The Tissue Level of Organization Flashcards
epithelial membranes
composed of epithelium attached to a layer of connective tissue
Mucous membranes (mucosa)
lines internal cavities and passageways that open externally. produces mucus and has underlying connective tissue (lamina propria) ex: respiratory, digestive tracts
serous membrane (serosa)
line cavities and organs that do not open externally. produces serous fluid. ex: pleura, pericardium,peritoneum
cutaneous membrane (skin)
cabers external body surface. keratinized cells protect the body from desiccation and pathogens
connective tissue membranes
composed of connective tissues but also has a synovial membrane which lines the internal cavity of moveable joints. Produces synovial fluid
What are the properties of epithelial tissue?
cells connected by celll junctions, with little extracellular material in between they are avascular so the thickness limits nutrients, waste exchange and life span. Also capable of reproduction because of wear and tear
What are the function of epithelial tissue?
Protection from mechanical and chemical injury, and from foreign pathogens
Sensory functions to monitor changes in the environment, eg skin, nose, eye, ear
Produces secretions, eg hormones, mucus, digestive juices, sweat
Barrier to control movement of gases, solutes and fluid across it
What’s the structure of epithelial tissue?
Organized into layers
Apical (free) surface: interacts with external environment
Basement membrane: permeable material (reticular and basal laminae) linked to connective tissue
Types of epithelial tissue
Membranous epithelium (covering or lining): lines serous cavities, blood & lymphatic vessels, respiratory, digestive, and genitourinary tracts Glandular epithelium: secretory units of endocrine and exocrine glands
What are the different cell junctions? and what do they do?
1.Anchoring junctions: common on lateral and basal surfaces of cells
provide strong and flexible connections.
- Desmosomes: cadherin (adhesion protein) link adjacent cell membranes
- Hemidesmosomes integrin (adhesion protein) link cells to basal lamina
- Adherens junctions actin (contractile protein) link patches or form a “belt” inside the cell: influence shape and folding of epithelial tissue.
5.Tight junctions: no extracellular space between cells
stops substances moving between cells and from one
separates cells into apical and basal compartments.
6.Gap junctions: form intercellular passageways between membranes of adjacent cells
Allow substances to move quickly and directly between cytoplasm of adjacent cells
Allow coordination of function in large groups of cells
Types of epithelial tissue based on layers
- Simple: single layer
- Stratified: 2 or more layers
- Pseudostratified: single layer that looks stratified
- Transitional: specialized stratified epithelium with shapes that stretch and change
Types of epithelial tissue based on shape of cells at the top layer
- Squamous: flattened and thin
- Cuboidal: boxy, as wide as it is tall
- Columnar: rectangular, taller than it is wide
what are Glands?
Gland are modified epithelium cells that can synthesize and secrete chemical substances. Most glands consist of groups of epithelial cells.
What are the different Types of Glandular Epithelium? Along with their description and some examples
- Exocrine Glands
Description: secretions leave through a duct that opens to the external environment
Examples: goblet cells, sweat glands, salivary glands, mammary gland
Types of Secretions: Mucous, sweat, saliva, and breast milk - Endocrine Glands
Description: ductless gland that releases secretions directly into surrounding tissues and fluids
Examples: anterior pituitary, thymus, adrenal cortex, and gonads
Types of Secretions: Hormones
What are the different Methods and Types of Exocrine Secretion?
- Merocrine secretion (most common type)
Secretions are enclosed in vesicles and released by exocytosis at apical surface of the cell: cause little damage to cell
Examples: watery mucous, eccrine sweat glands - Apocrine secretion
Secretions, together with part of the cell membrane, are pinched off and released: cause little damage to cell
Examples: apocrine sweat glands in axillary and genital areas - Holocrine secretions
Secretions are released when cell bursts: ruptures and destroys entire gland cell
Examples: sebaceous glands that produce oils on skin and hair