Chapter 4- Tissues Flashcards
1
Q
Tissues
A
any grouping of cells that are similar in structure and carry out a similar or common function in the body.
2
Q
Benefits of tissues
A
cellular specialization allows the body to carry out complicated functions
3
Q
Drawback of tissues
A
destruction of one cell type could be catastrophic. A disease could enter the body to target the cells of one tissue. If a tissue is destroyed, there’s not much you can do
4
Q
What are the 4 primary types of tissues?
A
- Nervous tissue- control tissue
- Muscle tissue- movement tissue
- Epithelial tissue- covering tissue
- Connective tissue- support tissue
5
Q
Muscle tissue
A
Movement tissue- innervated, well vascularized
6
Q
What must occur for muscle contraction?
A
Microfilaments actin and myosin allow for muscle contraction/movement- they do this by physically interacting with each other- this must occur for contraction
7
Q
What are the 2 types of muscle tissue?
A
- Skeletal
- Cardiac
- Smooth
8
Q
Skeletal muscle
A
voluntary control with striations. Attaches to bones and uses the bones to produce movement. A single muscle cell has multiple nuclei.
Skeletal muscle uses the bones like levers to move
9
Q
cardiac muscle
A
involuntary control with striations, found only in the walls of the heart
Uninucleate- one nucleus per cell
10
Q
Smooth muscle
A
involuntary control without striations. Found in the walls of hollow organs (not including the heart) to squeeze substances through the organ.
Also uninucleate
11
Q
Epithelial tissue
A
The type of tissue that covers body surfaces, lines cavities, and forms glands
12
Q
Epithelial tissue functions (2)
A
- Boundary forming, separates one area/region of the body from another
- Substances received or given off by the body must pass through the epithelium
13
Q
What are the 2 forms of epithelial tissue
A
- Covering epithelium
2. Glandular epithelium
14
Q
Covering epithelium
A
outer layer of skin, dips into and lines the urogenital, digestive, and respiratory systems. Covers the wall/organs of closed body cavities
15
Q
Glandular epithelium
A
makes up the glands of the body
16
Q
Apical basal polarity
A
Epithelial tissue has 2 surfaces that differ in structure in function. The apical surface and the basal surface
17
Q
Apical surface
A
the exposed side of epithelial tissue- faces the lumen or outside of the body. Most have microvilli, others have cilia. The skin you can see is the apical surface of the epithelial layer
18
Q
Lumen
A
an empty space through which something travels
19
Q
Microvilli function
A
used to increase surface area, like the epithelia lining the intestines and kidney tubules
20
Q
Cilia function
A
create current to propel substances through open space, like those lining the trachea
21
Q
Basal surface
A
attaches to connective tissue
Has attached basal lamina- filters what can/can’t enter the epithelial layer. Also acts as a scaffolding along which epithelial cells can migrate to repair a wound.
22
Q
Basal lamina
A
The basal lamina is a noncellular and adhesive sheet attached to the basal surface of epithelial tissue that consists mostly of glycoproteins secreted by the epithelial cells and some collagen fibers. Filters what can and can’t enter the cell, is one of the layers in the basement membrane
23
Q
How are epithelial cells held together?
A
Joined by tight junctions and desmosomes
Epithelial tissue forms sheets- prevents passage of material between cells, resists mechanical stress
24
Q
Basement membrane
A
lies between epithelial layer and connective tissue
Functions- reinforces epithelial sheet to resist stretching/tearing, defines epithelial boundary. Reinforces the desmosomes to strengthen the attachment. It has 2 layers: the basal lamina and the reticular lamina.
Semipermeable to certain substances- this is necessary because nutrients must diffuse through to the epithelium
25
Reticular lamina
contains fibers that belong to connective tissue. Deep to the basal lamina
26
What is an important characteristic of
| cancerous epithelial cells?
An important characteristic of cancerous epithelial cells is their failure to respect the basement membrane boundary, which they penetrate to invade the tissues underneath
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Does the epithelium have blood vessels?
No, it is avascular. It receives nourishment by diffusion and disposes of waste the same way
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Is the epithelium innervated?
Yes
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Is the epithelium able to regenerate?
Yes, there is a high capacity for regeneration.
Epithelial layers are subject to high levels of abrasion and hostile conditions (internal and external). For example, the stomach has a low pH, so the epithelia is constantly being destroyed
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What begins when the epithelium is damaged?
When epithelial tissue is damaged, cell reproduction begins. If dead cells are not replaced, you lose the function
31
How many parts does the name of epithelial tissue have?
Two parts, like a first and last name. Thickness comes first, then the shape of the cells
32
Simple epithelia
Refers to the thickness of the tissue- contains only 1 layer of cells. Usually seen where absorption, secretion, and filtration are desired and a thin barrier is necessary, especially in areas where quick diffusion is needed, like the alveoli. These cells usually have the same shape.
33
Stratified epithelia
Refers to the thickness of the tissue- contains 2+ layers of cells. Usually seen in areas subjected to high levels of abrasion/contact (chemical or mechanical stress) like the skin surface and the inside of the mouth. These cells can have different shapes and are therefore named according to the shape of the cells in their apical layer
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Squamous epithelia
The cells are flattened/squashed, the nucleus is flattened as well
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Cuboidal epithelia
The cells are cube shaped and the nucleus is spherical
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Columnar epithelia
The cells are tall and column shaped, the nucleus is elongated and closer to the cell base
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Why isn't simple epithelia used for protection?
There's only one layer of cells
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Simple squamous epithelium
Resemble a tiled floor, thin and permeable- includes the mesothelium and endothelium
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Simple squamous epithelium function
absorption, secretion, filtration- part of the filtration membrane in the kidneys that filters blood to make urine.
Found in the lungs- must bring in oxygen at a regular rate and dispose of CO2 quickly- a thin layer allows for quick diffusion.
40
Mesothelium
A type of simple squamous epithelium, epithelium of the serous membranes that cover the ventral body cavity and organs
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Endothelium
A type of simple squamous epithelium, forms slick/slippery linings. Lymphatic vessels and cardiovascular system- promotes the flow of the circulating material. Capillaries consist exclusively of epithelium- thinness encourages efficient exchange of nutrients and wastes between the bloodstream and surrounding tissue cells
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Simple cuboidal epithelium
Single layer of cells as tall as they are wide
Nuclei are spherical and stain darkly
Locations- kidney tubules, ovary surface, some small glands
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Simple cuboidal epithelium function
secretion and absorption
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Simple columnar epithelium
Single layer of tall, closely packed cells. Many have microvilli on the apical surface of absorptive cells and tubular glands made primarily of cells that secrete mucus containing intestinal juice. Some have cilia that help move substances or cells through an internal passageway
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Simple columnar epithelium functions
absorption and secretion
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Simple columnar epithelium locations
digestive tract, gallbladder, small bronchi, uterine tubes, parts of uterus
47
Pseudostratified columnar epithelium
“False” stratified cell nuclei lie at different levels- the nuclei are displaced so it looks like there are multiple layers of cells.
Only some cells stretch from the apical surface to the basal surface. “Short” cells give rise to “tall” cells (the cells are different sizes). Shorter cells attach to the basement membrane
If tall cells are killed off, the shorter cells will replace them to prevent a loss of function.
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Pseudostratified columnar epithelium function
secretion and absorption. Many types are ciliated.
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Pseudostratified columnar epithelium locations
```
respiratory tract (cilia propels sheets of dust trapping mucus away from the lungs), male ducts, ducts of large glands
The respiratory tract has a ciliated version with mucus containing goblet cells
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50
How does stratified epithelia regenerate?
regenerate from the bottom up, the cells closest to the basement membrane divide mitotically to replace cells being rubbed off on the top
51
Stratified squamous epithelia function?
Thick, forms a good protective barrier
52
Why are the apical cells in stratified squamous epithelia poorly nourished?
the epithelium depends on diffusion for nutrients so apical cells in thicker tissues might actually be dead
53
Where is stratified squamous epithelia found in general?
Forms the external surface of the skin and extends a short distance into every body opening that is directly continuous with the skin
54
Where is the stratified squamous epithelia keratinized?
The outer layer (epidermis) of the skin is keratinized (its surface cells contain the tough protective protein keratin). The other stratified squamous epithelia of the body are non keratinized.
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Stratified cuboidal epithelia
rare, usually consists of just 2 layers
Locations- mostly ducts of sweat glands and mammary glands, has 2 layers of cuboidal cells. Layers are mostly too thick to function
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Stratified columnar epithelia
also rare, only apical cells are columnar
Locations- male urethra, part of pharynx, some ducts. Occurs at transition areas or junctions between two layers of epithelia
57
Transitional epithelium
Basal cells are mostly cuboidal/columnar, apical cell shape varies.
Typical of urinary organs- constantly being stretched- allows for greater flow of urine to flow through a tubelike organ
As the organs are stretched, the cells will look squamous in appearance
Cells will change shape as bladder fills/empties
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Glands
one or more cells that produce and secrete a particular product (called a secretion)
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Secretion
an aqueous fluid that contains proteins. Manufactured from the blood supply. Secretion is an active process- glandular cells obtain needed substances from the blood and transform them chemically into a product that is then discharged from the cell
60
What makes secretions different from each other?
The type of protein found in them makes one different from another
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How are glands classified?
1. Location of release- endocrine vs exocrine
| 2. Number of cells that makes up gland- unicellular vs multicellular
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Endocrine glands
ductless glands. They release their secretion directly into the bloodstream (internally). They are not epithelial in nature and are multicellular. They produce hormones that are released to extracellular space via exocytosis
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What types of organs/systems can endocrine glands form?
Can form
1. Compact multicellular organs (cells are clumped together into a common structure) or
2. Diffuse endocrine systems (the cells making up a gland are spread out).
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Hormones
chemical messengers- target specific organs to respond in a specific way. They will go from the extracellular space to the blood or lymphatic fluid and travel to specific target organs.
65
Exocrine glands
secrete products onto surfaces/into cavities (externally secreting). Epithelial in nature, have a duct- a tube that empties the secretion onto a surface or into a body cavity- not into the bloodstream. Can be unicellular or multicellular.
66
Unicellular exocrine glands
release product onto surface via exocytosis. Individual cells that are scattered through epithelia with cells of different functions
Tend to be embedded in surrounding epithelial tissue
Example- goblet cells (digestive system), mucous cells (respiratory system)
Both produce and secrete mucin- dissolves in water to create mucus
67
Multicellular exocrine glands
release product onto surface via a duct- more structurally complex. Multicellular epithelial glands form by invagination (inward growth) of an epithelial sheet into the underlying connective tissue. These glands can be classified by structure (simple or compund) and mode of secretion.
68
Exocrine gland examples (5)
liver, pancreas (endocrine and exocrine), salivary glands, sweat glands, oil glands
69
What are the 2 parts of the multicellular exocrine gland?
1. Duct- derived from epithelium. It’s just a passageway
| 2. Acinus- secretory unit made up of cells that produce and secrete product
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How are multicellular exocrine glands classified based on structure?
1. Simple- unbranched duct- one straight tube into secretory unit (acinus) or
2. Compound- branched duct(s)
71
How are multicellular exocrine glands classified based on mode of secretion?
1. Merocrine
2. Holocrine
3. Apocrine
72
Merocrine secretion
product secreted from the acinus via exocytosis, cell remains unchanged
Example- sweat or salivary glands
73
Holocrine secretion
product released as a result of cell rupture
Product builds up in the cell until the plasma membrane can’t hold it and it bursts
The cells that rupture are quickly replaced
Example- sebaceous glands
74
Apocrine secretion
similar to holocrine, but do not truly rupture
The cells have a small tear in the membrane so the secretion can leave, and the membrane quickly reassembles
Mammary glands could be an example
75
How is the secretory unit (acinus) of an exocrine gland characterized?
1. Tubular- duct and acinus are the same width
2. Alveolar- acinus is wider than the duct
3. Tubuloalveolar- too tubular to be classified as alveolar and vice versa
76
What type of tissue is most abundant and widespread?
Connective tissue
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Characteristics of connective tissue (3)
1. Possession of extracellular matrix (ECM)
2. Origin- all connective tissue arises from mesenchyme
3. Vascularization varies widely between the different types of connective tissue
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extracellular matrix (ECM)
nonliving matrix that separates living cells of the tissue. The living cells are widely separated and the ECM makes up most of the tissue.
79
Importance of the extracellular matrix in connective tissue
Because of its matrix, connective tissue can bear weight, withstand great tension, and endure trauma and abrasion
80
The extracellular matrix is made up of (2)
Made up by ground substance and fibers
81
Mesenchyme
The embryonic tissue that all connective tissue arises from. This tissue will eventually differentiate into all other connective tissue cells. Some cells will remain and provide a source of new cells in mature connective tissues.
82
Why does the skin have a large amount of connective tissue?
The skin has a huge amount of connective tissue so it can stretch and be supportive
83
Why doesn't the nervous system have a lot of connective tissue?
Connective tissue is not conductive and could interfere with the conduction of electrical impulses.
84
What are the 4 classes of connective tissue?
1. Connective tissue proper
2. Cartilage
3. Bone
4. Blood
85
What are the major functions of connective tissue? (5)
1. Support
2. Protection
3. Insulation
4. Storage
5. Transport
86
What are the 3 main structural components of connective tissue?
1. Ground substance
2. Fibers
3. Living cells
87
Ground substance
viscous liquid that fills space between cells, contains fibers. Made up of 3 different components
88
What are the 3 components of ground substance?
1. Interstitial fluid
2. Cell adhesion proteins- “glue” that hold living cells to ECM
3. Proteoglycans
89
Interstitial fluid
allows dissolved substances (like nutrients) to diffuse between the blood capillaries and the cells. The fibers in the ground substance make it less pliable and hinder diffusion somewhat. Found in ground substance
90
Proteoglycans
Consists of protein core with polysaccharide attachment
| Gives ground substance its consistency, more proteoglycans= more viscous ground substance
91
What are the 3 types of fibers found in connective tissue?
1. Collagen fibers
2. Elastic fibers
3. Reticular fibers
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Collagen fibers
Contain the protein collagen. Assemble and cross link with other collagen fibers spontaneously, and are able to resist pulling forces. Strong, flexible- collagen fibers are stronger than steel fibers of the same size
93
Elastic fibers
Long and thin, form branching networks. Contains protein elastin- easily stretched, can return to normal shape
94
Where are elastic fibers typically found?
High density in areas of the body that are subjected to frequent stretching- skin, lungs
95
Reticular fibers
Continuous with collagen fibers- shorter and finer than other fibers and extensively branched to form fine networks
96
Where are reticular fibers typically found?
High density in areas of the body where connective tissue attaches to another tissue (basement membrane of epithelial tissues and around capillaries- allows more stretch than the other collagen fibers).
97
What are the 2 categories of cells that can be found in connective tissue?
1. -blast cells
| 2. -cyte cells
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blast cells
are actively mitotic, lay down ground substance/fibers
99
cyte cells
Mature cells that maintain what is/was laid down by -blast cells. Will signal blast cells if not enough ground substance. They can revert to their more active -blast form if the matrix is injured
100
Fibroblast/fibrocyte
Cells associated with the connective tissue proper
101
Chondroblast/chondrocyte
Cells associated with the cartilage
102
Osteoblast/osteocyte
Cells associated with bone
103
Adipocytes
Associated with adipose (fat) tissue
104
Macrophages
engulf foreign material in a variety of body tissues
105
Mast cells
oval cells that cluster along blood vessels and detect foreign microorganisms and initiate local inflammatory responses against them.
Mast cell cytoplasm contains secretory granules with chemicals that mediate inflammation, especially in severe allergies.
106
What types of chemicals are contained in mast cell cytoplasm? (3)
1. Heparin
2. Histamine
3. Proteases- protein degrading enzymes
107
Histamine
a substance that makes capillaries leaky
108
Heparin
an anticoagulant chemical- prevents blood clotting when free in the bloodstream but regulates the action of other mast cell chemicals in mast cells
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What contributes to a high amount of diversity between different types of connective tissue?
The composition and arrangement of the 3 components varies drastically- each connective tissue is adapted to perform a certain function in the body. All have a common structural plan, however.
110
Marfan syndrome
a genetic disorder that affects the body’s connective tissue- causes elastic fibers of connective tissue to lose flexibility and strength. Symptoms vary and may not appear until adulthood
111
What causes Marfan syndrome?
Results from a mutation in the FBN1 gene, which codes the production of fibrillin. This protein contributes to strength and elasticity
Individuals produce the wrong amount of fibrillin (usually not enough) or they won’t produce it at all.
112
Which organs/organ systems are typically most affected by Marfan syndrome?
1. Bones/joints
2. Heart/blood vessels
3. Respiratory tract- loss of elasticity in the lungs
4. Eyes
113
What type of bone/joint problems can a person with Marfan syndrome experience?
Bones and joints have fibers for strength and elasticity. Marfan syndrome may result in-
“Fighter fingers”- fingers and toes are especially long, but people tend to be very tall and lanky. Scoliosis is also common.
The sternum can be malformed- can sink in or project out
114
What types of cardiovascular problems can a person with Marfan syndrome experience?
blood is pumped out of the heart to the aorta, which stretches as blood passes through it. A person with Marfan syndrome will have an aorta that will lose elasticity and will be permanently stretched out
Results in inefficient blood flow, the walls of the aorta become thinner and will eventually split open if the walls become thin enough
115
What types of eye problems can a person with Marfan syndrome experience?
difficulty focusing vision- fibers holding the lens of the eye in place break/lose strength
116
Connective tissue proper
any connective tissue that is not bone, cartilage, or blood. Contains 2 broad types
117
What are the 2 broad types of connective tissue proper?
1. Loose connective tissue
| 2. Dense connective tissue
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3 types of loose connective tissue
1. Areolar
2. Adipose
3. Reticular
119
Areolar connective tissue
most widely distributed, has a loose arrangement of fibers and a thick ground substance that can hinder movement of cells. Some WBCs can secrete an enzyme to liquify the ground substance and move through, but some pathogenic bacteria can do the same thing.
Areolar connective tissue is a universal packing material between other tissues- binds body parts together but allows them to move freely over one another.
It is also the connective tissue that most epithelia rest on and is present in all mucous membranes as the lamina propria
120
Areolar connective tissue functions
Functions- supports/binds other tissues (fibers), holds body fluids (ground substance), defends against infection (WBCs and macrophages), stores nutrients as fat in adipocytes (fat cells)
121
Areolar connective tissue chief cell type
Chief cell type is the fibroblast
| Can also have adipocytes, macrophages, and mast cells
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Adipose tissue
huge energy/nutrient source that will be used if the body is low on carbohydrates, composed mostly of adipocytes. Limited matrix. Adipose tissue is very important, too much removal of fat (through liposuction) can send the body into severe shock.
123
Where is adipose tissue usually found?
mostly subcutaneous (where it acts as a shock absorber, insulation, and energy storage site for the entire body), but can be found anywhere areolar tissue is found
124
What type of tissue has high metabolic activity
Adipose tissue. High metabolic activity- high turnover rate. Even if you maintain the same body fat percentage, the adipose tissue will change over time as its being used or replaced
125
Does the number of adipocytes in your body change?
No, when you lose weight, you’re just changing the amount of lipids deposited.
126
Reticular connective tissue
```
forms stroma (supportive network) to support free blood cells in lymph nodes, spleen, and bone marrow
Good for supporting cells that are large in size
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127
Adipose tissue function
it acts as a shock absorber, insulation, and energy storage site for the entire body- fat is a poor conductor of heat and therefore acts as an insulator
128
Where can fat accumulate in the body?
Fat can also accumulate around the kidneys, behind the eyeballs, and at genetically determined areas (abdomen and hips)
129
How do highly active organs meet their nutrient needs?
Smaller deposits of fat (not subcutaneous) serve the local nutrient needs of highly active organs. This can occur around the heart, lymph nodes, and in the muscles and bone marrow
130
3 types of dense connective tissue
1. Regular
2. Irregular
3. Elastic
131
Dense regular connective tissue
There are a lot of fibers and a lot of fibroblast cells- limited matrix and ground substance. Collagen fibers run in the same direction and are packed together- that tension can only be applied in the same direction that the fibers are running. Tension pulling up or down makes it easy to cause damage.
Athletes that have to very suddenly move laterally will pull tendon fibers in the wrong direction, and ACL can break
132
Dense regular connective tissue usually forms (3)
Forms tendons (muscle to bone), aponeuroses (usually muscle to muscle, flat and sheetlike), and ligaments (bones to bones)
133
Dense irregular connective tissue
Collagen fibers are thicker than dense regular, there is an irregular arrangement of fibers with fibers are going in multiple directions
Can also withstand tension- tension can be applied in multiple directions
134
Where is dense irregular connective tissue usually found (2)?
Found in the dermis, joint capsules
135
Elastic connective tissue
Very elastic- tissue recoils easily after stretching
| Found in parts of the body that stretch frequently- lungs, skin, large arteries
136
Cartilage (4)
Flexible, but still tough
Avascular, not innervated
Ground substance is very thick/firm, but it still contains large volumes of water
Will return to original shape if pressure is applied
137
3 types of cartilage
1. Hyaline
2. Elastic
3. Fibrocartilage
138
Where is cartilage found?
Nose, external ear, precursor to bones in children
139
Hyaline cartilage
most abundant, individual cells are spread out. Firm yet pliable.
140
Elastic cartilage
Much more flexible than hyaline cartilage, found in areas requiring strength and exceptional stretchability - the external ear and epiglottis
141
Where is hyaline cartilage typically found? (5)
1. Covers the ends of long bones as articular cartilage- provides springy pads that absorb compression at joints
2. Supports the tip of the nose
3. Connects the ribs to the sternum
4. Supports most of the respiratory system passages (like the trachea, keeps them open)
5. Makes up most of the embryonic skeleton before bone forms. Skeletal hyaline cartilage persists during childhood as the epiphyseal plates
142
Fibrocartilage
an intermediate between hyaline cartilage and dense regular connective tissues.
Rows of chondrocytes alternate with rows of thick collagen fibers
143
Where is fibrocartilage typically found?
found in areas of the body that need a lot of support/bear a lot of weight. Fibrocartilage discs are found between vertebrae
144
Why does cartilage heal very slowly?
Cartilage heals very slowly because it’s avascular and aging cartilage cells lose their ability to divide
145
Osseous tissue
Found in bone, highly vascularized- cells need oxygen and need to dispose of waste. Red bone marrow needs access to blood vessels so cells that it makes can enter.
146
What type of cells does osseous tissue contain?
Contains osteoblasts, osteocytes reside in the lacunae within the matrix
Bone salts deposited on/within fibers
147
What makes osseous tissue the hardest tissue in the body?
tissue contains inorganic calcium salts that make it rigid
148
Osseous tissue function
Support and protect body structures, provide cavities for storing fat and synthesizing blood cells
149
Why is blood considered a connective tissue?
it forms from the mesenchyme. Blood does not support/attach structures.
150
Where are blood fibers found?
Fibers form during blood clotting only- not usually found. Fiber formation must be very highly localized or blood flow and blood cell movement will be blocked.
151
What is the matrix of blood?
Plasma is the fluid matrix
152
What is the cellular portion of blood?
Blood cells- WBC, RBC, platelets. RBCs are the most common type
153
What is the function of blood
Does not provide support or physically connect one tissue to another
Function- transports nutrients, waste, gases, etc
154
What are the 3 types of covering and lining membranes?
1. Cutaneous (skin)
2. Mucous
3. Serous
155
Cutaneous membrane
The skin, dry membrane. Composed of keratinized stratified squamous epithelia- keratin makes the skin dry, preventing infection as pathogens don't like dry surfaces
156
Mucous membranes
Lines any body cavity that leads out of the body
| Wet/moist membrane that has the function of absorption and secretion.
157
The epithelial cells of the mucous membrane are attached to
lamina propria (areolar connective tissue)
158
Serous membranes
Lines body cavities that are closed to the outside. Have visceral and parietal layers separated by serous fluid: visceral clings to organ, parietal clings to body cavity wall. Prevent organs from painfully rubbing against other things
159
Where are mucous membranes found?
Found in the hollow organs of the digestive, respiratory, and urogenital tract
160
Where are serous membranes found?
Can be pleurae (lungs), pericardium (heart), or peritoneum (abdominopelvic organs)
161
What are 3 protective barriers the body has?
1. Skin and mucosa
2. Cilia of the epithelial cells lining the respiratory tract
3. Strong acid produced by the stomach glands
162
What happens when the protective barriers of the body are penetrated?
An inflammatory or immune response will occur. The injury must be closed off so nothing can get in and blood can't leave
163
What are the 2 ways in which tissue repair can occur?
1. Regeneration- occurs for small injuries. Surrounding healthy cells will divide and migrate to the area
2. Fibrosis- scar tissue formation as well as clotting will occur for more severe injuries
164
Granulation tissue
The type of tissue that replaces a blood clot. Injured tissue looks bumpy/grainy and contributes to inflammation. Capillary growth in the injured area gives it a granular appearance
165
What are the 3 steps of tissue repair?
1. Inflammation
2. Organization restores blood supply (this mostly co-occurs with step 1)
3. Regeneration and fibrosis effect permanent repair
166
What happens when inflammation occurs?
Inflammation occurs when blood vessels bleed and inflammatory chemicals are released.
Local blood vessels become more permeable and increase in diameter to increase blood flow and allow for WBCs, clotting proteins, and other substances to flood the area.
Clotting occurs, the surface dries and forms a scab
167
What occurs when organization restores blood supply?
The clot is replaced with granulation tissue, which restores blood flow under the scab surface (if a scab is ripped off too early, it will bleed as new capillaries are being ripped open)
Fibroblasts produce collagen fibers that bridge the gap of the injury- the collagen fibers are pulled to close the injury
Macrophages phagocytize dead and dying cells and other debris
Surface epithelial cells multiply and migrate over the granulation tissue
168
What occurs when regeneration and fibrosis cause permanent tissue repair?
The fibrosed area matures and contracts, the epithelium thickens
A fully regenerated epithelium with an underlying area of scar tissue results
169
Why would a scarred area of skin be discolored?
scar tissue has a different structure and will not be replacing the actual epithelium, so the color is different.
170
Neoplasm
A mass of cells that is caused by unregulated division of cells. Can be benign or malignant (very metabolically active).
171
What are the most common forms of cancer (4)?
Lung, skin, prostate, breast
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What is the primary cause of cancer
The primary cause of cancer is mutation in DNA that alters the expression of multiple genes
This can be caused by a lot of things (smoking, toxins, UV radiation, prolonged infection, certain traumas)
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Tumor suppressor genes
Normal genes that slow down cell division, p53 is an example
174
Oncogenes
A gene that is a mutated (changed) form of a gene involved in normal cell growth. Oncogenes may cause the growth of cancer cells
175
Proto-oncogenes
A gene involved in normal cell growth. Mutations (changes) in a proto-oncogene may cause it to become an oncogene, which can cause the growth of cancer cells.
176
Sarcoma
cancer arising in mesenchyme derived tissues (connective tissues and muscle)
177
Adenoma
any neoplasm of glandular epithelium, begin or malignant. A malignant type would be called an adenocarcinoma
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What is the basement membrane made up of?
Fibers (like collagen), not cells
