BSC2010 - BIOLOGICAL SCIENCE 1 – FALL 2012Principles and ConceptsBSC2010-01- BIOLOGICAL SCIENCE 1- FALL 2012Principles and ConceptsBSC2010 - BIOLOGICAL SCIENCE 1- FALL 2012Antimicrobial peptides and proteinsApoptosisBarrier defensesEosinophylsGranzymeHistamineInflammatory responseInnate immunityPrinciples and ConceptsBSC2010 - BIOLOGICAL SCIENCE 1- FALL 2012Principles and ConceptsBSC2010 - BIOLOGICAL SCIENCE 1 – FALL 2012STUDY GUIDE 19: THE CIRCULATORY SYSTEMIntroduction- Diffusion is rapid only over small distanceso Body size and shape keep cells in direct contact with the environment. Each cell can exchange materials directly with the surrounding medium.o Circulatory system that moves fluid between each cell’s immediate surroundings and the tissues where exchange occurs.- Animals that lack a circulatory system:o Central gastrovascular cavity functions borth in digestion and in the distribution of substances throughout the body. A single opening maintains the continuity between the fluid inside the cavity and the water outside. As a result, both sides are bathed by fluid. Only cells in the inner layer have direct access to nutrients but since the body wall is two cells thick, nutrients diffuse a short distance to reach the cells of the outer layer.o A flat body optimizes diffusional exchange by increasing surface area and minimizing diffusion distances. Open and Closed Circulatory Systems- The circulatory system connects the aqueous environment of the body cells to the organs that exchange gases, absorb nutrients and dispose of wastes.- A circulatory system has three components:o A circulatory fluido A set of interconnecting tubeso A pump: heart that uses metabolic energy to elevate the pressure of circulatory fluid.- Open circulatory system: fluid bathes the organs directly.o The circulatory is called hemolymph which is also the interstitial fluid. Contraction of the heart pumps the fluid through the system of vessels into interconnected sinuses. Relaxation draws it back in through pores. o The open circulatory system of larger crustaceans includes more extensivesystem of vessels as well as an accessory pump. - Closed circulatory system is when the blood is confined to vessels and is distinct from the interstitial fluid.o One hear pumps blood into large vessels that branch into smaller ones through the organs.o Materials are exchanged between the smallest vessels and the fluid bathes the cells.- Low hyrostatic pressures are associated with open systems and make them costly than closed systems.- Closed systems allow for high BP which enable the effective deliver of oxygen and nutrients to the cells of more active animals. Circulatory systems- A closed system is also called the cardiovascular system.- Main types of blood vessels:o Arteries, which carry blood away from the heart. Branch into arterioles, small vessels that convey blood to the capillaries. o Capillaries are vessels with thin walls. Network of these vessels are capillary beds. Diffusion between the blood and fluid occurs here.o Veins carry blood back to the heart.- Arteries and veins are distinguished by the way they carry blood, not by the oxygen content.- Portal veins carry blood between capillary beds.- Heart:o Chambers that receive blood entering are called the atria.o Chambers responsible for pumping blood out are ventricles.- Single circulation:o In fishes, rays and sharks, the heart consists of two champers, and atrium and ventricle. Blood passes through the heart in one complete circuit: single circulation. Blood entering the heart collects in the atrium before the transfer tothe ventricle. Contraction of ventricle pumps blood to gills. Oxygen goes in the blood and CO2 out. As blood leaves the gills, capillaries converge into a vessel that carries oxygen rich blood to the beds throughout the body Blood then returns to the heart.o Blood that leaves the heart passes through two capillary beds before returning to the heart. When flowing through the bed, BP drops This drop limits the rate of blood flow.- Double circulation:o Two distinct circuits. One pump on the right side delivers oxygen poor blood to the capillary beds of gas exchange tissues. - Oxygen in, CO2 out.- THIS IS THE PULMONARY CIRCUIT.- It is called pulmocutaneous circuit if it includes the capillaries in both the lungs and skin. After the oxygen enriched blood leaves the gas exchange tissues it enters the pump, the left side of the heart.- Contraction propels the blood to capillary beds in organs. Systemic circuit is one full round.o Double circulation provides flow of blood to brain, muscles, and other organs because the hear repressurizes the blood destine for these thissues.- Adaptations:o Amphibians: Three chambered heart with two atria and one ventricle. Ventricle diverts the oxygen poor blood from the right atrium into the pulmonary circuit. o Reptiles: Three chambered heart with a spetum that separates the ventricle into right and left chambers. o Mammals: Two atria, two ventricles. This four chambered heat supports the endothermic way of life.- Our hearts deliver ten times as much fuel to tissues.Circulatory system in mammals1. Contraction of right ventricle pumps blood.2. Blood goes to pulmonary arteries.3. Bloof flows through capillaries in the left and right lungs which loads oxygen and unloads carbon dioxide.4. Oxygen rich blood returns from the lungs via pulmonary veins to left atrium.5. Oxygen rich blood flows into the left ventricle. (blood goes to tissues)6. Blood leaves the ventricle via aorta. (blood goes to arteries.)7. Branches of aorta lead to beds in the head and arms.8. Aorta goes to abdomen which supplies blood toa. Oxygen poor blood9. The arteries leading to the organs and legs.10. Oxygen poor blood is channeled to superior vena cava.11. Inferior vena cava drains blood.12. Blood goes to right atrium and the oxygen poor blood flows to right ventricle. The Mammalian heart- Two atria have thin walls and serve as collection chambers for blood returining to the heart.- Contraction of the atria transfers the remainder before the ventricles begin to contract. - The heart contracts and relaxes in a rhythmic cycle.o When it contracts, it pumps blood. (systole)o When it relaxes, the chambers fill with blood (diastole) This sequence is called a complete cardiac cycle- The volume of blood each ventricle pumps per minute is the cardiac output.o
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