Tissue types Flashcards
lots of diff types
Classification of Epithelia
Epithelial tissue (epithelium) is a sheet that covers a body surface or lines a body cavity
* Covering and lining epithelium forms the outer layer of skin, lines open cavities, and covers walls and organs of the ventral body cavity. ○ (i.e. skin, lining of urogenital, digestive, and respiratory systems) * Glandular epithelium forms glands of the body. ○ Salivary glands
Main functions: protection, absorption, filtration, excretion, secretion, and sensory reception.
Simple squamous epithelium
Single layer of flattened cells
Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances
○ Functions where rapid diffusion is priority like your air sacs, heart, and kidneys
* Simple epithelia - involved in absorption, secretion or filtration processes
Simple cuboidal epithelium
- Single layer of cells (cube-like)
- Function: secretion and absorption
Involved in secretion and absorption
○ Small glands involved in secretion, like kidney tubules.
Forms walls of smallest ducts of glands and many kidney tubules
Simple columnar epithelium
Single layer of tall, closely packed cells
Some cells have microvilli, and some have cilia (ciliated move mucus)
Some layers contain mucus-secreting goblet cells
Involved in absorption and secretion of mucus, enzymes and other substances
Pseudostratified Columnar Epithelium
- Pseudo means false
○ It’s single layer, but looks like it isn’t. Appears multi-layered. The shape gives it more structural integrity. For areas that would experience stresses or damage the epithelia like your trachea. Organized this way so it’s less vulnerable for things like tearing.
Involved in secretion (esp mucus) and also in movement of mucus via ciliary sweeping action.
Upper respiratory tract
Stratified squamous
Surface cells are flattened
Regenerative
Skin looks like this.
Transitional
- Forms lining of hollow urinary organs
○ Found in bladder, ureters, and urethra.
○ Depends on amount of pressure. Can change shape
Exocrine glands
- Secretions are released onto body surfaces, such as skin or into body cavities
- They secrete products into ducts
○ Like mucous, sweat, etc. - Can be:
○ Unicellular
- They secrete products into ducts
Has all cellular functions. Packed full of secretory vesicles. Containing the protein that’s responsible of this, coming to the surface. To release content to the general area above. Secreted by exocytosis.
When sick, immune system secretes more products to flush out the system
Epithelial can be anything in your body, not just skin
What basic structure do all cellular membranes share?
Phospholipids, proteins, and carbs
Phospholipid tails can be saturated
or unsaturated (Chapter 2). This is true of phospholipids in plasma membranes as well. Which type—saturated or unsaturated—would make the membrane more fluid? Why?
- Unsaturated phospholipid tails make the membrane more fluid. This is because unsaturated tails contain one or more double bonds, which create kinks in the fatty acid chains. These kinks prevent the tails from packing tightly together, increasing the space between them.
- In contrast, saturated tails have no double bonds and can pack more closely, making the membrane more rigid. So, in terms of membrane fluidity, unsaturated phospholipids enhance flexibility and allow for better movement within the membrane structure.
Compare the structure and function of tight junctions, desmosomes, and gap junctions
- Tight junctions
○ Impermeable
○ Forms continuous seals around the cell
○ Prevent molecules from passing between cells
○ Two different compartments- Desmosomes
○ Anchoring junctions
○ Binds adjacent cells together like Velcro
○ Keeps cells from tearing apart - Gap junctions
○ Communicating junctions, cells are very close, and connected by hollow cylinders.
○ Allows ions and small molecules to pass from cell to cell
Particularly important in heart cells and embryonic cells
- Desmosomes
Four basic tissue types
Nervous tissue (brain, spinal cord, nerves)
Muscle tissue (skeletal, cardiac, smooth)
epithelial tissue (lining of organs, glands, skin surface)
Connective tissues (bones, bones)
Special characteristics of epithelial tissues
polarity
specialised contacts
supported by connective tissue
avascular but innervated
regeneration
Classification of epithelia (into two different classifications)
covering and lining epithelium (forms outer layer of skin, cavities) like skin, digestive
glandular epithelium forms glands of the body (like salivary)
Main functions of epithelia cells
protection, absorption, filtration, excretion, and sensory reception
You would expect to find what fibres in an areas that undergo a lot of stretch and rebound
collagen fibres
Single squamous epithelium (describe, function, list examples and two types)
single layer of flattened cells with disc shaped
allows materials to pass by diffusion, filtration in sites where protection is not important. also secretes substances.
where rapid diffusion is priority like air sacs, heart and kidneys
Two special simple squamous epithelia
endothelium (lining of lymphatic
vessels, blood vessels, and
heart)
mesothelium (serous
membranes in ventral body
cavity)
Simple cuboidal epithelium (describe, function, list examples and two types)
single layer of cells (cubelike)
function - secretion and absorption. Small glands involved in secretion like kidney tubules
forms the wall of these ducts, like in kidney tubules and ovary surface
Simple columnar epithelium (describe, function, list examples)
single layer of tall, closely packed cells
some cells have microvilli, some have cilia
some layers contain mucus secreting goblet cells
function in absorption, secretion of mucus, enzymes and other substances
found in digestive tract, gallbladder, bronchi and uterine tubes
pseudostratified columnar epithelium
single layer. but looks like it isn’t.
The shape gives it more structural integrity. For areas that would experience stresses or damage the epithelia like your trachea. Organized this way so it’s less vulnerable for things like tearing.
involved in secretion (esp mucus), and in movement of mucus via ciliary sweeping action
found in trachea, upper respiratory tract
stratified squamous epithelium
type of tissue made up of multiple layers cells. main role is to protect underlying structures in areas of the body that has a lot of friction
stratified = multiple layers
basal layer constantly regenerates new cells that replace older ones
surface is flattened, regenerative.
Cuboid cells flatten out. The deeper cuboidal cells become flattened as they migrate towards the surface. This helps create the layered structure that provides strength and protection.
* Because of its structure, stratified squamous epithelium is ideal for protection. It’s found in places where the body experiences high wear and tear, such as: ○ The epidermis of the skin. ○ The lining of the mouth, esophagus, and vagina.
Transitional epithelium
resembles both stratified squamous and cuboidal. Depends on organ stretch
designed to stretch and change shape in response to diff levels of pressure
found in bladder (expands and contracts) and lining of hollow urinary organs
Glandular epithelial tissue (describe, 2 sites, and diff number of cells)
made up of cells that specialize in secretion. produce and release substances like enzymes, mucus or hormones
Gland - one or more cells that make and secrete an aqueous fluid
sites
endocrine - ductless gland that releases hormones directly into bloodstream or surrounding tissue fluid. important for functions like growth, metabolism and reproduction
exocrine - secrete products onto body surfaces or body cavities (sweat glands)
number of cells forming gland
unicellular - composed of single cell capable of secretion like goblet cells
multicellular - composed of many cells that form a complex structure, like multicellular glands
multicellular exocrine glands
composed of many cells. connective tissue surrounds and supports these glands
classified by mode of secretion
merocrine - by exocytosis
holocrine - accumulate products
until rupture
apocrine - accumulates products
but only apex ruptures
modes of secretion in human exocrine glands
exocytosis - most common, where cells produce secretory products within vesicles
cells get destroyed in holocrine glands. entire cell fills up with product that needs to be secreted, then disintengrates to release it’s content.
Two characteristics make connective tissue different from other primary tissue
The extracellular matrix ECM. surrounds and supports living cells suspended within it. made of fibres (like collagen, elastic). Connective tissues are mostly composed of this matrix
functions of this matrix, supports cells and gives connective tissue strength. allows connective tissue to bear weight and withstand any stresss
- Has a ground substance. a gel like material that fills up spaces between cells and fibres
mesenchyme
type of embryonic tissue that all connective tissues arise from.
during embryonic development, mesenchymal cells differentiate into the different types of connective tissue found in the body, like bone, cartilage, fat or blood.
this common origin helps explain why different connective tissues have similarities in function and structure
All connective tissues have three main components
ground substance
(gel like substance, includes interstitial fluid and solutes)
fibres
cells
Areolar connective tissue
most widely distributed. supports and binds other tissues
connective tissue fibres
provide support. includes:
collagen fibres - strongest and most abundant.
elastic fibres - networks of long, thin, elastin fibres for stretching and recoil
reticular fibre - short, fine highly branched collagenous fibres
connective tissue cells
blast - immature
cyte - mature form
fibroblasts - contributes to the formation of connective tissue
chondroblasts - cells that play an important role in the formation of cartilage
osteoblasts - cells that form new bones and grow and heal existing bones
adipocytes - provide energy storage, insulation from extreme temperatures and cushioning around soft organs
leukocytes - ) A type of blood cell that is made in the bone marrow and found in the blood and lymph tissue (helps fight infections)
mast cells - detects foreign microorganisms
macrophages - breaks down foreign materials and dead cells
adipose lct
functions - provides reserve food fuel and important source of energy
location - under skin in subcutaneous tissue.
white fat - greater nutrient storage
brown fat - uses lipids to heat bloodstream
reticular lct
functions: fibres form a soft internal skeleton that supports other cell types (like white blood cells, mast cells, etc)
common in lymph nodes and in immune system
dense regular dct
present in parts of body where there’s wear and tear like your joints
location - tendons, most ligaments
takes a lot of time to recover
dense irregular dct
irregular arranged around collagen fibres
functions - withstands tension exerted in many different directions
locations - fibrous capsules of organs and joints, dermis and like shoulder joint
same as regular but collagen way thicker and irregularly arranged
elastic dct
made entirely of elastic
functions - allows tissues to recoil after stretching
location: walls of large intestine. aorta
resilient tissue, very hard to be compromised
fibrocartilage - connective tissue
matrix similar but firmer than hyaline cartilage. thick collagen fibres.
function - tensile strength allows it to absorb compressive shock
location - intervertebral discs. pubic synthesis.
Bone - connective tissue
hard calcified matrix that has many collagen fibres.
function - supports and protects, provides levers for muscles to act on. stores calcium and other minerals. marrow inside bone is for blood cell formation
has more collagen compared to cartilage
