Chapter 23. Circulation

Transcription

1 Chapter 23 Circulation

2 Standards CORE: I can describe the components and function of blood. I can describe structure and function of blood vessels. I can compare and contrast systemic and pulmonary systems. I can outline blood flow through the heart. I can explain why blood pressure is related to overall heath. I can compare and contrast adult and fetal circulation. ADVANCED: I can trace a red blood cell through the body and back to its starting point. I can describe nervous control of the heartbeat.

3 How Does Gravity Affect Blood Circulation? Few animals seem less alike than the giraffe and the corn snake Despite their differences they have many features in common What do you think they have in common??

4 Most animals have a circulatory system that transports O 2 and nutrients to cells and takes away CO 2 and other wastes The circulatory system of land animals must deal with the problem of gravity

5 LM 700 Hank circulatory system 23.1 The circulatory system connects with all body tissues In many animals, microscopic blood vessels called capillaries form an intricate network among the tissues These capillaries are fed by arteries and empty into veins Red blood cell Figure 23.1A Capillary Nuclei of smooth muscle cells

6 Bloody Blood! STRUCTURE AND FUNCTION OF BLOOD Figure (left part) Blood consists of red and white blood cells suspended in plasma Plasma is about 90% water And contains various inorganic ions, proteins, nutrients, wastes, gases, and hormones Constituent Water Salts (ions) Sodium Potassium Calcium Magnesium Chloride Bicarbonate Plasma proteins Fibrinogen Immunoglobulins (antibodies) Plasma (55%) Major functions Solvent for carrying other substances Osmotic balance, ph buffering, and nerve and muscle function Osmotic balance and ph buffering Clotting Immunity Centrifuged blood sample Substances transported by blood Nutrients (e.g., glucose, fatty acids,vitamins) Waste products of metabolism Respiratory gases (O 2 and CO 2 ) Hormones

7 Red blood cells (erythrocytes) Transport O 2 bound to hemoglobin White blood cells (leukocytes) Function both inside and outside the circulatory system to fight infections and cancer Centrifuged blood sample Cell type Erythrocytes (red blood cells) Leukocytes (white blood cells) Basophil Platelets Cellular elements (45%) Number per L (mm 3 ) of blood Functions 5 6 million Transport of oxygen (and carbon dioxide) Eosinophil Neutrophil 5,000 10,000 Defense and immunity 250, ,000 Lymphocyte Monocyte Blood clotting Figure (right part)

8 CONNECTION Too few or too many red blood cells can be unhealthy Anemia is an abnormally low amount of hemoglobin or red blood cells Figure The hormone erythropoietin regulates red blood cell production Some athletes artificially increase their red blood cell production, a dangerous practice why would they want to do this??

9 THE MAMMALIAN CARDIOVACULAR SYSTEM 23.4 The human heart and cardiovascular system are typical of mammals The mammalian heart Has two thin-walled atria that pump blood into the ventricles Has thick-walled ventricles that pump blood to all other body organs Right atrium Left atrium Semilunar valve Atrioventricular (AV) valve Semilunar valve Atrioventricular (AV) valve Figure 23.4A Right ventricle Left ventricle

10 Blood flow through the human cardiovascular system Superior vena cava 8 Capillaries of head, chest, and arms Pulmonary artery Capillaries of right lung Aorta 2 Pulmonary artery Capillaries of left lung Pulmonary vein Right atrium Pulmonary vein Left atrium Right ventricle Inferior vena cava Left ventricle Aorta Figure 23.4B 8 Capillaries of abdominal region and legs

11 23.5 The structure of blood vessels fits their functions A single layer of epithelial cells forms the walls capillaries Arteries and veins have smooth muscle and connective tissue Capillary Epithelium Basement membrane Valve Artery Epithelium Smooth muscle Connective tissue Epithelium Smooth muscle Connective tissue Vein Figure 23.5 Arteriole Venule

12 Muscle contractions and one-way valves keep blood moving through the veins to the heart Direction of blood flow in vein Valve (open) Skeletal muscle Valve (closed) Figure 23.9B

13 Capillaries are the sites of exchange between blood and interstitial fluid and are one cell layer thick Capillary Interstitial fluid Diffusion of molecules Figure 23.1B Tissue cell

14 TEM 5, Capillaries allow the transfer of substances through their walls Capillary wall Iumen Interstitial fluid Nucleus of epithelial cell Figure 23.12A Muscle cell Cleft between two epithelial cells of the capillary wall

15 CONNECTION Not all of our capillaries can be used at the same time if they are you will go into shock! Our body controls entry of blood into capillary networks using sphincters in the arterioles prior to a capillary network Apart from avoiding shock, when and why would our bodies want to do this?

16 Flow of blood through the heart

17 Heart Beat, Beat, Beat 23.6 The heart contracts and relaxes rhythmically Figure 23.6 During diastole blood flows from the veins into the heart chambers During systole Contractions of the atria push blood into the ventricles Stronger contractions of the ventricles propel blood into the large arteries Cardiac output is the amount of blood/minute pumped into the systemic circuit Heart valves prevent the backflow of blood 1 Heart is 2 Atria relaxed. contract. AV valves are open. Diastole 0.4 sec 0.1sec Systole 0.3 sec 3 Ventricles contract. Semilunar valves are open.

18 23.7 The pacemaker sets the tempo of the heartbeat The pacemaker (SA node) generates electrical signals that trigger contraction of the atria The AV node relays these signals to the ventricles Pacemaker (SA node) AV node Specialized muscle fibers Right atrium Figure 23.7 ECG Right ventricle Apex

19 ECG / EKG An electrocardiogram (ECG) records the electrical changes in the heart Heart rate adjusts to body needs

20 CONNECTION 23.8 What is a heart attack? A heart attack is damage to cardiac muscle usually resulting from a blocked coronary artery Superior Vena cava Pulmonary artery Right coronary artery Aorta Left coronary artery Blockage Figure 23.8A Dead muscle tissue

21 Atherosclerosis In atherosclerosis plaques develop in the inner walls of arteries and can block blood flow Connective tissue Smooth muscle Epithelium Plaque LM 160 LM 60 Figure 23.8B

22 Hypertension Is a serious cardiovascular problem resulting from consistent high blood pressure in the arteries

23 Aorta Arteries Arterioles Capillaries Venules Vains Venae cavae Velocity (cm/sec) Pressure (mm Hg) 23.9 Blood exerts pressure on vessel walls Blood pressure Is the force blood exerts on vessel walls Depends on cardiac output and the resistance of vessels Pressure is highest in the arteries and lowest in the veins Relative sizes and numbers of blood vessels Diastolic pressure Figure 23.9A Systolic pressure

24 CONNECTION Measuring blood pressure can reveal cardiovascular problems Blood pressure is measured as systolic and diastolic pressures Blood pressure 110 systolic 70 diastolic (to be measured) Rubber cuff inflated with air Pressure in cuff above Pressure in cuff at Pressure in cuff at Figure Artery Artery closed Sounds audible in stethoscope Sounds stop

25 The transfer of materials between the blood and interstitial fluid occurs By diffusion By pressure flow through clefts between epithelial cells Blood pressure forces fluid out of the capillary at the arterial end and osmotic pressure draws fluid at the venous end Tissue cells Arterial end of capillary Osmotic pressure Osmotic pressure Venous end of capillary Blood pressure Blood pressure Interstitial fluid Net fluid Movement out Net fluid Movement in Figure 23.12B

26 Colorized SEM 3, Blood clots plug leaks when blood vessels are injured When a blood vessel is damaged platelets help trigger the conversion of fibrinogen to fibrin, forming a clot that plugs the leak Figure 23.15B

27 The blood-clotting process 1 Platelets adhere to exposed connective tissue Epithelium 2 Platelet plug forms 3 Fibrin clot traps blood cells Connective tissue Platelet Platelet plug Figure 23.15A

28 CONNECTION Stem cells offer a potential cure for blood cell diseases Stem cells divide in bone marrow to produce all blood cells and may be used to treat some blood disorders Stem cells Stem cells Erythrocytes Basophils Platelets Eosinophils Figure 23.15B Lymphocytes Monocytes Neutrophils

29 Fetal Circulation The fetus does not use lungs for acquiring oxygen. Why???

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31 Fetal Circulation Placenta - organ responsible for delivery of nutrients, removal of waste products and delivery of oxygenated blood to the fetus via diffusion and active transport mechanisms.

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33 Fetal Circulation 4 differences AKA: The Fetal Four 1. Umbilical cord A. Umbilical vein (1)- A vessel which delivers oxygenated and nutrient rich blood from the placenta to the fetus. B. Umbilical arteries (2) vessels that carries deoxygenated blood from iliac arteries out to the placenta. 2. Venous duct - receives blood from the umbilical vein and directs it to the posterior/inferior vena cava. This venous duct acts as a liver bypass and moves blood into the fetal systemic circulation. Function to bypass the liver Why bypass the liver??

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35 Fetal Circulation 3. Foramen Ovale - an opening between the right atrium and left atrium Function to bypass the lungs Why bypass the lungs??

36 Fetal Circulation 4. Ductus Arteriosus - A vessel that connects the pulmonary artery to the aorta. Function to bypass pulmonary circuit.

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39 Lymph System Is a one way transport system (tissues to blood) Takes excess fluid from capillary beds of body and returns it to the blood CONSISTS of lymph veins (have valves) and capillaries Fluid is called lymph Joins blood at subclavian vein

40 Main Functions of Lymphatic System 1. Take up excess tissue fluid 2. Transport fatty acids (from LACTEAL) 3. Fight infection (lymphocytes) lymph system

41 Parts of Lymphatic System 1. LACTEAL: dead ends of lymph vessels in villi of the small intestine. 2. LYMPH NODES - small oval structures that produce and store lymphocytes, filter the lymph of damaged cells and debris. 3.SPLEEN: stores blood. 4.THYMUS GLAND -production and maturation of some lymphocytes.

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