Quiz 4 TISSUES Flashcards
TISSUE
- homogenous group of cells with a similar structure and function which work together as a unit
- differ greatly in size, shape, composition and nature ranging from fluid blood to compact bone
- this vast difference is the sum of two variables: CELL TYPE & EXTRACELLULAR FLUID (ECM)
Extracellular Fluid
- fluid rich in proteins that serve to connect and aid communication with neighboring cells
- produced by the very cells it surrounds, and together with any endogenous matter it comprises the interstitial space
- in essence, the inside and outside of a cell determines the tissue type
Cell Differentiation
- we start as one cell
- two cells each carrying half the genetic code for a human being unite into one (fertilization)
- DNA merges, copies are made, and the one cells begins to divide
- eventually, we are 75+ trillion cells forming our unique anatomic and physiological self
Potency
- we start out totipotent
- within a few days of fertilization CELL DIFFERENTIATION begins and our cells are now pluripotent
- as cell division continues, differentiation continues and we are born with cells that are multipoint and fully differentiated cells
Totipotent
Pluripotent
Multipotent
Fully Differentiated
Totipotent: the first cell has the potential to express any and all of our genes (Zygote)
FIRST DIFFERENTIATION (Blastocyst and Trophoblast)
Pluripotent (Fetus, embryonic)
Multipotent: some potential to still differentiate into many cell types (Infant, adult)
Fully Differentiated: no potential for producing anything but an exact replica of itself (can not be a stem cell)
4 basic tissue types
Epithelial
Connective
Nervous
Muscular
Epithelial Tissue: Unifying Concepts
- Avascular: does not have blood supply to actual tissue itself, blood to surrounding tissue
- Innervated: has a nerve supply
- Labile: changeable (e.g. callous on foot)
- Includes linings, coverings, barriers, and glands
- Forms sheets (prevents stuff from leaking out, eases diffusion)
Asymmetry (upside/downside; inside/out)- Luminal Surface: not in contact with other cells and may be smooth, villous, or ciliated
- Basal Surface: anchored to underlying cells via a basement membrane
- Named by their architectural design
- squamous, cuboidal, columnar, transitional
- simple, stratified, pseudostratified
Epithelial Tissue: Functions
vary among the different types of epithelial tissue, and include: protection, absorption, excretion, secretion
Epithelial Tissue: Glands
- specialized secretion forming epithelial cells
Anatomy: Unicellular (mucus: goblet cells)
Multicellular (sweat, milk, enzymes, bile, waste)
Type: Endocrine: secrete into circulation (hormones)
Exocrine: secrete into a hollow structure for eventual excretion (Serious: watery, protein rich; Mucous: thick, carb rich; Sebaceous: oily, lipid rich)
Mechanism:
Merocrine, Apocrine, Holocrine
Merocrine, Apocrine, and Holocrine (mechanism of glands)
Merocrine: no cellular damage with secretion
Apocrine: part of cell membrane and some cytoplasm pinched off with secretion
Holocrine: total cell death with secretion
Apoptosis & Necrosis
Apoptosis: programmed cell death (DNA)
Necrosis: caused by factors external to the cell or tissue such as toxins, infection, physical trauma, lack of nutrients, etc.
Connective Tissue: Unifying Concepts
- vascular, innervated, labile, everywhere
- includes cells and a protein matrix secreted by the cells (vast ECM)
- includes all of our support/connecting structures
Connective Tissue: Function
vary among the different CT types, and include:
storage, support, protection, transport
Connective Tissue: Types
CT Proper:
- Loose CT: areolar, adipose
- Dense CT (dense regular: tendons, ligaments; dense irregular: capsules and membranes surrounding various organs)
Specialized CT:
- blood, bone, cartilage, lymph, elastic CT
Nervous Tissue: Unifying Concepts
- permanent, excitable
- dependent on ion gradients, specifically Na, K, Ca
- includes brain, spinal chord, and nerves
