Function: Transportation of Oxygen Nutrients Waste Hormones gases
Pericardium: double sac of serous membrane filled with fluid (pericardial fluid to be exact) that surrounds the heart. Parietal pericardium: tough outermost portion of pericardium. Attached to sternum and diaphragm. Visceral pericardium (epicardium): thinner, less tough membrane that hugs the heart.
myocardium: thick bundles of cardiac muscle that contract. Endocardium: really thin internal lining of heart.
1. pulmonary system: blood flow through lung tissue; from pulmonary trunk to lungs and back to left atria. Oxygenates blood. 2. systemic system: blood flow through body tissue; from aortic arch to body cells and back to right atria. Deoxygenates blood.
3. Cerebral circulation: blood flow through brain tissue; from left common carotid artery to internal carotid artery and circle of Willis in the brain. These meet with the vertebral arteries that come off the subclavian arteries.
4. Hepatic Portal Circulation: blood flow from the digestive organs, spleen, and pancreas to the liver via the hepatic portal vein then leaves via the hepatic veins to inferior vena cava. Liver filters and processes nutrients and chemicals before entering the rest of the body.
5. Fetal Circulation: blood flow from mother to child; placenta and umbilical veins take oxygen/nutrient rich blood to fetus. Lungs are shut off; use of foramen ovale (hole in heart between atria) and ductus arteriosus (connects pulmonary trunk with aorta becomes ligamentum arteriosum) 6. coromary circulation: the blood that flows throught the heart muscle.
Arteries: take blood away from the heart Arterioles: small arteries that connect to capillaries. Capillaries: tiniest blood vessels; where the rubber meets the road gas and nutrient exchange Venules: small veins that connect to capillaries. Veins: take blood to the heart
Tunics (coats) line all vessels except capillaries. Tunica interna: lines the lumen (internal tube); made of squamous epithelials that form a slick surface (water slide). Tunica media: thick middle coat; made of smooth muscle and elastic tissue; control blood pressure. Tunica externa: thin outer layer; made of fibrous connective tissue; gives support.
Arteries vs Veins
Capillaries: Transparent (tunica interna only) One cell thick Easy exchange of chemicals with cells and tissues Capillary bed: 1. has a vascular shunt and 2. has true capillaries. 3. has precapillary sphincters
How much blood do you have? 6 Quarts (5.7 L) How many times does that blood flow through your body per day? 1000 times Your heart pumps about 6000 quarts of blood per day.
Cardiac muscle does not have to have electrical conduction to contract! Different areas contract at different rates: atria = 60/minute and ventricles = 20-40/min. This makes a contracting MESS that must be regulated!
Contraction Control Mechanisms: 1. nerves of the autonomic nervous system; will increase or decrease heart rate via sympathetic and parasympathetic systems are at work. 2. intrinsic conduction system (nodal system)
Intrinsic (nodal) conduction system: Mutant hybrid tissue of awesomeness cross between muscle and nerve Depolarization can only flow in one direction from atria to ventricles Forces a steady rate of 75 beats/minute Parts: sinoatrial (SA) node, atrioventricular (AV) node, atrioventricular (AV) bundle, bundle branches, Purkinje fibers
Intrinsic (nodal) conduction system: 1. SA node (AKA pacemaker): starts the contraction; in the right atria 2. AV node: causes atrial contraction 3. AV bundle, bundle branch and Purkinje fibers: flow from atria through interventricular septum to the apex of heart. This wrings the venticles from the apex up.
Homeostatic imbalances: Ischemia: lack of blood supply to heart = fibrillation. Tachycardia: rapid heart rate: 100+/min Bradycardia: REALLY low heart rate: <60 beats/min Murmurs: indicate valve problems usually; sounds of blood hitting heart walls unevenly.
Heart Sounds: Systole (ventricle contraction) Diastole (ventricle relaxation) Cardiac cycle: one complete heart beat (about.8 seconds)
Heart Sounds 1. mid-to-late diastole: atria contracts forcing blood to ventricles through AV valves. 2. ventricular systole: ventricles contract sending blood out the arteries, atria relax & fill with blood, AV valves close (make lub sound) 3. early diastole: ventricles relax, semilunar valves shut quickly ( dub sound), ventricles fill back up with blood
Cardiac Output (CO): amount of blood pumped out by each ventricle in one minute. Stroke volume: amount of blood pumped out the ventricles each beat. Calculated as the product of the heart rate (75 beats/min) x stroke volume (70 ml/beat). About 5250 ml/min.
Regulating stroke volume: Starling s law of the heart: how much cardiac muscle cells are stretched before contracting. Heart rate Exercise (skeletal muscle pump) Blood loss
Regulation of heart rate: Autonomic nervous system Blood loss Hormones Physical factors (age, gender, body temp, michaelness)
Vital signs: arterial pulse, blood pressure, respiratory rate and temperature Arterial pulse: the alternating expansion and recoil of an artery that occurs with each beat of the left ventricle creating a pressure wave, or pulse, traveling through the entire atrial system. Usually the same as the heart rate
Blood pressure: the pressure the blood exerts against the inner walls of the blood vessels, specifically the arteries. Blood flows from high to low pressure Highest in arteries close to the heart; lowest in the vena cavas. (ex: cuts) Remember! Veins have valves, skeletal muscle contractions and breathing to keep blood flowing back to the heart.
Measuring blood pressure Systolic pressure Pressure in arteries at ventricular contraction Top number of pressure reading Read when first pulse is heard in stethoscope Diastolic pressure Pressure in arteries at ventricular dilation Bottom number of pressure reading Read when last pulse is heard in stethoscope Normal: 110-140/75-80
Blood pressure effectors Cardiac output and peripheral resistance Peripheral resistance: the amount of friction encountered by the blood as it flows through the vessels. Constriction of vessels Atherosclerosis Increased blood volume Blood viscosity
Blood pressure effectors 1. neural factors: sympathetic division causes vasoconstriction (narrowing of blood vessels) ex standing rapidly, blood loss, exercise/fear 2. renal factors: alters blood volume (more volume = more pressure) via water and hormones
Blood pressure effectors 3. temperature: cold = vasoconstriction; hot = vasodilation (red face) 4. chemicals: Epinephrine & nicotine = vasoconstriction Alcohol & histamine = vasodilation (red face) 5. diet: low salt, saturated fat, and cholesterol
Homeostatic imbalances 1. hypotension: low blood pressure (below 100 systolic pressure); not bad usually. 2. hypertension: high blood pressure (above 140/90) silent killer 3. Atherosclerosis: hardening of the arteries; can lead to hypertension