1. Cells and Tissues Flashcards
List the organisation of higher organisms?
Cell -> Tissue -> Organ -> System -> Organism
Define a cell?
The fundamental unit of all living things - performs all basic function of life
What 5 components are a cell made up of?
Membrane Cytoplasm Organelles Nuclear region Cytoskeleton
Define a eukaryote?
Multi-cellular organism e.g. humans
What are the properties of a eukaryotic cell?
Nucleus (karyon) with DNA
Size 10-40 μm (some larger)
Extensive organelles
Define a prokaryote?
Single-cell organism
What are the properties of a prokaryotic cell?
Lack nucleus; hereditary material in cytoplasm Size 1-5μm No organelles Cell wall and capsule
What is cytosol?
“where the action happens”
Cytosol is within eukaryotic cell
Inside plasma membrance
Viscous fluid - water, ions, proteins
Organelles are suspended in it
Also called cytoplasm
What are organelles?
Discrete structures that have a defined function e.g. nucleus, mitochondria, ER, lysosome etc
What is the plasma membrane?
“gate keeper” or “door man”
Defines boundaries
Communicates with other cells
Controls flow of substances - selectively permeable
Maintains cellular homeostasis
Composition (lipids 90-99% proteins 1-10%)
Fluid Mosaic
Where are receptors located?
In the plasma membrance
What do receptors do?
Determine cell responses
Define cell function
What is the nucleus?
“control centre” or “the mayor”
Contains chromosomes which carry the genetic information for life - DNA
Nucleolus - RNA
Directs activity within cell
What is DNA?
Deoxyribonucleic acid, it dictates which proteins the cell produces
What is the endoplasmic reticulum?
“big factory complex” or “assembly line”
controls all protein production in the cell
prepares proteins for transport to golgi apparatus or other cell parts
ribosomes dot the surface
What are the two types of Endoplasmic reticulum?
Rough (dotted with ribosomes) - protein synthesis
Smooth - lipid synthesis
What is the golgi complex/apparatus?
“packaging plant”
Receives proteins from ER Packaging, Modifying and sorting proteins into vesicles
What is mitochondria?
“power plant”
Provides energy for the cell by converting sugars into ATP
Contains it’s own DNA which bears no resemblance to ours
What is ATP?
Adenosine triphosphate
What is the lysosome?
“Recycling centre”
Break down waste and detoxify poisons
Contains enzymes
What are secretory granules?
“Container transporters”
Contains a product to be realeased into the circulation
Granules bind to plasma membrane and their contents are released by exocytosis
What are ribosomes?
“small factories”
Found on the ER or floating in the cytoplasm
Follow instructions from nucleus
Create proteins the cell needs
Label the cell?
What are tissues?
Tissues are an aggregation of cells with a specialised structure and or function
What are the basic tissues?
Epithelium
Connective
Muscle
Neural
What is epithelium?
“Covering”
Layers of closely bound cells i.) covering internal and extrenal surfaces of organs ii.) linings of cavities and tubes
Supported by basemement membrance
What is the function of epithelium?
Protective/barrier
Control absorption and secretion
Give an example of where epithelial cells can be found?
GI Tract
How are epithelial cells classified?
By shape (squaemous, cuboidal or columnar)
By cell layers (simple or stratified)
What are simple squamous epithelial cells?
Flat surface cells
One layer thick
Function: exchange of nutrients and gases
Location: blood vessels and alveoli
What are stratified squamous epithelial cells?
Flat surface cells
Many layers
Function: barrier, protection
Location: oral cavity, anus, vagina, oesophagus, skin
What are keratinised stratified squamous epithelial cells?
Flat surface cells
Many Layers
Keratin (protein)
Function: protection, barrier, waterproofing
Location - skin, hair, footpads of animals
What is simple cuboidal epithelium?
Cuboid cells
One layer
Function: secretion and absorption
Location: salivary glands, lachrymal glands, pancreas, kidney tubules
What is simple columnar epithelium?
Tall cells with basally located nuclei
One layer
Function: absorption and secretion
Location: many sites in the GI tract e.g. gall bladder
What is modified simple columnar epithelium?
Tall cels with basally located nuclei
One layer
May have modifications e.g. microvilli
Function; ansorption and secretion
Location: enterocytes in the GI tract
What is complex columnar epithelium?
Appear stratified
All cells touch basement membrane
Modifications - cillia and goblet cells
Functions: mucocilliary escalator
Location: trachea and large respiratory airways
How do cell membranes of epithelial cell bind to one another?
Tight junctions or gap junctions
What is connective tissue?
Supporting tissue
Non-living material
Living material e.g. fibroblasts
Structural/metabolic support
What is specialised connective tissue?
Consists of extracellular matrix:
- proteins; proteoglycans, water (“ground substance”)
- tissue fluid
- fibres (collagen, reticular, elastic)
Give some exampls of specialised connective tissue?
Bones and cartilage - hard tissues, high density of cells
Ligament - less dense/fibrous
Adipocytes - loose connections
Blood - cells and proteins
What does muscle tissue consist of?
Muscle cells - fibres
What does muscle tissue do?
Contracts (shortening) and therefore can produce movement
How many types of muscle tissue are there and what are they?
Three - skeletal, cardiac, smooth (hollow organs and blood vessels)
Where is neural tissue found?
In the brain and spinal cord - Central nervous system
Also peripheral nervous system
What are the three main parts of neural tissue?
Dendrite, cell body, axon
