Basic Tissues Flashcards
1
Q
What is the body organised into?
A
- Cells - fundamental structural and functional unit of the body
- Tissues - A collection of cells that perform a particular function
- Organs - multiple tissues that perform a particular function by working together
- System - group of organs with a collective function
- Organism - whole individual
2
Q
What are the basic tissues?
A
- epithelia
- connective tissue
- muscle
- nervous
3
Q
What’s the location of the epithelia?
A
- Covers surfaces
- Lines cavities and tubes
- forms glands
4
Q
What are some important characteristics of epithelia?
A
- attached to a membrane
- Provide physical protection
- Control Permeability
- Provide sensation (have a large sensory nerve supply)
- Produce specialized secretions (gland cells)
- Avascularity (no blood vessels in the cells)
- Regenerate
- Polarity (apical - faces lumen/surface and basal - attached to basement membrane)
5
Q
How can you classify epithelia?
A
Based on number of cell layers and the shape of the cells
6
Q
In epithelia what are the number of cell layers called?
A
Simple: one layer
Stratified: two or more layers
7
Q
What are the different shapes of epithelial cells you can get?
A
- squamous (flat)
- Cuboidal (cube)
- Columnar (rectangle)
You can see this in the nucleus of the cell
8
Q
What are the main types of epithelial cells?
A
- simple squamous
- keratinised stratified squamous
- Non-Keratinised stratified squamous
- Simple cuboidal
- Simple columnar
- Pseudostratified columnar with goblet cells
9
Q
Give features of Simple Squamous epithelia
A
- Flat cells - oval shaped nuclei
- One layer of cells
- Main function: exchange of nutrients and gases
- Smooth edge
- Location: blood vessels, lining the heart, alveoli
10
Q
Give features of Keratinised Stratified Squamous epithelia
A
- Flat surface cells with oval shaped nuclei
- Many layers
- Keratin
- Major function: protection, barrier (waterproof because of Keratin)
- Location: skin and some areas of oral cavity (gums and hard palette)
- usually located where mechanical stresses are severe
11
Q
Give features of Non-Keratinised Stratified Squamous epithelia
A
- Flat surfaces with oval shaped nuclei
- Many layers
- Major function - protection, barrier
- Location - oral cavity, oesophagus
- resists abrasion but will dry out and deteriorate unless kept moist
12
Q
Give features of Simple Cuboidal Epithelium
A
- Square cells with round nuclei
- One layer
- Major function: secretion and absorption
- Location: glands, kidney tubules
13
Q
Give features of Simple Columnar Epithelium
A
- Tall cells with oval, basally located nuclei
- One layer
- Major function: absorption and secretion
- Location: gastrointestinal tract
- Surface modifications: microvilli
14
Q
Give features of Pseudostratified Ciliated Columnar Epithelium with Goblet cells
A
- Tall cells: column
- Appears stratified as some cells don’t reach free surface (lumen/apical membrane)
- All cells touch basement membrane
- Modification with cilia and goblet cells
- Functions: mucociliary escalator
- Location: trachea and large respiratory airways
15
Q
What are intracellular junctions?
A
Specialised areas of cell membrane that bind to one another. Found in epithelial cells
16
Q
What are examples of intracellular junctions?
A
- Desmosomes
- Hemidesmosomes
- Tight Junctions
- Gap Junctions
17
Q
Give features of Desmosomes
A
- Very strong connections between adjacent cells
- Resist stretching and twisting
- made of proteoglycans
18
Q
Give features of Hemidesmosomes
A
- Attach cells to the basement membrane
- Stabilise the position and anchor cell to underlying tissue
19
Q
Give features of Tight junctions
A
- Interlocking proteins bind tightly together near apical edge
- Prevent passage of water and solutes between cells (e.g. in digestive tract)
20
Q
Give features of Gap Junctions
A
- Cells held together by interlocking membrane proteins containing a central pore called connexons
- Allows movement of small molecules and ions between cells: found in cardiac muscle
21
Q
What are the functions of connective tissue?
A
- forms a structural framework for the body
- Supports, surrounds and interconnects other tissue types
- Protects delicate organs
- Transports fluids and dissolved minerals
- Stores energy reserves
- Defends body from microorganisms
22
Q
What do all types of connective tissue consist of?
A
Cells within an extracellular matrix
23
Q
What type of cells can be found in connective tissue?
A
- Fibroblasts; the main type that synthesises the extracellular matrix
- Other cell types; adipocytes, macrophages and mast cells
24
Q
What does the extracellular matrix in connective tissue consist of?
A
- Ground substance
- Tissue (extracellular fluid)
- Fibres; collagen, reticular and elastic
25
How can you classify Connective tissue?
```
Specialised Connective tissue:
- Blood (fluid matrix)
- Bone (solid matrix)
- Cartilage (mixture of both)
Connective tissue proper (packaging between organs)
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26
How is Connective Tissue proper classified?
According to type, arrangement and abundance of fibres, cells and ground substance
27
What are the three main types of Connective Tissue proper?
- Loose areolar
- Dense irregular
- Dense regular
28
Give features of Areolar Connective Tissue
- Lots of ground substance
- Forms a layer that separates the skin from deeper structures
- Few fibres (collagen and elastic)
- Variety of cells: Fibroblasts, Adipocytes and Macrophages
- Found under the epithelium that lines the body surfaces
29
Give features of Dense Irregular Connective Tissue
- Little ground substance
- Many collagen fibre bundles arranged haphazardly
- Few cells (mainly fibroblasts)
- Resists excessive stretching and distention
- Found in the dermis of the skin
30
Give features of Dense Regular Connective Tissue
- Little ground substance
- Many densely packed bundles of collagen fibres arranged in parallel rows
- Few cells (mainly fibroblasts)
- Found in tendons and ligaments
31
What does muscle tissue do?
Produces movement and is specialised for contraction
32
What are the three types of muscle tissue?
- Skeletal
- Smooth
- Cardiac
33
What are the similarities between the different muscle types?
- Elongated parallel to axis of contraction
- Numerous mitochondria
- Contractile elements
34
Give features of Skeletal Muscle
- Moves and stabilises the skeleton
- Forms Sphincter (when arranged in a circular manner and can constrict and block, e.g. the anus) in digestive and urinary tracts
- Involved in respiration
- Long cylindrical cells
- Striated (striped) because of arrangement of contractile filaments
- Multinucleated (lots of nuclei located at the peripheral of the cell)
- Innervated by the somatic nervous system
35
Give features of Smooth Muscle
- Located in the walls or organs, blood vessels and airways
- Gastrointestinal movement
- Alters diameter of airways and blood vessels
- Short, fusiform (spindle shaped) cells (narrower on the ends and wider in the middle)
- Non-striated
- Single, centrally located nucleus
- innervated by autonomic nervous system
36
Give features of the Cardiac muscle
- found in the heart wall
- helps to circulate blood and maintains blood pressure
- branched muscle fibres
- striated
- 1-2 central nuclei
- intercalated discs - join the cells with gap junctions
- innervated by the autonomic nervous system
37
What is neuroepithelium?
an epithelium that is specialized to perform a particular sensory function
38
What are epithelial cells specialised for?
- The movement of fluid over its surface providing protection and lubrication
- The movement of fluids across the epithelium to control permeability
- The production of secretions that provide physical protection or act as chemical messengers
39
What is the basement membrane composed of?
A basal lamina and a reticular lamina
40
What is the basal lamina?
It is the layer of the basement membrane closer to the epithelium. It is an amorphous ill organized layer, thought to act as a selective filter. It is secreted by the adjacent layer of epithelial cells. The basal lamina restricts the movement of proteins and other large molecules from the underlying connective tissue into the epithelium
41
What is the reticular lamina?
The deeper portion of the basement membrane that gives it it's strength. Attachments between the fibres of the basal lamina and those of the reticular lamina hold the two layers together and hemidesmosomes attach the epithelial clls to the composite basement membrane
42
What is a mesothelium?
The simple squamous epithelium that lines body cavities enclosing the lungs, heart and abdominal organs
43
What is an endothelium?
The simple squamous layer lining the inner surface of the heart and all the blood vessels
44
Where are stratified cuboidal epithelia found?
They are relatively rare and are located along the ducts of sweat glands and in the larger ducts of the mammary glands
45
Wat is a transitional epithelium?
An unusual stratified epithelium. It's cells can change between squamous and cuboidal in shape so can tolerate repeated cycles of stretching without damage. Found in the urinary bladder
46
Where are stratified columnar epithelia found?
They are relatively rare, providing protection along portions of the pharynx, epiglottis, anus and urethra as well as along a few large excretory ducts
47
What do endocrine glands do?
Release secretions directly into the blood. E.g. the thyroid gland
48
What do exocrine glands do?
Release their secretions directly onto an epithelial surface or into passageways called ducts that open onto an epithelial surface. E.g. enzymes entering the digestive tract
49
What is another way connective tissues can be classified?
- connective tissue proper
- fluid connective tissues
- supporting connective tissues
50
What are fluid connective tissues?
They have a distinctive population of cells suspended in a watery matrix that contains dissolved proteins. The two types are blood and lymph
51
What are supporting connective tissues?
They protect soft tissues. They have a much less diverse cell population that connective tissue proper and contain a matrix with very densely packed fibres. The two types are cartilage and bone
52
What are the features of Fibroblasts?
- The only cells always present in connective tissue proper
- Secrete hyaluronan and proteins
- Secretes protein subunits that assemble to form extracellular fibres
53
What is Hyaluronan?
One of the ingredients which helps to lock epithelial cells together. In connective tissue proper extracellular fluid, hyaluronan and proteins interact to form the proteoglycans that make ground substance viscous
54
What are fibrocytes?
The second most abundant fixed cell in connective tissue proper. They are spindle shaped
55
What are Adipocytes?
Also known as fat cells. A typical adipocyte contains a single enormous lipid droplet
56
What are Mesenchymal cells?
Stem cells that are present in many connective tissues. These cells respond to local injury or infection by dividing to produce daughter cells that differentiate into fibroblasts, macrophages or other connective tissue cells
57
What are Melanocytes?
Cells that synthesise and store melanin which gives tissues a dark colour. They are common in the epithelium of the skin
58
What are Macrophages?
Large phagocytic cells that engulf damaged cells or pathogens that enter the tissue. They are either fixed which spend long periods of time in tissue or free macrophages which migrate through tissues
59
What do Mast cells do?
Circulate the blood in an immature form before they migrate to other vascularized tissues and undergo final maturation. Their cytoplasm if filled with granules containing histamine and heparin. Histamine is released after an injury of infection and stimulates local inflammation
60
What do lymphocytes do?
Migrate through the body and gather where damage occurs. Some develop into plasma cells which produce antibodies
61
What are microphages?
Phagocytic blood cells that normally move through connective tissues in small numbers. They are attracted to the site of an infection by chemicals released by the macrophages and mast cells
62
How are collagen, reticular and elastic fibres formed and maintained?
Fibroblasts form all three my secreting protein subunits which interact in the matrix. Fibrocytes then maintain these fibres.
63
Give features of collagen
- most common fibre
- Long, straight and unbranched
- each fibre consists of a bundle of fibrous protein subunits wound together like strands of a rope
- Found in tendons and ligaments
64
Give features of reticular fibres
- contain the same protein subunits as collagen but arranged differently
- thinner than collagen fibres
- form a branching interwoven framework that is tough yet flexible
- they resist forces from many directions
65
Give features of elastic fibres
- contain the protein elastin
| - branched and wavy
66
Why can't bacteria get through connective tissue proper?
Because the ground substance is so viscous the bacteria can't get through
67
What is Messencyme?
The first connective tissue to appear in a developing embryo
68
Give features of adipose cells
- Contains many adipose cells
- provides padding, absorbs shock and acts as an insulator
- Most of it is white fat
- Metabolically active cells
- Deflate when nutrients are scarce and their lipids are broken down and the fatty acids are released to support metabolism
69
What is an aponeurosis?
a tendinous sheet that attaches a broad flat muscle to another muscle or to several bones of the skeleton. It can also stabilise the positions of tendons and ligaments
70
What are fasciae?
Connective tissue layers and wrapping that support and surround organs
71
What does superficial fascia refer to?
The subcutaneous layer. This layer of areolar and adipose tissue separates the skin from the underlying tissues and organs
72
Give features of deep fascia
- consists of sheets of dense regular connective tissue
- in each layer making up the sheet all fibres run in the same direction but the orientation of the fibres changes from layer to layer. This helps the tissue resist forces coming from many directions
- the tough capsules that surround most organs are bound to this layer
73
What is subserous fascia?
A layer on areolar tissue that lies between the deep fascia and the serous membranes that line true body cavities
74
What is the water matrix in blood called?
plasma
75
Give features of Cartilage
- the matrix is a firm gel that contains polysaccharide derivatives called chondroitin sulfates Theses form complexes with proteins in ground substance producing proteoglycans
- Cartilage cells (chondrocytes) are the only cells in the cartilage matrix. They occupy small chambers known as lacunae
- The physical properties of cartilage depends on the proteoglycans of the matrix and on the type and abundance of extracellular fibres
- it is avascular
- cartilage is set apart from surrounding tissues by a fibrous perichondirum
76
What are the three major types of cartilage?
- Hyaline cartilage (e.g. nasal cartilages)
- Elastic cartilage (e.g. the external flap of the outer ear and the epiglottis
- fibrocartilage (lies between spinal vertebrae and around tendons and within or around joints)
77
How does cartilage grow?
- Interstitial growth (enlarges the cartilage from within)
- appositional growth (gradually increases the size by adding to it's outer surface)
- both of these take place in development
78
Why does bone have a strong but flexible composition?
About 2/3 of the matrix bone is calcified consisting of a mixture of calcium salts. The rest of the bone is dominated by collagen fibre. This combination produces a strong but flexible composition
79
What are the four types of tissue membranes found in the body and what are they each made up of?
They are each made up of an epithelium supported by a connective tissue
the four types are:
- Mucous membranes: line passageways and chambers that open to the exterior. Must be kept moist to reduce friction
- Serous membranes: line the sealed, internal cavities of the trunk (cavities that are not open to the exterior)
- The cutaneous membrane: covers the outer surface of the body
- Synovial membrane: line joint cavities and produce synovial fluid within a joint
