Connective and Adipose Tissue Flashcards
What is endocytosis?
The transport of solid matter or liquid into a bell by means of a coated vacuole or vesicle.
What is phagocytosis?
The engulfment and digestion of bacteria and other foreign particles by a cell.
What is exocytosis?
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.
What is connective tissue?
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.
What are the characteristics of connective tissue?
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
- fibres in a protein and polysaccharide matrix
What are the four basic tissue types?
- Epithelial
- Connective
- Muscular
- Nervous
How is connective tissue classified?
-
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
When is the ECM the predominant feature in connective tissue?
In tissue with a mechanical function - ligament, tendon and bone.
When are cells the predominant feature in connective tissue?
When tissue is specialised for protection (WBC in haemopoiesis) or metabolic maintenance (adipose and RBC).
How are red blood cells stored?
Packed red cells can be stored at 6ºC for 42 days or frozen for 10 years.
How can cells be separated from tissues?
Collagenase breaks down collagen in tissues releasing cells.
How are cells held together in tissue?
- Attachment to each other (lateral domain)
- Attachment to the basement membrane (basal domain)
- Attachment to the ECM (integrins)
What are integrins?
Transmembrane proteins that function mechanically and biochemically.
Functions:
- cell to ECM attachment
- signal transduction from ECM to cell
- immune patrolling
- cell migration
How do cells attach to each other?
-
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
What is the basement membrane?
Structural site for overlying cells and underlying connective tissue. Cells attach to the basement membrane by hemidesmosomes and focal adhesions.
What are hemidesmosomes?
Attachment proteins. Found in tissues that are subject to abrasion such as skin and epithelium of oral cavity. Made of integrin and plaque.
What are focal adhesions?
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.
How are cells cultured?
- Cells are separated from tissues using collagenase or microdissection
- Cultured in petri dishes or flasks
- Requires:
- nutrients
- pH control
- temperature
- oxygen
- preventing bacterial contamination
Why are cell cultures useful in research?
- 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)
What is direct contact communication?
Contact between cells through gap junctions (connexon). Ions and small molecules pass through.
What is autocrine communication?
A cell secretes a chemical to act on itself and stimulate a response.
What is paracrine signalling?
A cell secretes a chemical to act on a nearby cell to affect their function.
What is endocrine communication?
A hormone is secreted directly into the blood to travel to a distant site and bind to a target cell.
What is synaptic communication?
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
What is neurocrine communication?
Neurone releases a chemical into the bloodstream to act on a target cell with specific receptors.
Examples: hypothalamus, posterior pituitary, adrenal medulla.
What is necrosis?
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.
What is apoptosis?
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.
What is mitosis?
A type of cell division in which a single cell produces two genetically identical daughter cells.
Which cell renewal in the body is static?
- CNS
- Cardiac
- Skeletal muscle cells
Which type of cell renewal in the body is stable?
- Fibroblasts
- Endothelium
- Smooth muscle cells
Which cells in the body renew?
- blood
- skin epithelium
- gut epithelium
Cancer is most likely to occur in cells that have a high cell turnover.
How are cells powered?
Proton pump in the mitochondria
What is a prokaryote?
Unicellular organism with no nucleus and no mitochondria. Example: bacteria
What is a eukaryote?
Organisms that have a nucleus enclosed in a membrane.
What is an epithelium?
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)
What is epithelioid?
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
How can the apical domain be specialised?
- 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.
What is the latin origin of tissue?
To weave/ woven - cells are woven together
What are the four basic types of tissue?
- Nerve
- Muscles
- Epithelial
- Connective (connective tissue proper)
What are the six specialised connect tissue?
- Adipose
- Lymphatic
- Blood
- Haematopoetic
- Cartilage
- Bone
What are the functions of connective tissue?
- 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
