Blood Vessels and Circulation Slides PDF

BLOOD VESSELS & Biology 1203 Unit 4 CIRCULATION Laura Solteiro  FUNCTION OF BLOOD VESSELS Carry blood to and from heart Carry blood around body Arteries  Branch to become smaller arterioles Capillaries (site of gas/nutrient exchange) Veins  Venules converge to become larger veins...

BLOOD VESSELS & Biology 1203 Unit 4 CIRCULATION Laura Solteiro  FUNCTION OF BLOOD VESSELS Carry blood to and from heart Carry blood around body Arteries  Branch to become smaller arterioles Capillaries (site of gas/nutrient exchange) Veins  Venules converge to become larger veins STRUCTURE OF BLOOD VESSELS TUNICA INTERNA: Endothelium Basement membrane Valve Internal elastic lamina TUNICA MEDIA: Smooth muscle External elastic lamina TUNICA EXTERNA Lumen Lumen (a) Artery (b) Vein ▪ Also called the tunica intima ▪ Endothelial layer (simple squamous epithelium) ▪ Lines the lumen of all vessels and is in direct contact with the blood ▪ Continuous with endocardial lining of heart ▪ Regulates capillary exchange and can alter blood flow (endothelins can constrict smooth muscle to increase blood pressure) ▪ Smooth muscle and elastic fiber ▪ Controls vasoconstriction/vasodilation ▪ Collagen and elastic fibers ▪ Protects and reinforces vessels ARTERIES Blood vessels that carry blood away from heart Usually carries oxygenated blood (exception is the pulmonary artery) Arteries have thicker muscle (tunica media) and elastic lamina; needed to withstand pressure coming from heart Arteriole  small artery  resistance and regulation of blood pressure  leads to a capillary VEINS Blood vessels that carry blood to heart Usually carries deoxygenated blood (exception is the pulmonary vein) Veins have thinner muscle walls; blood in veins under lower pressure Veins contain valves (one-way doors) to prevent backflow of blood Contraction of surrounding skeletal muscle also helps move blood through veins Venule = small vein ARTERY AND VEIN HISTOLOGY CAPILLARIES Very thin: composed of only tunica intima (endothelium and basement membrane) Supplies blood to tissues (perfusion) Site of exchange between blood plasma and cells/interstitial fluid Vary in diameter and permeability depending on location Lumen Endothelium Basement membrane  BLOOD PRESSURE = force exerted by blood on the walls of the blood vessels or the chambers of the heart during ventricular systole (typically refers to the systemic arterial blood pressure) WHAT FACTORS CAN LEAD TO AN INCREASE IN BLOOD PRESSURE? 1. Increase in heart rate 2. Increase in contraction strength (contractility) 3. Increase in blood volume 4. Increase in blood viscosity 5. Decrease in blood vessel diameter (vasoconstriction) 6. Increase cardiac output STOP & THINK Which of the following factors does not lead to an increase in blood pressure? A. Increase in blood viscosity B. Increase in blood vessel diameter C. Increase in blood volume D. Increase in contraction strength E. Increase in heart rate BLOOD PRESSURE OF A HEALTHY INDIVIDUAL Systolic pressure: arterial pressure resulting from the ejection of blood during ventricular contraction (systole) Diastolic pressure: arterial pressure of blood during ventricular relaxation (diastole) Healthy young adults have a blood pressure of 120/80: their systolic pressure is 120 mm Hg, their diastolic pressure is 80 mm Hg Hypertension: above average blood pressure Unsplash.com REGULATION OF BLOOD PRESSURE 1. Nervous system: indirectly affects blood pressure by changing heart rate or diameter of blood vessels using baroreceptors and chemoreceptors 2. Autoregulation: active tissue cells, and also cells inside the blood, can change blood pressure indirectly by releasing chemicals that change the diameter of blood vessels, especially at precapillary sphincters 3. Endocrine system: hormones can be produced that can change blood viscosity or ion levels  Unit 1: Epinephrine/Norepinephrine, Aldosterone, ADH  Unit 3: Erythropoietin BARORECEPTOR-INITIATED FEEDBACK ARTERIAL PULSE Alternate expansion and recoil of an arterial muscle wall can be felt – i.e. no other muscles are in the way Used to measure heart rate in beats per minute (BPM) Locations include:  Wrist → radial artery  Neck → carotid artery  Temporal to eye → superficial temporal artery  Thigh → femoral artery  Upper arm → brachial artery MAIN ARTERIES MAIN ARTERIES MAIN VEINS Femoral MAIN VEINS Femoral  MAIN ARTERIES (HEART TO UPPER BODY) Pulmonary veins Left atrium Left ventricle Arch of aorta Brachiocephalic trunk Right Left subclavian subclavian (left shoulder) (right shoulder) Right common Left common carotid carotid (neck) Right axillary to (neck) Left axillary to brachial (down arm) brachial (down arm)  MAIN VEINS (UPPER BODY TO HEART) Right atrium Superior vena cava Right brachiocephalic Left brachiocephalic Right subclavian Right jugular Left jugular Left subclavian (right shoulder) (neck) (neck) (left shoulder) Brachial to axillary Brachial to axillary (from arm) (from arm) MAIN ARTERIES (HEART TO LOWER BODY) Pulmonary veins Left atrium Left ventricle Arch of aorta Hepatic artery (liver) Descending aorta Gastric artery (stomach) Mesenteric artery (intestines) Renal artery (kidney) Right common iliac artery Left common iliac artery (pelvic) (pelvic) Right femoral artery (thigh) Left femoral artery (thigh)  MAIN VEINS (LOWER BODY TO HEART) Right atrium Hepatic portal vein (liver) Inferior vena cava Hepatic vein (liver) Gastric vein (stomach) Mesenteric vein (intestines) Renal vein(kidney) Right common iliac vein Left common iliac vein (pelvic) (pelvic) Right femoral vein (thigh) Left femoral vein (thigh)