4.3 & 4.5: Muscles

forehead

Frontalis

temples

Temporalis

eyes

Orbicularis Oculi

cheeks

Buccinator

jaw

Masseter

mouth

Orbicularis Oris 

shoulder

Deltoid

Pectoralis

Pectoralis

front of arm

Bicep

Abdominals

Abdominals

side abs

Oblique

neck

Trapezius 

back of arm

Tricep

back

Latissimus Dorsi

butt

Gluteus

back to knee

Sartorius

front of thigh

Quadricep

back of thigh

Hamstring

back of calf

Tibialis 

back of calf

Soleus 

identify

Sarcolemma

identify

Myofibril

identify

alternating Dark A bands

identify

alternating Light I bands

identify

Z disc (I)

identify

H zone (A)

identify

sarcomere

identify

actin (thin myofilament)

identify

myosin (thick myofilament)

Muscles can only ___

PULL

What happens when a nerve sends an impulse to muscle fibers?

Calcium ions are released.

What does calcium do in muscle contraction?

Releases acetylcholine (ACh)

What does acetylcholine (ACh) trigger on the sarcolemma?

It activates the sodium-potassium pump until an action potential is reached.

What happens after the action potential is reached?

The action potential causes muscle contraction.

What stops the muscle contraction?

Acetylcholinesterase (AChE) breaks down ACh.

What happens in the sarcolemma?

Actin & myosin bind together until the muscle is fully contracted

Graded response

Each muscle fiber’s all or nothing response

What happens during ADP Phosphorylation?

Creatine phosphate donates a phosphate to ADP, forming ATP.

Does ADP Phosphorylation need oxygen?

No, it does not require oxygen.

How long does ADP Phosphorylation last?

It depletes quickly.

What happens during Aerobic Respiration?

Forms 32 ATP.

Is Aerobic Respiration fast or slow?

It’s slow but lasts the longest.

What happens during Anaerobic Glycolysis?

Forms 2 ATP.

How long does Anaerobic Glycolysis last?

It depletes quickly

What happens when a stimulated muscle can’t contract?

It’s experiencing muscle fatigue

What causes muscle fatigue?

Lack of oxygen prevents oxidation of lactic acid buildup.

Why is recovery time important between workouts?

It allows cells to replenish oxygen.

What is true muscle fatigue?

When the body shuts down from extreme exhaustion.

What does constant movement create in muscles?

Muscle tone — fibers stay slightly contracted from daily activity.

What happens with inactivity?

Muscles weaken.

What does aerobic exercise (like cardio) do?

Increases blood flow, stores more oxygen in muscles, and improves digestion and coordination.

What does anaerobic exercise (like lifting) do?

Strengthens muscle fibers and connective tissue by forcing strong contractions.