biology: circulation

• Organisms without special transport systems are simple and use:                            

  1. diffusion (slow process) 2. gastrovascular activity
• Jellyfish and the hydra do not have a true circulatory system and rely on the incoming water currents and their  gastrovascular cavity to help move material around the body.
• Grasshopper- open circulatory system- lacking vessels-allowing the blood to move in large sinuses. Insects only one definite blood vessel running the dorsal side.  Blood enters openings at the posterior end called ostia. 
• Insects-Have tracheal which are tubes of trachea leading from the outside of the body inward. The openings are called spiracles.
• closed circulatory system- one that has vessels (veins and arteries) to move the blood and the blood does not flow through sinuses.
• The epidermis of the earthworm acts as a  surface for gas exchange. 
• arteries take blood away from the heart.   
• veins take blood to the heart.        
• capillaries connect arteries and veins
• veins is where the exchange of  materials takes place.
• Veins and arteries have a layer of muscle and an outer layer of connective tissue. 
• atrium is the chamber  of the heart that receives blood.
• The ventricle is the chamber of the heart that pumps blood away from the heart.  It is a very thick-walled layer of muscle.
• Fish have just a two chambered heart.
• Amphibian and most reptiles- three chambered heart; 2 chambered heart 1 ventricle but the ventricle is partially divided preventing complete mixing of blood.
• The right atria receives blood from the body, and the left atria receives blood from the lungs (and skin in some cases).
• Both atria dumps the blood into the ventricle      
•  Blood leaving the right side of the ventricle is diverted to the lungs (and skin in some cases) to pick up O2 and deliver CO2. Blood leaving the left side of the ventricle is diverted to the body to pick up CO2 and deliver O2.
• Birds, crocodiles, and mammals have a four chambered heart 
• Pulmonary circuit takes blood to the lungs to pick up O2 and deliver CO2. 
• Systemic circuit takes blood out to the body to to pick up CO2 and deliver O2.
• Most aquatic animals evolve respiratory organs are found on the outside of the body called gills   
• Blood vessels are very close to the surface of the gills. This clam has cilia to move the water over its gills for gas exchange.
• The water is moving in the opposite direction of the blood.  This is the countercurrent exchange system. It allows for maximum exchange of gasses.
• lungs are found in terrestrial vertebrates and they range from simple sac structures to very complicated subdivided chambers that increase surface area tremendously.
• endotherms  need more oxygen/body weight than ectotherms  
• Birds have well developed lungs and air sacs that allow for unidirectional flow of air in the lungs and  *better efficiency of obtaining oxygen.
• Mammals breathe via negative- pressure breathing- that is air is drawn in by increasing the volume of the lungs by the contraction of the diaphragm. 
• a phloem, B xylem, c cortex, d vascular bundle, e phloem, f epidermis

  
• g epidermis, h cortex, i vascular bundle

  
• • xylem-Dead at maturity and moves minerals (inorganic nutrients) and water UP a stem
• • phloem- Living at maturity moves organic nutrients (sugars, amino acids etc.) up a tree. 
• • epidermis-outside covering.  Protects the herbaceous stem.
• • Vascular cambium makes the cork cells for bark. does mitosis and makes xylem and phloem.  This adds girth to a tree.
  • cork cambium - mitosis makes the bark layer
  • Cork or bark- Waterproof and protects the trunk of the tree.

  
• palisade and spongy mesophyll -underneath the epidermis where photosynthesis occurs.
• vein- Where movement of materials occurs.
• guard cells regulate the stomatal opening. 
• stomata- pore where gas exchange occurs.  CO2 enters and O2 leaves
• tact theory- this is accepted for movement of water and minerals through xylem.
• tension- When the leaf loses H2O via transpiration the H2O is replaced by water from other cells.