Red Blood cell
Red blood cells perform the most important blood duty. A single drop of blood contains millions of red blood cells, which are constantly travelling through the body delivering oxygen and removing waste. If they weren't, everything in the body would slowly die.
Red blood cells are red only because they contain a protein chemical called Haemoglobin, which is bright red in colour. Haemoglobin contains the element Iron, making it an excellent vehicle for transporting oxygen and carbon dioxide. As blood passes through the lungs, oxygen molecules attach to the Haemoglobin. As the blood passes through the body's tissue, the Haemoglobin releases the oxygen to the cells. The empty haemoglobin molecules then bond with the tissue's carbon dioxide or other waste gases, transporting it away. The structure of these cells is a flying disk shaped like a donut, this is so maximum haemoglobin can be carried allowing maximum amount of oxygen to be transported.
Plant cell and Animal Cell
There are two types of cells: prokaryotic cells and eukaryotic cells.
The simplest cells are prokaryotic cells like bacteria. Eukaryotic cells are more complex and are found in plants, animals and fungi. A plant cell is made up in a similar way to animal cell but also has it differences so it can perform its particular functions. The shape form and content of individual cells show much variation. The structural characteristics of a particular cell are closely related to its function.
Plant cells
The cells of plants, like fungi have outer cell walls made from tough fibres of cellulose surrounded by a matrix of other polysaccharides this is in addition to the already present cell membrane, this cell wall is used for protection and to keep the cell rigid. Other additions to a plant cell are the vacuole, which contains sugar and salts, and it affects the concentration of cytoplasm and is a store in-organic ions. Also during osmosis the vacuole swells up as it is surrounded by weak solution and causes turgid pressure, this gives support to green plant tissue. Photosynthetic cells packed with Chloroplasts perform the task of photosynthesis in the internal membrane system where this reaction is catalysed. These Chloroplasts contain chlorophyll, which absorbs the suns energy and the process of photosynthesis.
Animal Cells
These cells are less developed than the plant cells due to there being no need to carry out photosynthesis and keeping the cell rigid. The cell is made from water so this can lead to it bursting. On the cell surface membrane Animal cells have a plasma membrane which controls the movement of substances into and out of the cell. A phospholipid layer constructs it with hydrophilic tails in the middle; these act as a pathway in and out of the cells.
Muscle cell
There are three types of muscles in the body:
- Smooth muscle,
- Triated muscle (skeletal muscle),
And
Smooth muscles are involuntary (i.e., they cannot be controlled freely). Their cells have a variable length. Smooth muscles are found in the digestive system, in the wall of the trachea, uterus, and bladder. The contraction of smooth muscle is controlled from the brain through the nervous-system.
Striated muscles, are also called skeletal muscles because of their basic location, are formed from a large number of muscle fibres. Each fibre forms a (muscle) cell and are distinguished by the presence of alternating dark and light bands.
Cardiac muscle is also striated, but differs in other ways from skeletal muscle: Not only is it involuntary, but also when excited, it generates a much longer electric impulse than does skeletal muscle, lasting about 300 ms. Correspondingly, the mechanical contraction also lasts longer. Furthermore, cardiac muscle has a special property: The electric activity of one muscle cell spreads to all other surrounding muscle cells, owing to an elaborate system of intercellular junctions.
Cardiac muscles: centrally located nuclei, muscle cells are branched and the present of intercalated discs.
