Circulatory System: Introduction. Dr. Carmen E. Rexach Anatomy 35 Mt. San Antonio College

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1 Circulatory System: Introduction Dr. Carmen E. Rexach Anatomy 35 Mt. San Antonio College

2 Components Cardiovascular system Lymphatic system

3 Cardiovascular system Heart, blood vessels, blood Functions: transport of nutrients, hormones, oxygen, waste, carbon dioxide

4 Lymphatic system Lymph nodes, lymphatic vessels, lymph Functions Immune Response Absorption of fat from gi tract (lacteal) Controlling volume of interstitial fluid and blood

5 Cardiovascular system and Lymphatic system work in tandem

6 Hematology Study of blood and components Two parts Formed elements Erythrocytes Leukocytes Thrombocytes (Platelets) Plasma

7 Hematocrit

8 Plasma (Blood Matrix) Predominately water Major solutes Salts minerals bicarbonate buffer sugars, amino acids, vitamins

9 Plasma Proteins Predominately made in liver Major plasma proteins Albumins Lipoproteins Clotting Factors Globulins Including antibodies Gamma globulins made by lymphocytes

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11 Formed Elements

12 Erythrocytes Red blood cells anucleate lack mitochondria millions of hemoglobin molecules Life span = 3-4 months Formed elements

13 Leukocytes Nonspecific Neutrophils Eosinophils Basophils NK cells Monocytes, macrophage Specific T-lymphocytes B-lymphocytes granulocytes

14 Neutrophils (PMN s) the first WBC at an infection site 50-60% of circulating leukocytes voracious phagocytes use lysozyme and oxygen radicals to destroy microbes Polymorphonuclear cells.can you tell why?

15 Eosinophils Note the large red stained granules slightly phagocytic Effective against helminths Allergic and hypersensitivity reactions Contribute to chronic inflammation

16 Basophils mature into mast cells of loose connective tissue Smallest immune effector cells Produce: heparin an anticoagulant histamine Vasodilator increases capillary permeability important to inflammation, especially related to allergies Note large blue granules

17 Monocytes Large C-shaped nucleus.and no granules! Become macrophage when activated eat microbes cellular debris Antigen Presenting Cells link nonspecific body defenses to the immune response

18 Diapedesis macropha

19 Lymphocytes Involved in specific immune response Present in small numbers until activated T cells primarily circulate, B cells primarily in lymph nodes Large nucleus almost completely fills cell

20 Formed elements Thrombocytes Formed by disintegration of megakaryocytes Released into plasma Last 3-5 days Important in blood clotting

21 Platelet plug formation Activation of platelets makes them sticky Results in the formation of a platelet plug when blood vessel is damaged

22 The Heart a dual pump (R and L) Functions: 1) unidirectional flow of blood through heart and vessels 2) dual pump to lungs and systemic circulation to pick up oxygen, distribute it to tissues, carry CO 2 back to lungs to be eliminated 3) develops blood pressure by alternate cycles of relaxation and contraction

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26 Layers of heart wall Endocardium Tunica intima of the heart Composed of simple squamous epithelium + loose CT Myocardium Tunica media cardiac muscle branched interdigitated 1 centrally located nucleus striated intercalated discs Epicardium Tunica externa or visceral pericardium simple squamous epithelium and loose CT Parietal pericardium a fibrous CT loose fitting sac Lined with simple squamous epi.

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31 Four chambers Dual pump Functional Pulmonary circuit Systemic circuit Two regions Atria Ventricles

32 Atria thin walled receiving chambers derived from veins auricles folded extensions of the atria increase volume pectinate muscle atrial muscle, honeycomb appearance

33 Atria R atrium receives blood from the systemic circuit Openings superior vena cava inferior vena cava coronary sinus (thebesian valve) L atrium receives blood from the lungs openings from pulmonary veins

34 Ventricles thick walled pumping chambers derived from arteries trabeculae = crossbars of flesh R ventricle thinner wall pumps to lungs moderator bands control the volume of the RV if present L ventricle 2-3 X s thicker than the RV pumps to systemic circuit

35 Septa cross walls or dividers of the hearts interatrial - between atria interventricular - between ventricles atrioventricular - between atria and ventricles

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37 Atrioventricular septum Two parts 1. cardiac skeleton a fibrous CT skeleton supporting the heart valves and chambers 2. heart valves(in the atrioventricular septum) atrioventricular (cuspid valves) between atria and ventricles semilunar valves between ventricles and major arteries

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39 Atrioventricular valves Function Permit atrioventricular flow Prevent ventriculoatrial reflux Attached to accessory structures chordae tendineae fibrous cords heart strings papillary muscles fingerlike muscles attached to chordae tendineae keep valves closed during ventricular contraction

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41 Semilunar (SLV) valves Between ventricles and major arteries pulmonary trunk aorta Permit ventriculoarterial flow Prevent arterioventricularreflux

42 Intrinsic conduction System sends rhythmic impulses through the heart to synchronize heart rate and stimulate contraction sinoatrial (SA) node Pacemaker located in R atrium near the superior vena cava

43 Cardiac conduction system Atrioventricular (AV) node first structure used to stimulate contraction of the ventricles, located near the center of the AV septum atrioventricular (AV) bundle Bundle of HIS bundle branches lead to the L and R ventricle respectively Purkinje fibers terminal branches of the conduction system continuous with cardiac muscle fibers.

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46 Embryonic Development of the Heart day 18-20: the entire embryo is disc shaped all blood vessels begin as blood islands in splanchnic mesoderm surrounding the head and neck Dorsal view For more detailed information,

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48 Development of heart day 20-21: embryo curls the heart folds into the thorax & becomes a pair of tubes

49 Heart Development day 22 pair of tubes fuse heart begins pumping 4 bulges develop (beginning at bottom: venous to arterial) sinus venosus atrium ventricle bulbus cordis

50 Before 2 months the heart forms an S shape- ventricle moves caudally (to bottom) atrium moves cranially (to top)

51 By 2 months 4 distinct chambers develop interatrial septum grows caudally (from top to bottom) interventricular septum grows cranially (from bottom to top) foramen ovale and a hole in the superior interventricular septum retained until birth bulbus cordis splits into the pulmonary trunk and ascending aorta

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54 Major CVS Circuits 1. systemic high variable resistance circuit Includes coronary circulation the vasa vasorum of the heart 2. pulmonary low, constant resistance circuit