Biology Topic 2

• Tissue - A group of cells.
• Organ - A group of tissues.
• Organ system - Group of organs.

Animal Tissues:

• Glandular - Secrete hormones & enzymes.
• Muscular - Contract & relax.
• Epithelial - Secretion, absorption & protection.

Plant Tissues:

• Epidermal - Covers the outer surface.
• Palisade mesophyll - Chloroplasts for photosynthesis.
• Spongy mesophyll - Diffuses gas (has many air spaces) and photosynthesises.
• Xylem - Transports water and dissolves material.
• Phloem - Transports dissolved food.
• Stomata - Lower epidermis, diffusion and helps guard cells close.

A biological catalyst.

• Controls metabolism (the sum of all reactions).
• Denature - Active site loses shape because too hot/ cold or PH being wrong.
• Active site - Where the reaction happens - has unique shape.
• Enzymes are a long chain of folded amino acids (specific).

• Amylase -  Carbs & Starch to sugars.
• Protease - Protein to amino acids.
• Lipase - Fatty acids to speed up reactions.
• Pancrease - Produces enzymes.
• Liver - Produces bile.
• Mouth - Contains saliva glands, teeth, toungue & amylase.
• Oesophagous - Transports the food.
• Stomach - Contains protease. Churns food. 
• Small intestine -  Large surface area. Enzymes are used for food digestion (molecules made smaller).
• Large intestine - Water is absorbed.

Transpiration

• Guard cells and stomata let water & minerals in/ out of the cell.
• Xylem moves them from root to leaves.
• Provides water for photosynthesis, transports mineral ions, cools the leaf and helps keep the plant healthy.
• Affected by: light, temperature and humidity.

Gas Exchange

• Nose -> Trachea -> Bronchi -> Bronchioles -> Alveoli.
• Alveoli have many capillaries and a large surface area.
• Breathing in - Diaphram flattens, ribs out, volume increases and low pressure.
• Breathing out - Diaphram goes up and out, ribs out,volume decreases and Higer pressure.

Helping the heart.

• Stent - Small mesh tube inserted into partially blocked artery. A balloon is inflated to expand the stent. The ballon is removed from the expanded stent.
• Vavle Replacement - Lasts 12 - 15 years, the faulty valve is replaced with a working one.
• Pace maker - A small device implanted in the chest to regulate the heartbeat.
• Artificial Heart - Temporary, risk of blood clots, no tissue match is needed.
• CHD - The narrowing of the coronary arteries ( that supply blood to the heart) causing blood clots.

Blood/ Blood Vessels

• Veins - Thin walls, low pressure, in the heart allow safe backflow.
• Arteries - Thick muscular walls, higher pressure, oxygenated blood away from the heart.
• Capillaries - One cell thick for diffusion.
• Red Blood Cells - No nucleus, haemoglobin binds to O2, disk shaped.
• White Bloods Cells - Produce: antibodies & antitoxins, engulf & digest pathogens.
• Platelats - Cell fragments that help blood clotting. (For example, scabs)
• Plasma - Transports blood cells & other substances. (For example, glocose)