AS Biology - Organisation

AS Biology - Levels of organisation:
Covering:
Tissues,
Muscles,
Organs

Transcript

2. Differentiation and specialisation • Single celled organisms carry out life functions within a single cell • Multicellular organisms have specialised cells (that form tissues and organs) which have various structures and roles • Stem cells have the potential to become any type of cell in the body • Differentiation is the development of a cell into a specific type
3. Tissues A tissue is a group of cells (that have the same structure and function) working together
4. Mammalian tissues – Epithelial • Forms a continuous layer that covers/lines internal and external surfaces • No blood vessels but some have nerve endings • Sit on a basement membrane • Have a protection or secretory function
5. Simple cuboidal epithelium • Simplest form of epithelial tissue • Cells have a cube shape • Only one cell thick (simple) Found: • Proximal convoluted tubule of kidney nephron • Ducts of salivary glands Simple cuboidal epithelial cell Nucleus Basement membrane
6. Columnar epithelium • Elongated cells • Some may have cilia Found: • Oviduct (fallopian tube) • Trachea Cilia Ciliated columnar epithelium cell Nucleus – Usually at the bottom of the cell Basement membrane
7. Squamous epithelium • Flattened cells on a basement membrane Found: • Alveoli walls • Renal (Bowmans) capsule of the nephron Nucleus Squamous epithelial cell Basement membrane
8. Mammalian tissue – Muscle • 3 main types • Slightly different structures and functions
9. Skeletal muscle • Striped or serrated muscle • Bands of long cells or fibres • Can get easily tired • Generates locomotion in mammals • Voluntary and powerful contractions • Found attached to bones
10. Smooth muscle • Unstriped or non serrated muscle • Does not have stripes • Individual spindle-shaped cells • Involuntary contractions, not as powerful as skeletal • Contract rhythmically • Found in skin, blood vessel walls, digestive tract and respiratory tract
11. Cardiac muscle • Has stripes • Lacks long fibres • Does not tire • Contracts rhythmically without stimulation • Involuntary and myogenic contractions
12. Mammalian tissue - Connective • Connects, supports or separates tissues and organs • Contains elastic and collagen fibres in an extracellular fluid or matrix • Fat storing cells (Adipose cells) and cells of the immune system are in-between the fibres
13. Organs An organ is a group of tissues (in a structural unit) working together and performing specific function
14. Organ – Example A leaf is an organ of a plant