1 - Cell Specialization Flashcards
How does each cell start out?
As non-specific
What does non-specific cell mean?
Its functions are no different from other cells
How do all multicellular organisms begin?
As a single cell
ex. a zygote
What major process is responsible for tissue and organ growth and development?
Differentiation
What is another word for a non-specialized/non-specific cell in a multicellular organism?
stem cell
Depending on the signal a non-specialized cell receives, what two things can it do?
- replicate OR
2. differentiate
What is produced if a non-specialized cell replicates?
Another non-specialized cell
What is produced if a non-specialized cell differentiates?
It will become a specialized cell
Describe totipotent
A word to describe an embryonic stem cell because it is non-specialized, so it has the potential of differentiating into any kind of cell type
TOTal POTential
From a single celled zygote, how many specialized human cell types will differentiation result in?
a few hundred specialized human cell types
What is another word for a differentiated cell?
specialized cell
T or F: each type of specialized cell will have the same appearance and same proteins
FALSE.
Each type of specialized cell will have a unique appearance and a unique combination of proteins
hence, ‘specialized’
In addition to carrying out the basic cell functions of all cells, specialized cells also….
Function in a more specific way that contributes to the survival of the organism
and has structures and a shape that is conducive to its specific function
What are 2 examples of specialized cells?
- Skeletal muscle cells
Structure: network of aligned filaments made up of unique contractile proteins
Function: muscle contraction
- red blood cells
Structure: mature cells lose important cell structures to become a donut shape filled with hemoglobin to help them move efficiently through capillaries
Function: transport oxygen throughout the body
What is established as embryonic development proceeds?
three major cell lines (germ lines)
What do each of the major cell/germ lines divide to form?
three germ layers
What will the germ layers develop into?
different tissue types in an adult organism and eventually different organs
What are the three germ layers?
ectoderm
mesoderm
endoderm
What does the ectoderm develop into?
skin and nervous system
What does the mesoderm develop into?
skeleton, muscle, kidney, heart muscle, and blood
What does the endoderm develop into?
gut, liver, and lungs
How are tissues produced?
When specialized cells with similar structure and function group
What are tissues?
Groups of similar specialized cells
What are organs composed of?
tissues
How are organs organized?
Into organ systems
What are the four types of animal tissues?
epithelial
nervous
muscle
connective
T or F: most cells look like the general drawing of cells? why/why not?
FALSE. Most cells do not look like the generalized cells because they have specific functions and their shape/structures will be specific to that function
T or F: the structure of each tissue relates directly to its function
True
What is histology?
the study of tissue appearance and tissue organization under a microscope
What is the order of the cell life?
single cell (ex. zygote)
differentiation or replication
if differentiation, it will become a specialized cell
Specialized cells:
- epithelial
- muscle
- nerve
- connective
groups of similar specialized cells become tissues
Groups of tissues form organs
groups of organs form organ systems
groups of organ systems form an organism
What are the four types of specialized animal cells
epithelial cell
muscle cell
nerve cell (neuron)
connective cell
Describe the location, function, structure and characteristics of epithelial cells and tissues
LOCATION:
external surface layers of the body and the linings of lumens (cavities like the intestine)
FUNCTION:
forms a barrier between two environments
STRUCTURE:
- tightly packed with strong connections between cells so that external particles cannot enter unregulated
- minimal extracellular matrices
- distinct apical and basal sides/significant structural polarity
Other characteristics:
- rapid turnover (short-lived) because environments are hostile
- very selective membranes for movement of particles through cells
How are epithelial tissues classified into subgroups?
Based on cell characteristics and the number of layers they have
What are the subgroups of epithelial tissues
- number of layers:
Simple or Stratified (or also pseudo-stratified) - shape:
Squamous, cuboidal, columnar - other characteristics:
Ciliated or non-ciliated
Describe simple vs. stratified epithelial tissues
Simple: one layer of cells
Stratified: many layers of cells
Describe squamous vs. cuboidal vs. columnar shaped epithelial tissues
Squamous: cells are spindle-shaped (skinny edges, big in the middle - like a lemon)
Cuboidal: cells are square
Columnar: cells are long and narrow like columns
Describe cell polarity
When specialized cells have asymmetric organization
When/why does cell polarity occur?
Cell polarity occurs when different parts of a single cell have different functions
Different function = different structure
What two kinds of cells is cell polarity most common in?
epithelial and nervecells
Describe the location, function, structure and characteristics of nerve cells
Location: throughout the body (brain, spinal cord, muscles and glands)
Function: Send signals (communication) between cells
Structure:
- dendrites (network)
- cell body
- axon (long and skinny, lots of surface area for action potential)
T or F: neurons are the only type of cell in nervous tissue
FALSE. Many different types of supportive cells called glial are important for the functions of the nervous system
Describe glial
Cells with supportive functions in the nervous system
ex. form blood-brain barrier, degrade neurotransmitters
Describe muscle cells
Excitable cells that contract to produce movement in an organism
What are the 3 basic types of muscle cells?
skeletal
smooth
cardiac
What types of movement can muscle cells produce?
both voluntary and involuntary
What structural differences exist between the types of muscle tissues?
skeletal muscles: striated, LOTS of nuclei
Cardiac: striated, not as many nuclei
Smooth: not striated (hence, ‘smooth’), not as many nuclei
Describe connective tissues
A very large category of tissues that function in either:
connection
support
protection of other tissues
basically anything that is not epithelial, muscle, or nervous
Which tissue type has the most extensive extracellular matrix?
Connective tissue
Which tissue type has the least extensive extracellular matrix?
epithelial
What determines the properties of connective tissues?
the extracellular matrix
Describe extracellular matrix
A network of proteins and molecules that surround, support and provide structure to cells and tissues
T or F: connective tissues have a wide spectrum of ECM compositions
True
What are the 5 compositions of connective tissues? Give examples
More rigid (ex. collagen fibres)
more elastic (ex. elastin fibers)
gel-like (ex. water-binding proteoglycans)
liquid (blood matrix - plasma)
mineralization (bone)
What are three general categories of connective tissues?
Loose
Dense
Fluid
Give examples of loose connective tissues
fatty tissue
sub-dermal parts of the skin
outermost layers of blood vessels
Describe dense connective tissues and list the categories
Contain collagen to provide more strength and resistance
categories:
Irregular - ex. muscle fascia
Regular - ex. ligaments and tendons
Skeletal - ex. cartilage and bone
Describe fluid connective tissues and give examples
cells circulate in a liquid extracellular matrix
ex. blood, lymph
The walls of most of our internal organs contain which tissues?
epithelial - the lining
connective - between layers
muscle - smooth
nerve - action of tissues/organs
How is tissue integrity maintained?
replacement of specialized cells as new ones are produced and old ones die
continued presence of stem cells is necessary
What are the 2 kinds of cell death?
Necrosis
Apoptosis
Describe necrosis
A type of accidental cell death caused by oxygen or nutrient deprivation, or physical injury, or the environmental conditions
Describe the process of necrosis
The cell loses the ability to control fluid and ion balance so it and its organelles SWELL until it ruptures and releases its contents
This will cause an inflammatory response
Phagocytic cells clean up cellular debris but can damage nearby non-necrotic cells
Describe apoptosis
Programmed cell death
Describe the process of apoptosis
The cell will SHRINK, but organelles maintain their structure and remain inside the cell membrane
There is no inflammatory reaction
Cell may be ingested by macrophages or remain in the tissue to contribute to the function of the tissue (ex. eye lens, skin keratinocytes)
Compare and contrast necrosis and apoptosis
Similarities:
Both are types of cell death that can occur in tissues.
Differences:
Necrosis is accidental cell death that is caused by oxygen or nutrient deprivation or physical harm. Whereas, apoptosis is programmed cell death.
Necrosis causes the cell to swell up and rupture its contents, whereas apoptosis causes the cell to shrink and its contents remain inside the cell membrane.
Necrosis causes an inflammatory response, whereas apoptosis does not.
If a cell dies by necrosis, it will be ingested by phagocytic cells. Whereas with apoptosis, the cell MAY be ingested by macrophages, but also may remain as a dead cell in the tissue because it contributes to the function of the tissue
Describe how cancer cells arise
If a cell does not die when it is supposed to
How do cancer cells appear in comparison to normal cells?
Very different
Often have many mutations, including mutations that prevent cell death by apoptosis
- large, variably shaped nuclei
- many dividing cells with disorganized arrangement
- variation in size and shapes
- loss of normal features
