Connective Tissue

Question 1

Ground substances

Answer 1

• Made up of many substances including Hyaluronic acid which is capable of binding water which is responsible for changes in the permeability and viscosity of the CT.
• Ground substance plays a role in preventing or retarding the spread of microorganisms and toxic materials at sites of infections.

Question 2

Fibres in the CT

Answer 2

The fibres in CT are collagen, reticular and elastic produced by fibroblasts.

Question 3

Fibroblasts

Answer 3

Fibroblasts (most common CT cells) are flattened cells with elliptical nuclei that contain 1 or 2 nucleoli.

Question 4

Mast cells

Answer 4

Mast cells are large, ovoid cells with large granules in the cytoplasm and can control vasodilation - increases permeability of capillaries so that excess plasma enters the CT spaces, causing swelling.

Question 5

Plasma

Answer 5

Plasma cells appear ovoid in shape with eccentrically placed nuclei in which the chromatin may be distributed along the nuclear envelope forming the “clockface” nucleus. Plasma cells produce the immunoglobulins (antibodies) that form a defence against infections.

Question 6

Lymphocytes

Answer 6

Lymphocytes are cells that have come from the blood into the CT and are responsible for initiating the cell-mediated immune response (T cells). They have a small dark nucleus and little cytoplasm.

Question 7

Macrophages

Answer 7

Macrophages are phagocytosing cells of the CT responsible for removing particulate matter and assisting in the immune response. They originate in bone marrow, circulate in the blood as monocytes, and migrate into the CT where they perform their functions.

Question 8

Loose CT (areolar)

Answer 8

Characterized by much ground substance and tissue fluid housing the CT cells: fibroblasts, adipose cells, macrophages, and mast cells, as well as some undifferentiated cells.

• also loosely woven collagen, reticular, and elastic fibers
• found below the skin, adventitia of blood vessels and resp. tract
• binds organs and organ components
• Because this tissue lies immediately beneath the epithelia of the digestive and respiratory tracts, it is where the body first attacks antigens and bacteria.

Question 9

Functions of connective tissue

Answer 9

Transport: CT carry blood vessels and lymphatics, mediate the exchange of metabolites
(nutrients, wastes, gases) between tissues and the blood
Repair: scar tissue formation after injury
Defense: phagocytes (macrophages), antibodies (plasma cells)
Packing: space between epithelium, muscle, and glands.

Question 10

White fat

Answer 10

flat peripherally located nucleus and a thin ring of cytoplasm, the rest of the cell is filled by a single, large droplet of lipid (unilocular)
-Function: storage depot, production of energy, insulation, packing material and shockabsorbing pads in the palms of the hands, soles of the feet, around the eyeball and kidneys.

Question 11

Brown Fat

Answer 11

Cells are smaller than white fat but show centrally placed round nuclei with a cytoplasm filled with numerous small droplets of lipid (multilocular).
Location: in the fetus and newborn mammals and some hibernating animals
Function: thermoregulation.

Question 12

Periochondrium

Answer 12

The inner region is cellular (chondrogenic) composed of cells, which differentiate into chondroblasts, and begin to make matrix.
The outer region is fibrous (elastic, collagen, fibroblasts, blood vessels) and also contains chondroblasts, which have been pushed out as a result of inner growth.

In areas where the cartilage has no perichondrium e.g. the articular surfaces of a synovial joint, the cartilage cells receive their nutrients from the synovial fluid that flows in joint surfaces.

Question 13

Cartilage formation

Answer 13

Starts with the differentiation of embryonic mesenchymal cells to form chondroblasts. Secretion of extracellular
material traps each chondroblast in a space or lacuna within the cartilaginous matrix. Each
chondroblast then undergoes mitotic divisions to form a small group of mature cells(chondrocytes) separated by extracellular material.

Question 14

Hyaline Cartilage

Answer 14

• The most common type has ground substance, type II collagen fibres (40% of matrix) and small groups of chondrocytes.
• Location: nasal septum, larynx, tracheal rings, bronchi

Question 15

Elastic Cartilage

Answer 15

Is a variety of hyaline cartilage except it also contains elastic fibers between type II collagen fiber bundles. It has a perichondrium whose outer fibrous layer is rich in elastic fiber. It grows by apposition.
Location: where support with flexibility is required, e.g. the ear pinna, auditory tube, epiglottis

Question 16

Fibrocartilage

Answer 16

Serves as a transition between dense CT and hyaline cartilage.Unlike the other 2 types of cartilage,
fibrocartilage does not possess a perichondrium. Location: where support and tensile strength is needed, e.g. intervertebral discs, menisci, and pubic symphysis.