L5 Connective Tissue Cells And Immune Cells

Question 1

What is CT

Answer 1

connective tissue forms a continuum with epithelial tissue, muscle and nervous tissue as well as other components of CT to maintain a functionally integrated body

Question 2

What is the origin of CT

Answer 2

From mesoderm in the middle germ layer of the embryonic tissue that contains mesenchymal stem cells (multi potent cells)

Question 3

What are components of CT

Answer 3

Composed of cells and extra cellular matrix consisting of ground substance and fibers

Question 4

What are the functions of the CT

Answer 4

Differ according to type of CT and its components generally:
Structural support
Medium for exchange
Aiding in defense and protection
Forming site of storage of fat

Question 5

How are CT cells classified

Answer 5

Fixed: resident population of cells that have developed and remain in place within connective tissue ex: fibroblasts and adipose cells
Transient: free cells originate mainly in bone marrow and circulate in bloodstream where they reach the CT in response to specific signals
Ex: mast cells, macrophages(can become resident) plasma cells lymphocytes,neutrophils,eosinophils, basophils and monocytes

Question 6

Describe the structure and function of fibroblasts

Answer 6

▪️Most abundant
▪️Function: responsible for synthesis and secretion of extracellular components
▪️Functional forms: active:with protein synthesis machine when cell is actively manufacturing matrix such as in wound healing
Inactive( fibrocytes) smaller and more ovoid with less organelles
Contain actin and myosin filaments resembling smooth muscles

Question 7

Describe structure and function of adipose cells

Answer 7

Do not undergo cell division
Function: storage and synthesis of triglycerides
Types: unilocular: cells with single lipid droplet and form white adipose tissue
Multilocular:multiple small lipid droplets and form brown adipose tissue

Question 8

Describe unilocular fat cells

Answer 8

Cont store fat until they enlarge and displace cytoplasm and nucleus peripherally against plasma membrane giving signet ring profile under LM

Question 9

Describe multilocular fat cells

Answer 9

Smaller and more polygonal than unilocular fat cells

Have more mitochondria

Question 10

Describe mast cells structurally and functionally

Answer 10

Ovoid and possess a centrally placed spherical nucleus
Characterized by abundant secretory granules that contain different chemical mediators such as heparin histamine and leukotrienes,interlukins and tumor necrosis factor
Function: immune system by initiation of inflammatory response known as immediate hypersensitivity reaction(anaphylactic reaction)

Question 11

Why is hypersensitivity reaction induced

Answer 11

By foreign antigens such as bee venom pollen and certain drugs

Question 12

What do mast cells contain instead of heparin in alimentary tract

Answer 12

Mucosa contains chondroitin sulphate

Question 13

Why does hay fever occur

Answer 13

Dud to effects of histamine being released by mast cells from nasal mucosa

Question 14

How do asthma attacks occur

Answer 14

Extra release of leukotrienes in lungs which results in difficulty in breathing

Question 15

Describe macrophages structurally and functionally

Answer 15

Arise from circulating monocytes and they are most abundant phagocytotic cells in CT
Function: Remove cellular debris and protect body against foreign invaders
Structure: large cells with irregular surface that show blunt projections or filopodia reflecting cell motility and abundance of lysosomes reflecting active phagocytosis

Question 16

Describe plasma cells structurally and functionally

Answer 16

Derived from b lymphocytes and manufacture antibodies
Cytoplasm is intensely basophilic(presence of RER) except in prenuclear area which appears pale and is referred to as a negative Golgi image

Question 17

What how are WBCs classified

Answer 17

▪️Granulocytes
Neutrophils
Eosinophils
Basophils

▪️Non granulocytes
Lymphocytes
Monocytes

Question 18

Describe neutrophils

Answer 18

▪️60-70% of total leukocyte population
▪️Multi lobed nucleus held by chromatin
▪️Pale cytoplasm
▪️Barr body in females
Functions:
▪️First line of defense against bacterial infection (phagocytose and destroy bacteria by content of their granules)
▪️Can migrate through blood capillary wall to reach CT sites where there is bacterial infection to act in phagocytosis
▪️After preforming their function: cells die and form pus cells

Question 19

Describe eosinophils

Answer 19

Bilobed nucleus and eosinophilic granules

Function:phagocytose antigen-antibody complexes and kill parasitic invaders

Question 20

What inc formation of eosinophils and what dec it

Answer 20

Release of histamine and IL-5 from CT cells in vicinity of antigen antibody complexes

Elevation of blood corticosteroid levels dec number of eosinophils

Question 21

Describe basophils

Answer 21

Characterized by s shaped nucleus and abundant basophilic granules in cytoplasm
Function: meditate allergic and inflammatory reaction through release of granules content such as histamine and heparin

Question 22

What is anaphylactic shock and how does it happen

Answer 22

It occurs due to a second exposure of same allergen resulting in an intense generalized response
Large number of basophils and mast cells degranulate and result in widespread vasodilation and sweeping reduction in blood volume and person goes in to circulatory shock
Smooth muscles of the bronchial tree constrict causing respiratory insufficiency

Question 23

Describe monocytes

Answer 23

Largest wbcs
Kidney shaped nucleus
Irregular surface with projection from cell membrane
Possess abundant lysosomes
Migrate in to CT and become macrophages
Phagocytose and destroy dead and defunct cells as well as antigens and foreign particulate matter (occurs within phagosomes)

Question 24

Functions of monocytes

Answer 24

Phagocytose unwanted material
Produce cytokines that are required for anti inflammatory and immune responses
Present epitopes to t lymphocytes thus acting as antigen presenting cells to elicit and immune response

Question 25

Describe lymphocytes

Answer 25

Rounded cells round big nucleus
B(15%)
T(80%)
Null cells(5%)

Question 26

Function of lymphocytes

Answer 26

No function in blood stream but in CT they are responsible for proper functioning of immune system
B cells mature and leave bone marrow as mature b cells
T cells migrate to thymus where they become mature and immunocompetent

Question 27

What happens when lymphocytes become immunologically competent

Answer 27

Leave respective sites of maturation and enter lymphoid system and undergo mitosis and form clones
Clones can recognize and respond to same antigen

Question 28

What do b and t cells proliferate in to

Answer 28

Memory cells and they do not participate in immune response but remain as part of the clone with an immunological memory
Effector cells and are classified as b cells and t cells

Question 29

What are myofibroblasts

Answer 29

Myofibroblasts:represent transitional modifications of fibroblasts responding to signaling molecules within a regional intercellular matrix as in areas undergoing wound healing