L15: Tissues of the Human Body Flashcards
What are the four types of tissue found in the body?
- Epithelial
- Connective
- Muscle
- Nervous
True or false: Tissues are made up of cells with a similar embryological origin
True
True or false: Tissues are made up of different types of cells with varying functions
False. Tissues are made up of similar cells that are specialised for a particular function
Fill in the gap:
Tissues are made up of cells and, often, ______.
Matrix
This is non-living material produced by cells
What type of molecule forms the matrix?
Glycosaminoglycans (GAGs). Usually sulphated GAGs.
Because the matrix is formed by GAGs, what does it say about the compressibility of tissue matrix?
It will have a low compressibility
What is “histology”?
The study of tissues
If the primary role of a tissue is to protect something else, what type of tissue could it be?
Epithelial or connective.
Muscle and nervous tissue don’t generally serve to provide protection.
If the primary role of a tissue is to serve as a lining of some sort, what type of tissue could it be?
Epithelial
If the primary role of a tissue is locomotion, which type of tissue could it be?
Muscle
If the primary role of a tissue is the movement of food, what type of tissue could it be?
Muscle
If the primary role of a tissue is filtration or secretion, what type of tissue could it be?
Epithelial
If the primary role of a tissue is support and binding, what type of tissue could it be?
Connective tissue
If the primary role of a tissue is to transmit impulses to achieve communication, coordination and control, what type of tissue could it be?
Nervous
If the primary role of a tissue is energy storage, what type of tissue could it be?
Connective
What type of tissue are bone, ligaments, and tendons?
Connective
Which type of tissue responds to stimuli?
Nervous tissue
There are 5 subtypes of epithelial tissue. What are they?
- Squamous
- Cuboidal
- Columnar
- Ciliated
- Glandular
There are 3 subtypes of muscular tissue. What are they?
- Striated
- Nonstriated
- Cardiac
There are 5 subtypes of connective tissue. What are they?
- Areolar
- Dense regular (tendons & ligaments)
- Adipose
- Skeletal (cartilage & bone)
- Fluid (blood & lymph)
True or false: Nervous tissue is not classified into subtypes
True
True or false: Epithelial cells are always arranged in multiple strata
False.
Epithelial cells are closely packed in single continuous sheets or in multiple layers
How are cells attached to each other?
Junctions between them
Define ‘apical surface’
The epithelial tissue’s surface which is exposed. This could be in a body cavity, lining an organ, or exposed to the exterior (skin)
True or false: You might find microvilli or cilia on the apical surface
True
What is the difference between microvilli and cilia?
Microvilli increase the surface area of the cell; cilia are microtubules that aid the transportation of substances across the surface of the cell
Define ‘basal surface’
The surface of epithelial tissue that is attached to a basement membrane.
This basement membrane is secreted by the cells and adheres the epithelial tissue to nearby connective tissue.
Describe the blood flow to epithelial tissue
Epithelial cells are avascular, so there is no blood flow.
If they are avascular, how does epithelial tissue get a supply of nutrients, and dispose of waste?
They rely on diffusion from the capillaries in connective tissue
True or false: Epithelia do not have a nerve supply
False. Usually there is a nerve supply to epithelial tissues
How do epithelia usually regenerate?
Mitosis replaces cells lost to wear and tear
What is an endothelium?
The epithelium exposed on the inside of a structure (e.g lining of blood vessel)
What is a mesothelium?
the epithelium that lines the pleurae, peritoneum, and pericardium
True or false: There are epithelial cells with a sensory function
True. For example, nasal cells can detect chemical stimuli and retinal epithelial cells can detect light
What are the 5 functions of simple epithelium?
- Diffusion
- Osmosis
- Filtration
- Secretion
- Absorption
Describe simple epithelium
Single layer of epithelial cells, each cell reaching the apical and basal surface
Describe stratified epithelium
Multiple layers of cells
What is the main function of stratified epithelium?
Protect deeper layers from wear and tear
What is pseudostratified epithelium?
A single layer of cells which appears to have multiple layers. Not all cells reach the surface.
Some pseudostratified epithelia are __1__ or secrete __2__ (aka __3__ cells)
- ciliated
- mucus
- goblet
What term is used to describe epithelia which are flat, with oval nuclei?
Squamous
Why are squamous cells thin?
To promote diffusion
What term is used to describe epithelia which are cube-like, with central nuclei?
Cuboidal
What are the functions of cuboidal cells?
Can produce secretions and participate in absorption
What term is used to describe epithelia which are column-shaped, with variable nuclei?
Columnar
What are the functions of columnar cells?
Protect underlying tissue and can be involved in secretion and absorption
What term is used to describe epithelia which can change shape to accommodate distension, expansion, or movement of body parts?
Transitional
E.g. In the bladder. When empty the cells are cuboidal; when the bladder is full, the cells are squamous.
What are the rules for naming epithelium?
- Firstly, name the type of layering (simple, stratified, or pseudostratified)
- Then by cell shape (squamous, cuboidal, columnar, transitional)
- If it has multiple layers of different type, name it after the top layer
What type of epithelia line the nasal cavity?
Pseudostratified ciliated columnar
What type of epithelia line the oesophagus?
Stratified squamous
What type of epithelia line the lung alveoli?
Simple squamous
What type of epithelia line the intestines?
Simple columnar
What type of epithelia line the kidney tubules?
Simple cuboidal
Which epithelium:
- is adapted for absorption and secretion?
- can possess a brush border of microvilli
- can contain goblet cells which produce mucus
- lines the digestive tract, gall bladder, and large ducts of glands
Non-ciliated simple columnar epithelium
Give three places in the body where you could find ciliated simple columnar epithelium
- Uterus
- Bronchi
- Paranasal sinuses
Fill in the gaps:
Ciliated simple columnar cells possess apical ___1___ formed from ___2___ and aid in movement of substances across epithelial surface.
(1) cilia
(2) microtubules
What would you call a single layer of column-shaped cells that appears multi-layered?
Pseudostratified columnar epithelia
Are pseudostratified columnar epithelia ciliated or non-ciliated?
Can be either ciliated or non-ciliated
Where can you find non-ciliated pseudostratified columnar epithelia?
Found in parts of the male urethra
Could you find goblet cells on non-ciliated pseudostratified columnar epithelia?
No
In stratified epithelia with multiple cell types, how do determine the name of tissue?
It would be named after the top-most layer
What is the primary function of stratified squamous epithelia?
Protects against abrasion
What cell types can you expect to find in stratified squamous epithelia?
Top layer is squamous, lower layers are cuboidal and columnar
In stratified squamous epithelia, how are the top cells replaced?
Top layers slough off; base layers are mitotic and replicate to replace lost cells
Fill in the gaps:
Stratified squamous epithelia can be non-___1___ or ___2___ by the protein ___3___
(1) keratinised
(2) keratinised
(3) keratin
Fill in the gaps:
Non-keratinised stratified squamous epithelia remains __1__ and lines the __2__, __3__ and __4__.
(1) moist
(2) mouth
(3) vagina
(4) anus
Where is keratin produced?
Keratinocytes - basal cuboidal/columnar cells found in the stratified squamous epithelia of the skin
Describe the journey of a cell travelling from the basal layer to the top to replace a sloughed off cell.
Mitotic basal cells divide and the daughter travels up through the layers of cuboidal and columnar cells. As this happens, the traveling cells fill with keratin (keratinisation), become squamous and anucleate, and eventually die (apoptosis) as they reach the top layer
What is desquamation?
The keratinised cells are sloughed off
Why do we need keratinised cells?
To form a waterproof barrier that protects against abrasion and pathogenic organisms
Describe the appearance of the cells on the top layer of skin
No nucleus, no shape
What are the 3 (or 4) zones of the epidermis?
- Superficial zone
- Intermediate zone
- Basal zone
(4. Basement membrane)
The top layer of stratified cuboidal epithelia is made up of what cell type?
Cuboidal
True or false: Stratified cuboidal epithelia is mainly protective
True
Where would you find stratified cuboidal epithelia?
Larger salivary glands, parts of the male urethra
True or false: The main function of stratified columnar epithelia is secretion
False. The main function is protection, but it is sometimes also involved in secretion
Where would you find stratified columnar epithelia?
Salivary glands and parts of the male urethra
What are transitional epithelia?
Variable cells that can accommodate stretching without rupture
What functions do transitional epithelia have? What junction types support this? Where are they found?
Function: Hold fluids, prevent leaking, resist diffusion
Junction: Tight cell junctions
Location: Urinary bladder, ureters, and parts of the urethra
What is a gland?
A single or a group of epithelial cells adapted for secretion
There are two major types of glands. What are they called?
1) Exocrine glands
2) Endocrine glands
Which type of gland secretes materials directly into the ducts or onto the apical epithelial surface?
Exocrine glands - composed of glandular epithelia and secrete mucus, sweat, oil, earwax, and digestive enzymes
Which type of gland secretes materials through the basal surface, which diffuses through the basement membrane, connective tissue and into the bloodstream?
Endocrine glands - produce hormones
What structural classifications can be applied to exocrine glands?
1) Unicellular
2) Multicellular
True or false: Unicellular glands usually have ducts
False. Unicellular glands never have ducts
True or false: Goblet cells secrete mucus and are examples of unicellular glands
True
True or false: Most glands are multicellular
True
Multicellular glands usually involve ducts. What are shape classifications that can be applied to duct systems?
1) Tubular
2) Alveolar
Each can either be simple (meaning the duct portion is unbranched) or compound (meaning the duct portion branches)
True or false: Simple tubular ducts can be sub-classified again as being simple, coiled, or branched
True
Which duct system looks like a maple leaf?
Compound tubular
Which duct system looks like an experimental flask?
Simple alveolar
What are the three functional classifications of exocrine glands?
1) Holocrine
2) Apocrine
3) Merocrine (eccrine)
How does a holocrine gland secrete?
The cell accumulates the substance to be secreted and then disintegrates, releasing the substance
How does a merocrine gland secrete?
Merocrine glands secrete by exocytosis and the cells remain undamaged
How does an apocrine gland secrete?
Small pieces of cell containing secretion break off and the cell repairs itself
Give an example of a holocrine gland and its secretion
Sebaceous glands secreting oil
Give an example of a merocrine (eccrine) gland and its secretion
Sweat glands secreting sweat
Give an example of an apocrine gland and its secretion
Mammary gland secreting milk lipid droplets
What is the main difference between exocrine and endocrine glands?
Endocrine are always ductless; exocrine usually have ducts
True or false: Endocrine glands usually act close to the target of the secretion
False. They are often at a distance and rely on the blood stream to carry their hormone to the right part of the body
True or false: Exocrine ducts work via basal secretion
False. Endocrine ducts work via basal secretion
True or false: Endocrine secretion diffuses into bloodstream?
True
Which tissue type is responsible for protection, lining, secretion, filtration, and absorption?
Epithelial
Which tissue type is responsible for protection, support and binding, energy storage, transport, and immunity?
Connective
What is the most abundant tissue in the body?
Connective
True or false: Similar developmental origin are responsible for groupings within connective tissues
True
What is the difference between epithelial tissue and connective tissues with regards to the cell-to-matrix ratio?
Connective tissue has fewer cells and more matrix
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