Chapter 2- Tissue types Flashcards
What is the definition of a tissue, organs, and an organ system?
Tissue- cells with similar structures and functions grouped together.
Organs- tissues that are grouped together to perform a function
Organ system- a group of organs grouped together to perform a function and to form a whole multicellular organism.
What are the four main types of tissue and what is their brief function in one word?
1- Nervous tissue- Controls
2- Muscle tissue- Moves
3- Connective tissue- supports
4- Epithelial tissue- covers
The nervous tissue is the main component of?
The nervous system
What two components is the nervous tissue made up of?
1- Nerve cells- AKA neurons
2- Support cells- more commonly known as gila
What is gila?
A family of cells that support, protect, and insulate the delicate neurons.
What do neurons do?
Generate and transmit electrical impulses.
Muscle tissues are composed of what?
Myocytes (muscle cells)
What are myocytes?
Cells that contract to produce force and motion
What are the three types of muscle tissue?
1- Skeletal muscle
2- Smooth muscle
3- Cardiac muscle
Give a brief overview of the skeletal muscle
1- Attaches to the skeleton
2- Stripy in appearance
3- Capable of generating lots of force
Give a brief overview of the smooth muscle
1- Lines hollow organs, e.g, stomach
2- Non stripy
3- Capable of sustained activity, e.g, continuously pushing food through digestive system.
Give a brief overview of the cardiac muscle
1- Within the heart
2- Stripy with branched fibres
3- It is myogenic
Whats the definition of myogenic?
Activation arising locally from within the muscle tissue.
What are some of the things that the muscle is responsible for?
1- Movement
2- Posture
3- Generating heat (by shivering)
4- Regulating sight and hearing
What is connective tissue?
Supports, protects, and binds other tissues together.
What is connective tissue made up of?
1- The ground substance
2- Fibres
3- Cells
What is the extracellular matrix?
The thing that makes connective tissue extremely tough and durable.
What makes up the extracellular matrix?
The ground substance and fibres
What is the ground substance?
Unstructured material that fills the space between the cells and contains the fibres.
What is the ground substance made up of?
1- Interstitial fluid- containing dissolved nutrients
2- Cell adhesion proteins- that binds connective tissue cells to the extracellular matrix
3- Proteoglycans and glycoproteins- traps water
What example is composed largely of a ground substance?
The vitreous humour
What are fibres?
Proteins that provide support
What are the three types of fibres?
1- Collagen fibres
2- Reticular fibres
3- Elastic fibres
Give an overview of Collagen fibres
- Thickest of the connective tissue fibres
- Strongest and most abundant
Give an overview of reticular fibres
- Thicker than elastic but thinner than collagen fibres.
- Often form a network that cradles other tissues
Give an overview of elastic fibres
1- Composed of elastin.
2- Thinner than collagen
3- Stretches readily and return to their original form after a force is removed.
4- Ideal for supporting moving structures, e.g, skin, lungs
What are the cells inside the connective tissue called?
Fibroblasts
What are fibroblasts?
They secrete the fibres and the ground substance.
There are other less, numerous cells. What are they and whats their function?
1- Plasma cells- produces antibodies
2- Macrophages- responsible for phagocytosis- eating other cells
3- Mast cells- detects foreign organisms and initiates local inflammatory responses against them
What are the types of connective tissue?
1- Specialist connective tissue- cartilage, blood, bone, etc
2- Connective tissue proper
Connective tissue is separated into two types. What are the two types?
Loose connective tissue proper- fibres loosely arranged
Dense- fibres densely arranged.
Loose connective tissue can be subdivided into what?
areolar and adipose
Dense connective tissue can be sub divided into what?
Regular and irregular
Give an overview of loose areolar connective tissue proper
1- Is the packaging material of the body
2- Soft and flexible
3- Most widely distributed form of connective tissue
What is the function of the loose areolar connective tissue proper?
It traps fluid, e.g, bruising is an example of fluid being trapped.
What is an areola?
Small open space
Give an overview of loose adipose connective tissue proper
1- Similar to areolar in structure, but its nutrient storing ability is much greater.
2- It is largely made up of fat cells (adipocytes)
What do adipocytes look like and why do they look like that?
They appear as white spaces as all organelles have been pushed to the side and the whole cell lis occupied by a fat droplet.
What is the function of loose adipose connective tissue proper?
1- Acts as a shock absorber
2- Acts as insulation
3- Acts as an energy storage site.
Give an overview of the structure of dense regular connective tissue proper
1- Highly fibrous
2- Contains closely packed bundles of collagen fibres, all running in the same direction.
What does the structure of dense regular connective tissue proper enable?
Allows enormous, tensile strength- resistance to pulling in a single direction.
What is dense regular connective tissue proper useful for?
Ideal for tendons- attaching muscle to bone
Ideal for ligaments- attaching bone to bone
Give an overview of the structure of the dense irregular connective tissue proper
1- The same basic elements as dense regular, but the bundles of collagen fibres are much thicker and run in all directions.
What does the structure of the dense irregular connective tissue proper enable?
The structure allows strength in all directions
Where is the dense irregular connective tissue proper useful for?
Useful in skin, and for surrounding certain internal organs, e.g, kidney
What is an epithelial tissue?
A sheet of cells that covers a body surface. They form boundaries between different environments.
Epithelia come in two main forms:
1- Covering epithelia- lines the surfaces of the outer body and internal organs.
2- Glandular epithelia- forms the various glands of the body
What is the function of covering epithelia?
1- Protection
2- Absorption
What is the structure of epithelial cells?
1- Usually polyhedral in shape
2- Has strong attachments between adjacent cells.
What are the characteristics of epithelial tissue?
Most epithelial tissue is highly regenerative- able to recover from damage
They are highly innervated- has sensory and motor nerve fibres
They are avascular- have no blood vessels
Where do all epithelial sheets rest?
On a basement membrane that helps it resist stretching and tearing.
What is the basal surface?
The side of the epithelium that rests on the basement membrane
What is the apical surface?
The other free side of the epithelium
Most apical surfaces are covered with what?
Microvilli or cilla- hairs that are important for movement and sensation, e.g, hearing
How is covering epithelia classified?
1- Based on the shape of the cells
2- The number of layers
What are the three primary types of shape for covering epithelia?
1- Squamous
2- Cuboidal
3- Columnar
What are the two types of layers for covering epithelia?
1- Simple layer- one layer
2- Stratified layer- multiple layers
What is simple epithelia useful for?
When an exchange of substances is required
What is stratified epithelia useful for?
Protection
Always found in areas subject to abrasion, e.g, skin, cornea
Stratified epithelia are usually what in humans?
Squamous
Altogether, there are 8 types of epithelia. Give some examples
Simple squamous, Simple cuboidal, simple columnar, etc.
The other two types of epithelia are what?
1- Pseudo stratified- simple columnar epithelia that look stratified
2- Transitional- cells that are round in shape when the organ is relaxed, but flatten when there is pressure e.g, the bladder
What forms the various glands of the body?
Glandular epithelial cells
What is a gland?
A group of cells that make and secrete a particular product
What is the gland involved in?
The production and release of many different secretory products, such as sweat, saliva, and hormones.
What are the types of glandular secretion?
1- Serous- a watery substance often containing proteins, e.g, saliva
2- Mucous- a thick, sticky substance
3- Sebaceous- an oily substance, e.g, in the armpit
Glands are classified as either…
1- Exocrine glands- secrete their products onto the epithelial surface
2- Endocrine glands- secrete hormones into the interstitial fluid, where they go on to enter the blood.
Give an overview of endocrine glands
Structurally diverse and most are multicellular.
Generally ductless
Their secretions are varied
In multicellular exocrine glands, where do secretions travel?
Up to the surface via a series of connecting cells that form a duct.
What is a unicellular exocrine gland?
When a single cell produces and secretes
What is the most common example of a unicellular exocrine gland?
Mucus secreting goblet cell.
Where are goblet cells found?
In the epithelium of the trachea and digestive tube (to protect/ lubricate)
What is a multicellular exocrine gland?
Consists of groups of secretory cells connected to a free surface by ducts.
If there is only a single duct in a multicellular exocrine gland, what is it called?
Simple
If there are multiple ducts in a multicellular exocrine gland, it is called?
Compound
Multicellular exocrine glands can be classified based on:
1- Shape of their secretory units
2- Mode of secretion
What are the different shapes of secretory units?
1- Tubular- if secretory units form tubes.
2- Alveolar- if secretory units form small hollow cavities.
3- Can also be a bit of both- tubuloalveolar
What are the different modes of secretion for multicellular exocrine glands?
1- Merocrine- if the product is released via exocytosis
2- Holocrine- if whole cell ruptures to release product.
3- Apocrine- tip of cell is shed and cell repairs the damage.
