Lab 4: Blood Vessels & Circulation PDF

## LAB 4 ### Blood - Transportation of nutrients and wastes - Maintaining homeostasis - Protecting the body - Carries red cells, white cells, hormones, and controls blood pressure - Monitors blood composition ### Blood Vessels - Transporting blood throughout the body - Carry red cells, white ce...

## LAB 4 ### Blood - Transportation of nutrients and wastes - Maintaining homeostasis - Protecting the body - Carries red cells, white cells, hormones, and controls blood pressure - Monitors blood composition ### Blood Vessels - Transporting blood throughout the body - Carry red cells, white cells, hormones, and control blood pressure - Monitor blood composition ### Heart - The pump that drives the blood through the body ### Circulatory plan of the body - **Closed system:** Blood is circulated through closed vessels at all times #### Arteries - Vessels leaving the heart - Can carry oxygenated blood or not to the capillaries - **Elastic arteries:** Higher percentage of elastic fibers in tunica media than muscular arteries (most in the body) - Help pump blood throughout the body when ventricles are relaxing - Pressure reservoir when heart is in diastole - **Arterioles** - Arteries flow into smaller vessels #### Capillary beds - From arterioles - Allow for gas, nutrient, waste exchange between cells and capillary lumen - Simple squamous endothelial #### Venules - Small veins from capillary beds #### Veins - Larger diameter vessels from venules - Collection portion of the system - Lead back to the heart - More veins than arteries - Under less pressure than arteries, so they contain up to 70% of the total blood supply - **Venous valves:** Formed from folds in the tunica interna to prevent backflow of blood - Essential to maintain flow back to the heart ### Blood Vessel Structure - 4 vessels: Arteries, arterioles, veins, venules #### Vasodilation - Smooth muscle relaxes - The diameter of the lumen increases #### Vasoconstriction - Smooth muscle contracts - The diameter of the lumen decreases #### Tunics - Layers that surround the lumen (center where blood is found) **Arteries and arterioles** play a major role in the regulation of blood pressure - **Tunica externa (adventitia):** External layer of vessel composed of dense irregular connective tissue for anchoring to surrounding tissue - Slightly thicker in veins than arteries - **Tunica media:** Middle layer composed of circular smooth muscle cells and elastic fibers - Tunica media is more predominate in arteries - Typically the thickest layer in elastic artery (more rigid and round shape) - Where as it is reduced in veins (collapsed) - **External elastic lamina:** Additional layer of elastic tissue located on the border of the tunica externa and media; arteries only - Elastic fibers gives vessels their elastic and contractile properties - Smooth muscle alters the vessel diameter - **Tunica interna:** Single layer of endothelium lining the lumen of the vessel - **Internal elastic lamina:** Band of connective tissue appears folded on the inner surface of the artery, between the endothelium and tunica media; only in arteries ### Hemodynamics - Physiology of blood flow; heart pumps blood, blood vessels, body - **Blood pressure:** The force the blood puts on the walls of the blood vessels - Measured in mmHg - Comes from the force that the heart pumps - **Pressure gradient:** In relation to their distance from the left side of the heart; pressure is higher in aorta and lower in vena cavas - **Blood flow:** Amount of blood that flows through blood vessel per minute - Directly proportional to pressure gradient (both for b) - Inversely proportional to resistance - **Peripheral resistance:** Anything that impedes blood flow in the circulatory system - **Blood vessel radius:** Can alter diameter by contracting or relaxing tunica media; inversely related to blood pressure - **Blood vessel length:** Longer the vessel, the higher the blood pressure because blood needs to move a longer distance - **Blood viscosity:** Viscosity is fairly constant except when components of blood are altered; the more viscous, the higher the blood pressure - **Blood volume:** Increase in volume means filling the vessel more, causing more pressure on walls - **Vessel compliance:** Ability for blood vessel to stretch to accommodate the extra volume; veins are more compliant than arteries - **Measuring blood pressure:** We report the blood pressure in the arteriol portion of the circulatory system. - Systolic pressure is the numerator - Diastolic pressure is the denominator - **Systole:** Heart in contracting & sends a wave of pressure through the system; 120 mmHg - **Diastole:** Heart is relaxing & there is still pressure throughout the system; 80 mmHg #### Sphygmomanometer and stethoscope - **Cuff placed over brachial artery while stethoscope placed in antecubital to hear turbulent blood sounds:** - Cuff inflated to above individuals systolic pressure (140 mmHg) to cut off blood traveling through brachial artery; no sound - Cuffs pressure slowly released; once cuff & systolic pressure are equal a small amount of blood can squirt through, hear sound - First sound recorded as systolic pressure - Cuff continues to drop, artery slowly opens, blood squirted through in each pressure wave; last sound is diastolic pressure ### Gross Anatomy of Vascular System - **Pulmonary circuit:** Brings deoxygenated blood from heart to lungs where CO₂ is exchanged for O₂ and blood then returned to heart - Blood collected by superior and inferior vena cava → right atrium → right ventricle - Heart contracts → pulmonary trunk → right and left pulmonary arteries→lungs (exchange CO₂ for O₂)→ 4 pulmonary veins (2 per lung) → left atrium - **Systemic circuit:** Pumps oxygenated blood from heart to body, and returns deoxygenated blood back to heart - **Celiac:** Abdominal cavity - **Gastric:** Stomach - **Gonadal:** Gonads (reproductive organs) - **Hepatic:** Liver - **Mesentery:** Double fold of serous membrane surrounding small and large intestines - **Renal:** Kidney - **Splenic:** Spleen #### Figure 4.1. General circulatory pathway schematic - **Pulmonary circulation:** Right ventricle deoxygenated blood to pulmonary artery → capillaries of lungs→ oxygenated blood to pulmonary veins → left atrium → left ventricle - **Systemic circulation:** Left ventricle oxygenated blood to aorta → capillary network → deoxygenated blood to veins → right atrium → right ventricle