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MCAT Biology by me > Muscle, Bone, SKin > Flashcards

Muscle, Bone, SKin Flashcards

1
Q

H Zone

A

Only has myosin. The middle zone

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2
Q

M line

A

line going down the middle of the H zone

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3
Q

A Band

A

The thick band. Has both actin and myosin. A band includes the H zone. Covers most of the sarcomere in the middle

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4
Q

I band

A

only has actin. Thin band. Covers regions of two separate sarcomeres

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5
Q

What makes up a muscle? From the smallest unit to a muscle. What’s a muscle cell, also known as muscle fiber?

A

Myofibril –> sarcomeres wrapped around in sheet, sarcolemma covering it up. Several myofibrils wrapped by sarcolemma have multiple nuclei and mitochondria embedded between above, and around the bundle of myofibrils. This bundle make up a muscle cell (muscle fiber). Several muscle cells make up a muscle fascicle, which is a bundle of muscle cells. Muscle fascicles then make up a muscle.

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6
Q

Muscle fascicle

A

A bundle of muscle fibers which are bundles of muscle cells

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7
Q

relationship between T-tubule and sarcoplasmic reticulum

A

the action potential is transferred from T-tubule to the sarcoplasmic reticulum to contract the muscle

the ion channels get activated in the sarcolemma creating an action potential that travels down into the T-tubules then into the sarcoplasmic reticulum which releases the calcium ions

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8
Q

Physiology of skeletal muscle contraction. Describe the states of myosin when the ATP, and ADP+PI are on. What happens when ADP+PI is dislodged. What happens when the ATP is added on again?

A

myosin head is straight up with ADP+PI, its default mode. once tropomyosin exposes the binding site (calcium attached to troponin), the myosin head attaches to the actin binding site forming a cross bridge)`. The removal of ADP+PI causes the head to tilt, causing the contraction of the muscle.

Attachment of ATP to myosin dislodges the myosin from the actin. The head is still tilted. But catalysis of ATP to ADP+PI causes the head to tilt.

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9
Q

Muscle fatigue

A

running out of ATP, unable to generate a muscle contraction

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10
Q

Type I

Contraction time, force production, resistance to fatigue, activity

Aerobic or anaerobic

Where is it found?

A

Slow twitch

Red - lots of myoglobin

Contracts slowly, weak force production but resistant to fatigue; Force distributed over a long period of time

more efficient at using oxygen to generate more fuel (known as ATP) for continuous, extended muscle contractions over a long time. They fire more slowly than fast twitch fibers and can go for a long time before they fatigue - marathon and bicycle for a long time

Aerobic

postural muscles

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11
Q

Type II - A

Contraction time, force production, resistance to fatigue, activity, myoglobin content, where it’s found

Long or short term; Aerobic or anaerobic oxidation

A

AKA: Fast/Oxidative twitch

Appears Red (lots of myoglobin)

Upper Legs

fast contraction time, strong force, easy to fatigue

short term anaerobic activity, can be aerobic

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12
Q

Type II - B

Contraction time, force production, resistance to fatigue, activity, myoglobin content

A

AKA: glycolytic twitch - lots of glycogen

B - white (low myoglobin, lots of glycogen, appear white)

upper arms

Fast contraction time, really strong force, easy to fatigue,

long term anaerobic activity

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13
Q

Cardiac muscle -

Is it striated?

multi or single nucleus

what is intercalated discs in cardiac muscle

A

Striated (has sarcomeres)

single nucleated

intercalated dics - has gap junctions that allow an easy electrical flow between the cells through the synapse, easy synchronization of the contraction of the cardiac muscle cells - make the cell function like a net that contracts upon it self like squeezing a fist

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14
Q

Why is the repolarization time much longer in the heart? What is the importance of calcium in the heart contraction?

A

Calcium lingers much longer inside the cell - slow voltage gated calcium channels

It lengthens the time of the contraction - preventing a new action potential from starting in the middle of the previous contraction. This prevent tetanus that happens in the skeletal muscles which can be deadly in the heart

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15
Q

Smooth muscle - striation, nucleation, structure

How does the smooth muscle contract?

A

No striation (no sarcomeres)

single nucleus

organized into dense bodies. contain intermediate filaments (like actin) which are attached to dense bodies distributed throughout the cell (network of highways). Upon contraction, this dense network system causes the smooth muscle cell to contract and shrink

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16
Q

How are the single units of smooth muscle cells connected?

A

connected by gap junctions

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17
Q

Osteoblast and osteocyte

Can they both multiply?

A

osteocyte is an osteoblast trapped in lacunae that communicate via canaliculi - differentiated version of osteoblast.

both can’t multiply

osteoblast secrete collagen (matrix - network it surrounds itself in).

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18
Q

Differentiation of osteoblast

A

osteocyte

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19
Q

Function of osteocyte

A

exchanges nutrients and waste with the blood. Osteoblast and osteocyte both can’t multiply. Specialized in mediating input and output

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20
Q

Osteoclast are thought to have developed from what?

A

WBC - monocytes

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21
Q

Epiphyseal plate

A

sheet of hyaline cartilage between metaphysis and epiphysis in the long bone

grows in response to growth hormone in childhood and adolescence

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22
Q

long shaft of bone

A

diaphysis

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23
Q

Spongy bone vs. compact bone

A

Spongy bone (trabecular bone) - contain red bone marrow; RBC formation and storage

Compact bone (cortical bone) - surrounds the hollow cavity called the medullary cavity, contain yellow bone marrow; adipose cells for fat storage

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24
Q

Remodeling in the bone

A

formation of osteon by osteoclast and osteoblast

osteoclast tunnels and makes way, osteoblast then adds on the matrix on the tunnel wall, making concentric rings called the lamellae. Osteoblasts leave open space in the center of lamellae to for Haversian canals which include blood and lymph nodes

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25
Calcium solubility in blood
only slightly soluble in blood - not found in free forms in the blood usually bound to phosphates, and other anions
26
Joint
where bones connect
27
Fibrous joint
two bones held closely and tightly together by fibrous connective tissues. Extremely minimal movement; teeth connected to the mandible, skull bones
28
Cartilaginous joints
two bones tightly connected by the cartilage such as the ribs and sternum. allow little movement
29
Synovial joints What is it? Range of movement What is significant about synovial fluid? Function?
not directly bound b the intervening cartilage wide range of movement is possible; shoulder and knee two bones are separated by a capsule filled with synovial fluid that provide nourishment and lubrication to the cartilage. The synovial fluid contains phagocytic cells that remove microbes and particles.
30
90% of epidermis is composed of _______
keratinocytes
31
Keratinocytes where is it
cells that produce keratin epidermis
32
Melanocytes where is it
transfer melanin to keratinocytes epidermis
33
Langerhans cells where is it
interact with the helper T cells of the immune system epidermis
34
Merkel cells where is it
attach to the sensory neurons and function in the sensation of touch epidermis
35
The deepest layer of the epidermis contain _____ and _____ cells
Merkel cells, and stem cells
36
tendon
muscle to bone
37
ligament
bone to bone
38
the origin of the muscle which part of the muscle, where it attaches to, and the breadth of movement, and how close it is to the midpoint of the body
point on the muscle that attaches to a larger bone and remains relatively stationary closest to the midpoint of the body
39
the insertion of the muscle where it is on the muscle, where it attaches to, how close it is to the midpoint
farthest from the origin attached to small bones and farthest from the midpoint of the body
40
how do synergistic muscles help the agonist muscles
help the agonist muscle by stabilizing the origin or by positioning the insertion bone during the movement
41
The shivering reflex: what muscle does it contract? what is the purpose? and how does it affect the body?
the shivering reflex affects the skeletal muscles. it is controlled by the hypothalamus upon stimulation from the skin and spinal cord it happens because there is glycogen storage in the skeletal muscles so the body tries to release the energy so that it can provide heat for the body
42
is there mitochondria and nucleus within the muscle fibril/muscle cell?
nope but around it between the muscle fibrils
43
levels of organization of the muscle
from smallest to biggest bundles within bundles within bundles muscle cell/muscle fibril --> fiber --> fascicle
44
distinction of heart's mitochondria
large and ample for production of ATP
45
functionality of the slow repolarization of the heart muscle
it gives the heart enough time to refill with blood and prevents tetanus, the sustained contraction that can occur in skeletal muscle that could be deadly if it occurred in the heart
46
where do intercalated discs occur
in the Z line - desmosomes and gap junctions forming a fused mass of cells
47
What's responsible for the plateau after depolarization? and what is the charge inside the membrane? what is the purpose of slower rate of repolarization of the cardiac muscle?
slow voltage-gated calcium channels which allow calcium to enter and maintain the inside of the membrane at a positive potential difference as a result, the repolarization of the cardiac muscle is slower and more frequent than that of skeletal muscle The action potentials of cardiac muscle are unusually sustained. This prevents premature relaxation, maintaining initial contraction until the entire myocardium has had time to depolarize and contract
48
are smooth muscles organized into sarcomeres?
nope
49
what are dense bodies in the smooth muscle cells
dense bodies function as Z lines in the skeletal muscle containing actinin and Z-line proteins the intermediate filaments are attached to the dense bodies, being organized into a network
50
single unit vs. multi-unit of smooth muscle
depends on the attachment of autonomic neuron to the smooth muscle cells. in a single unit, autonomic neuron attaches to a single mass of smooth muscle cells connected by gap junctions so that electrical activity travels down fast in multi unit, each muscle cell is attached to one or more than one neuron. each fiber is attached directly to a neuron so each group of multi-unit smooth muscle fibers can contract independently of other
51
where are single unit smooth muscles found? where are the multi unit smooth muscles found?
single unit - small arteries, veins, stomach, intestines, uterus, urinary bladder multi unit - large arteries, bronchioles, pili muscle attached to hair follicles and the iris
52
what is the dermis of the skin what does it contain
connective tissue derived from mesodermal cells blood vessels, nerves, glands, and hair follicles, collagen and elastin fibers sensation of touch: pressure, pain, temperature
53
what is in the subcutaneous layer?
fat functioning as a heat insulator for the body some nerve endings reaching deep down into the fat layer
54
in the epidermis: what is in the corneum, granulosum, spinosum, and basale
corneum: keratinized cells granulosum: granular cells spinosum: spinous cells
55
what is cartilage mainly consisted of what happens if cartilage is worn out and bones grind against each other
collagen osteoarthritis
56
what is a hyaline cartilage?
it's the most common type of cartilage that reduces friction and absorbs shock in joints
57
fibrous joints
two bones held closely and tightly together by a fibrous connective tissue permitting minimal movement teeth with the mandible after early childhood, skull bones form fibrous joints with each other, strengthening and hardening the skull
58
cartilaginous joints
little movement bones connected by cartilage ribs and sternum
59
synovial joints
not bound directly by intervening cartilage so a wide range of movement is possible separated by a capsule called synovial fluids - lubrication and nourishment to the cartilage, contain phagocytotic cells that remove microbes and particles shoulder and knee between femur and tibia
60
types of joints
differ by the range of movement what's holding the two bones together
61
what do osteoblasts secrete are they capable of mitosis when they trap themselves with the matrix material they release, what do they differentiate to
secrete collagen and organic compounds upon which the bone is formed incapable of mitosis trap themselves and become osteocytes
62
what do osteocytes do do they mutilply by mitosis?
exchange nutrients and waste materials with the blood. ex. release Ca2+ in response to PTH cannot under mitosis - can't multiply to replace more cells
63
how do osteoclasts develop
develop from monocytes
64
What is the myofibrils wrapped in
Sarcoplasmic reticulum
65
Myofibril is wrapped in what layers?
Sarcoplasmic reticulum and sarcolemma
66
Type 1 muscle
Red muscle, less powerful; slower of contract In the calf Slower to control and slower to fatigue; marathon
67
Type 2 muscle
White, biceps Faster to contract and faster to fatigue
68
Are cardiac muscles striated? Describe cardiac muscles
Yes Involuntary, intercalated discs, only one nucleus, not attached to a bone. They are connected via intercalated discs which has gap junctions between them.
69
Smooth muscle
Dense bodies Actin filaments radiate from dense bodies One nucleus; NOT striated

MCAT Biology by me (16 decks)

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