Cells
Cells have many basic functions, but others can have specialist functions.
Cell- They are the basic unit of living material
Tissues- groups of cells joined together to carry out a particular task
Organ- a collection of tissues joined together to carry out a specific function
Organ system- a group of organs responsible for similar functions
Electron microscope- necessary to see detail of cell contents. A very powerful type of microscope, needed
to see inside cells.
Photomicrograph- a photograph taken of an object magnified using a microscope.
o Respiration- cells require and absorb oxygen to produce heat and energy.
o Growth- cells grow to maturity by manufacturing proteins, they then divide or specialise.
o Excretion- waste products pass out through the cell membrane.
o Irritability- cells can respond to a physical, chemical, or thermal stimulus.
Organelle- a tiny body inside a cell, which carries out its own functions.
Cell membrane- an outer coating which transports substances in and out of the cell, “cell
material”.
Cytoplasm- semi fluid material, like a gel which can flow slowly. Many chemical reactions take place here.
Metabolism takes place here.
Nucleus- the control centre of the cell which regulates its functions. Contains genetic material, a source of
ribonucleic acid. 23 pairs of chromosomes in a human cell- contains DNA.
Ribosomes- made up of RNA and protein so that they can manufacture other proteins.
Rough and smooth endoplasmic reticulum- manufactures, stores, and transports materials within and
outside of the cell. Rough ER- made up of ribosomes and has the function of making cell proteins and
acting as a temporary storage area. Smooth ER- has not attached ribosomes and involved in the
metabolism of lipids of fats.
Mitochondria- situated in the cytoplasm, they are the powerhouse of the cell providing all the energy. ATP-
a chemical in mitochondria capable of trapping and storing energy, ADP- a chemical left after ATP has
released its stored energy to do work.
Golgi apparatus- modifies and stores manufactured protein and transports it out of the cell. Produces
lysosomes.
Lysosomes- contains enzymes which digest worn out parts of the cell for recycling and elimination of waste
products. “Suicide bags”. Destroys bacteria and foreign materials.
Centrioles- play a part in cell division, made up of protein.
Characteristics of tissues
Epithelial, connective, muscle, and nervous tissues.
Epithelial tissues
Function of the epithelial tissue- protect underlying structures like organs, secrete (goblet cells line the
digestive system to secrete enzymes and mucous), absorb (lines the lungs absorb oxygen from the air)
Structure of the epithelial tissue- four different types of simple epithelial tissue and 2 different types of
compound epithelium.
A simple cuboidal are cube shaped cells which have a large nucleus which is spherical and central. It
allows substances to pass by diffusion and osmosis. Can absorb and secrete substances. They are found on
the surface of ovaries, thyroid gland, and kidney tubules.
A simple squamous is very flat, has thin cells, forms a
large lump. They allow substances to pass through
by diffusion and osmosis. They are found in the walls
of blood capillaries, alveoli of the lungs.
A simple columnar can be found in the ear, nose.
Used for protection and absorption/ transportation
of transport. They are tall column-like cells which are
slightly oval nuclei at the base of the cells.
A ciliated are tall column like cells, they have hair like
structures called cilia. They line the respiratory tract
and line the oviducts. They move in wave like motions which removes duct and bacteria, and they move
the ova through the oviduct.
, A simple compound/ stratified epithelium consists of several
layers of cells, the outer layer of which may be worn away.
Usually found where the body is subject to wear and tear.
Stops movement of substances and protects the body. Found
in the vagina, mouth, tongue, and oesophagus.
In keratinised compound epithelium like our skin, the outer
layers of cells are dead, flattered and filled with a protein
called keratin. This gives the tissue a waterproof outer layer.
Diffusion- the passage of molecules from a high concentration to a low concentration.
Osmosis- the passage of molecules from a region of high concentration of water molecules to one of a low
concentration.
Where I can find the epithelial tissues- form the covering of all body surfaces, line body cavities and hollow
organs, and are the major tissue in glands.
Connective tissues
Function of the connective tissue- to provide structural support (for bones and cartilage in the skeletal
system and areolar tissue which bonds to skin and muscle), protect (skull protects the brain and ribs protect
the heart and lungs), insulate (adipose tissue contain fatty deposits to help prevent heat loss)
Structure of the connective tissue- they are background materials known as the matrix, they may be liquid
like blood, jelly like areolar tissue, firm like cartilage, or hard like bone.
Cartilage- Elastic, which is the most flexible, hyaline is the 2 nd most flexible, fibrocartilage is the least
flexible, provides the most support but is less rigid than bone. More stable than a muscle and allows
flexibility for movement- can be found at the ends of the bone.
Adipose- fatty tissue, store energy in the form of fat, cushions and insulates the body, adipose tissue
is located under the skin but also around internal organs.
Areolar- surrounds blood vessels, nerve bundles, muscles and holds organs in place. It fills spaces
between organs and connects skin to the underlying muscular layers. - found under the dermis of
the skin.,
Bone- mineralized connective tissue that exhibits four types of cells, exerts important functions in the
body such as locomotion, support and protection of soft tissues, calcium and phosphate storage
and harbouring of bone marrow. Found- in the spine and throughout the body
Blood- carries oxygen around the body for all cells to function. Arterial blood- flows from the heart
and is usually bright red oxygenated blood. Venous blood- flows towards the heart and is usually
dark red deoxygenated blood. Found- in the circulatory system and throughout the body
Where can I find the connective tissues- cartilage, adipose, areolar, bone, and blood.
