Connective tissues Flashcards
What is the structure of the subcutaneous layer?
Loose connective tissue attached to underlying bone and muscle
What is the function of the subcutaneous layer?
Supplies skin with vessels, nerves, fibroblasts, adipocytes, macrophages; contains half the body’s stored lipids
What are loose connective tissues?
Adipose and reticular tissue
What are dense connective tissues?
Blood, bone, cartilage, muscle and nervous tissue
What are chondrocytes?
Cartilage cells, which produce collagen and proteoglycans, to maintain cartilage ECM
Describe the structure of cartilage.
Chondrocytes in a matrix, surrounded by collagenous pericondrium. No blood vessels or nerves.
Where is hyaline cartilage found and what is is it for?
Sternum, trachea, bronchi, ribs, synovial joints.
For support and flexibility.
Contains evenly dispersed collagen.
Where is elastic cartilage found and what is it for?
Larynx, epiglottis, ear, auditory canal.
For support and elasticity.
Where is fibrocartilage found and what is it for?
Knees, pelvis, intervertebral discs.
Resists compression, movement and bone-bone contact.
Contains thick bundles of collagen.
What does an osteoblast do?
Forms bone, secretes Type I collagen and HA
What does an osteoclast do?
Destroy bone by secreting acid
What is the structure of an osteoclast?
Large, multinucleated, macrophage like, derived from monocytes in bone marrow
What is an osteocyte?
An osteoblast suspended in the bone matrix, has long cell processes which communicate with other cells at gap junctions
Describe the structure of an osteon (Haversian system).
Blood vessels + lamellae + osteocytes
What are the names of the transverse and longitudinal canals that connect osteons?
Haversian (longitudinal) and Volkmann (transverse) canals.
What is the role of vitamin A in bone formation?
Stimulates osteoblast activity
What is the role of vitamin C in bone formation
Stimulates production of collagen
What is the role of vitamin D in bone formation?
Stimulates Ca2+ absorption
Describe the function of calcitonin.
Released from thyroid gland in response to high blood calcium. Causes:
- Increased excretion of calcium from the kidneys
- Calcium deposition in bone
Describe the function of PTH.
Released from parathyroid gland in response to low blood calcium. Causes:
- Increased reabsorption of calcium by the kidneys
- Calcium release from bone
- Increased calcitriol production
What is the function of calcitriol?
Increased Ca2+ absorption of calcium by the digestive system
What are lamellae?
Concentric rings of lamellar (compact) bone
What are the two types of bone?
Lamellar (compact) bone and spongy (cancellous) bone. Cancellous bone is found at the ends of long bones, and lamellar at the shafts.
Which types of collagen are found in cartilage and in bone?
Type II and Type I respectively.
