Circulatory Systems. All cells need to take in nutrients and expel metabolic wastes.

Transcription

1 Circulatory Systems All cells need to take in nutrients and expel metabolic wastes. Single celled organisms: nutrients from the environment can diffuse (or be actively transported) directly in to the cell and wastes can diffuse out. Why? 1

2 Circulatory Systems Multi cellular organisms: Diffusion is not fast or efficient enough to meet the needs of all the cells Circulatory systems are developed to deliver oxygen and food to cells, and remove waste products. There are two types of circulatory systems: Open circulatory systems Closed circulatory systems There are three main components to the circulatory system of an organism: A pumping mechanism (e.g. Heart) A transport medium (e.g. Blood) Transport vessels (e.g. Arteries / Veins) 2

3 Comparative Anatomy of Circulatory Systems Open and Closed Circulatory Systems In Open Circulatory Systems, there is no separation between blood and interstitial fluid (combination of these fluids is called hemolymph). The hemolymph fills a body cavity, bathes all cells directly, and is circulated relatively slowly. In Closed Circulatory Systems, the blood and interstitial fluid are kept separate and blood circulates relatively quickly in a complex network of vessels. 3

4 Open Transport System Open vs. Closed Transport System 1. An open transport system is a transport system in which the blood does not always stay contained within blood vessels. 2. There is no true heart or capillaries. 3. Instead of the heart, the blood vessels pump the blood with force. 4. The blood here is not actually blood, it s a combinaon of blood and intersal fluid called the hemolymph. 5. The organs are bathe in blood which provide nutrients, fluid, and oxygen directly 6. In most cases, animals with open transport system have low blood pressure. 7. An advantage of this system is that it requires less energy for distribuon 4

5 Closed Transport System 1. A closed transport system is a transport system in which the blood is pumped around the body within a closed network of vessel. 2. Provides a faster flow of blood 3. The blood does not bathe the cells directly. 4. The larger vessels collect blood for pumping, while the smaller vessels distribute blood throughout the body and capillaries. 5. Blood only circulate in one direcon passing animal respiratory system 5

6 Comparative Anatomy of Hearts Single systemic circuit that carries blood to the gills for gas exchange. Heart has 2 chambers: 1 ventricle, 1 atrium Three circuit system Have systemic and pulmonary circuits like mammals. Have a third circuit that bring deoxygenated blood to the skin for gas exchange. Heart has 3 chambers: 1 ventricle, 2 atria Two circuit system in which the circulation to the lungs is separated from the rest of the body. 4 chambered heart creates a double pump where the 2 circuits intersect: 2 ventricles, 2 atria Some vocabulary: ventricle: heart chamber that pumps blood to the body. atrium: heart chamber that receives the collected blood from the body and pumps it into the ventricle. pulmonary circuit: circulates blood to the lungs for gas exchange with the external environment. systemic circuit: circulates blood around the body to deliver oxygen, nutrients, and other substances to the body cells, and to pick up CO 2. 6

7 The Human Heart 7

8 Arteries and Veins of the Heart Vena Cava (Superior and Inferior) Return deoxygenated blood from body to the right atrium Pulmonary Artery Transfers deoxygenated blood from right ventricle to lungs Pulmonary Vein Returns oxygenated blood from lungs to left atrium Aorta Transports oxygenated blood from left ventricle to body Coronary Arteries and Veins Supply oxygenated blood to heart and return deoxygenated blood to right atrium 8

9 The Human Heart Hard working and reliable, works independently, excellent at multi tasking Average heart rate = 70 beats per minute AT REST 60 minutes per hour with 24 hours per day = minutes per day 70 beats per minute X minutes per day = beats per day Average Canadian life expectancy = 80 years 365 days per year over 80 years of life = days in a lifetime beats per day X days = beats per lifetime 70 ml of blood per beat X beats per lifetime = ml That's the volume of nearly olympic sized swimming pools! 9

10 The Human Heart The heart is the major pump that moves blood through the body. It consists of 2 pumps which move blood through 2 different circuits (1. pulmonary to the lungs 2. systemic to the body) at the same time. Each pump has 2 chambers: an atrium and a ventricle The Atrium = the thin walled chamber that receives blood from the veins and pumps it at low pressure to the ventricle. The Ventricle = the thick walled chamber that receives blood from the atrium and pumps it at high pressure into the arteries. 10

11 The Sound of the heartbeat actually comes from 11

12 Heart Valves A series of valves keeps blood moving in one direction as it is pumped through the heart. Atrioventricular (AV) valves: Also called cuspid valves (have flaps) Prevent blood from flowing back to the atria The right AV valve has 3 flaps and is called the tricuspid valve. The left AV valve has 2 flaps and is called a bicuspid valve, but is more commonly referred to as the mitral valve (bicuspid valve). 12

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14 Heart Valves Semilunar valves: Prevent blood from re entering the heart after being pumped into the arteries. They are shaped like half moons. Pulmonary valve and Aortic valve The closing of the heart valves is responsible for the lub dub sound of the heart beat. The Lub (softer) occurs when the AV valves close and the Dub (louder) occurs when the semi lunar valves close. 14

15 The Cardiac Cycle The Cardiac Cycle is the sequence of events which occurs when the heart beats. It occurs in two phases: Systole heart chambers contract Muscle surrounding both ventricles contracts Pressure inside rises causing AV valves to close, this makes first heart sound "LUB" Blood is forced through the semilunar valves into the arteries Also at this time, blood returning from the body (through vena cava and pulmonary vein) enters both atria The muscle surrounding the atria is relaxed Diastole heart chambers are relaxed When the blood has been pumped from the ventricles into arteries, the muscles surrounding the ventricles will relax, causing the ventricular pressure to decrease which leads to the closing of the semilunar valves This action makes the second heart sound "DUB" The atria are now filled and the muscles surround them contracts This increases pressure in the atria forcing the AV valves to open so blood can move into the ventricles The pumping of blood occurs during systole 15

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