Connective and Adipose Tissue

Question 1

What is endocytosis?

Answer 1

The transport of solid matter or liquid into a bell by means of a coated vacuole or vesicle.

Question 2

What is phagocytosis?

Answer 2

The engulfment and digestion of bacteria and other foreign particles by a cell.

Question 3

What is exocytosis?

Answer 3

The transport of material out of a cell by means of a vesicle that first engulfs the material and then is extruded through an opening in the cell membrane.

Question 4

What is connective tissue?

Answer 4

The tissue that supports, binds or separates more specialized tissues and organs or functions as a packing tissue of the body.

Also has a role in metabolic support.

Question 5

What are the characteristics of connective tissue?

Answer 5

Cells are scattered throughout an extracellular matrix of fibrous proteins and glycoproteins attached to a basement membrane.

• Extracellular matrix
  
  • fibres in a protein and polysaccharide matrix
    
    • glycoproteins, fibrous proteins and GAGs
  • secreted and organised by cells in the ECM
  • main component is water

Question 6

What are the four basic tissue types?

Answer 6

• Epithelial
• Connective
• Muscular
• Nervous

Question 7

How is connective tissue classified?

Answer 7

• Connective tissue proper
  
  • loose irregular connective tissue (e.g. lymph)
  • dense irregular connective tissue (e.g. dermis)
• Specialised connective tissue
  
  • dense regular connective tissue (e.g. tendons and ligaments)
  • cartilage
  • adipose tissue
  • haemopoietic tissue
  • blood
  • bone

Question 8

When is the ECM the predominant feature in connective tissue?

Answer 8

In tissue with a mechanical function - ligament, tendon and bone.

Question 9

When are cells the predominant feature in connective tissue?

Answer 9

When tissue is specialised for protection (WBC in haemopoiesis) or metabolic maintenance (adipose and RBC).

Question 10

How are red blood cells stored?

Answer 10

Packed red cells can be stored at 6ºC for 42 days or frozen for 10 years.

Question 11

How can cells be separated from tissues?

Answer 11

Collagenase breaks down collagen in tissues releasing cells.

Question 12

How are cells held together in tissue?

Answer 12

• Attachment to each other (lateral domain)
• Attachment to the basement membrane (basal domain)
• Attachment to the ECM (integrins)

Question 13

What are integrins?

Answer 13

Transmembrane proteins that function mechanically and biochemically.

Functions:

• cell to ECM attachment
• signal transduction from ECM to cell
• immune patrolling
• cell migration

Question 14

How do cells attach to each other?

Answer 14

• Tight junctions
  
  • found between epithelial cells
  • forms a selective and sealed barrier
• Desmosomes
  
  • strengthens the bond between cells
  • resistant against stretching and twisting
• Gap junctions
  
  • connections for channels for small ions to pass through
  • communication

Question 15

What is the basement membrane?

Answer 15

Structural site for overlying cells and underlying connective tissue. Cells attach to the basement membrane by hemidesmosomes and focal adhesions.

Question 16

What are hemidesmosomes?

Answer 16

Attachment proteins. Found in tissues that are subject to abrasion such as skin and epithelium of oral cavity. Made of integrin and plaque.

Question 17

What are focal adhesions?

Answer 17

Attachment protein for basement membrane. Anchor intracellular actin filaments to the basement membrane. Play a prominent role in cell movement and migration of epithelial cells in wound repair.

Question 18

How are cells cultured?

Answer 18

• Cells are separated from tissues using collagenase or microdissection
• Cultured in petri dishes or flasks
• Requires:
  
  • nutrients
  • pH control
  • temperature
  • oxygen
  • preventing bacterial contamination

Question 19

Why are cell cultures useful in research?

Answer 19

• cells behave and look different to when they are in tissues
  
  • contact inhibition - regulatory mechanisms where cells grow in one layer thick
• senescence (limited life span)

Question 20

What is direct contact communication?

Answer 20

Contact between cells through gap junctions (connexon). Ions and small molecules pass through.

Question 21

What is autocrine communication?

Answer 21

A cell secretes a chemical to act on itself and stimulate a response.

Question 22

What is paracrine signalling?

Answer 22

A cell secretes a chemical to act on a nearby cell to affect their function.

Question 23

What is endocrine communication?

Answer 23

A hormone is secreted directly into the blood to travel to a distant site and bind to a target cell.

Question 24

What is synaptic communication?

Answer 24

The electrical signal travels along the nerve cell to trigger the release of neurotransmitter at the end of the synapse. The electrical signal is converted into a chemical signal. The target cell is stimulated.

Either acetylcholine or adrenaline

Question 25

What is neurocrine communication?

Answer 25

Neurone releases a chemical into the bloodstream to act on a target cell with specific receptors. Examples: hypothalamus, posterior pituitary, adrenal medulla.

Question 26

What is necrosis?

Answer 26

The death of some or all of the cells in an organ or tissue caused by disease, physical or chemical injury or interference with the blood supply.

Question 27

What is apoptosis?

Answer 27

Programmed cell death which results in the ordered removal of cells and occurs naturally as part of the normal development, maintenance and renewal of cells, tissues and organs.

Question 28

What is mitosis?

Answer 28

A type of cell division in which a single cell produces two genetically identical daughter cells.

Question 29

Which cell renewal in the body is static?

Answer 29

* CNS * Cardiac * Skeletal muscle cells

Question 30

Which type of cell renewal in the body is stable?

Answer 30

* Fibroblasts * Endothelium * Smooth muscle cells

Question 31

Which cells in the body renew?

Answer 31

* blood * skin epithelium * gut epithelium Cancer is most likely to occur in cells that have a high cell turnover.

Question 32

How are cells powered?

Answer 32

Proton pump in the mitochondria

Question 33

What is a prokaryote?

Answer 33

Unicellular organism with no nucleus and no mitochondria. Example: bacteria

Question 34

What is a eukaryote?

Answer 34

Organisms that have a nucleus enclosed in a membrane.

Question 35

What is an epithelium?

Answer 35

A tissue composed of cells that covers the exterior body surface and lines internal closed cavities and body tubes that communicate with the exterior. Epithelium also forms the secretory portion of glands and lines their ducts. In addition, specialised epithelium functions as receptors for the special senses (smell, taste, hearing and vision)

Question 36

What is epithelioid?

Answer 36

Epithelial cells that _do not_ have a free apical surface. Examples; * **Leydig cells** in the testis, **Lutein cells** of the ovary * **Islets of Langerhans** in the pancreas * The **parenchyma of the adrenal gland**

Question 37

How can the apical domain be specialised?

Answer 37

* Microvilli * **cytoplasmic processes** that extend from the cell surface. Examples are the intestine and kidney tubules. * Stereovilli * particularly **long microvilli** limited to the epididymis and sensory hair cells of the ear. * Cilia * **motile cytoplasmic processes** that can beat in synchrony with a rapid forward movement called the *effective* stroke and a slower return *recovery* stroke. Examples: tracheobronchial tree and the oviducts. Contain **actin filaments.**

Question 38

What is the latin origin of tissue?

Answer 38

To weave/ woven - cells are woven together

Question 39

What are the four basic types of tissue?

Answer 39

* Nerve * Muscles * Epithelial * Connective (*connective tissue proper*)

Question 40

What are the six specialised connect tissue?

Answer 40

* Adipose * Lymphatic * Blood * Haematopoetic * Cartilage * Bone

Question 41

What are the functions of connective tissue?

Answer 41

* Connects * cells to form tissues * some tissues can provide support as well as s (cartilage and bone) * Transportation * medium for diffusion of nutrients and wastes * Protection * provides a cushion between tissues and organ * insulation (adipose) * Storage * (adipose) * Defence * against infection (blood, lymph, wandering cells) * Wound healing * macrophages, fibroblasts, myofibroblasts