Anatomy Cardiovascular System

University:
Northwest College
Course:
ANT 201 | Anatomy
Academic year:

2023
Views:

197

Pages:

61
Author:

Yesenia M.

AnatomyCardiovascular System Blood Flow Components • Cardiovascular system • Lymphatic system Cardiovascular system • Heart, blood vessels, blood • Functions: – transport of nutrients, hormones, oxygen, waste, carbon dioxide Lymphatic system • Lymph nodes, lymphatic vessels, lymph • Functions – Immune Response – Absorption of fat from gi tract (lacteal) – Controlling volume of interstitial fluid and blood Cardiovascular system and Lymphatic system work in tandem Hematology • Study of blood and components • Two parts – Formed elements • Erythrocytes • Leukocytes • Thrombocytes (Platelets) – Plasma Hematocrit Plasma (Blood Matrix) • Predominately water • Major solutes – Salts – minerals – bicarbonate buffer – sugars, amino acids, vitamins Plasma Proteins • Predominately made in liver • Major plasma proteins – Albumins – Lipoproteins – Clotting Factors – Globulins • Including antibodies – Gamma globulins – made by lymphocytes Formed Elements Formed elements • Erythrocytes – Red blood cells – anucleate – lack mitochondria – millions of hemoglobin molecules – Life span = 3-4 months Leukocytes • Nonspecific – – – – – Neutrophils Eosinophils Basophils NK cells Monocytes, macrophage • Specific – T-lymphocytes – B-lymphocytes granulocytes 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? Eosinophils • slightly phagocytic • Effective against helminths • Allergic and hypersensitivity reactions • Contribute to chronic inflammation Note the large red stained granules 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 Monocytes • Become macrophage when activated • eat microbes cellular debris • Antigen Presenting Cells Large C-shaped nucleus….and no granules! – link nonspecific body defenses to the immune response macropha Diapedesis 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 Formed elements • Thrombocytes –Formed by disintegration of megakaryocytes –Released into plasma –Last 3-5 days –Important in blood clotting Platelet plug formation • Activation of platelets makes them sticky • Results in the formation of a platelet plug when blood vessel is damaged 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 CO2 back to lungs to be eliminated – 3) develops blood pressure by alternate cycles of relaxation and contraction Components of Conduction System 3 Layers of heart wall • Endocardium – Tunica intima of the heart – Composed of simple squamous epithelium + loose CT • Myocardium – Tunica media – cardiac muscle • • • • • branched interdigitated 1centrally located nucleus striated intercalated discs • Epicardium – Tunica externa or visceral pericardium-(Secretes serous fluid)This is the innermost layer of the pericardium!!! – simple squamous epithelium and loose CT • Parietal pericardium – a fibrous CT loose fitting sac – Lined with simple squamous epi. Structures of the Heart Wall • Epicardium( Visceral Pericardium) – Visceral pericardium – Serous membrane – Supporting layer of areolar CT • Myocardium – Layers of cardiac muscle tissue – CT,blood vessels, nerves • Endocardium – Simple squamous epithelium – Continuous with mesothelium of blood vessels Four chambers • Dual pump – Functional • Pulmonary circuit • Systemic circuit – Two regions • Atria • Ventricles Atria • thin walled receiving chambers • derived from veins • auricles – folded extensions of the atria – increase volume • pectinate muscle – atrial muscle, “honeycomb” appearance 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 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 Septa • cross walls or dividers of the hearts – interatrial - between atria – interventricular - between ventricles – atrioventricular - between atria and ventricles Direction blood pumps through the heart 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 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 Semilunar (SLV) • Between ventricles and major arteries – pulmonary trunk – aorta • Permit – ventriculoarterial flow • Prevent – arterioventricular reflux valves 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 Cardiac conduction system • Atrioventricular (AV) node – first structure used to stimulate contraction of the ventricles, located near the center of the Atrioventricular 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. Components of Conduction System 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, http://pie.med.utoronto.ca/HTBG/HTBG_content/HTBG_heartEmbryologyApp.ht ml Development of heart • day 20-21: – embryo curls – the heart folds into the thorax & becomes a pair of tubes 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 Before 2 months • the heart forms an S shape• ventricle moves caudally (to bottom) • atrium moves cranially (to top) 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 Fetal Heart Major CVS Circuits • 1. systemic – high variable resistance circuit – Includes coronary circulation • the vasa vasorum of the heart • 2. pulmonary – low, constant resistance circuit