BIOS 251 Final Study Guide Anatomy 2
Final Study Guide Anatomy 2
Chapter 10:
• 3 types of Muscular Tissue-
o Skeletal-
▪ Location- Skeletal System
▪ Function- Moves Bone
▪ Appearance- Multi Nucleated and Striated
▪ Control- Voluntary
o Cardiac-
▪ Location- Heart
▪ Pumps Blood
▪ Appearance- One Nucleus, Striated, and intercalated Discs
▪ Control- Involuntary
o Smooth-
▪ Location- Various Organs. Ex: GI tract
▪ Function- Various Functions. Ex peristalsis (Digestion)
• Functions of Muscular Tissue
o To Produce Body Movements
o Stabilizing body position
o Storing and Mobilizing substances within the body
o Generating Heat
• Properties of Muscular Tissue
o Electrical Excitability- If a muscle tissue is shocked, it will contract.
o Contractility- muscle can contract
o Extensibility- The ability for muscle to extend, within limits, without being
damaged
o Elasticity- The ability for muscle to move back to its original form after being
extended.
• Making a Skeletal Muscle
o Step 1: Myofilaments bundle together to make a myofibril
o Step 2: Myofibrils bundle together with endomysium, making one muscle fiber.
o Step 3: Muscle fibers are wrapped with perimysium making one muscle fascicle
o Step 4; Muscle Fascicles are wrapped by epimysium, making one muscle fiber.
• Components of a Sarcomere
o Z Discs- Narrow, Plate shaped regions of dense material that sperate one
sarcomere to the next
o A Band- Dark, middle part of the sarcomere that extends the entire length of thick
filaments and includes those parts of thin filaments that overlap thick filaments.
o I Band- Lighter, Less dense area of a sarcomere that contains thin filiments, but
no thick filiments. A Z Discs passes through each I band
o H Zone- Narrow region in the center of each a band that contains thick filiments
but no thin filiments
,BIOS 251 Final Study Guide Anatomy 2
o M Line- Region in the center of the H Zone that contains proteins that hold thick
filaments together at the center of the sarcomere
• Muscle Proteins-
o Contractile: Generate force during muscle contractions
▪ Myosin- Thick Filiment, Binds to Actin
▪ Actin- Main component of thin filament, contains myosin binding sites
o Regulatory: Help switch the muscle contraction prorocess on and off
▪ Troponin- Componet of thin filament, When CA ions bind, it changes
shape, this change moves tropomyosin away from actin, muscle
contraction begins as myosin binds to actin.
▪ Tropomyosin- Componet of thin filament, when muscle fibers relax, this
covers actin molicules, preventing myosin from binding to actin.
o Structural
▪ Titin- Connects Z Discs to the M line of a sarcomere
▪ Nebulin- Wraps around the entire length of each thin filament, helping
them anchor to Z- Discs
▪ Alpha Actin- Protein of Z Discs that attaches to actin and titin molecules
▪ Myomesin- Forms the M line of the sarcomere
▪ Dystrophin- Helps transmit tension generated by sarcomeres to tendons
• Sliding Filament Mechanism-A mechanism of muscle contraction in which the actin
and myosin filaments of striated muscle slide over each other to shorten the length of the
muscle fibers. Myosin-binding sites on the actin filaments are exposed when calcium ions
bind to troponin molecules in these filaments. This allows bridges to form between actin
and myosin, which requires ATP as an energy source. Hydrolysis of ATP in the heads of
the myosin molecules causes the heads to change shape and bind to the actin filaments.
The release of ADP from the myosin heads causes a further change in shape and
generates mechanical energy that causes the actin and myosin filaments to slide over one
another.
• The Contraction Cycle-
o Step1: ATP hydrolysis- Myosin head hydrolyzes ATP and becomes energized and
oriented
o Step 2: Myosin head binds to actin, forming a cross bridge
o Step 3: Power Stroke- Myosin head pivots, pulling the thin filament past the thick
filament towards the center of the sarcomere
o Step 4: As Myosin head binds ATP, the ross bridge detaches from actin
• Excitation–Contraction Coupling- the physiological process of converting an electrical
stimulus to a mechanical response. It is the link between the action potential generated in
the sarcolemma and the start of a muscle contraction.
o A motor neuron connects to a muscle at the neuromuscular junction, where a
synaptic terminal forms a synaptic cleft with a motor-end plate.
o The neurotransmitter acetylcholine diffuses across the synaptic cleft, causing the
depolarization of the sarcolemma.
, BIOS 251 Final Study Guide Anatomy 2
o The depolarization of the sarcolemma stimulates the sarcoplasmic reticulum to
release Ca2+, which causes the muscle to contract.
o Motor-end plate: post junctional folds which increase the surface area of the
membrane (and acetylcholine receptors) exposed to the synaptic cleft
o Sarcolemma: a thin cell membrane that surrounds a striated muscle fiber
• Length Tension Relationship- Indicates How the forcefulness of Muscle Contractions
depends on the lengths of the sarcomere within a muscle before the contraction begins.
• Neuromuscular Junction-
o The place where a neuron and a muscle ALMOST touch.
o Synaptic Cleft- The space in between the neuron and a muscle
o The 2 cells communicate by releasing a chemical messenger called a
neurotransmitter
• Muscle Metabolism-
o Creatine Phosphate- Stores ATP for muscle to use for up to 10 seconds
o Anaerobic Glycolysis- Continues to provide ATP for muscle after creatine
phosphate is depleted for up to 2 minutes.
o Cellular Respiration- If enough oxygen is present, pyruvic acid formed by
glycolysis enters the mitochondria, where it under goes a series of oxygen
requiring reactions to generate large amounts of ATP
• Muscle Fatigue-
o Inadequate release of calcium from the sarcoplasmic reticulum
o Depletion of creatine phosphate, oxygen and nutrients
o Build up of Lactic Acid and ADP
o Insufficient Release of ACh at the Neuro Muscular Junction
• Oxygen Consumption After Exercise
o After we stop exercising, we continue to breath heavily afterwards. This extra
oxygen goes toward:
▪ Replenishing Creatine Phosphate
▪ Converting Lactate into Pyruvate
▪ Reloading O2 into Myoglobin
• Twitch Contraction- The brief contraction of all muscle fibers in a motor unit in a single
action potential. There are 4 phases:
o Latent period
o Contraction Period
o Relaxation Period
o Refractory Period
• Tetanus- A muscle Contraction
o Unfused Tetanus- Brief period of rest in between continuing contractions
o Fused Tetanus- Contraction is continually tense
• Muscle Tone- Even when at rest, a skeletal muscle exhibits a small amount of tension,
called tone.
o Tone is established by the alternating involuntary activation of small groups of
motor units in a muscle
Final Study Guide Anatomy 2
Chapter 10:
• 3 types of Muscular Tissue-
o Skeletal-
▪ Location- Skeletal System
▪ Function- Moves Bone
▪ Appearance- Multi Nucleated and Striated
▪ Control- Voluntary
o Cardiac-
▪ Location- Heart
▪ Pumps Blood
▪ Appearance- One Nucleus, Striated, and intercalated Discs
▪ Control- Involuntary
o Smooth-
▪ Location- Various Organs. Ex: GI tract
▪ Function- Various Functions. Ex peristalsis (Digestion)
• Functions of Muscular Tissue
o To Produce Body Movements
o Stabilizing body position
o Storing and Mobilizing substances within the body
o Generating Heat
• Properties of Muscular Tissue
o Electrical Excitability- If a muscle tissue is shocked, it will contract.
o Contractility- muscle can contract
o Extensibility- The ability for muscle to extend, within limits, without being
damaged
o Elasticity- The ability for muscle to move back to its original form after being
extended.
• Making a Skeletal Muscle
o Step 1: Myofilaments bundle together to make a myofibril
o Step 2: Myofibrils bundle together with endomysium, making one muscle fiber.
o Step 3: Muscle fibers are wrapped with perimysium making one muscle fascicle
o Step 4; Muscle Fascicles are wrapped by epimysium, making one muscle fiber.
• Components of a Sarcomere
o Z Discs- Narrow, Plate shaped regions of dense material that sperate one
sarcomere to the next
o A Band- Dark, middle part of the sarcomere that extends the entire length of thick
filaments and includes those parts of thin filaments that overlap thick filaments.
o I Band- Lighter, Less dense area of a sarcomere that contains thin filiments, but
no thick filiments. A Z Discs passes through each I band
o H Zone- Narrow region in the center of each a band that contains thick filiments
but no thin filiments
,BIOS 251 Final Study Guide Anatomy 2
o M Line- Region in the center of the H Zone that contains proteins that hold thick
filaments together at the center of the sarcomere
• Muscle Proteins-
o Contractile: Generate force during muscle contractions
▪ Myosin- Thick Filiment, Binds to Actin
▪ Actin- Main component of thin filament, contains myosin binding sites
o Regulatory: Help switch the muscle contraction prorocess on and off
▪ Troponin- Componet of thin filament, When CA ions bind, it changes
shape, this change moves tropomyosin away from actin, muscle
contraction begins as myosin binds to actin.
▪ Tropomyosin- Componet of thin filament, when muscle fibers relax, this
covers actin molicules, preventing myosin from binding to actin.
o Structural
▪ Titin- Connects Z Discs to the M line of a sarcomere
▪ Nebulin- Wraps around the entire length of each thin filament, helping
them anchor to Z- Discs
▪ Alpha Actin- Protein of Z Discs that attaches to actin and titin molecules
▪ Myomesin- Forms the M line of the sarcomere
▪ Dystrophin- Helps transmit tension generated by sarcomeres to tendons
• Sliding Filament Mechanism-A mechanism of muscle contraction in which the actin
and myosin filaments of striated muscle slide over each other to shorten the length of the
muscle fibers. Myosin-binding sites on the actin filaments are exposed when calcium ions
bind to troponin molecules in these filaments. This allows bridges to form between actin
and myosin, which requires ATP as an energy source. Hydrolysis of ATP in the heads of
the myosin molecules causes the heads to change shape and bind to the actin filaments.
The release of ADP from the myosin heads causes a further change in shape and
generates mechanical energy that causes the actin and myosin filaments to slide over one
another.
• The Contraction Cycle-
o Step1: ATP hydrolysis- Myosin head hydrolyzes ATP and becomes energized and
oriented
o Step 2: Myosin head binds to actin, forming a cross bridge
o Step 3: Power Stroke- Myosin head pivots, pulling the thin filament past the thick
filament towards the center of the sarcomere
o Step 4: As Myosin head binds ATP, the ross bridge detaches from actin
• Excitation–Contraction Coupling- the physiological process of converting an electrical
stimulus to a mechanical response. It is the link between the action potential generated in
the sarcolemma and the start of a muscle contraction.
o A motor neuron connects to a muscle at the neuromuscular junction, where a
synaptic terminal forms a synaptic cleft with a motor-end plate.
o The neurotransmitter acetylcholine diffuses across the synaptic cleft, causing the
depolarization of the sarcolemma.
, BIOS 251 Final Study Guide Anatomy 2
o The depolarization of the sarcolemma stimulates the sarcoplasmic reticulum to
release Ca2+, which causes the muscle to contract.
o Motor-end plate: post junctional folds which increase the surface area of the
membrane (and acetylcholine receptors) exposed to the synaptic cleft
o Sarcolemma: a thin cell membrane that surrounds a striated muscle fiber
• Length Tension Relationship- Indicates How the forcefulness of Muscle Contractions
depends on the lengths of the sarcomere within a muscle before the contraction begins.
• Neuromuscular Junction-
o The place where a neuron and a muscle ALMOST touch.
o Synaptic Cleft- The space in between the neuron and a muscle
o The 2 cells communicate by releasing a chemical messenger called a
neurotransmitter
• Muscle Metabolism-
o Creatine Phosphate- Stores ATP for muscle to use for up to 10 seconds
o Anaerobic Glycolysis- Continues to provide ATP for muscle after creatine
phosphate is depleted for up to 2 minutes.
o Cellular Respiration- If enough oxygen is present, pyruvic acid formed by
glycolysis enters the mitochondria, where it under goes a series of oxygen
requiring reactions to generate large amounts of ATP
• Muscle Fatigue-
o Inadequate release of calcium from the sarcoplasmic reticulum
o Depletion of creatine phosphate, oxygen and nutrients
o Build up of Lactic Acid and ADP
o Insufficient Release of ACh at the Neuro Muscular Junction
• Oxygen Consumption After Exercise
o After we stop exercising, we continue to breath heavily afterwards. This extra
oxygen goes toward:
▪ Replenishing Creatine Phosphate
▪ Converting Lactate into Pyruvate
▪ Reloading O2 into Myoglobin
• Twitch Contraction- The brief contraction of all muscle fibers in a motor unit in a single
action potential. There are 4 phases:
o Latent period
o Contraction Period
o Relaxation Period
o Refractory Period
• Tetanus- A muscle Contraction
o Unfused Tetanus- Brief period of rest in between continuing contractions
o Fused Tetanus- Contraction is continually tense
• Muscle Tone- Even when at rest, a skeletal muscle exhibits a small amount of tension,
called tone.
o Tone is established by the alternating involuntary activation of small groups of
motor units in a muscle
