Lecture 2 (FIRST MIDTERM) Flashcards
There are ____ different cell types but __ tissue types.
200, 4
Types of tissue AND description of each:
- Epithelial: covers/lines exposed surfaces and forms glands
- Connective: fills internal spaces, provides structural support, transports material, and stores energy
- Muscle tissue: specialized for contraction (skeletal muscle, cardiac muscle, and smooth muscle)
- Neural tissue: carries information via electrical impulses
Epithelial “type” tissues are usually derived from what?
Mesenchymal “type” tissues are usually derived from what?
Epithelial: ectoderm and endoderm
Mesenchymal: mesoderm
Features/characteristics of epithelia:
Cellularity: cells stuck together tightly
Polarity: one side is different from the other
Attachment: basal lamina attaches them to connective tissue
Avascularity: no blood vessels
Regeneration: cells can be replaced (either rapidly or constantly)
Functions of epithelia:
Protection: from abrasion, dehydration, destruction by chemical agents
Control permeability: keep fluids in or out
Sensation: sensitive to stimulation because richly innervated; neuroepithelium performs a particular sensory function
Secretion: from specialized gland cells; glandular epithelium produces secretions
What are cilia for?
Microvilli?
Cilia: on surfaces where moving substances takes place
Microvilli: on surfaces where absorption and secretion take place
Tight junctions:
Gap junctions:
Tight junctions: prevent the passage of water
Gap junctions: rapid/direct communication between cells (also in cardiac muscle cells)
In glandular epithelia, the secretions are packaged at the bottom and released at the top. What packages secretions?
Golgi apparatus
Tight junctions come from structures known as __________
desmosomes
A desmosome is formed by…
two cells
Two types of desmosomes and functions:
- Spot desmosome: small discs that tie adjacent cells together
- Hemidesmosome: half a spot desmosome; attach a cell to extracellular structures (like the protein fibers in the basement membrane)
The continual division of _______ cells is the only way the epithelium can maintain its structure over time.
Where are these cells found?
And what are they also known as?
Stem cells
Located near the basement membrane (a relatively protected location)
Also called germinative cells
Main shapes of epithelia:
Squamous
Cuboidal
Columnar
Squamous cells’ shape is…
thin, flat, and close together
Two basic categories of epithelia:
Simple
Stratified
Layers in…
Simple epithelium
Stratified epithelium
Simple: one
Stratified: two or more
Simple squamous epithelium
Functions and basic locations:
Functions: reduces friction, controls vessel permeability, absorption and secretion
Locations: alveoli of lungs, pericardial and peritoneal cavities, lining of heart and blood vessels, pleura
Stratified squamous epithelium
Functions and basic locations:
Functions: protection against abrasion, pathogens, chemicals
Locations: surface of skin; lining of mouth, throat, anus, rectum, and vagina
The simple squamous epithelium that lines the body cavities enclosing the lungs, heart, and abdominal organs is called a…
mesothelium
Simple columnar epithelium
Functions and basic locations:
Functions: protection, secretion, absorption
Locations: lining of intestine, stomach, gall bladder, uterine (Fallopian) tube
Pseudostratified columnar epithelium
Functions and basic locations:
Functions: protection, secretion, move mucus with cilia
Locations: lining of trachea, nasal cavity
How do we know pseudostratified epithelium is not really layered?
Each cell is attached to the basement membrane
Transitional epithelium
Functions and basic locations:
Functions: stretching and recoiling
Basic locations: bladder, ureters, renal pelvis
Two basic types of glandular epithelia and description:
Endocrine glands: release into intestinal fluid
Exocrine glands: release into ducts that open onto epithelial surface
Modes of secretion and description:
- Merocrine: product is released by exocytosis (like sweat, mucus)
- Apocrine: loss of the apical portion along with the product
- Holocrine: destruction of the whole gland cell when product is released
3 basic types of connective tissue:
Proper connective tissue
Fluid connective tissue
Supporting connective tissue
Connective tissue cells have what kind of tissue pattern? Meaning what?
Mesenchymal; more disorganized and more space in between each cell
Proper connective tissue makeup:
Cells + extracellular fibers in a fluid medium called ground substance
Divisions of proper connective tissue:
Loose and dense
Types of cells that may exist in proper connective tissue AND description:
- Fibroblasts: secrete hyaluronan (makes the ground substance viscous - thicker)
- Macrophages: clean up debris and other cells; release chemicals to stimulate immune system
- Adipocytes: fat cells; single lipid gets bigger or smaller
- Mast cells: house histamine (swelling) and heparin (anticoagulant - blood thinner) for inflammatory response
- Lymphocytes: immune cells; specific against certain material
What does hyaluronan do?
Makes ground substance thicker and helps “lock” epithelial cells together
Why can connective tissue have blood vessels?
The cells are far apart
Extracellular fibers in connective tissue:
Collagen fibers
Reticular fibers
Elastic fibers
What are collagen fibers composed of and where are they found?
composed of the protein collagen
tendons and ligaments
Reticular fibers
structure:
location:
Structure: interwoven “network”
Location: parenchyma of organs (such as the liver)
What are elastic fibers composed of?
the protein elastin
Types of loose connective tissues:
Description:
Location:
Areolar tissue: very elastic; between skin and deeper muscle tissue
Adipose tissue: fat - stores energy and cushions; everywhere, but particularly surrounding organs and in joints
Reticular tissue: support tissues in the liver, kidneys, spleen, lymph nodes
Dense regular connective tissue location and structure:
Found in tendons and ligaments
Fibers are parallel with each others
Dense irregular connective tissue location and structure:
Found in skin, perichondrium (surrounding cartilage), periosteum (surrounding bones)
Reticular structure; no pattern but strong all around
What is elastic tissue composed of and where is it located?
Mainly elastic fibers
Found in elastic ligaments (help stabilize the positions of the vertebrae along spinous processes, not body of vertebrae)
Types of cartilages, their locations, and functions.
Hyaline: covers the end of bones (articular) for smooth articulation, supports trachea and larynx
Elastic: gets deformed then goes back to normal shape; in ears, nose, epiglottis
Fibrocartilage: prevents bone-to-bone contact (cushioning); intervertebral discs and in knees
Exception! Cartilage is usually mesenchymal, but the trachea and larynx cartilage comes from…
Ectoderm
Bone is vascular or avascular?
vascular; blood vessels in the middle
The periosteum of a bone is made of what kind of tissue?
Dense irregular connective tissue
Osteocytes communicate with blood vessels and with one another by….
canaliculi
Differences between cartilage and bone
- Fluid (ground substance)
- Vascularity
- Covering
- Strength
- Oxygen demands
- Nutrient delivery
- Repair
- Cartilage has fluid; bone has very little
- Cartilage is avascular; bone is vascular
- Perichondrium (2 layers); periosteum (2 layers)
- Bends, hard to break; no distortion until break
- Cartilage = low; bone = high
- Diffusion through matrix; diffusion through cytoplasm & interstitial fluid in canaliculi
- Cartilage = limited; Bone = easier
Muscle types:
Skeletal
Smooth
Cardiac
Skeletal muscle components:
- Striated
- Voluntary
- long & thin multinucleated cells that make up muscle fibers
- cells contain proteins actin and myosin
Cardiac muscle components:
- Striated
- Involuntary
- cells are short and branched with single nucleus
- connected by gap junctions created by intercalated discs
Smooth muscle components:
- Not striated
- Involuntary
- cells are short and “football” shaped and have one nucleus
- under autonomic nervous system control (not controlled)
2 basic cells of neural tissue:
Neurons (focus our time on these) Glial cells (supporting cells)
