BIOL 251 Anatomy & Physiology I | Exam 2
Review Questions & Answers (Latest 2025)
Muscles make up how much of your weight? - ANSWER ✔---about 1/2
What are the three types of muscles? - ANSWER ✔---skeletal, smooth, cardiac
Muscles are specialized to convert ____ energy to ____ energy. - ANSWER ✔---chemical,
mechanical
How many skeletal muscles are in the human body? - ANSWER ✔---more than 600
Skeletal muscle includes: - ANSWER ✔---skeletal muscle tissue, connective tissues, nerves and blood
vessels
,Skeletal muscles do not contract until what occurs? - ANSWER ✔---They are stimulated by a nerve
to do so. This is different from cardiac and smooth muscle.
Skeletal muscle cells are also called - ANSWER ✔---muscle fibers
What are the connective tissues of muscles? - ANSWER ✔---endomysium, perimysium, epimysium,
fascia
Endomysium - ANSWER ✔---Thin sleeve that surrounds each muscle fiber, creates room for
capillaries and nerve fibers to reach every muscle cell.
Perimysium - ANSWER ✔---Sheath that bundles muscle fibers into units called fascicles. Larger
blood vessels, nerves, and stretch receptors will be found within this sheath.
Epimysium - ANSWER ✔---Fibrous sheath that surrounds the entire muscle and bundles multiple
fascicles together.
Fascia - ANSWER ✔---Sheet of connective tissue outside of the epimysium that separates muscles
from one another.
What is direct vs indirect attachment? - ANSWER ✔---Direct: looks like directly attached, but is not,
short connection of collagen fibers.
Indirect: attaches by tendon, obvious band.
What are the characteristics of muscle? - ANSWER ✔---excitability: muscle cells can become excited
electrically
conductivity: electrical signals will travel along the cell
contractility: muscle cells and shorten when stimulated
extensibility: muscle cells can stretch between contractions
elasticity: when a muscle cell is stretched and then released, it recoils to a shorter length.
, Is skeletal muscle voluntary or involuntary? - ANSWER ✔---voluntary
Why are there striations in muscle fibers (skeletal muscle)? - ANSWER ✔---Due to the overlapping
arrangement of contractile proteins.
Structure of skeletal muscle fibers - ANSWER ✔---Sarcolemma: plasma membrane with T tubules
(infoldings).
Sarcoplasm: cytoplasm. Made of long proteins called myofibrils/myofilaments. Myoglobin, glycogen
strorage.
Sarcoplasmic reticulum: smooth endoplasmic reticulum, surround each myofibril. High amounts of
calcium, which is important for contraction, are stored there.
Sacrolemma - ANSWER ✔---Plasma membrane of a muscle fiber that forms T tubules (tubular
infoldings).
Sarcoplasm - ANSWER ✔---Cytoplasm of a muscle cell. Made of long proteins called myofibrils.
Contains a large amount of glycogen as well as myoglobin (an oxygen binding protein).
Sarcoplasmic reticulum - ANSWER ✔---Smooth endoplasmic reticulum, surround each myofibril.
High amounts of calcium, which is important for contraction, are stored there.
What are the three kinds of myofilaments? - ANSWER ✔---thick, thin, elastic
What is the structure of thin, thick, and elastic myofilaments? - ANSWER ✔---Thick: consists of many
molecules of protein myosin
Thin: is made of two intertwined strands of actin. Each bead of the actin has an active site that can bind
to the head of a myosin molecule. Also includes the protein tropomyosin, which covers these active sites
at rest. Each tropomyosin has troponin bound to it.
Elastic: composed of titin, anchors the ends of thick filaments to the Z line.
Review Questions & Answers (Latest 2025)
Muscles make up how much of your weight? - ANSWER ✔---about 1/2
What are the three types of muscles? - ANSWER ✔---skeletal, smooth, cardiac
Muscles are specialized to convert ____ energy to ____ energy. - ANSWER ✔---chemical,
mechanical
How many skeletal muscles are in the human body? - ANSWER ✔---more than 600
Skeletal muscle includes: - ANSWER ✔---skeletal muscle tissue, connective tissues, nerves and blood
vessels
,Skeletal muscles do not contract until what occurs? - ANSWER ✔---They are stimulated by a nerve
to do so. This is different from cardiac and smooth muscle.
Skeletal muscle cells are also called - ANSWER ✔---muscle fibers
What are the connective tissues of muscles? - ANSWER ✔---endomysium, perimysium, epimysium,
fascia
Endomysium - ANSWER ✔---Thin sleeve that surrounds each muscle fiber, creates room for
capillaries and nerve fibers to reach every muscle cell.
Perimysium - ANSWER ✔---Sheath that bundles muscle fibers into units called fascicles. Larger
blood vessels, nerves, and stretch receptors will be found within this sheath.
Epimysium - ANSWER ✔---Fibrous sheath that surrounds the entire muscle and bundles multiple
fascicles together.
Fascia - ANSWER ✔---Sheet of connective tissue outside of the epimysium that separates muscles
from one another.
What is direct vs indirect attachment? - ANSWER ✔---Direct: looks like directly attached, but is not,
short connection of collagen fibers.
Indirect: attaches by tendon, obvious band.
What are the characteristics of muscle? - ANSWER ✔---excitability: muscle cells can become excited
electrically
conductivity: electrical signals will travel along the cell
contractility: muscle cells and shorten when stimulated
extensibility: muscle cells can stretch between contractions
elasticity: when a muscle cell is stretched and then released, it recoils to a shorter length.
, Is skeletal muscle voluntary or involuntary? - ANSWER ✔---voluntary
Why are there striations in muscle fibers (skeletal muscle)? - ANSWER ✔---Due to the overlapping
arrangement of contractile proteins.
Structure of skeletal muscle fibers - ANSWER ✔---Sarcolemma: plasma membrane with T tubules
(infoldings).
Sarcoplasm: cytoplasm. Made of long proteins called myofibrils/myofilaments. Myoglobin, glycogen
strorage.
Sarcoplasmic reticulum: smooth endoplasmic reticulum, surround each myofibril. High amounts of
calcium, which is important for contraction, are stored there.
Sacrolemma - ANSWER ✔---Plasma membrane of a muscle fiber that forms T tubules (tubular
infoldings).
Sarcoplasm - ANSWER ✔---Cytoplasm of a muscle cell. Made of long proteins called myofibrils.
Contains a large amount of glycogen as well as myoglobin (an oxygen binding protein).
Sarcoplasmic reticulum - ANSWER ✔---Smooth endoplasmic reticulum, surround each myofibril.
High amounts of calcium, which is important for contraction, are stored there.
What are the three kinds of myofilaments? - ANSWER ✔---thick, thin, elastic
What is the structure of thin, thick, and elastic myofilaments? - ANSWER ✔---Thick: consists of many
molecules of protein myosin
Thin: is made of two intertwined strands of actin. Each bead of the actin has an active site that can bind
to the head of a myosin molecule. Also includes the protein tropomyosin, which covers these active sites
at rest. Each tropomyosin has troponin bound to it.
Elastic: composed of titin, anchors the ends of thick filaments to the Z line.
