bone and muscle Flashcards
(32 cards)
what are the 3 types of muscle
skeletal/voluntary
cardiac
smooth
describe skeletal muscle cells
straited, unbranched, multinucleate
long cylinders 10-100μm in diameter and 1,000-200,000μm in length
What are muscle fibers grouped into?
bundles called fascicles
what does a muscle typically contain
several fascicles.
What is the connective tissue that surrounds the muscle as a whole called?
epimysium.
What is the connective tissue around a single fascicle called?
perimysium.
what is the connective tissue around a single muscle fiber called?
endomysium.
what are sarcomeres
‘unit of contraction’, of the muscle cell
smallest contractile elements in the striated muscle cell.
Why do skeletal muscle fibers appear ‘striated’?
under the microscope, the fibers have a regular pattern of bands running across the fiber at right angles to the long axis.
Is the striation pattern true for both skeletal and cardiac muscle?
yes
What causes the striated appearance of muscle fibers?
sarcomeres in the myofibrils, with their alternating dark and light bands, being held in registry with one another across the fiber.
What does it mean for sarcomeres to be held in “registry”?
it means that the Z-disks in the sarcomere of one myofibril align with the Z-disks of the sarcomeres in the surrounding myofibrils
what are the 3 types of skeletal muscle fibres
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.
what are the features of cartilage
Semi-rigid and Deformable
Permeable
Avascular
Cells nourished by diffusion through the
extracellular matrix
features of bone
Rigid
Not Permeable
Cells within the bone must be nourished by blood
vessels that pervade the tissue.
Comparison of Cartilage and Bone
what are the cells found in cartilage called
chondrocytes (chondroblasts when immature) - live within space in the extracellular matrix - lacuna.
Chondrocytes are active cells which secrete and maintain extracellular matrix around them.
what is the most common type of cartilage
Hyaline - 75% water 25% organic material
blue white colour and translucent
Describe the shape of chondrocytes near the perichondrium compared to deeper in tissue.
flat neat perichondrium and round or angular deeper in tissue
Where are some common sites for hyaline cartilage?
Articular surfaces, tracheal rings, costal cartilage, epiphyseal growth plates, and as a precursor in fetuses to many bones.
What is the characteristic of the matrix in hyaline cartilage?
basophilic and metachromatic, especially in the lacunar capsule.
What type of tissue is fibrocartilage?
Dense, opaque white fibrous tissue rich in collagen type I.
How are chondrocytes arranged in fibrocartilage?
arranged singly or in isogenous groups, often in long rows.
What characterizes the matrix of fibrocartilage?
The matrix is acidophilic and contains coarse collagen type I fibers
What properties does fibrocartilage have in larger quantities?
It has great tensile strength and elasticity, as seen in intervertebral discs.
