Transport in Animals and Plants

Transport in Animals and Plants

• William Harvey, an English physician, described blood circulation in 1628.
• Botanists in 1720 focused on how materials move inside plants.
• Transport is a vital physiological process, nourishing and supplying cells with oxygen.
• Animals and plants have common functions in nourishing cells and supplying them with basic needs.
• Transport systems collect and transport waste, move immune system components, and carry hormones (endocrine gland secretions in animals).

Transport in Simple Animals

• Organisms with a two-cell layer covering obtain gases and excrete wastes through diffusion.
• In simple animals like sponges and cnidarians, gas exchange occurs between water from the environment and circulating body fluids.
• In sponges, water flows through porocytes to the spongocoel (central cavity).
• Cnidarians (like hydra) have cells contacting water containing oxygen and nutrients.
• The gastrovascular cavity acts as both a digestive and rudimentary circulatory system.

Transport in Roundworms (Nematodes)

• Body fluids are used for circulation in roundworms (nematodes).
• No distinct circulatory systems (hearts, blood vessels, blood) exist in pseudocoelomates.
• Nutrients, oxygen, and waste move through body fluids by diffusion.
• Their simple body structure allows diffusion to serve their needs.

Types of Circulation in Animals

• Open Circulatory System: Circulating fluid (hemolymph) isn't contained in vessels; it's pumped into a network of channels and cavities (hemocoels) and gas exchange occurs in hemocoels.
• Closed Circulatory System: Blood flows within blood vessels, transported away from and back to the heart.

The Human Circulatory System

• Heart: A muscular organ pumping blood throughout the body. It develops early in embryo development and beats constantly.
• Heart Structure: Composed of cardiac muscle, the pericardial cavity (covered by pericardium), a septum dividing it into right and left sides, with each side further divided into atria and ventricles. The chambers have one-way atrio-ventricular valves.
• Heart Function: The right side receives deoxygenated blood from the body, while the left side receives oxygenated blood from the lungs. Blood flows from the superior/inferior vena cava to the right atrium, through the tricuspid valve to the right ventricle, then through the pulmonary valve to the pulmonary arteries and to the lungs for oxygen. Oxygenated blood returns to the heart through pulmonary veins to the left atrium, through the mitral valve, to the left ventricle, then through the aortic valve, and out to the aorta.
• Heart Sounds ("Lub Dub"): The "lub" sound results from tricuspid and mitral valves closing, while the "dub" sound comes from the aortic and pulmonary valves closing.
• Blood: The body's internal circulating medium, transporting oxygen, nutrients, and nitrogenous waste. It's composed of 55% plasma and 45% blood cells (red blood cells, white blood cells, platelets).

Blood Components

• Red Blood Cells (Erythrocytes): Transport oxygen and carbon dioxide, contain hemoglobin.
• White Blood Cells (Leukocytes): Defense and immunity (neutrophils, lymphocytes, monocytes, eosinophils, basophils).
• Blood Platelets (Thrombocytes): Crucial for blood clotting. They clump at injury sites to prevent blood loss.
• Plasma (Blood): Water (about 90%), proteins, electrolytes, hormones, nutrients, and waste products.

Blood Vessels

• Arteries: Thick-walled vessels carrying oxygenated blood (except pulmonary arteries). The aorta is the largest artery.
• Veins: Thinner-walled, carry deoxygenated blood (except pulmonary veins). The vena cava are the largest veins.
• Capillaries: Microscopic, connect arteries and veins, sites of material exchange between blood and cells due to their thin walls.

Pathways for Water and Minerals in Plants

• Land plants (embryophytes) can be nonvascular (bryophytes) or vascular (tracheophytes).
• Vascular plants have a vascular system with xylem and phloem.
• Xylem transports water and minerals.
• Phloem transports food made during photosynthesis.
• Pathways for water and mineral transport are: apoplast, symplast, and transmembrane.
• The xylem sap is pulled up by transpiration forces.

Xylem Transport

• Transpiration (evaporation) from leaves creates a pulling force that moves water and minerals through xylem.
• Cohesion-tension theory- water molecules stick to each other (cohesion) and to the walls of xylem vessels (adhesion) to move upward.
• Water potential drives the movement of water.

Phloem Transport

• Translocation moves food (sugars) throughout the plant.
• Pressure-flow model describes how pressure differences (created by water movement driven by osmosis) drive sap flow from source (sugars produced in the leaves) to sink (regions where sugars are stored or needed for growth).

Check Your Understanding – possible questions

• Differences between transpiration and translocation
• Relevance of cohesion, adhesion, and water potential in xylem transport.
• Pressure-flow theory, and relevance of turgor pressure.
• Radial rays, examples of plants.
• Drawing of apoplast, symplast, and transmembrane pathways, labeled.

Explore the crucial transport systems in animals and plants, focusing on how nutrients and gases are circulated. Learn about historical contributions to our understanding of blood circulation and the mechanisms simple organisms use for gas exchange. This quiz covers the physiological processes that nourish and support life in these diverse forms of life.