Biology 11: Muscloskeletal System

Question 1

what are the three subtypes of muscle

Answer 1

skeletal

smooth

cardiac

Question 2

skeletal muscle

Answer 2

muscle responsible for voluntary movement - somatic

striped/striated bc alternating actin and myosin sarcomeres

multinucleated bc individual muscle cells fuse in long rods

nuclei are found at cell periphery

Question 3

red fibers / slow-twitch fibers

Answer 3

fibers in skeletal muscle

have high myoglobin content and derive most of their energy aerobically

have lots of mitochondria to carry out oxidative phosphorylation

numerous in muscles that contract slowly and can sustain activity

Question 4

white fibers / fast-twitch fibers

Answer 4

fibers in skeletal muscle

contain less myoglobin, less iron, lighter color

numerous in muscles that contract rapidly but fatigue quickly

Question 5

myoglobin

Answer 5

an oxygen carrier that uses iron in a heme group to bind O2, imparting a red color

Question 6

smooth muscle

Answer 6

muscle responsible to involuntary action - autonomic

cells have a single nucleus in the center

contain actin and myosin in fibers not well organized - not striated

can do tonic contraction - constant low-level contraction

myogenic activity - responds directly to stretch and other stimuli

Question 7

myogenic activity

Answer 7

the ability of muscle to contract without nervous system input

present in smooth and cardiac muscle

Question 8

cardiac muscle

Answer 8

muscle found in the heart - involuntary - autonomic

appears striated

primarily uninucleated but sometimes w two nuclei

can define and maintain rhythm through myogenic activity

Question 9

intercalated discs

Answer 9

connect cardiac muscle cells and contain gap junctions

gap junctions - connections between the cytoplasm of adjacent cells, allowing for the flow of ions directly between cells

allows for rapid and coordinated muscle cell depolarization and efficient contraction

allows progressive depolarization to spread via ion flow across

Question 10

pathway of electrical depolarization through the heart

Answer 10

sinoatrial node –> atrioventricular node –> bundle of His –> Purkinje fibers

Question 11

what provides parasympathetic outflow to heart?

Answer 11

vagus nerve

Question 12

what neural innervations increases heart rate?

Answer 12

norepinephrine from sympathetic neurons or epinephrine from adrenal medulla binds to adrenergic receptors in heart

increases heart rate and greater contractility

Question 13

which filament in a sarcomere is composed of actin?

thin or thick

Answer 13

thin

thin filaments also consist of troponin and tropomyosin to regulate interaction between the two filaments

Question 14

which filament in a sarcomere is composed of myosin?

thin or thick

Answer 14

thick

Question 15

titin

Answer 15

protein in sarcomeres that acts as a spring and anchors the actin and myosin filaments together

prevents excessive stretching of muscle

Question 16

M-line

Answer 16

line that runs down the center of the sarcomere, through the middle of the myosin filaments

middle of the myosin filaments

Question 17

Z-line

Answer 17

defines the boundaries of each sarcomere

z is the end of the alphabet, the end of the sarcomere

Question 18

I-band

Answer 18

the region containing exclusively thin filaments (actin)

I is a thin layer, thin filaments only

Question 19

H-zone

Answer 19

region containing exclusively thin filaments (myosin)

H is a thick letter, thick filaments only

Question 20

A-band

Answer 20

region that contains the thick filaments in their entirety, including any overlap with thin filaments

all of the thick filament whether overlapping or not

Question 21

how do the H-zone, I-band, Z-lines, M-lines, A-lines of a sarcomere change during contraction?

Answer 21

H zone, I band becomes smaller

distance between Z lines and M lines all become smaller

A band’s size remains constant

Question 22

myofibrils

Answer 22

end-to-end attachment of sarcomeres

surrounded by sarcoplasmic reticulum

Question 23

sarcoplasmic reticulum

Answer 23

a modified endoplasmic reticulum that contains high concentrations of Ca2+ ions

Question 24

sarcoplasm

Answer 24

modified cytoplasm located just outside sarcoplasmic reticulum

Question 25

sarcolemma

Answer 25

cell membrane of a myocyte capable of propagating an action potential and can distribute the action potential to all sarcomeres through **T-tubules**

Question 26

transverse tubules / T tubules

Answer 26

tubes oriented perpendicularly to myofibrils propagates action potentials to all sarcomeres in a muscle

Question 27

neuromuscular junction

Answer 27

site where motor neurons reach muscles **acetylcholine** binds to receptors on the **sarcolemma**, causing **depolarization**

Question 28

how are muscle contractions initiated?

Answer 28

* **acetylcholine** release at neuromuscular junction -\> **depolarization of sarcolemma** * action potentials reach **T-tubule** -\> **sarcoplasmic reticulum** * **Ca2+** released in sarcoplasmic reticulum, bind to **troponin**, cause **conformational** change in **tropomyosin** to expose **myosin-binding site on actin**

Question 29

how are sarcomeres shortened?

Answer 29

* heads of myosin have **ADP + Pi** = able to **bind** to myosin-binding site on actin, **forming crossbridge** * **release of ADP and Pi** provides energy for **powerstroke** * **ATP** binds to myosin = **release** of myosin from actin * ATP is **hydrolyzed to ADP and Pi**, causes myosin to **recock** for the next powerstroke

Question 30

what causes the relaxation of muscle?

Answer 30

* **acetylcholine degraded** in synapse by **acetylcholinesterase** * allows sarcolemma to **repolarize** * **Ca2+ release decreases**, sarcoplasmic reticulum takes up Ca2+ from sarcoplasm * **ATP binds to myosin** heads to free them from actin * with no Ca2+, **myosin-binding sites are covered** by tropomyosin

Question 31

simple twitch

Answer 31

the response of a single muscle fiber to a brief stimulus at or above threshold latent period - contraction period - relaxation period

Question 32

latent period

Answer 32

the time between **reaching threshold and the onset of contraction** the action potential spreads along the muscle and allows for **Ca2+ to be released** from the sarchoplasmic reticulum

Question 33

frequency summation

Answer 33

muscle exposed to **frequent and prolonged stimulation**, no time to relax **contractions combine, become stronger** and more prolonged

Question 34

tetanus

Answer 34

contractions become so frequent that the **muscle is unable to relax at all** between stimulations results in muscle fatigue

Question 35

besides O2, what are two extra energy reserves for slow-twitch/red fibers to avoid oxygen debt?

Answer 35

creatine phosphate myoglobin

Question 36

creatine phosphate

Answer 36

alternative energy reserve in muscles the case of oxygen debt can **transfer a phosphate group to ADP**, creating ATP

Question 37

myoglobin

Answer 37

heme-containing protein muscular O2 reserve, binds O2 with high affinity

Question 38

what's the difference between endoskeletons and exoskeletons?

Answer 38

**exoskeletons** - encase organisms, protect soft tissue underneath; must be **shed** with growth **endoskeletons** - internal, can't protect but are able to **accomodate** **growth**

Question 39

from which gastrulation layer is bone derived from?

Answer 39

mesoderm

Question 40

compact bone

Answer 40

type of bone is **dense** and **strong**

Question 41

spongy / cancellous bone

Answer 41

type of bone has a lattice-like structure of bony spicules - **trabeculae** cavities are filled with **bone marrow**

Question 42

what is the difference between **red marrow** and **yellow marrow**?

Answer 42

**red marrow** - filled with hematopoietic stem cells **yellow marrow** - composed primarily of fat and relatively inactive

Question 43

periosteum

Answer 43

fibrous sheath that surrounds the long bone to **protect** it and serve as a site of **muscle attachment** cells may **differentiate into osteoblasts**

Question 44

what is the difference between a tendon and a ligament?

Answer 44

**tendons** attach muscle to bone **ligaments** hold bone together at joints

Question 45

what is the difference between haversian canals and volkmann's canals?

Answer 45

both contain blood vessels, nerve fibers, and lymph vessels that maintain the health of the bone **haversian canals** are longitudinal **volkmann's canals** are transverse to the bone

Question 46

where are osteocyes in bone matrix housed?

Answer 46

in lacunae between the lamellar rings

Question 47

parathyroid hormone

Answer 47

peptide hormone released by parathyroid gland in **response to low blood Ca2+** promotes resorption of bone -\> **increased Ca2+ and PO4- in blood**

Question 48

vitamin D

Answer 48

activated by parathyroid hormone promotes resorption of bone, **encouraging growth of stronger bone**

Question 49

calcitonin

Answer 49

peptide hormone released by **parafollicular cells** of thyroid in **response to high blood Ca2+** promotes bone formation, **lowering Ca2+ levels**

Question 50

chondrin

Answer 50

**firm but elastic** matrix surrounding cartilage secreted by **chondrocytes**

Question 51

how is cartilage different from bone?

Answer 51

* cartilage is flexible and cushioning * cartilage is avascular and is not innervated

Question 52

endochondral ossification

Answer 52

the creation of bone by the hardening of cartilage creates most **long bones** in the body

Question 53

intramembranous ossification

Answer 53

the **replacement** of undifferentiated embryonic connective tissue (**mesenchymal tissue**) by bone occurs in bones of the **skull**

Question 54

immovable joints

Answer 54

joints made of bones that are **fused together to form sutures** or fibrous joints primarily in the head, anchoring bones of the **skull** together

Question 55

movable joints

Answer 55

hinge joints (elbow, knee), ball-and-socket joints (shoulder, hip) permit bones to **shift relative to one another** strengthened by **ligaments** **synovial capsule** - encloses the joint cavity (articular cavity)

Question 56

synovial fluid

Answer 56

secreted by synovium - soft tissue layer lubricates the movement of structures in the joint space

Question 57

what is the difference between the **origin** and **insertion** of muscles?

Answer 57

**origin** is the end of the muscle with a **larger attachment to bone** (usually proximal) **insertion** is the end with the **smaller attachment to bone** (usually distal)

Question 58

what is the difference between a **flexor** muscle and an **extensor** muscle?

Answer 58

**flexor** muscle **decreases the angle** across a joint **extensor** muscle **increases or straightens** the angle

Question 59

what is the difference between an abductor and an adductor?

Answer 59

**abductor** moves a part of the body **away from the midline** **adductor** moves a part of the body **toward the midline**

Question 60

what is the difference between **medial** and **lateral** rotation?

Answer 60

a **medial rotator** rotates the axis of the limb **toward the midline** a **lateral rotator** rotates the axis of the limb **away from the midline**

Question 61

osteoblasts

Answer 61

bone cells involved in the **secretion of bone matrix** build bone

Question 62

osteoclasts

Answer 62

polynucleated cells actively involved in **bone resorption** chew bone

Question 63

where does longitudinal bone groth occur?

Answer 63

epiphyseal plate

Question 64

which bones constitute the **axial skeleton**?

Answer 64

skull vertebral column ribcage hyoid bone

Question 65

what bones constitute the **appendicular skeleton**?

Answer 65

limbs pectoral girdle pelvis