Human Anatomy Exam 3 (Ch. 9, 10, 11, 20 & 21)

Which muscle type is non-striated, can replicate, and is myogenic?

Smooth muscle

Which muscle type is branched, myogenic, forms scar tissue, and pumps blood?

Cardiac muscle

Which muscle type is multinucleated, pulls on bones, and can function voluntarily or myogenically?

Skeletal muscle

The following are functions of which muscle type?

• Production of movement

• Maintain body posture and position

• Support soft tissue

• Regulate entrance/exit of material

• Maintain body temperature

Skeletal muscle

What tissue is pictured?

Skeletal muscle

What is structure #1?

Epimysium

What is structure #2?

Muscle fascicle

What is structure #3?

Endomysium

What is structure #4?

Perimysium

What is structure #5?

Nerve

What is structure #6?

Muscle fibers

What is structure #7?

Blood vessels

What is the structure pictured?

Muscle fascicle

What is structure #1?

Perimysium

What is structure #2?

Muscle fiber

What is structure #3?

Endomysium

What is the structure pictured?

Muscle Fiber

What is structure #1?

Sarcolemma

What is structure #2?

Myofibril

What is structure #3?

Endomysium

What is structure #4?

Myosatellite cell

What is structure #1?

Endomysium

What is structure #2?

Capillary

What is structure #3?

Perimysium

What is structure #4?

Muscle cell

What is structure #5?

Nucleus

What is the smallest functional unit of muscle?

Sarcomere

What is structure #1?

Mitochondria

What is structure #2?

Sarcolemma

What is structure #3?

Myofibril

What is structure #4?

Thin filament

What is structure #5?

Thick filament

What is structure #6?

Triad

What is structure #7?

Sarcoplasmic reticulum

What is structure #8?

T tubules

What is structure #9?

Terminal cisterna

What is structure #10?

Sarcolemma

What is structure #11?

Sarcoplasm

What structure is #12?

Myofibrils

What is structure #1?

Myofilaments

What is structure #2?

Sarcomere

What is structure #3?

Myofibril

What is structure #4?

Muscle fiber

What is structure #5?

Fascicle

What is structure #6?

Muscle

What is the structure pictured?

Sarcomere

What is structure #1?

Sarcomere

What is structure #2?

H band

What is structure #3?

Myofibril

What is structure #4?

Z line

What is structure #5?

M line

What is structure #6?

M line

What is structure #7?

Titin

What is structure #8?

Myosin head

What is the sliding filament theory?

The concept explaining how muscles contract to generate force:

• Myosin filaments slide past actin filaments during contraction

• Filament lengths remain relatively constant

• ONLY the sarcomere shortens

What is action potential?

Rapid change in membrane potential over the surface of a cell

Which cells experience action potentials?

• Muscle cells

• Sensory cells

• Neurons

• Some endocrine cells

Which neurotransmitter is released during APs?

Acetylcholine (ACh)

What is the name of the muscle surface that ACh binds to?

Motor end plate

What is the enzyme responsible for the degradation of ACh in the synaptic cleft?

Acetylcholinesterase (AChE)

What steps are involved in the initiation of muscle contraction?

1. ACh is released and binds receptors

2. AP reaches T tubule

3. Sarcoplasmic reticulum releases Ca²⁺

4. Active site is exposed and cross-bridge forms

5. Contraction begins

What steps are involved in ending muscle contraction?

6. ACh removed by AChE

7. Sarcoplasmic reticulum recaptures Ca²⁺

8. Active sites covered, no cross-bridge interaction

9. Contraction ends

10. Relaxation occurs, passive return to resting strength

What is a reflex arc?

An automatic pathway that mediates a response to a stimulus

What are the parts of a reflex arc?

• Sensory receptor

• Afferent neuron

• IC

• Efferent neuron

• Effector organ

T/F: Motor units function in an all or nothing manner.

T; a motor unit will contract or it will not

T/F: Tension strength per contraction is constant per motor unit.

T; but tension is additive

What causes increases in muscle tension?

• Increased frequency of motor unit stimulation

• Recruitment

Which muscles lack slow fibers?

Hand and eye muscles

What are characteristics of slow fibers?

• Smaller diameter

• Darker color (myoglobin)

• Fatigue resistant

What are characteristics of fast fibers?

• Larger diameter

• Paler color

• Easily fatigued

What is muscle tone?

Tension in a resting muscle

What muscle structure acts as stretch receptors and play a role in tone and growth?

Muscle spindles

What is hypertrophy?

• Increase in cell size and increase in number of myofibrils

  • Cell number stays CONSTANT

T/F: Atrophy results in increased mitochondria, glycolytic enzyme concentration and glycogen reserves.

F; Hypertrophy results in the above actions

What is atrophy?

• Reduction in muscle size, tone and power due to disuse, age or disease

• Can also be caused by decrease in cell number

The applied force and load are on opposite sides of the fulcrum in which lever type?

First-Class lever; changes the amount of force transmitted to the load and alters the direction and speed of movement

The load is between the applied force and the fulcrum in which lever type?

Second-Class lever; increases force at the expense of distance and speed, direction of movement remains unchanged

Applied force is between the load and fulcrum in which lever type?

Third-class lever; increases speed and distance moved, but requires a larger applied force

Which is the most common lever type in the body?

Third-class lever

What anatomical structures is responsible for the redirection of tension?

Anatomical pulleys (i.e. patella and lateral malleolus)

What is an origin?

Muscle attachment point that remains stationary

What is an insertion?

Muscle attachment point that moves

T/F: Muscles can be grouped by primary actions.

T

What are agonsists?

Muscles responsible for producing a particular movement

What are antagonists?

Muscles opposing action of agonist

What are synergists?

Muscles assisting the agonist in performing an action

What are fixators?

Agonist and antagonist contracting at the same time to stabilize a joint

What muscle type increases in diameter as it contracts?

Parallel muscle

Which muscle type has a varying direction of tension and is weaker than parallel muscle cells?

Convergent muscle

Which muscle type has the shortest contraction distance and produces more force than parallel muscles?

Pennate muscle

Which muscle type regulates the opening and closing of an orifice?

Circular muscles