Blood Vessels: The Human Transport System SBI3U PDF

Blood Vessels: The Human Transport System SBI3U  Importance Carries nutrients to cells Carries waste away from cells Carries chemical messages from one part of the body to anoth Distributes heat Maintains an acceptable level of body fluid Helps de...

Blood Vessels: The Human Transport System SBI3U  Importance Carries nutrients to cells Carries waste away from cells Carries chemical messages from one part of the body to anoth Distributes heat Maintains an acceptable level of body fluid Helps defend against invading organisms by circulating immune cells  Need Organisms with 1 or 2 germ layers have no need for a circulatory system. Diffusion with the outer aqueous environment will take care of the needs of those cells. Animals with 3 germ layers need a circulatory system to service the middle layers of cells that are not in direct contact with the outer environment.  Recall: Primary Tissue Layers Endoderm – innermost layer – digestive and respiratory tracts and other organs Mesoderm – middle layer – muscle, connective tissues, blood vessels Ectoderm – outer layer, develops to skin and nervous system  Simpler Circulatory System Open System – no closed vessels – Hymolymph: interstitial fluid and blood mixture, surround cells directly – sinus: body cavity surrounding internal organs – Not always used for O2 transport, often animals with lower metabolism  Simpler Circulatory Systems Closed System – true blood vessels – pumping system – Significant variation:  Two-circuit circulatory system Systemic Circulation – Between body and heart – oxygenated blood to tissue and deoxygenated blood to heart Pulmonary Circulation – between lungs and heart – deoxygenated blood goes to lungs and oxygenated blood goes to heart  Try P. 481 # 2-5  The Human Transport System ► In humans, the circulation of blood is carried out by three interconnected subsystems: 1. PULMONARY - vessels that carry blood to and from the lungs 2. SYSTEMIC - vessels that carry blood to and from the body 3. CARDIAC – blood within the heart. Coronary arteries are an important branch of the aorta that supply the muscles of the heart with oxygen and nutrients.  Arteries ► Take blood Away from heart. (Artery = Away) ► Rapid transport of blood under high pressure. ► Carry oxygenated blood ► except pulmonary artery that takes deoxygenated blood away from heart to lungs.  Arteries ► Inner lining = single layer of endothelial cells (called the endothelium) ► Middle layer = smooth muscle tissue for expansion and strength ► Outer layer = connective tissue ► Includes elastin (Very elastic 🡪 able to stretch and coil rapidly) Arteries ► When heart contracts to pump blood out, arteries expand slightly with the “buldge” of blood under high pressure ► Outer layer of the arteries includes elastin which gives elasticity ► Heart relaxes – walls of the arteries return to their original size ► Elasticity of artery wall ensures there is continuous blood flow through blood vessels Arteries ► Can you feel this “buldge” of blood in your artery? ► It is your pulse!  Arteries ► Branches to small arteries called arterioles. Arterioles ► The arteries that branch from the aorta further branch and rebranch into the smallest arteries, which are called arterioles. ► Because the arterioles have smooth muscle in their walls, they can be controlled by the nervous system. ► Signals from the nerves can regulate the diameter of the arterioles and control the blood flow to certain parts of the body.  Arterioles ► Smooth muscle layer causes vasoconstriction or vasodilation to regulate the flow of blood in the body. ► Aids in thermoregulation ► The diversion of blood to organ systems that need it most at any given time (ex. Stomach after eating) ► When too hot, blood rushes to skin’s surface for cooling(creates a flushed look) ► All under nervous control.  Controlling blood flow in arterioles ► When the body is overheated, nerve impulses cause the smooth muscle in the arterioles in the skin to relax. ► This relaxation increases the diameter of the blood vessel, which allows an increased flow of blood to the skin and produces a flushed look. ► This is a cooling strategy: warm blood close to the surface of the skin loses thermal energy to the surrounding environment. ► The relaxation of the smooth muscle=vasodilation. ► Opposite happens when you are cold (vasoconstriction) Thermoregulation When else might these processes occur? ► When resting: blood moved from muscles ► When digesting: blood moved to digestive system ► During exercise: blood moved to lungs and muscles Think-Pair-Share ► Why do you get frost-bite?  Capillaries ► Smallest blood vessel in the body (RBCs must travel single-file) ► Consist of single layer of endothelial cells. ► No smooth muscle  Capillaries ► Pre-capillary sphincter muscles control the flow of blood. ► If blood not needed in capillary bed, sphincters close it off  Capillaries ► Come in contact with individual cells where exchange takes place. ► Diffusion occurs because the rate of blood flow slows due to the increased cumulative cross-sectional area of the capillary bed.  Veins ► Capillaries lead to venules that merge to form veins. ► Take blood towards the heart ► Carry deoxygenated blood ► except the pulmonary vein that brings oxygenated blood to the heart from the lungs. Veins  Veins ► Carry low-pressure blood ► Consist of thinner walls and lining of muscle. ► Contain one-way valves to prevent back flow of blood, valve disorders lead to varicose veins.  Blood Pressure ► Blood in your vessels is always under pressure, pressure is greatest when the heart contracts. ► The highest blood pressure is the systolic pressure, the lowest (between heartbeats) is the diastolic pressure. ► Pressure is measured with a sphygmomanometer  Blood Pressure 1. Cuff inflates to stop blood flow in brachial artery 2. Pressure in cuff is released until blood flow is heard (systolic pressure) 3. When blood is no longer audible the pressure is noted (diastolic pressure)  Blood Pressure ► Average blood pressure: ► Systolic = 120 mm Hg ► Diastolic = 80 mm Hg ► Recorded as 120/80 mm Hg ► Blood pressure is greatest nearest the heart and lowest starting in the capillaries. High Blood pressure High sodium diet Increased salt in blood will result in osmosis and increased water in the vessels. = higher pressure. High Blood Pressure ► Effects on body: ► Can also lead to: ► Blocked arteries ► Damage to your brain: transient ischemic attack (temp. disruption of ► Aneurism (bulge in wall of artery blood to the brain), stroke, bursting) dementia/cognitive impairment (lack ► Coronary Artery Disease (plaque build of O2 supply to brain) up affects vessels supplying heart ► Damage to kidney: high pressure in the muscle) – leads to heart attack vessels leading to kidneys leads to ► Enlarged left heart (it is working too kidney failure, kidney scarring hard pushing blood out to body, ► Damage to Eye thickening ventricle wall, which stiffens it) ► Heart failure  Homework ► Section 11.3 ► P. 494 #1-7 ► practice sheets regarding blood vessels and lymphatic system ►