Cells & Tissues

Cells & Tissues

Tissue
1. Cells that are specialised that are grouped together with other cells that have similar functions that make up animals or plants
2. There are four basic animal tissue types: epithelial, muscular, connective & nervous
3. Plant tissues can be put into two types: meristematic & permanent
4. A group of cells form a tissue, group of tissues form an organ and group of organs form an organ system
Stem Cell
1. Are a cell that is undifferentiated fertilized egg and is able to divide itself and then has the potential to either stay as a stem cell or become differentiated and become another cell with a specialised function like a red blood cell, and this can happen in the body during growth and early life. They are able to make all organs and tissues in the body.
2. Stem cells in adult bodies have a slight different role, the s.cells are used to repair and replace damaged cells or tissues.
3. Stem cells are unspecialised cells that are able to change what cell they are by cell division and they are able to become tissue or organ specific cells with special certain functions however this is under experimental conditions.
Cell Differentiation
1. Process of generic embryonic cells that become a specialised cell type
  1. Happens via process called gene expression; where the combination of genes are expressed/repressed and dictates how a cell functions. Gene differentiation occurs many times during development of multicellular organism as the zygote changes from a simple to complex system of cells and tissues
2. Purpose: Allows more complex organisms to live in the first place. Cells are first known as stem cells; no specialisation, the growth of more complex organisms allows cells to be able to go into different organs and tissues. Differentiation allows multiple cells to share their function of their specialised cell so that they would not have a small amount of cells taking on the functions which could result in organism not to survive as there wouldn't be enough cells to complete the functions of the specialised cell.
Tissues & Adaption for their role
1. Small Intestine
  1. Absorbs nutrients and minerals from food and digestion of food occurs ninety percent here.
  2. Length of intestine allows that food remains up to 8 hours, giving enough time for digestion
  3. Food and enzymes are mixed but the process of reaching to the ileum needs to be delyaed so the small intestine has a large surface area due to length and the villi also increases surface area x10, then each villi has microvilli that also increase surface area by x20.
  4. Layer of columnar epithelial cells that is an absorptive surface that ensures diffusion to be quick which helps the absorption function, also has moist absorptive surface that is due to water in digestive juices, needed and important as diffusion only occurs in solution.
  5. The villi helps the food to stay in contact with surface by stirring food as villi has smooth muscle fibers.
  6. Each villus has blood capillaries that are able to take solution to the liver, to remove absorbed nutrients. Also has bile which emulsifies fats which allows better digestion
2. Alveolus of lung
  1. A large surface area allows gas exchange to be efficient. Thin surface allows quicker diffusion to occur. The surfaces are moist which helps when gas transport when diffusion occurs.
  2. Helps gas exchange to be more efficient, to get oxygen in the blood and remove carbon dioxide from the blood
  3. Has many small capillaries that help the difussion to be efficient as the exchange of oxydgen and carbon dioxide happens through the capillarity wall.
3. Large artery
  1. Carries blood away from the heart
  2. The artery is wide and the walls are elasticised which allows pulse wave to dissipate when the blood(pulse wave) leaves the heart. Muscular walls help to stand the pressure of the blood and to allow to apply force
    1. As the artery expands, the elastic walls help to shrink and expand in time with the beats of the heart and allows blood to be pump blood steadily through vessels.
4. Peripheral nerve
  1. Nerve in control of limbs of the body, connects to the CNS to limbs, communication occurring between brain and other parts further away.
  2. Adapted to role: By going through process of myelination, which allows electrical signs to be sent at a faster speed, which picks up the lac of diameter size of the nerves. The nerve is very long about a metre long which is needed as it allows nerve to spread.
5. Skeletal muscle
  1. Cells are striated, meaning more cells are able to fit, that allows more cross bridges to form to allow contraction of muscles
  2. Helps to maintain posture, making sure body is upright posture
  3. Proteins the muscle has allows the role to be carreid out as the proteins-myofibrils(are cylinders of muscle proteins) are contained in the muscle fiber
  4. Has calcium ions that are stored in the membrane system called sarcoplasmic reticulum, the ions are binded to troponin and then moves to tropomyosin away from the actin filament which allows the myosin head to bind to the actin which then enables the contraction.

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	Created by kiirenxox2052 almost 10 years ago