Gas Exchange in Animals

Gas Exchange in Animals

• Thorax Structure: The thorax is a cage-like structure enclosed by ribs. Intercostal muscles lie between the ribs; the diaphragm separates the thorax from the abdomen. The trachea, bronchi, and bronchioles are part of the airway system. Alveoli are tiny air sacs in the lungs. Pleural membranes line the lungs and thorax, reducing friction during breathing.

• Ventilation: Intercostal muscles and the diaphragm work together to change the volume of the thoracic cavity, causing air to move in and out of the lungs.

• Alveoli Adaptation: Alveoli are thin-walled, maximizing the surface area for gas exchange. The blood in surrounding capillaries has a high concentration of carbon dioxide, which diffuses into the alveoli. Oxygen in the alveoli diffuses into the blood.

• Smoking's Effects: Smoking damages the lungs and circulatory system, leading to conditions such as coronary heart disease.

• Practical Application: Practical investigations should focus on breathing, carbon dioxide release, and exercise effects.

Transport in Plants

• Phloem Function: Phloem transports sucrose and amino acids from leaves to other plant parts.

• Xylem Function: Xylem transports water and mineral ions from roots to the rest of the plant.

• Water Absorption: Root hair cells absorb water from the soil via osmosis.

• Transpiration: Transpiration is water evaporation from a plant's surface.

• Transpiration Factors: Environmental factors like humidity, wind speed, temperature, and light intensity affect the rate of transpiration.

• Practical Application: Practical investigations should investigate the role of environmental factors on transpiration rates.

Excretion

• Excretion Organs: Lungs, kidneys, and skin remove waste products from the body.

• Kidney Function: Kidneys perform excretion and osmoregulation. They filter waste products from the blood.

• Urinary System: The urinary system includes the kidneys, ureters, bladder, and urethra. Urine travels through the system and is expelled.

• Nephron Structure: Nephrons are the functional units of the kidneys. They include the Bowman's capsule, glomerulus, convoluted tubules, loop of Henle, and collecting duct.

• Ultrafiltration: Fluid is filtered in the Bowman's capsule. The filtrate contains most substances in blood except blood cells and large proteins.

• Water Reabsorption: Water reabsorption occurs in the collecting duct, controlled by hormones.

• Glucose Reabsorption: Glucose is selectively reabsorbed in the proximal convoluted tubule.

• ADH Role: Antidiuretic hormone (ADH) regulates water reabsorption in the collecting ducts, balancing water levels in the blood.

• Urine Composition: Urine consists of water, urea, and ions.

Coordination and Response

• Plant Responses: Plants respond to stimuli, such as light and gravity.

• Geotropism and Phototropism: Roots exhibit positive geotropism (growing towards gravity) and negative phototropism (growing away from light). Stems show negative geotropism and positive phototropism.

• Auxin Role: Auxin is a plant hormone influencing stem growth and phototropism.

• Central Nervous System: The human central nervous system (CNS) includes the brain and spinal cord. It controls rapid responses.

• Sensory Input: Receptors in sense organs send electrical signals (impulses) along nerves to the CNS, leading to responses.

Explore the intricacies of gas exchange in animals, focusing on the structure of the thorax, ventilation processes, and the importance of alveoli. Understand how smoking impacts respiratory health and the practical applications of this knowledge in investigations. Test your knowledge on these vital biological concepts.