Lesson 4 Immune system and Excretory systems

• Substance exhange between an animal and it's sourrounding works on a?

  Cellular level
• Homeostasis is maintained through negative feedback loops that are controlled by hormones, nerves or both.
• Animals require O2, which enters the cytoplasma by crossing the plasma membrane
• The metabolic by products of animals are CO2, which exits the cell by crossing the plasma membrane
• Diffusion is the net movement of molecules down their concentration gradient (from higher to lower concentrations)
• Osmosis is the movement of water across a selectively permeable membrane from a region of high solute concentration to one of low solute concentration
• Multicellular organisms require specialized system that carry out exchange with the environment and transport materials between sites of exchange and the rest of the body.
• For organisms with gills, blood vessels lie beneath the surface of each filament of the gills. There a diffusion of O2 from the water to blood and diffusion of CO2 from the blood to the water
• Non polar molecules (O2 and CO2) can move between surroundings by diffusion
• The time it takes for a substance to diffuse from one place to another is proportional to the square of the distance.
• Simple diffusion and a gastrovascular cavity are sufficient for small animals with low metabolic rates
• Larger body sizes require more complex body plans and higher metabolic demands
• A muscular pump (or heart) uses metabolic energy to generate hydrostatic pressure that forces the fluid through the circuit.
• In an open circulatory system blood cells move from the vessels into the interstitial fluid.
• Interstitial fluid: Fluid found in the spaces around cells. Helps bring oxygen and nutrients cells and remove waste products.
• Arthropods, molluscs have a ?

  open circulatory system
• Circulatory fluid in open circulatory systems is called?

  Hemolymph (free movement of cells between the vessels and the interstitial cells)
• In a closed circulatory system, the circulatory fluid is called blood.
• In a closed circulatory system, one or more heart pumps blood into large vessels that branch into smaller ones that infiltrate the organs.
• In a closed circulatory system chemical exchange occurs between the blood and the interstitial fluid.
• In the human system blood cells remain within the vessels at all times.
• There are three types of blood vessels, which ones ?

  Arteries, Arterioles, Capillaries (Blood only flows in one direction)
• Arteries: Carry blood away from the heart to organs throughout the body
• Arterioles: Small arteries that branch off arteries to carry blood to capillaries
• Capillaries: microscopic blood vessels that connect arteries and veins.
• Arteries carry blood from the heart TOWARD capillaries.
• Veins return blood to the heart FROM capillaries.
• The typical osmolarity of human blood is 300 mOsm/L
• Homeostasis requires osmoregulation
• Regulation of solute concentrations and water balance by a cell or organism. Animals control solute concentrations and balance water gain an loss.This is called?

  Osmoregulation
• Animals in an ocean environment depend on conserving water. And eliminating excess salts.
• Fresh water animals survive by conserving solutes and absrobing salts from their surroundings.
• Disposal of nitrogen-containing metabolites and other wate products. This is called?

  Excretion
• Water enters and leaves cell by osmosis
• Osmosis occurs when two solutions separated by a membrane differ in total solute concentration.
• two solutions with the same osmolarity are ?

  Isoosmotic
• The solution with greater concentration of solute is said to be ?

  Hyperosmotic
• The more dilute solution is said to be?

  Hypoosmotic
• Osmoconformer (when there is a change in the environment) will permit its internal osmolarity to change
• An Osmoregulator (when there is a change in the environment) will resist a change in internal osmolarity.