Cells and tissues
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- Created by: Jade
- Created on: 17-12-20 14:08
What are cells?
These are the structural and functional units of the human body.
They carry out the chemical activities needed to sustain life, and they divide to form/repair tissues.
They carry out the chemical activities needed to sustain life, and they divide to form/repair tissues.
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What are the three main regions of cells?
Nucleus
Plasma membrane
Cytoplasm
Plasma membrane
Cytoplasm
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What are the three main types of cell junctions?
Tight junctions
Desmosomes
Gap junctions
Desmosomes
Gap junctions
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What are tight junctions?
Adjacent plasma membranes fuse together tightly and prevent substances from passing through the extracellular space between cells.
E.g. In the small intestine, these junctions prevent digestive enzymes from seeping into the bloodstream.
E.g. In the small intestine, these junctions prevent digestive enzymes from seeping into the bloodstream.
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What are desmosomes?
Anchoring junctions which prevent cells subjected to mechanical stress (e.g. heart muscle cells and skin cells) from being pulled apart.
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What are gap junctions?
A type of cell junction in which adjacent cells are connected through protein channels. These channels connect the cytoplasm of each cell and allow molecules, ions, and electrical signals to pass between them.
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Give examples of passive processes of membrane transport.
Diffusion - movement of a substance from an area of higher concentration to an area of lower concentration.
Filtration - the movement of substances through a membrane from an area of high hydrostatic pressure, to an area of lower fluid pressure.
Filtration - the movement of substances through a membrane from an area of high hydrostatic pressure, to an area of lower fluid pressure.
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What is the driving force of filtration?
Blood pressure
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What is simple diffusion?
The unassisted diffusion of solutes through selectively permeable membranes, e.g. the plasma membrane.
Solutes transported this way are lipid-soluble (e.g. fats, oxygen and carbon dioxide).
Solutes transported this way are lipid-soluble (e.g. fats, oxygen and carbon dioxide).
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What type of diffusion provides passage for substances that are both lipid-insoluble and too large to pass through the membrane pores?
Facilitated diffusion
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What is Adenosine triphosphate (ATP)?
The
energy-rich molecules that power cellular activities.
energy-rich molecules that power cellular activities.
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What occurs during active transport?
Substances are moved across the membrane against an electrical or a concentration gradient
by proteins called solute pumps. The solute pumps are energised by ATP.
by proteins called solute pumps. The solute pumps are energised by ATP.
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What occurs during vesicular transport?
Uses ATP to fuse or separate membrane vesicles and the cell membrane.
Vesicular transport moves substances into/out of cells “in bulk” without them crossing the plasma membrane directly.
Vesicular transport moves substances into/out of cells “in bulk” without them crossing the plasma membrane directly.
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What are the two types of vesicular transport?
Exocytosis - the mechanism that cells use to actively secrete hormones, mucus, and other cell products or to eject certain cellular wastes.
Endocytosis - particles are taken up by enclosure in a vesicle. Includes phagocytosis and pinocytosis.
Endocytosis - particles are taken up by enclosure in a vesicle. Includes phagocytosis and pinocytosis.
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What is phagocytosis?
Uptake of solid particles
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What is pinocytosis?
Uptake of fluids
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What are the phases of cell division?
Mitosis - nuclear division
Cytokinesis - division of the cytoplasm
Cytokinesis - division of the cytoplasm
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What are the four stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
Metaphase
Anaphase
Telophase
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What occurs during the prophase?
The chromatin threads coil and shorten so that the barlike chromosomes become more visible.
The centrioles separate and move toward opposite sides of the cell, directing the assembly of a mitotic spindle.
The centrioles separate and move toward opposite sides of the cell, directing the assembly of a mitotic spindle.
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What will have happened by the end of the prophase?
By the end of the prophase, the nuclear envelope and the nucleoli have broken down and disappeared, and the chromosomes have attached to the spindle fibres by their centromeres.
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What occurs during the metaphase?
The chromosomes line up at the metaphase plate.
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What occurs during the anaphase?
The centromeres that have held the chromatids together split. The chromatids (now called chromosomes again) are drawn toward opposite ends of the cell.
This careful division ensures that each daughter cell gets one copy of every chromosome.
This careful division ensures that each daughter cell gets one copy of every chromosome.
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What occurs during the telophase?
The chromosomes at opposite ends of the cell uncoil to become threadlike chromatin again.
The spindle breaks down and disappears, a nuclear envelope forms around each chromatin mass, and nucleoli appear in each of the daughter nuclei.
The spindle breaks down and disappears, a nuclear envelope forms around each chromatin mass, and nucleoli appear in each of the daughter nuclei.
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What is the result of mitosis?
The result is two daughter nuclei, each identical to the mother nucleus.
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What stage of the cell cycle occurs before mitosis?
Interphase
The cell spends most of its life in this phase. The DNA in chromosomes copies itself ready for mitosis.
The cell spends most of its life in this phase. The DNA in chromosomes copies itself ready for mitosis.
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What is Cytokinesis?
A contractile ring made of microfilaments forms a cleavage furrow over the midline of the spindle, and it pinches the original cytoplasmic mass into two parts.
This forms two daughter cells.
This forms two daughter cells.
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When does Cytokinesis occur?
It usually begins during late anaphase and completes during telophase.
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What happens if Cytokinesis does not occur?
This condition leads to the formation of binucleate (two nuclei) or multinucleate cells. This is fairly common in the liver and in the formation of skeletal muscle.
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What are body tissues?
Groups of cells that are similar in structure and function.
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What are the four primary tissue types?
Epithelial tissues
Connective tissues
Nervous tissues
Muscle tissues
Connective tissues
Nervous tissues
Muscle tissues
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What is epithelial tissue?
The lining , covering , and glandular tissue of the body.
Covering and lining epithelium covers all free body surfaces, both inside and out, and contains versatile cells.
Covering and lining epithelium covers all free body surfaces, both inside and out, and contains versatile cells.
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What are the functions of epithelial tissue?
Protection - e.g. epithelium of the skin protects against bacterial and chemical damage.
Absorption - e.g. in digestive system organs.
Filtration - e.g. in the kidneys, epithelium both absorbs and filters.
Secretion - e.g. glandular epithelial tissue.
Absorption - e.g. in digestive system organs.
Filtration - e.g. in the kidneys, epithelium both absorbs and filters.
Secretion - e.g. glandular epithelial tissue.
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What two criteria are used to classify epithelial tissues?
Cell shape
Cell arrangement
Cell arrangement
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What are the classifications by cell arrangement (layers)?
Simple Epithelium - one layer of cells
Stratified Epithelium - more than one cell layer.
Stratified Epithelium - more than one cell layer.
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What are the classifications by cell shape?
Squamous (skwa ′ mus) cells - flattened like fish scales.
Cuboidal (ku-boi ′ dal) cells - cube shaped
Columnar cells - shaped like columns.
Cuboidal (ku-boi ′ dal) cells - cube shaped
Columnar cells - shaped like columns.
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What are the functions of Simple Squamous Epithelium?
Diffusion and filtration
Secretion in serous membranes
Secretion in serous membranes
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Where can Simple Squamous Epithelium
be found?
be found?
Simple squamous epithelium is in the air sacs of the lungs (alveoli).
It forms the walls of capillaries.
It also forms serous membranes, the slick membranes that line the ventral body cavity and cover the organs in that cavity.
It forms the walls of capillaries.
It also forms serous membranes, the slick membranes that line the ventral body cavity and cover the organs in that cavity.
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What are the functions of Simple Cuboidal Epithelium?
Secretion and absorption; ciliated types propel mucus or reproductive cells.
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Where can Simple Cuboidal Epithelium be found?
Common in glands and their associated ducts (e.g. the salivary glands and pancreas).
It also forms the walls of the kidney tubules and covers the surface of the ovaries.
It also forms the walls of the kidney tubules and covers the surface of the ovaries.
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What are the functions of Simple Columnar Epithelium?
Secretion and absorption; ciliated types propel mucus or reproductive cells.
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Where can Simple Columnar Epithelium
be found?
be found?
Goblet cells which produce a lubricating mucus, are often seen in this type of epithelium.
Simple columnar epithelium lines the entire length of the digestive tract from the stomach to the anus.
Simple columnar epithelium lines the entire length of the digestive tract from the stomach to the anus.
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What is the function of a Stratified Squamous Epithelium?
Protection
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Where can Stratified Squamous Epithelium be found?
Sites that receive a good deal of abuse or friction e.g. the surface of the skin, the mouth, and the oesophagus.
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What is the function of a Stratified Cuboidal Epithelium?
Protection; these tissue types are rare in humans.
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What is the function of a Stratified Transitional Epithelium?
Protection; stretching to accommodate distension of urinary structures.
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Where can Stratified Transitional Epithelium be found?
The lining of only a few organs— the urinary bladder, the ureters, and part of the urethra.
As part of the urinary system, all of these organs are subject to considerable stretching.
As part of the urinary system, all of these organs are subject to considerable stretching.
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What is connective tissue?
Connective tissue connects body parts. It is found everywhere in the body.
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What are the primary functions of connective tissues?
Protecting , supporting , and binding together other body tissues.
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What are the characteristics of connective tissues?
Variations in blood supply - most connective tissues are well vascularized, but there are exceptions. E.g. tendons and ligaments have a poor blood supply, and cartilages are avascular.
Extracellular matrix - a non-living substance found outside the cells
Extracellular matrix - a non-living substance found outside the cells
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What are the two main elements of the Extracellular Matrix?
A structureless ground substance and fibres.
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What causes the to matrix vary in consistency?
Cell adhesion proteins allow the connective tissue cells to attach to the matrix fibres embedded in the ground substance. Charged polysaccharide molecules will trap water as they intertwine, these polysaccharides cause the matrix to vary in consistency.
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Other cards in this set
Card 2
Front
What are the three main regions of cells?
Back
Nucleus
Plasma membrane
Cytoplasm
Plasma membrane
Cytoplasm
Card 3
Front
What are the three main types of cell junctions?
Back
Card 4
Front
What are tight junctions?
Back
Card 5
Front
What are desmosomes?
Back
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