Chapter 7: Transportation in Animals and Plants
7.1 Circulatory System
Blood and its Components
- Blood: A fluid that flows in blood vessels, transporting digested food, oxygen, and waste products.
- Plasma: The fluid part of the blood in which various cells are suspended.
- Red Blood Cells (RBC): Cells containing haemoglobin, a red pigment that binds with oxygen and transports it throughout the body.
- White Blood Cells (WBC): Cells that fight against germs and infections entering the body.
- Platelets: Specialized blood cells responsible for blood clotting to stop bleeding.
Blood Vessels
- Arteries: Thick-walled, elastic vessels that carry oxygen-rich blood away from the heart at high pressure.
- Veins: Thin-walled vessels with valves that carry carbon dioxide-rich blood back to the heart. Valves prevent backflow.
- Pulse: The throbbing movement felt in arteries due to blood flow. A resting adult has a pulse rate of 72 to 80 beats per minute.
- Capillaries: Extremely thin tubes that connect arteries to veins, allowing exchange of substances with tissues.
- Pulmonary Artery: Carries carbon dioxide-rich blood from the heart to the lungs (exception to typical arteries).
- Pulmonary Vein: Carries oxygen-rich blood from the lungs to the heart (exception to typical veins).
The Heart
- Heart: A muscular organ, roughly the size of a fist, located in the chest cavity, acting as a continuous pump.
- Chambers: Divided into four chambers to prevent mixing of oxygen-rich and carbon dioxide-rich blood: two upper atria and two lower ventricles.
- Heartbeat: The rhythmic contraction and relaxation of heart muscles, measured using a stethoscope.
7.2 Excretion in Animals
Human Excretory System
- Excretion: The process of removing toxic waste products produced in cells from the body.
- Kidneys: Two organs that filter blood to remove waste products in the form of urine.
- Ureters: Tube-like structures that carry urine from the kidneys to the bladder.
- Urinary Bladder: A muscular sac that stores urine until it is passed out.
- Urethra: The muscular tube through which urine is eliminated from the body.
- Urine Composition: Typically consists of 95% water, 2.5% urea, and 2.5% other waste products.
- Dialysis: An artificial blood-filtering process used when a person's kidneys fail.
Excretion in Other Animals
- Aquatic Animals (e.g., Fish): Excrete cell waste as ammonia, which dissolves directly in water.
- Land Animals (e.g., Birds, Lizards, Snakes): Excrete a semi-solid, white compound called uric acid.
- Humans: Primarily excrete urea.
- Sweat: Contains water and salts; helps in removing waste and cooling the body.
7.3 Transport of Substances in Plants
Vascular Tissues
- Root Hairs: Increase the surface area of roots for absorbing water and mineral nutrients from the soil.
- Xylem: Vascular tissue forming a continuous network of channels to transport water and nutrients from roots to leaves.
- Phloem: Vascular tissue responsible for transporting food prepared by leaves to all parts of the plant.
Transpiration
- Transpiration: The evaporation of water through stomata on leaf surfaces.
- Suction Pull: Generated by transpiration, pulling water to great heights in tall trees. Also helps in cooling the plant.