Chap 18 – Blood Vessels Learning Objectives: 1.Describe the structure of blood vessels walls. 2.Differentiate between vasoconstriction and vasodilation. 3.Explain blood pressure and factors that influence blood pressure as well as elevation of blood pressure. 4.Compare and contrast the structures and functions of the various blood vessels. Homework: Read Chap 18. Review notes from class.

Critical Situation: Aorta Aneurism View a life-threatening scenario: are%20Animations/animAAA.htm are%20Animations/animAAA.htm Cool fact: The blood vessels of an adult human stretch for about 60,000 miles through the internal landscape of the body!

Discussion What are the three major types of blood vessels?

Artery and Vein Structure, pg 627 Arteries and veins are composed of three tunics: 1. tunica __________ 2. tunica _________ 3. tunica _________

Think-Pair-Share Instructions: 1.Quickly pair with a partner. 2.Review Table 18.1 Summary of Blood Vessel Anatomy and outline the following in your notes: a) The 6 types of vessels in the body b) What’s the smallest of the 6 vessels? 3. Be prepared to share with the class.

Elastic Conducting Arteries Thick-walled arteries _____ ____ _____; the aorta and its major branches –Large lumen allow low-resistance conduction of blood –Contain elastin in all three _______ –Withstand and smooth out large blood pressure _________ –Allow blood to flow fairly continuously through the body

Muscular Arteries and Arterioles Muscular arteries – ______ to elastic arteries; deliver blood to ____ _______ –Have thick tunica media with more smooth muscle and less elastic tissue –Active in vasoconstriction Arterioles – ________ arteries; lead to capillary beds –Control flow into capillary beds via vasodilation and constriction

Capillaries Capillaries are the ______ blood vessels –Walls consisting of a thin tunica interna, one ____ thick –Allow only a _____ RBC to pass at a time There are three structural types of capillaries: continuous, fenestrated, and sinusoids

Capillary Beds A microcirculation of interwoven networks of capillaries

Venous System: Venules Are formed when capillary beds ______ –Allow fluids and WBCs to pass from the bloodstream to ________ Postcapillary venules – smallest venules, composed of endothelium Large venules have one or two layers of ________ muscle (tunica media)

Veins Veins have much _____ blood pressure and _______ walls than arteries To return blood to the heart, veins have special adaptations –_______ (resembling semilunar heart valves), which prevent backflow of blood Veins are: –Formed when venules converge –Composed of _______ tunics, with a thin tunica media and a thick tunica externa consisting of collagen fibers and elastic networks –Blood reservoirs that contain __% of the blood supply

Review 1. What is the inner-most structural layer of an artery or vein? 2. What’s the main distinction between elastic arteries and muscular arteries? 3. What’s the smallest of the arteries?

Discussion What is Blood Pressure?

Understanding Blood Pressure ________ pressure (top number) – pressure exerted on arterial walls when ventricles contract _______ pressure (bottom number) – the pressure when the heart relaxes between beats For example: 118 / 76 Blood pressure below 120 over 80 mmHg (millimeters of mercury) is considered optimal for adults. A blood pressure reading of 140 over 90 or higher is considered elevated (high).

Maintaining Blood Pressure Maintaining blood pressure requires: –Cooperation of the _____, blood _______, and _______ –Supervision of the _______

Chemicals That Increase Blood Pressure Adrenal medulla hormones – ___________ and _________ increase blood pressure Antidiuretic hormone (ADH) – causes intense vasoconstriction in cases of extremely ____ BP Angiotensin II – kidney release of renin generates angiotensin II, which causes intense ___________ Endothelium-derived factors – endothelin and prostaglandin-derived growth factor (PDGF) are both vasoconstrictors

Chemicals That Decrease Blood Pressure Atrial natriuretic peptide (ANP) – causes blood _______ and ______ to decline Nitric oxide (NO) – has brief but potent vasodilator effects Inflammatory chemicals – ___________, prostacyclin, and kinins are potent vasodilators _________– causes BP to drop by inhibiting ADH

Kidney Action and Blood Pressure Kidneys act directly and indirectly to maintain long-term _____ _________ –Increased BP stimulates the kidneys to eliminate ______, thus reducing BP –Decreased BP stimulates the kidneys to increase blood volume and BP

Review 1. How does alcohol effect blood pressure? 2. What effect does epinephrine have on blood pressure? 3. In a blood pressure reading such as 120/80, the top number is “systolic”. What does that represent?

Circulatory Shock ___________ shock – results from large- scale blood loss (i.e., acute hemorrhage, severe burns) ________ shock – normal blood volume but circulation is poor as a result of abnomral expansion of the vascular vessels (i.e., severe sunburn ___________ shock – pump failure; heart is inefficient (i.e., resulting from multiple heart attacks)