Tissues Flashcards
What are tissues?
Tissues are a group of cells that are similar in structure and perform a common/related function
- a cell is the simplest living structure and contains organelles
- Histology is the study of tissues (subset of microscopic anatomy)
What are the functions of epithelial tissue?
- protection
- absorption and secretion ( as substances pass across epithelial lining)
-sensory reception (have little hairs that are connected to nerves and send signals to the brain)
What is the covering/lining type of epithelium?
Lining Epithelium
- forms outer layer of skin and internal structures
- separates different components of the body and protects
- lines a structure in a sheet formation and forms outer layer of skin and layers surrounding organs and internal structures
What is the apical surface of epithelial tissue?
apical (free) surface is the free surface exposed to the exterior environment or cavity of organ
- often have microvilli or cilla which are little hairs that help with sensory reception
- apical surface faces the outside world or interior of organ/structure
What is the basal surface of epithelial tissue?
The basal structure is the anchored lower surface
- epithelial will attach to whatever beneath them
What is the Basal lamina of epithelial tissue?
The basal lamina is the adhesive sheet beneath the basal surface; it joins epithelial tissue to connective tissue
What is the basement membrane?
the basement membrane is part of the anchoring system with the basal lamina
- The basement membrane can act as a filter as it decides what kind of things can cross over (absorption and secretion functions)
- can be able to pass all the way through into or out of the organ/structure (epithelial cells also help with this function)
Epithelial tissue facts
- tissue fit closely together to form continuous sheets
- sit upon and are supported by connective tissue (anchored to connective tissue)
- Avascular (does not get blood supply), but innervated (does get nerve supply)
- high regenerative capacity
if it is damaged, it regenerates very quickly (not all aspects of the body do this)
epithelial tissue gets oxygen and nutrients from nearby blood vessels - Cilia is often helpful in moving substances or involved in sensation (often found on epithelial tissue on apical surface)
- epithelial tissue always forms a boundary (substances that enter or leave must pass through it)
What is the simple epithelial tissue arrangement?
- single layer
- alignment of the apical surface and the basal surface in each cell
- useful for absorption and secretion because of the thin single-layer
What is the pseudostratified epithelial tissue arrangement?
- single layer
- every cell is in contact with the basement membrane
- seen in places where protection is important, but we also need substances to get through (not all)
- easier for substances to pass through
- commonly seen in the respiratory system
What is the stratified epithelial tissue arrangement?
- multiple cell layer
- not all the cells are in contact with the basement membrane
- better for protection because it’s difficult for things to penetrate (more layers=more protection)
- can have a combination of 2 cell shapes
What is the squamous cell shape in epithelial tissue?
flat looking cell
What is the cubical cell shape in epithelial tissue?
cube looking cells
What is the columnar cell shape in epithelial tissue?
long, skinny, tall cells
Simple Squamous Epithelium
- thinnest epithelial tissue
- located in areas where absorption/secretion is important (blood vessels, air sacs in lungs)
- areas where we are going to have things passing in or out (tiny molecules)
Stratified squamous epithelium
- Very thick
- found in areas where protection is important
- Apical layer of cells no longer have nuclear (died-> look dull)
- has more cuboidal cells closer to the basement membrane
- example of having 2 cell shapes in a epithelial tissue)
What is glandular epithelium?
- they have glands which consist of one or more cells-> there are some glands that are singular epithelial cells
- they make or secrete a particular substance (e.g., saliva, enzymes, hormones, etc.)
What are endocrine glands?
- substance is secreted into the bloodstream (usually hormones)
- can go anywhere in the body because blood travels everywhere and can be accepted to any place (non-specific destination)
- epithelial cells will make hormones and they will collect in the center, when they are ready to go, they will then diffuse through epithelial cells into blood vessels
- endocrine gland is close to hormone-producing cells
- The thyroid gland produces a number of hormones important for metabolism, most of the cells in the body will have receptors for these hormones
What are exocrine glands?
- substance travels through a duct (tube) to the destination
- controlled, putting it in one place
- there can be more than 1 layer of epithelial cells
-central collecting is in the middle is lumen (an open area of some kind of tube or structure) - common exocrine gland is the salivary gland
- there are 6 of them, located in the mouth or near the mouth and produce saliva
- set similarly (duct from the lumen into mouth)
What is connective tissue?
- it supports body structures
- all types of connective tissue come from the same type of cell when developing (mesenchyme cells- original cell type that turns into all connective structure)
Functions of connective tissue
- binding and supporting-> epithelial tissue almost always connects to connective tissue
- protecting
- insulating -> adding warmth
- storing reserve fuel (eg, bones strong calcium in marrow)
- Transporting substances-> blood=transportation
What are the components of connective tissue structure?
- made of 3 main things= ground substance, fibers (3 types), and cells
- ground substance: is a fluid (watery or gel), is background material, and helps bind all other structures
- elastic fibers: fibers made of protein that are stretchable and elastic
- Reticular fibers: made of collagen and glycoproteins, have middle toughness
- collagen fibers: collagen proteins that are extremely tough
- fibers add structural integrity to connective tissue
- when ground substance and fibers are together you get non-living component of connective tissue (extra-cellular matrix)
- rest of connective tissue is made up of cells (living)-> spread out within fibers and ground substance
What is connective tissue proper?
- connective tissue proper can contain a mix of the 3 types of fibers
- these can have small pink areas where it can contain water and salts (need reservoir in case we lose some -dehydration)
- 6 types (differ in density and fiber type, have different functions)
- found in adipose (fat), under (supporting) epithelia, and ligaments (connects bones)
Functions of connective tissue proper
- binding: eg, epithelial tissue is bound to connective tissue beneath it
- resist tension/mechanical stress: seen in ligaments (reduce tension and mechanical stress, and made of connective tissue proper and they connect 1 bone to another)
- fat storage
- provides reservoir for water and salts
Functions of cartilage connective tissue
- resists compression (high level of water in matrix in ground substance, makes it squishy, seen in joints)
- cushions and supports body structures
3 types of cartilage connective tissue
- hyaline: most common in human body (seen in joints)
- Elastic: more elastic, seen in nose and ears
- Fibrocartilage: very tough- has more mobility than hyaline, in some joints, seen in joints of pelvis to allow baby to pass through in females
Functions of connective tissue bone
- very hard, resists compression and tension
- when muscle contracts, bone pulls and has tension, bone is built to resist it
-support
-bone forms connective basis of entire body - collagen fibers and calcium give bone its strength
2 types of bone connective tissue
- compact
- spongy: more space, find marrow in spaces (storage component)
Functions of connective tissue blood
- fluid tissue: important in function of transport
- carries Oxygen, Carbon Dioxide, nutrients, wastes, and other substance (hormones)
- is connective tissue because it comes from those mesenchyme cells (original cells)
What is muscle tissue?
- has high cell concentration ( lots of cells and all packed close together)
- highly vascularized (gets a very high amount of blood supply because muscle is working all the time)
- responsible for most body movements
3 Types of muscle tissue
- cardiac muscle cell: only found in walls of heart
- skeletal muscle cell: conscious muscle of body (can control)
- smooth muscle cells: located within organs and blood vessels, involuntary (cannot control)
What is nervous tissue?
main component of nervous system : brain, spinal cord, nerves
- brain sends signals down spine
- brain brings information out to body cells
- brings information back to brain and spinal cord
2 cell types of nervous tissue
- neurons: electrical signaling cells
- supporting cells: helping cells that dont pass electrical signals
