Tissue Lecture 2 Flashcards
Exocrine Glands
Definition, Examples
Definition: Glands that release secretions into ducts or onto the surface of epithelium.
Examples: Sweat glands, sebaceous glands, lacrimal glands, pancreatic acinar cells.
Endocrine Glands
Definition, Examples
Definition: Glands that release secretions directly into the bloodstream.
Examples: Testes, ovaries, pancreas, pituitary gland.
Merocrine Glands
Definition, Examples
Definition: Exocrine glands where secretions are released via vesicles through exocytosis.
Examples: Pancreatic cells, salivary glands.
Apocrine Glands
Definition, Examples
Definition: Exocrine glands where secretions accumulate on apical surfaces and are released by pinching off a portion of the cell.
Examples: Apocrine sweat glands, mammary glands, ceruminous glands.
Holocrine Glands
Definition, Example
Definition: Exocrine glands where secretions accumulate in the cytosol and the entire cell dies, acting as a secretory vesicle.
Example: Sebaceous glands.
General CT Terms
Blasts, Chondroblasts, Osteoblasts, Fibroblast, Cytes
Blasts: immature cells that can replicate
Chondroblasts: cells that result in cartilage
Osteoblasts: cells that result in bone
Fibroblast: cells that produce ECM
Cytes: mature cells (chondrocytes, osteocytes, fibrocytes, etc.)
Structure of Connective Tissue
- Specialized cells
- Extracellular Matrix (ECM)
Two components of ECM:
Extracellular protein fibers
Fluid called ground substance
Extracellular Matrix (ECM)
- Matrix = Substance surrounding cells including solutes that ‘fill’ space
Made up of:
Ground substance
Fibers (collagen, elastin, reticular)
ECM - Ground Substance
- Fills space between cells and fibers
- Serves as support and binding for cells
Consists mainly of: - Water (H2O)
- Polysaccharides (GAGs)
- Proteins
ECM - GAGs
Glycosaminoglycans
- Long, linear polysaccharides with repeating units
- Contains amino groups
ECM - Fibers (3 types)
- Provide strength, structure, and movement to tissue
Three types found in ECM:
Collagen
Elastic
Reticular
ECM - Collagen Fibers
- Made up of collagen protein
- Provides majority of strength and stability to cartilage, tendons, and ligaments (appears white)
ECM - Elastic Fibers
- Made up of elastin and fibrillin protein
- Allows elasticity of fibers (up to 150% of original length)
ECM - Reticular Fibers
- Made up of collagen but thinner and more widespread forming a network
- Aids in support and strength
ECM - Reticular Fibers (Stroma)
- Forms stroma (“bed or covering”) of some organs
- Supportive framework of organs, especially solid organs
- Examples: spleen, kidney, liver
Types of Connective Tissue Cells
Fibroblast
- Most numerous connective tissue cell
- Creates and releases fibers
- Produces ground substance
Types of Connective Tissue Cells
Macrophage
- Involved in inflammatory & immune responses
- Phagocytizes pathogens (like Pac-Man)
Types of Connective Tissue Cells
Plasma Cell
- Develops from B-lymphocytes
- Involved in immune responses
- Produces antibodies
Types of Connective Tissue Cells
Mast Cell
- Involved in inflammatory response
- Produces histamine, which causes vasodilation in blood vessels but constriction of bronchioles in the lungs
Types of Connective Tissue Cells
Adipocyte
‘Fat cells’ that store lipid compounds
Types of Connective Tissue Cells
White Blood Cells (Leukocytes)
Involved in allergic, inflammatory, & immune responses
Embryonic CT
Mesenchyme, Mucous
Mesenchyme:
Tissue where all connective tissue arises.
Has stem cell capabilities.
Mucous:
Tissue in the umbilicus, precursor stem cells.
Connective Tissue Proper - Loose CT
Connective Tissue Proper - Loose CT
Areolar, Adipose, Reticular
Areolar CT: Most common type, provides strength and support.
Adipose Tissue: Mainly adipocytes, stores fat, temperature regulation.
Reticular CT: Reticular fibers, structural support in internal organs.
Dense Regular CT
Description, Function, Location
Description: Collagen fibers in a regular pattern, tightly packed and parallel.
Function: Provides strong linear strength.
Location: Found in tendons and ligaments.
Dense Irregular CT
Description, Function, Location
Description: Collagen fibers in an irregular pattern, disorganized.
Function: Provides strength to tissues, resistance to shearing in all directions.
Location: Found in the dermis, heart valves, sheaths, periosteum (skin for bones).
Elastic CT
Description, Function, Location
Description: Dominated by elastic fibers, yellow appearance.
Function: Allows for stretch and elasticity.
Location: Found in large blood vessels, lungs.
Cartilage
Description, Function, Major Types (3)
Description: Consists of a dense network of collagen & elastin embedded in chondroitin sulphate, firm gel.
Function:Endures high stress without losing shape, only one cell type (chondrocytes), avascular.
Major Types:
Hyaline Cartilage: Most abundant, found in ribs, sternum, articulations, nasal septum, and respiratory passageways.
Fibrocartilage:Strongest, resists compression, found in joints (meniscus), pubic symphysis, and intervertebral discs.
Elastic Cartilage: Mostly elastin, stretchable, found in ears and epiglottis.
Bone
Description, Function
Description:Makes up the skeletal system, bone cells, red and yellow bone marrow, minerals.
Function: Structural support, protection, somewhat flexible, resistant to shattering.
Fluid Connective Tissue
Description, Types (2)
Description: Aqueous matrix with suspended proteins, contains no insoluble fibers.
Types:
Blood: Found in vessels, plasma matrix, RBCs, WBCs, platelets.
Lymph: Collected from interstitial fluid, lymphocytes, returns to blood, maintains solute levels, alerts immune system.
