What is the motor unit signal?

this is the action potential that travels down the neuron

Discuss the different types of motor unit size

• gross motor unit

  • large motor unit

  • controls many muscle fibers

  • GROSS MOTOR MOVEMENTS

• small motor unit

  • controls only few muscle fibers

  • FINE MOTOR MOVEMENTS

Explain motor unit spacing and why it is helpful to preserving function if damage occurs.

Motor units are spaced in an intermingled arrangement. This evenly spreads activation among muscle fibers.

If an injury or neurodegenerative disease damages a specific motor neuron, the muscle fibers connected to it will lose their stimulation. Because those fibers are intermingled rather than clustered, their loss won't leave a dead zone or a massive hole in the muscle's functional capacity.

Why do muscle fibers only attach to 1 neuron?

muscle fibers do not attach to more than one neuron because we want a clear signal. Receiving multiple different signals would confuse the muscle fiber.

How do motor units respond?

in an all or nothing fashion

• either contract or dont

Grading force is characterize by what two properties?

1. the number of motor units active at one time → need a lot of force? activate A LOT of neurons!! need only a little force? activate only a FEW neurons.

2. frequency of firing of motor units → the more often the neuron fires the stronger the contraction. if you don’t need much force fire once or few times.

What is Henneman’s Size Principle?

This principle tells us the order by which motor units are activated

• Activated first: motor units with smallest number of fibers

• Activated last: motor units with biggest number of fibers

This translates to… SMALL MOTOR UNITS FIRST THEN GROSS MOTOR UNITS

What is the innervation ratio of motor units?

the innervation ratio is the number of fibers controlled by 1 neuron

• low if ~5

  • small fine motor movements

• high if ~1000

  • leg + thigh muscles

What is the motor neuron pool?

collection of motor neurons innervating a single muscle

• all the LMNs that control one specific muscle → lots of muscle fibers innervated by individual neurons

What is a facet?

a small area on structure where it contacts another structure

• often act like cup and saucers to create a joint

• joints in the larynx are facet joints

  • one side is hollowed and the other is a little bowed

What is articulation in anatomy?

a joint or juncture of bones or cartilages

“articulated structures” = structures that come together at a joint