The Cardiovascular System MS LUACES ANATOMY PHYSIOLOGY CHAPTER

The Cardiovascular System MS. LUACES ANATOMY & PHYSIOLOGY CHAPTER 11

CSI Investigation #11 ▪ Read the CSI Investigation on Pg. 406 silently ▪ Decide on two things that may be happening to the patient (either molecularly or on an organ level) ▪ Describe what your next steps would be in order to treat the patient

Overview ▪ Cardio (“heart”) and vasculum (“blood vessels”) make up the word Cardiovascular system ▪ Sometimes known as circulatory system ▪ Previously studied only anatomically, but now studied using waves (ultrasound) and sound to study blood flow and chemistry

Overview ▪ Begins to develop at 3 rd week after fertilization – first organ system to develop ▪ ▪ Heart starts beating at 3 weeks Develops from mesoderm tissue Does not immediately create blood vessels Exchanges nutrients and wastes between the embryo & the mothers body

Overview ▪ Vascularization (development and growth of blood vessels) does not develop until later, when angiogenesis factors direct the growth ▪ These factors also present during growing / healing process and in cancer cells

Circulatory System Vessels ▪ 3 major types of blood vessels: ▪ Arteries: muscular vessels that carry blood AWAY from heart ▪ Veins: thin vessels that carry blood TOWARDS the heart ▪ Capillaries: connect arteries to veins and exchange materials between the blood and cells (microcirculation) ; also controls fluid levels (hydrostatic pressure)

Circulatory System Vessels ▪ Major role of capillary vessel interaction is to control fluid levels – hydrostatic pressure ▪ Microcirculation will move gases & nutrients between blood and body cells

Arteries & Veins ▪ Composed of 3 distinct tissue layers: ▪ Tunica adventitia: tough, fibrous connective tissue ; collagen (strength) and elastin (flexibility) ▪ Tunica media: smooth muscle ; collagen & elastin also present ; controlled by parasympathetic & sympathetic nerves, hydrostatic pressure, and certain chemicals ▪ Tunica intima: simple, squamous cells ; provides a smooth lining – lumen – for central cavity

Arteries & Veins Arteries ▪ Distribute blood throughout body ▪ Stronger & thicker – mostly due to large tunica media ▪ Controls blood pressure Veins ▪ Return blood back to heart ▪ Thinner muscle layer, less elastin in tunica adventitia ▪ Low pressure due to blood passing through capillaries

Arteries & Veins ▪ Vasoconstriction: narrowing of the lumen which causes increased resistance in blood flow – raises blood pressure ▪ Vasodilation: relaxes the lumen which decreases resistance to blood flow – lowers blood pressure ▪ Veins require a mechanism that prevents downward pull of blood by gravity – use skeletal muscles, respiratory activity, and special one-way valves to prevent backflow ▪ Sometimes store blood (liver)

Small Vessels & Capillaries ▪ Composed of: ▪ Arterioles: small size, simple structure – control the flow of blood to particular parts of an organ / tissue ▪ Venules: large in diameter ▪ Capillaries: very small vessels that allow passage of blood cells – no tunica adventitia or smooth muscle ▪ Capillaries & Venules are the major vessels through which materials are exchanged

Small Vessels & Capillaries ▪ 2 types of Capillaries: ▪ Continuous: ▪ Most common, have tight connections to allow only certain materials to pass ▪ Found in CNS, lungs, muscles & skin ▪ Fenestrated: ▪ Much thinner with openings so that materials readily exchange ▪ Found in digestive, endocrine, and urinary systems

Check Your Understanding ▪ Pg. 416 Concept Checks ▪ CSI Case #11 Follow-Up Pg. 417 ▪ Analyze our patient using your newly learned knowledge about blood vessels– which of these could be responsible for his symptoms, and what is malfunctioning?

Structure of the Human Heart ▪ Muscular, 2 -part pump that forces blood throughout the body ▪ Left side – sends blood at high pressure to all parts except lungs ▪ Systemic Circulation ▪ Right side – sends blood at lower pressure to lungs ▪ Pulmonary circulation

Structure of the Human Heart ▪ Heart is nestled in the mediastinum (between the lungs) and separated by pericardium, which encloses and lubricates / protects the heart ▪ 3 layers: Fibrous pericardium (outermost, made of connective-tissue to protect & anchor), Serous Pericardium (middle, 2 epithelial layers to lubricate and prevent friction) and Pericardial Cavity (contains epicardium, filled with serous fluid)

Structure of the Human Heart ▪ Heart is composed mostly of thick sheets of cardiac muscle – myocardium and some fatty connective tissue ▪ Inner surface of the myocardium = endocardium

Structure of the Human Heart ▪ The heart must have a constant supply of oxygen and nutrients – provided by coronary arteries and veins that pass along the surface of the heart ▪ Blockage of these can result in cardiac ischemia (lack of oxygen) and cardiac infarction (death of cardiac muscle) ▪ Ischemia can lead to infarction (heart attack)

The Adult Heart ▪ Genetic factors determine functional parts, while environmental factors determine lifetime’s functionality ▪ Left side of the heart is larger (works harder to pump out to body) versus right side (smaller) ▪ 5 functional parts: ▪ ▪ ▪ 4 heart chambers, septum & vasculature Heart valves Vessels Electrical conduction system Autonomic nervous system innervations

The Adult Heart ▪ Heart is separated by a septum and contains 2 atriums (thin, upper chambers) and 2 ventricles (thick, lower chambers) ▪ Atria transfer / receive blood ▪ Ventricles pump blood out

The Adult Heart ▪ 4 valves include: ▪ Mitral (Bicuspid) valve: in-between left atrium & ventricle, prevents backflow ▪ Tricuspid valve: in-between right atrium & ventricle, “ “ ▪ Pulmonary valve: in-between right ventricle & lungs; prevent blood from backing up into heart ▪ Aortic valve: in-between left ventricle & body; “ “ ▪ AV (atrioventricular) valves are mitral & tricuspid ▪ Semilunar valves are pulmonary & aortic

The Adult Heart ▪ Vessels include: ▪ Superior & Inferior Vena Cava: receive blood from the head / upper body and lower body respectively into right atrium ▪ Aorta: pumps blood out to body ▪ Pulmonary artery: sends blood to lungs from right ventricle ▪ Pulmonary vein: receives blood from lungs into left atrium

The Adult Heart ▪ Electrical conduction system is composed of specialized cardiac muscle cells that act like a miniature nervous system – produce electrical signals to stimulate the contraction of particular regions ▪ SA node: “pacemaker” in right atrium, determines heart rate ▪ AV node: contracts ventricles ▪ Bundle of His & Purkinje system: also carry out ventricle contractions ▪ Autonomic nervous system regulates heart rate using the vagus nerve

The Fetal Heart ▪ By the end of week 8, the chambers are complete and the fetal heart is fully functional. However, it has 2 extra parts: ▪ Ductus arteriosus: diverts blood from pulmonary artery to aorta, usually lost day after birth and gone by 8 weeks old ▪ Foramen ovale: flap-like opening within the septum which sends blood from right atrium to left atrium, usually lost within a few weeks of birth

Heart Function ▪ Cardiac cycle has 2 stages that coordinate blood flow through the heart & body: ▪ Diastole: ventricles fill with blood ▪ Systole: contraction & discharge of blood from ventricles

Heart Function ▪ Flowchart for the cardiac cycle: ▪ SA node signal contraction of the atria stimulation of AV node AV valves open and fill ventricles with blood AV node signals bundle of His and Purkinje contracts ventricles AV valves close and pulmonary / aortic valves open pulmonary and system circulation ventricles relax pulmonary / aortic valves close REPEAT

Heart Function ▪ Heart beat is automatically stimulating the cardiac cycle. However, can be stimulated by: ▪ Sympathetic system: speed up rhythm ▪ Parasympathetic system: slow down rhythm ▪ Receives signals from the brain stem and hypothalamus

Heart Function ▪ Heart rate (# of ventricular contractions p/min) and stroke volume (amount of blood pumped through heart in 1 cycle) will give the cardiac output (volume of blood that the heart pumps in 1 min) ▪ CO = HR X SV ▪ Average cardiac output is 5. 25 L/min

Class Work ▪ Create a flow chart for the electrical impulse (heart function) through the heart ▪ Answer the concept check questions on Pg. 427 (2 sentences minimum each) ▪ Answer the CSI follow up question right underneath the concept check questions (paragraph form – 4 sentences explaining your reasoning).

Cardiovascular Pathology ▪ Split into vascular (arteries, veins and capillaries) and cardiac (directly involving heart areas) disorders ▪ Aneurysm: bulging of the wall of a blood vessel ; usually in large arteries ; caused by congenital defects, infectious diseases, and injuries ▪ Arrhythmia: deviation in the normal heartbeat rhythm and disturbs the electrical system ; heartbeat becomes too fast or too slow ; can be due to alcohol, caffeine, diet pills, stress, and other factors

Cardiovascular Pathology ▪ Atherosclerosis: plaque (usually cholesterol and fat) build up on the inner lining of an artery ▪ Causes the lumen to narrow and restricts blood flow ▪ Tissue damage may happen ▪ May lead to sudden cardiac death – abrupt loss of heart function (heart attack) ▪ Treatment: eat healthy and exercise! If it’s bad, surgery will be needed

Cardiovascular Pathology ▪ Heart murmurs: result of defective heart valves that don’t close properly ▪ Can be caused by fevers and pregnancy or congenital heart conditions ▪ Hypertension: high blood pressure (140/90) ▪ Usually caused by high fat diet ▪ Pericarditis: inflammation of the pericardium ▪ Causes are unknown, but can include bacterial infection, heart attack or heart surgery

Cardiovascular Pathology ▪ Prolapse involves the stretching of the heart valves (usually mitral valve) which causes an incomplete closure of the valve ▪ Reduces the blood–pumping capacity ▪ Causes a back-flow of blood (regurgitation)