Tissues Flashcards
What are tissues?
-A group of cells working together
What are the 4 types of tissues?
- Epithelial tissue
- Muscle tissue
- Nervous tissue
- Cardiac tissue
Epithelial tissue
-Covers and lines surfaces
Characteristics of Epithelial Tissue
- Highly cellular
- Polar (apical/basal surface)
- Basement membrane
- Avascular
- Regenerative
- Specialized contacts
What is simple squamous epithelium?
- a single layer of flat cells
- Filtration and diffusion
Where is simple squamous epithelium located?
- Alveolar air sacs of lungs
- Kidney glomerulus
Two special types of simple squamous epithelium
- Endothelium
- Mesothelium
Endothelium
-Lines circulatory system (blood vessels and heart) and lymphatic vessels
Mesothelium
-Lines serous membranes
Simple cuboidal epithelium
-Secretion and absorption
Simple cuboidal epithelium locations
- Kidney tubules
- Glands
Simple columnar epithelium
-Secretion and absorption
Location of simple columnar epithelium
- Digestive tract (stomach, intestines)
- Glands
- Uterine tubes
Pseudostratified columnar epithelium
- Single layer of cells, nuclei at various heights
- Secretion
Pseudostratified columnar epithelium location
- Trachea
- Glands
- Sperm carrying ducts
Stratified squamous epithelium
- Protection
- Found in areas exposed to a lot of friction
- Upper layer replaced by rapidly dividing cells in basal layer
Stratified squamous epithelium location
- Skin
- Mouth
- Esophagus
- Vagina
Stratified Cuboidal epithelium
- Rare
- Found in some sweat and mammary glands
- Typically two cell layers thick
Stratified columnar epithelium
- Rare
- Some parts of pharynx, male urethra and lining some glandular ducts
- Only apical layer columnar
Transitional epithelium location
- Bladder
- Ureters
- Urethra
Glands
-One or more cells that secrete a product (proteins, hormones, steroids)
Endocrine glands
- Ductless
- Secrete products into extracellular space by exocytosis
- Products are hormones
Examples of endocrine glands
- Pituitary gland
- Thyroid gland
- Adrenal gland
Exocrine glands
- Have ducts
- Secrete products onto body surfaces (skin) or into body cavities
Examples of exocrine secretions
-Mucus, sweat, oil, saliva, bile, digestive enzymes (pancreas)
Unicellular exocrine glands
- Single cell
- Ductless
- Ex: goblet cell
Where are unicellular exocrine glands found
- Intestines
- Trachea
Merocrine glands
- Most common
- Contents released by exocytosis
Examples of merocrine glands
- Sweat glands
- Goblet cells
Holocrine glands
- Contents released by rupturing
- Cells are killed in the secretion process
Examples of holocrine glands
-Oil gland
Functions of connective cells
- Connects tissues
- Supports other tissues
- Energy storage
- Transport
Characteristics of Connective Tissue
-Degrees of vascularity
Lots of extracellular matrix
Degrees of vascularity
- Avascular- Cartilage
- Highly vascular-adipose
Lots of extracellular matrix
- True for cartilage, bone, tendons, ligaments, areolar tissue, blood, reticular
- Not true for adipose tissue
Extracellular matrix
- Collagen
- Elastin
- Reticular fibers
- Ground substance
Collagen
- Tough thick fibers
- Able to withstand tension
Elastin
-Thin fibers, stretch and recoil
Reticular fibers
- Very fine collagen fibers
- Form a branched network to support tissue
Ground substance
-Interstitial fluid, proteoglycans, proteins and polysaccharides
Proteoglycans
- Giant protein/carbohydrate complexes
- Very negatively charged-attracts water and ions into extracellular space
Functions of proteoglycans
- Keep tissues hydrated
- Help lubricate fibers
- Helps withstand compression
Cell types
- Fibroblast
- Chondroblast
- Osteoblast
- Hematopoetic stem cell (hematocytoblast)
Fibroblast
-Makes collagen fibers
Chondroblast
-Makes cartilage
Osteoblast
-Makes bone
Hematopoetic stem cell
-Makes blood cells, not ECM
Blood borne cells
- White blood cells
- Macrophages
- Mast cells
White blood cells
-Help with tissue response to injury or infection
Macrophages
-Eat foreign particles by phagocytosis
Mast cells
-Release substances (histamine) from granules
Histamine
-Makes capillaries leaky
Areolar connective tissue components
ECM -Loosely packed fibers (all kinds) -Lots of ground substance Cells -Fibroblasts -Blood borne cells
Areolar connective tissue characteristics
- Vascular
- Found under layers of epithelium
Areolar connective tissue functions
- Wraps and cushions tissues
- Defense against infection
Adipose connective tissue characteristics
- Sparse ECM
- Highly cellular
- Highly vascular
Adipose connective tissue locations
- Subcutaneous
- Around organs
- Behind eyeballs
- Breast
- Abdomen
Adipose connective tissue functions
- Shock absorber
- Insulator
- Energy storage
Reticular connective tissue components
- Only reticular ECM fibers
- Many white blood cells
Reticular connective tissue location
- Spleen
- Lymph nodes
- Bone marrow
Reticular connective tissue function
-Provides a supportive framework for blood cells
Dense regular connective tissue characteristics
- Mostly parallel collagen fiber bundles (resists tension)
- Fibroblasts
- Avascular
Dense regular connective tissue locations
- Tendons
- Ligaments
- Aponeuroses
Tendons
-muscle to bone
Ligaments
-bone to bone
Aponeuroses
-muscle to muscle
Function of dense regular connective tissue
- connects bones and muscles
- resists tension
Dense irregular connective tissue components
- Irregularly arranged collagen fiber bundles (can withstand tension)
- Fibroblasts
