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BI 232 MIDTERM WEEK TESTS AND LESSONS
PRACTICE EXAM 2026
- short^ and^ branched^ cells
- muscles tissues or fibers that contract and relax to cause movement of body parts and organs
- Three types of muscle tissue
skeletal, cardiac, smooth
- skeletal muscle A muscle that is attached to the bones of the skeleton and provides the force that moves the bones.
- skeletal muscle number of nuclei
- skeletal muscle direction
- skeletal muscle; shape
- skeletal muscle; are there stria- tions?
- skeletal muscle; is it voluntary?
multinucleated
parallel
long and cylindrical
yes
yes
- cardiac muscle Muscle of the heart
- cardiac muscle; number of nuclei
uninucleate
- Extensibility^ the^ ability^ to^ be^ stretched^ or^ extended^ when^ relaxed
- cardiac muscle; voluntary?
- cardiac muscle; striations?
involuntary
striated
- Smooth muscle muscle found in internal organs
- Smooth muscle; shape
spindle shaped
- Smooth muscle; nuclei
- Smooth muscle; striations?
- smooth muscle; voluntary?
- 4 functional char- acteristics of mus- cle tissue
uninucleate
no striations
involuntary
excitability, contractility, extensibility, elasticity
- Excitability ability to respond to stimuli
- Contractility ability to shorten forcibly when stimulated (only in muscle tissue)
- Endomysium Connective tissue surrounding a muscle fiber
- How do nerves connect to mus- cle?
- how do muscles receive O2 and nutrients?
each muscle cell connects to a nerve (enters through epimysium) then branches throughout the muscle
veins and arteries
- Tendon Connects muscle to bone, cord shaped CT, one directional force
- Aponeurosis strong sheet of tissue that acts as a tendon to attach muscles to bone
- direct and indirect
Two types of mus- cle attachment
- direct attachment epimysium fused to periosteum of bone or perichondrium of cartilage
- indirect attatch- ment
The surrounding CT of muscle is connected to the fascia surrounding other muscles, cartilage and bone
- fascia a band or sheet of fibrous connective tissue that covers, supports, and separates muscle
- 2 muscle attach- ment points
origin and insertion
- origin attachment of a muscle that remains relatively fixed during muscular contraction (insertion moves toward the origin)(usually proximal)
- Insertion more movable attachment of a muscle (insertion moves toward the origin)(usu- ally more distal)
- Sarcolemma muscle cell membrane
- T tubules tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side
- Triad where the cisternae terminalae meets with t-tubule and another cisternae to form a group of three
- Myofibrils Microscopic protein filaments that make up muscle cells. (1000s can run the length of a cell) they are contractile elements
- Striations banded or striped appearance of myofibrils produced by overlapping thick and thin myofilaments
- zone of overlap where thick and thin filaments overlap
- 3 parts of the molecular compo-
Myosin Filament, Actin Filament, Elastic filament
sition of myofila- ments
- G-actin globular actin (with an active site that lets myosin bind to it)
- F- actin A fibrous protein made of a long chain of G actin molecules twisted into a helix; main protein of the thin myofilament
- tropomyosin a rod shaped protein that blocks the myosin binding site blocking actin
- 3 types of tro- ponin
TnI, TnT, TnC
- TnI inhibitory subunit, binds to actin
- TnT binds to tropomyosin
- TnC binds calcium ions
- thick filaments myosin (contains sites for actin and ATP)
- thin filaments actin (troponin, tropomyosin)
- elastic filiments provides for the recoil of the sarcomeres
- sliding fillament theory
This states that the lengths of the thick and thin filaments always remain the same; Actin and myosin filaments strands do not shorten in length during contraction, instead they just slide past each other.
- binding sites on myosin
- Binding sites on actin are blocked by by
- binding sites on actin
Binding Stroke Disconnect Hydrolysis (recocking)
actin and ATP
tropomyosin
allow for cross-bridge attachment with myosin
- what ion does tro- Ca++ (Ca++ will change the shape of troponin and move tropomyosin from actin ponin bind to?
- In order to contract you must have ?
- neuromuscular junction
- excitation-con- traction coupling
- electrical excita- tion-contraction
Action Potential (Cocking of the myosin head!)
point of contact between a motor neuron and a skeletal muscle cell
events that link the action potentials on the sarcolemma to activation of the myofilaments, thereby preparing them to contract
the action potential
- chemical excita- tion-contraction
- mechanical exci- tation-contraction
Ca++ being released from SR into sarcoplasm (to troponin)
Contraction due to calcium
- Calsequestrin and proteins that can bind calcium and return to the sarcoplasmic reticulum Calmodulin
- How can mus- cle contractions be varied in strength?
The number of muscle fibers contracting within a muscle-motor unit recruitment. The tension developed by each contracting fiber.
- motor unit A motor neuron and all of the muscle fibers it innervates
- muscle twitch the response of a muscle to a single brief threshold stimulus
- 3 phases of con- traction
latent, contraction, relaxation
- latent period time between application of a stimulus and the beginning of a response in a muscle fiber
- contraction peri- od
onset of contraction to peak
- fused tetanus when stimulus frequency is so high that no muscle relaxation takes place be- tween stimuli
- multiple motor unit summation
- in multiple motor unit summation which contracts more strongly? Muscle or the Fiber?
strength of contraction depends upon recruitment of motor units
MUSCLE not the fiber
- What is the treppe (Warm up) Phenomenon in which each successive twitch contracts more force- effect?
- How does treppe occur?
- isometric contrac- tion
fully than the previous one
increased availability of Ca++, heat, more eflcient enzyme
Muscle contracts but there is no movement, muscle stays the same length
- isotonic contrac- tion
muscle shortens because muscle tension exceeds load
- 2 types of isotonic concentric and eccentric contractions
- concentric con- traction
- eccentric contrac- tion
muscle shortens
muscle lengthens
- the interaction between actin and myosin forms a?
- What does the muscle metabo- lism do?
contraction
Provides energy for contraction (ATP)
- 6 seconds
oxidative phos- phorylation
- which process uses oxida- tive phospho- rylation: aero- bic or anaerobic process?
- how much faster is anaerobic than aerobic respira- tion?
The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.
aerobic respiration
2.5 times, but 5% as much ATP from glucose
- muscle fatigue the physiological inability of a muscle to contract
- rigor mortis stittness of the body that sets in several hours after death (ATP/ calcium contin- uing contractions)
- decreased ATP in muscles leads to be- cause?
cramping, muscles can't detach
- oxygen debt the amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose
- factors affecting muscle force
- only %- % of muscle energy is used for work, the
number of muscles, size of muscle, degree of stretch
25%-35%, heat
rest is converted to?
- factors affecting contraction veloc- ity and duration
- slow twitch oxida- tive fibers
- fast twitch gly- colytic fibers
- fast twitch oxida- tive fibers
- exercise can transform these two muscle fiber types
- smooth muscle fillaments
the load ( longer latent period, slower velocity/ duration)
Fatigue resistant small red cells (high myoglobin) slow contraction, highly aerobic
think: endurance
Fatigable Large, white cells; powerful less glycogen reserves; contract rapidly and fatigues quickly anaerobic
think: fast
moderately fatigue resistant medium sized red/ pink cell
think: middle
fast twitch glycolic, fast twitch oxidative
net like surrounding the muscle fiber,
muscle innervat- ed by
- (^) describe smooth muscle contrac- tion
slow, sustained, eflcient (only uses 1% of the energy skeletal muscle uses) and fatigue resistant ( lasts 30% longer than skeletal)
- Hyperplasiea Excessive growth of cells (think: uterus lining)
- Smooth muscle secretory func- tion
smooth muscle has the ability to produce and release protein, collagen, elastic fibers & proteoglycans. This allows them to make their own endomysium
- Endomysium Connective tissue surrounding a muscle fiber
- 2 main blood components
living cells & non-living matrix (CT)
- (^) 3 formed ele- ments of blood
erythrocytes (RBCs), leukocytes (WBCs), platelets
- What makes up 45% of blood vol- ume?
red blood cells (erythrocytes)
- (^) Plasma Straw colored, sticky fluid, More viscous than H2O (thicker)
- What makes up 55% of blood vol- ume?
plasma
- (^3) main functions of blood
distribution, regulation, protection
- blood distribution transports O2 from lungs and nutrients from digestive system to body cells. Transports metabolic waste to lungs and kidneys transports hormones to target cells
- blood regulation Regulates body temperature and pH balance in the body
- Blood protection Blood clotting, WBC and antibodies immunity
- 2 main compo- nents of Plasma
- 3 types of protein in plasma
H2O
Proteins
albumin, globulins, fibrinogen
- Albumin 60% protein in blood; maintains the proper amount of water in the blood
- Globulins antibodies and transport proteins (38% of blood proteins)
- Fibrinogen plasma protein that is converted to fibrin in the clotting process
- blood cell forma- tion is called
- do erythrocytes reproduce
- structural charac- teristics of ery- throcytes
- Do RBCs have a nucleus?
hematopoiesis
no, nor do they carry on extensive metabolic activities
Small, biconcave, "mini donut" flexible
no (anucleate)
- RBC functions transport oxygen and carbon dioxide
