18.1 MS system

Question 1

striated muscle - skeletal and cardiac - organized into SARCOMERES

Answer 1

Skeletal muscle innervated by ACh to stimulated contraction

Cardiac muscle innervated by ACh to inhibit spontaneous depolarization

Question 2

creatine phosphate

Answer 2

regenerates ATP from ADP + Pi

Question 3

myoglobin

Answer 3

globular protein similar to one of four subunits of hemoglobin

Question 4

myofibers = muscle cell -> muscle fibers - stretch entire length of the muscle - composed of a single skeletal muscle cell

FASCICLE = bundle of MANY muscle CELLS

multinucleate syncytia - fusion of individual cells during development

myofiber has a cell membrane called SARCOLEMMA, made of plasma membrane and layer of polysaccharide and collagen

myofiber is composed of small units called MYOFIBRILS - which generates contractile force

Answer 4

cardiac muscles are NOT syncytial (they have 1 nucleus)

Question 5

cardiac muscle

Answer 5

interconnected by GAP JUNCTIONS known as INTERCALATED DISKS

= allows APs to propagate

FUNCTIONAL SYNCYTIUM

Question 6

skeletal muscle

Answer 6

ALL CALCIUM for contraction comes from SARCOPLASMIC RETICULUM, INTRACELLULAR RESERVE

Question 7

cardiac muscle contraction not impacted by motor neurons

Answer 7

Vagus nerve releases ACh at chemical synapses with the heart that is INHIBITORY (parasympathetic)

Question 8

DENSE versus LOOSE connective tissues

Answer 8

Loose : packing tissues, areolar tissue (between cells) and adipose tissue (fat)

Dense: large amount of fibers, tendons/ligaments/cartilage/bone

Question 9

flat and long bones

Answer 9

flat = scapula, ribs, skulls - location of hematopoiesis

long = support and movement, diaphysis and epiphysis

Question 10

cartilage = secreted by CHONDROCYTES

Answer 10

hyaline = strong and flexible - larynx and trachea, joints have ARTICULAR cartilage

elastic cartilage = epiglottis, outer ear (support and more flexibility than hyaline) - contains ELASTIN

Fibrous cartilage = very rigid - strong support at pubic symphysis and intervertebral disks in spinal columns

Question 11

bone growth = ENDOCHONDRAL ossification

Answer 11

hyaline cartilage is produced, then replaced by bone

Question 12

growth of long bones

Answer 12

1. epiphyseal plate seen between diaphysis and epiphysis
2. the EP is a disk of hyaline cartilage that divides, forcing diaphysis and epiphysis apart
3. cartilage replaced by bone
4. stimulated by GH
5. at age 18, the diaphysis and epiphysis MEET and FUSE together

Question 13

remodeling

Answer 13

bones do NOT elongate, but are degraded and remade

• cells that make bone by laying down collagen and hydroxyapatite are called OSTEOBLASTS
• Lacuna - the space previous occupied by the osteoblast, and the osteoblast becomes an OSTEOCYTE

Osteoclasts DESTROY bone - phagocytic cousin of macrophage

Question 14

remodeling

Answer 14

bones do NOT elongate, but are degraded and remade

• cells that make bone by laying down collagen and hydroxyapatite are called OSTEOBLASTS
• Lacuna - the space previous occupied by the osteoblast, and the osteoblast becomes an OSTEOCYTE

Osteoclasts DESTROY bone - phagocytic cousin of macrophage - liberates calcium and phosphate into bloodstream

Question 15

regulation of calcium and phosphate

Answer 15

PTH, calcitonin, calcitriol (derived from vitamin D in the kidneys)

calcitriol INCREASES calcium

calcitonin REDUCES calcium

Question 16

remodeling

Answer 16

bones do NOT elongate, but are degraded and remade

• cells that make bone by laying down collagen and hydroxyapatite are called OSTEOBLASTS
• Lacuna - the space previous occupied by the osteoblast, and the osteoblast becomes an OSTEOCYTE

Osteoclasts DESTROY bone - phagocytic cousin of macrophage - liberates calcium and phosphate into bloodstream - bone resportion