The circulatory system in animals facilitates nutrient, oxygen, and waste transportation via the heart and blood vessels, including arteries, veins, and capillaries. Excretion removes metabolic wastes, with variations across species and specific mechanisms in humans. Plants utilize xylem for water and mineral transport, and phloem for food distribution, while transpiration drives water movement. These biological processes ensure essential substance circulation and waste elimination
CIRCULATORY SYSTEM
The circulatory system is the sophisticated network responsible for the internal transport of essential substances throughout an animal’s body. It ensures the delivery of nutrients, oxygen, and the removal of metabolic wastes. This system is primarily composed of the heart and blood vessels.
- Blood: A specialized fluid tissue that circulates within blood vessels, acting as a medium for transport.
- Plasma: The liquid matrix of blood, serving as a suspension medium for various cells and dissolved substances.
- Red Blood Cells (RBCs): Contain hemoglobin, a protein that binds to oxygen, facilitating its transport to all tissues and organs.
- White Blood Cells (WBCs): Function as part of the immune system, defending the body against infections and foreign invaders.
- Platelets: Small cell fragments that play a crucial role in blood clotting, preventing excessive blood loss.
- Blood Vessels: The network of tubes through which blood circulates.
- Arteries: Carry oxygenated blood away from the heart to the body’s tissues. They possess thick, elastic walls to withstand the high pressure of blood flow. The pulse, a rhythmic throbbing, is a manifestation of arterial blood flow.
- Veins: Carry deoxygenated blood from the body’s tissues back to the heart. They have thinner walls compared to arteries and contain valves that prevent backflow, ensuring unidirectional blood flow.
- Capillaries: Microscopic vessels that form a network connecting arteries and veins. They facilitate the exchange of gases, nutrients, and waste products between blood and tissues.
- Heart: A muscular organ that acts as a pump, propelling blood throughout the circulatory system.
- Located within the thoracic cavity, slightly left of center.
- Comprised of four chambers: two upper atria and two lower ventricles.
- A septum, a muscular wall, separates the right and left sides of the heart, preventing the mixing of oxygenated and deoxygenated blood.
- The rhythmic contraction and relaxation of the heart muscle constitute the heartbeat. The normal resting heart rate for an adult is approximately 70-80 beats per minute. A stethoscope is used to amplify heart sounds for diagnostic purposes.
- In simpler organisms like sponges and hydra, direct diffusion and water currents facilitate internal transport.
Blood Vessels
Blood vessels are essential components of the circulatory system, enabling efficient blood flow.
- They form an integral part of the circulatory system, working in conjunction with the heart.
- Arteries transport oxygen-rich blood, while veins return carbon dioxide-rich blood.
- The pulse is the result of blood flow through arteries.
- Capillaries facilitate the exchange of substances between blood and tissues.
Heart
The heart serves as the central pump within the circulatory system, ensuring continuous blood circulation.
- It works in tandem with blood vessels to maintain blood flow.
- Arteries carry blood away from the heart, and veins return blood to it.
- The heart’s muscular walls enable rhythmic contractions, crucial for pumping blood.
Heartbeat
The heartbeat is the rhythmic contraction and relaxation of the heart muscle, driving blood circulation.
- Each heartbeat generates a pulse, detectable in arteries.
- A stethoscope aids in listening to heart sounds.
- The normal adult heart rate is about 70-80 beats per minute.
EXCRETION IN ANIMALS
Excretion is the process by which animals eliminate metabolic waste products.
- Blood transports waste products to excretory organs.
- Excretion removes cellular wastes from the body.
- Aquatic animals excrete ammonia, land animals uric acid or urea.
- Lungs and digestive system also play roles in waste elimination.
Excretory System in Humans
The human excretory system filters blood and eliminates waste in the form of urine.
- Kidneys filter blood, reabsorbing essential substances and removing wastes.
- Urine travels through ureters to the bladder and is expelled through the urethra.
- Urine composition: primarily water, urea, and other waste products.
- The kidneys, ureters, bladder, and urethra constitute the excretory system.
TRANSPORT OF SUBSTANCES IN PLANTS
Plants transport water, minerals, and food throughout their bodies using specialized tissues.
- Leaves produce food through photosynthesis.
- Roots absorb water and minerals from the soil.
- Xylem tissue transports water and minerals upward.
- Phloem tissue transports food throughout the plant.
Transport of Water and Minerals
Plants absorb and transport water and minerals from the soil to their leaves and other parts.
- Root hairs increase the surface area for absorption.
- Xylem forms a continuous network for upward transport.
- Minerals dissolved in water move through the xylem.
Transpiration
Transpiration is the process of water evaporation from plant leaves, creating a transpiration pull.
- Water evaporates through stomata, small pores on leaf surfaces.
- Transpiration creates a suction force that pulls water up from the roots.
- Transpiration also helps to cool the plant.
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