bone and muscle

Question 1

what are the 3 types of muscle

Answer 1

skeletal/voluntary
cardiac
smooth

Question 2

describe skeletal muscle cells

Answer 2

straited, unbranched, multinucleate
long cylinders 10-100μm in diameter and 1,000-200,000μm in length

Question 3

What are muscle fibers grouped into?

Answer 3

bundles called fascicles

Question 4

what does a muscle typically contain

Answer 4

several fascicles.

Question 5

What is the connective tissue that surrounds the muscle as a whole called?

Answer 5

epimysium.

Question 6

What is the connective tissue around a single fascicle called?

Answer 6

perimysium.

Question 7

what is the connective tissue around a single muscle fiber called?

Answer 7

endomysium.

Question 8

what are sarcomeres

Answer 8

‘unit of contraction’, of the muscle cell
smallest contractile elements in the striated muscle cell.

Question 9

Why do skeletal muscle fibers appear ‘striated’?

Answer 9

under the microscope, the fibers have a regular pattern of bands running across the fiber at right angles to the long axis.

Question 10

Is the striation pattern true for both skeletal and cardiac muscle?

Answer 10

yes

Question 11

What causes the striated appearance of muscle fibers?

Answer 11

sarcomeres in the myofibrils, with their alternating dark and light bands, being held in registry with one another across the fiber.

Question 12

What does it mean for sarcomeres to be held in “registry”?

Answer 12

it means that the Z-disks in the sarcomere of one myofibril align with the Z-disks of the sarcomeres in the surrounding myofibrils

Question 13

what are the 3 types of skeletal muscle fibres

Answer 13

type I - elatively slowly contracting fibres that depend on oxidative
metabolism. They have abundant mitochondria and myoglobin, are resistant to fatigue and produce relatively less force. Often called ‘red’ fibres

type IIA - relatively
fast contracting, but are also reasonably resistant to fatigue. These fibres are relatively uncommon

type IIB - fast contracting fibres that depend on anaerobic metabolism. They have few mitochondria and less myoglobin than Type I fibres. They fatigue
relatively easily and produce relatively greater force. Often called ‘white’ fibres.

Question 14

what are the features of cartilage

Answer 14

Semi-rigid and Deformable
Permeable
Avascular
Cells nourished by diffusion through the
extracellular matrix

Question 15

features of bone

Answer 15

Rigid
Not Permeable
Cells within the bone must be nourished by blood
vessels that pervade the tissue.
Comparison of Cartilage and Bone

Question 16

what are the cells found in cartilage called

Answer 16

chondrocytes (chondroblasts when immature) - live within space in the extracellular matrix - lacuna.
Chondrocytes are active cells which secrete and maintain extracellular matrix around them.

Question 17

what is the most common type of cartilage

Answer 17

Hyaline - 75% water 25% organic material
blue white colour and translucent

Question 18

Describe the shape of chondrocytes near the perichondrium compared to deeper in tissue.

Answer 18

flat neat perichondrium and round or angular deeper in tissue

Question 19

Where are some common sites for hyaline cartilage?

Answer 19

Articular surfaces, tracheal rings, costal cartilage, epiphyseal growth plates, and as a precursor in fetuses to many bones.

Question 20

What is the characteristic of the matrix in hyaline cartilage?

Answer 20

basophilic and metachromatic, especially in the lacunar capsule.

Question 21

What type of tissue is fibrocartilage?

Answer 21

Dense, opaque white fibrous tissue rich in collagen type I.

Question 22

How are chondrocytes arranged in fibrocartilage?

Answer 22

arranged singly or in isogenous groups, often in long rows.

Question 23

What characterizes the matrix of fibrocartilage?

Answer 23

The matrix is acidophilic and contains coarse collagen type I fibers

Question 24

What properties does fibrocartilage have in larger quantities?

Answer 24

It has great tensile strength and elasticity, as seen in intervertebral discs.

Question 25

What role does fibrocartilage play in smaller amounts?

Answer 25

It provides strength, elasticity, and resistance to pressure and friction in structures like articular discs.

Question 26

what is the composition of bone

Answer 26

23% collagen
10% water
65% bioapatite
2% non collagen proteins

Question 27

describe the morphology of bone

Answer 27

outer shell(dense cortical bone) make up shaft
cancellous (fine meshwork) or trabecular bone at end of bone

Question 28

what are the living cells in bone

Answer 28

osteocytes

Question 29

what are cement lines

Answer 29

visible lines surrounding osteon

Question 30

what are the cells in bone

Answer 30

Osteoprogenitor cells: located on bone surfaces, serve as a
pool of reserve osteoblasts

Osteoblasts: bone forming cells found on the surface
of developing bone. have plentiful RER and prominent mitochondria.

Osteocytes: a bone cell trapped within the bone matrix.

Osteoclasts: large (up to 40μm or more) multinucleated cells. found on the surface of bone. responsible for bone resorption

Question 31

what happens during bone remodelling

Answer 31

a number of osteoclasts will congregate and begin to ‘drill’ into the bone, forming a tunnel. A blood vessel will grow into the tunnel bringing with it osteoblasts
which line the tunnel and begin
laying down new lamellar bone

Question 32

what do osteoblasts secrete and what is the result of this

Answer 32

collagen, glycosaminoglycans
(GAGs), proteoglycans and other organic components of
the matrix (osteoid)

becomes mineralized in extracellular space