Bone & Muscle

HA Block 1 Histology

endochondral ossification

making of cortical bone from cartilage

membranous ossification

making of trabecular bone

modeling

reshaping of bone

remodeling

maintenance of bone

cortical bone

synonymous with compact bone

trabecular bone

synonymous with cancellous bone

woven bone

new bone, first response to injury or fraction, also found in embryo

lamellar bone

remodeled bone, adult bone

osteoblasts

cells that build bone

osteoclasts

cells that break down bone

connective tissue

What type of tissue is bone?

organic material: non-collagenous and collagenous proteins, and inorganic material: minerals

What is the extracellular matrix of bone composed of?

lacunae/holes inside the cone

Where do osteocytes reside?

on the surface of bone

Where do osteoblasts reside?

osteoblasts secrete collagen as a precursor matrix called osteoid

Phase 1 of ECM production

mineralization of osteoid

Phase 2 of ECM production

osteoclasts have multiple nuclei while osteoblasts have 1 and line the surface of the bone

What is one way you can tell apart osteoclasts and osteoblasts histologically?

cortical bone

hard, rigid, macroscopic structure of bone found on the outside

trabecular bone

macroscopic structure of bone found on the inside

woven: not as dense, irregular; lamellar: dense & regular/organized

What is the histological differences between woven and lamellar bone?

periosteum

outer layer of tissue surrounding the bone

osteogenic/cambium layer

Which layer of the periosteum contains the osteoblasts?

osteogenic/cambium layer and fibrous layer

What are the 2 layers of the periosteum?

fibrous layer

Which layer of the periosteum contains vessels and nerves?

osteons

synonymous to haversian systems

cylindrical structure in bones that serve as a pathway for nerves and vessels

normal growth, microcracks, accommodate moving vasculature, repositioning of osteons, mineral homeostasis

reasons for bone remodeling

quiescence, activation, resorption, reversal, formation, quiescence

sequence of events for remodeling

membranous ossification

Which type of ossification is responsible for the thickening of long bones?

endochondral ossification

Which type of ossification is responsible for the lengthening of long bone?

membranous ossification

Which type of ossification is responsible for growth of most flat bones in the skull?

zone of reserve cartilage → zone of proliferation (chondrocytes grow) → zone of hypertrophy (chondrocytes die) → zone of calcification, blood vessels deposit osteoblasts to produce bone

How does endochondral ossification occur?

skeletal, cardiac, smooth

What are the 3 major types of muscle?

skeletal and cardiac

Which muscle type(s) appear striated?

voluntary: skeletal, involuntary: cardiac and smooth

Which type of muscle is voluntary and which is involuntary?

contractility, excitability, extensibility, elasticity

What are the special functional characteristics of muscle?

skeletal

What muscle is found in the abdominal wall and esophagus?

smooth

What muscle is found in tubular organs?

epimysium, perimysium, endomysium

What envelopes muscle from the outer most to inner most components?

whole muscle

What does the epimysium surround?

fasciculi

What does the perimysium surround?

myofibers

What does the endomysium surround?

fasciculi

What is the term for a bundle of muscle fibers?

muscle fibers

synonymous to muscle cells

myofibrils

contractile organelles of the myofibers made of consecutive linked sarcomeres

myofilaments

What makes up sarcomeres?

smooth

Which muscle type does not have the sarcomere structure?

calcium binds to troponin, tropomyosin reveals binding site on actin, myosin binds to actin forming a cross bridge and pulling actin toward the M line

Explain the interactions between troponin, tropomyosin, calcium, and myofilaments

t tubules

What structure carries nerve impulses to the muscle cell?

sarcoplasmic reticulum

What structure stores and releases calcium and surrounds myofibrils

cardiac muscle cells are single cells joined together while skeletal cells stretch the length of the muscle, cardiac muscle cells branch and only have 1-2 nuclei in the center

What are some differences between the structure of cardiac and skeletal muscle?

intercalated discs

What joins cardiac muscle cells?

purkinje fibers

highly modified cardiomyocytes that do not have t tubules

gap junctions and desmosomes

What joins purkinje fibers

1 central nucleus

How many nuclei do smooth muscle cells have?

calmodulin

What does calcium bind to in smooth muscle?

myosin light chain kinase (smooth muscle)

MLCK