Muscle and Skin Flashcards
True or False: The only muscle type in the body that is involuntary and striated is cardiac muscle, and its only location is in the heart.
True
True or false: Cytoplasmic calcium concentrations within skeletal muscle cells are normally very high, allowing for the rapid activation of myosin following neurotransmitter binding.
This statement is false. The concentration of free calcium in almost all cells is kept extremely low. In skeletal muscle, calcium is stored within the sarcoplasmic reticulum. It rapidly flows into the cytoplasm along a steep concentration gradient after depolarization is induced by neurotransmitter binding.
True or false: ATP binds to myosin and reduces its affinity for actin.
This statement is true. During the power stroke, ADP and phosphate are ejected from the myosin head. Following the power stroke, myosin remains bound to actin until ATP arrives and binds to myosin, which permits dissociation of the actin/myosin cross-bridge. After death, when ATP is depleted, the body’s muscles become rigid due to the binding of myosin to actin. This condition is known as rigor mortis. Since binding of ATP makes myosin more likely to dissociate from actin, the given statement about ATP binding reducing the affinity of myosin for actin is accurate.
Which layer of the skin consists mainly of vascularized adipose tissue?
The hypodermis, or subcutaneous layer, is mainly composed of connective adipose tissue, which requires a steady blood supply.
True or False: The epidermis is composed solely of epithelial cells
True
composed of many sarcomeres
myofibril
houses many myofibrils
mm fiber
Numerous muscle fibers are bundled together to create a
fascicle
How are cardiomyocytes connected?
Cardiac muscle cells are connected via intercalated discs containing gap junctions, which allow ions to be exchanged freely between adjacent cardiomyocytes. This allows cardiac tissue to synchronize muscle contraction. Cardiac muscle is involuntary and innervated by the autonomic nervous system.
True or False: During muscle contraction, calcium ions released from the sarcoplasmic reticulum associate with troponin within the tropomyosin complex, causing a conformational change which reveals the binding myosin binding site.
When released from the sarcoplasmic reticulum, calcium ions bind to troponin molecules throughout the tropomyosin complex. This causes a conformational change which reveals certain regions of actin. These regions are the binding site for myosin filaments.
Pirimicarb is an acetylcholinesterase inhibitor and is often used as an insecticide in order to control aphid populations. It is preferred by gardeners because it is effective on aphids but not potent enough to harm their predators, such as ladybugs. How would it impact bugs who ingest it?
Inhibition of acetylcholinesterase would increase the amount of acetylcholine in the neuromuscular junction. This will result in hyperstimulation of the acetylcholine receptors and subsequent duration of muscle contractions.
True or False: Smooth and striated muscle both contain actin and myosin
True
Thin Filament
Actin
Tick Filament
Myosin
Z line
Ends of Sarcomere where actin is anchored. In mm contraction, the distance between the zlines shorten
M line
Middle of sarcomere. M lines of adjacent sarcomeres will get closer to eachother during contraction
H zone
Place where there is only bits of thick filament found no overlap from actin. H zone shrinks as actin encroaches on it during contraction
I band
only contains actin and no myosin overlap. gets smaller during contraction
A Band
Spans length of myosin regardless of overlap. STAYS THE SAME LENGTH. It is the only part that stays the same during contraction.
What blocks actin before muscle contraction?
tropomyosin
Calcium binds to what in order to initiate muscle contraction
Troponin
True or False: Only acetylcholine would be found at the NMJ
True
True or False: the binding of acetylcholine causes calcium channels to open which then that influx depolarizes the sarcoplasmic reticulum to release more calcium
False: it lets in sodium
Responsible for breaking down acetylcholine in the NMJ
Acetylcholinesterase
Outermost layer of skin
Epidermis
True or False: merkel cells will be found in a higher abundance around areas of low sensitivity like the back
False, they will be more concentrated in more sensitive areas like fingertips
Below the epidermis
Dermis
True or False: Merkel cells are found in the epidermis
True
True or False: Ruffini, Pacinian Corpuscles, and Meissner Copuscles are found in the dermis
True
What is found in the hypodermis?
Adipocytes and macrophages
What is produced to protect the skin from harmful UV radiation?
Melanin is a substance produced by melanocytes in the epidermis that causes skin pigmentation, and it absorbs ultraviolet light.
True or False: Reuptake of Calcium ions by the sarcoplasmic reticulum is a passive process
Reuptake of calcium ions by the sarcoplasmic reticulum is carried out by an ATP-ase, which hydrolyzes ATP to ADP and inorganic phosphate.
The myosin head remains attached to the actin filament at the end of a powerstroke, a state known as rigor, until:
The binding of a new ATP molecule to the myosin head induces dissociation from crossbridge complex. If this does not occur, the muscle will remain contracted.
Why do corpses go into rigor mortis?
The binding of a new ATP molecule to the myosin head induces dissociation from crossbridge complex. If this does not occur, the muscle will remain contracted. Without ATP they will stay permananetly contracted as in rigor mortis.
True or False: the skin is involved in waste excretion
True: The skin contains glands and ducts which excrete waste such as ammonia found in sweat
