Respiration and Circulation Biology 155 Russo-Neustadt

Respiration and Circulation are coupled processes in most animals The systems function together to exchange gases with the environment and transport them to the tissues

Types of Respiratory Exchange “Organs”: The Body Surface – Requires no respiratory system Animal must be small or thin Must have low oxygen /energy requirements Diffusion alone accounts for gas exchange Oxygen Carbon Dioxide

Animals who use their body surface for respiratory exchange include Sponges Jellyfish Flatworms (previous slide) Sea stars

Muscles in oral cavity serve as pump for one-way water flow, due to density of water B. Gills – Evaginations from the body surface (In mouth to oral cavity over gills and out slit) 2. Used by aquatic animals Gill arch

Animals who use gills for respiratory exchange include Marine worms Clams and mussels Lobsters and shrimp Vertebrate fishes (previous slide)

C. “Lungs” Used by terrestrial animals Invaginations from the body surface to decrease water loss Two major types – True lungs – used by snails and slugs, vertebrates from amphibians to mammals Tracheal system of insects

a. True lungs – localized exchange surface where oxygen is loaded into the bloodstream Carbon dioxide oxygen Trachea with cartilaginous rings alveolus bronchus lung Bronchial tree

Ventilation uses tidal flow of air due to density

b. Trachea = system of air filled tubes that branches throughout body Tracheole delivers oxygen to individual cells Note unique uncoupling between respiratory and circulatory systems

D. All Respiratory Systems have the Following Things in Common – Large surface area to maximize gas exchange Thin exchange surfaces to maximize the rate of gas exchange

D. All Respiratory Systems have the Following Things in Common – continued Gills and true lungs are also – Ventilated = use muscle pumps to keep oxygen rich medium in contact with the exchange surface Perfused = use muscle pumps to move blood through the vessels at the exchange surface to keep oxygen depleted blood in contact with the exchange surface Together these processes ensure a large concentration gradient for oxygen diffusion

II. Circulation: A. Components- 1. The cardiovascular system = heart + blood vessels Function = Circulates the blood to and from the tissues

8 Superior vena cava Capillaries of head, chest, and arms Pulmonary artery Pulmonary artery Capillaries of right lung 9 Aorta Capillaries of left lung 2 7 2 3 3 5 4 10 4 Pulmonary vein Pulmonary vein 6 1 Right atrium Left atrium 9 Figure 23.3A Blood flow through the double circulation of the human cardiovascular system. Right ventricle Left ventricle Inferior vena cava Aorta Capillaries of abdominal region and legs 8

Right atrium To lung To lung Left atrium From lung From lung Semilunar valve Semilunar valve Atrioventricular (AV) valve Atrioventricular (AV) valve Figure 23.3B Blood flow through the human heart. Right ventricle Left ventricle

2. The lymphatic system = lymph vessels + lymph nodes Functions – immune defense returns some fluid from the tissues

Return of excess fluid from the tissues via the immune system

B. Functions of the Circulatory System Transport – oxygen, carbon dioxide, nutrients, wastes and hormones in blood Blood clotting – to seal breaks in vessels, uses platelets and clotting proteins Protection – internal defense using the white blood cells and the lymphatic system

C. Types of Circulatory Systems None – Only used by small animals and/or those with low rates of oxygen use Circulation occurs due to simple diffusion through the body tissues

Examples of Animals That Lack a Circulatory System sponges (not shown) jellyfish flatworms sea stars

Blood leaves vessels, loses pressure, thus low flow, low oxygen demand system 2. Few vessels (Pump) (Tissue sinuses) Few vessels 3. large vessels (arteries, arterioles) Blood stays in vessels, thus high pressure, high flow system for high oxygen demand (pump) Capillaries in tissues for exchange large vessels (veins)

Examples of Animals with an Open Circulatory System clams Crayfish, shrimp, lobsters (not shown) insects as exception to low oxygen use rule (remember the tracheal system)

Examples of Animals with a Closed Circulatory System vertebrates from fish to mammals

D. The Vertebrate Circulatory System - Blood consists of– Plasma = fluid with dissolved substances (examples – nutrients, hormones and most carbon dioxide) Cells and cell fragments – White blood cells – defense Red blood cells – oxygen transport Platelets – blood clotting

2. Vertebrate hearts and circulatory patterns - Note that the evolution of the four-chambered heart of the mammals and birds allows blood to be returned to the heart after exchanging gases at the lungs and to be pumped a second time before traveling to the tissues, needed for high oxygen demand associated with high body temperatures

(Pressure declines) CO2 O2 O2 CO2 Pulmonary vein Right atrium arteries aorta Pulmonary artery aorta Atrium = receiving chamber Ventricle = pump Right ventricle Left atrium Vena cava Vena cava CO2 O2 CO2 O2 Two-chambered heart with blood pumped once; lower pressure, lower flow system Mammals and And thus blood is pumped twice for a higher pressure, higher flow system

23.4 The heart contracts and relaxes rhythmically During diastole, blood flows From veins Into heart chambers During systole, blood flows From atria Into ventricles For the BLAST Animation Cardiac Cycle Overview, go to Animation and Video Files. Student Misconceptions and Concerns 1. Students often expect that the blood flowing through the heart supplies the heart muscle. The need for coronary arteries and veins is not clear to them. (The thickness of the walls of the heart does not permit efficient diffusion, and furthermore, the oxygen content of the blood in the right atrium and ventricle is very low.) 2. One function of the circulatory system that is rarely discussed is the transport of heat. Blood vessels near the surface of the body expand when we are overheated, releasing some of this excess to the environment. Conversely, during periods of exposure to cold, blood is shunted away from the skin to conserve heat. Teaching Tips 1. Students often benefit from brief, concrete demonstrations of abstract ideas. When discussing the cardiac cycle, take the time to have students quickly take their own pulse as they are seated in class to help them relate the lecture topic to their own anatomy. This very short activity will provide a small break in the lecture routine and refocus the attention of those students whose minds may have begun to wander. 2. Having students take their own pulses also provides an opportunity to stimulate further curiosity. You may want to assign students to measure and record the variation in their pulse rates during the day's different activities, perhaps before and after drinking coffee, or prior to and during exercise. Copyright © 2009 Pearson Education, Inc.

Semilunar valves closed Heart is relaxed. AV valves are open. 0.4 sec 1 Heart is relaxed. AV valves are open. 0.4 sec Figure 23.4 A cardiac cycle in a human with a heart rate of about 72 beats a minute. Diastole

Atria contract. Semilunar valves closed Heart is relaxed. 0.1 sec 2 Atria contract. Semilunar valves closed 1 Heart is relaxed. 0.1 sec Systole AV valves are open. 0.4 sec Figure 23.4 A cardiac cycle in a human with a heart rate of about 72 beats a minute. Diastole

Atria contract. Semilunar valves closed Heart is relaxed. 0.1 sec 2 Atria contract. Semilunar valves closed 1 Heart is relaxed. 0.1 sec Systole AV valves are open. 0.3 sec 3 Ventricles contract. 0.4 sec Figure 23.4 A cardiac cycle in a human with a heart rate of about 72 beats a minute. Diastole Semilunar valves are open. AV valves closed

3. Generation of the heart beat – note that all cardiac cells are autorhythmic and contract on their own Pacemaker (fastest rate of contraction) = Electrical signals = action potentials pass due to intercalated discs (Holds signal before passing to ventricles, connective tissue between atria and ventricles prevents immediate passage of signal