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I. OVERVIEW OF BLOOD VESSEL STRUCTURE AND FUNCTION
OVERVIEW: Parts & Function Arteries and arterioles: Capillaries Veins and Venules TOPICS Histology Gross Anatomy Physiology Blood Flow Blood Pressure Disorders How Capillary’s Function Specific Blood Vessels & Identification Arteries Capillaries Veins ADDED
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Ch. 19-b The Cardiovascular System: Blood Vessels
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II. PHYSIOLOGY OF CIRCULATION
OVERVIEW IMPORTANCE: All Organs/Tissues Need Adequate Blood– O2, Co2 & Nutrients & To Get Rid Of Wastes Heart gets blood into Vessels, then Vessels take over getting blood to cells BLOOD VESSEL FUNCTIONS Systemic Blood Pressure (Overall) must be maintained to keep blood moving to all the tissues as a whole Blood Flow is Altered To Specific Organs/Tissues to supply what they need when they are active or not Interrelated
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II. PHYSIOLOGY OF CIRCULATION …
A. Definitions and Physics of Blood Flow, Blood Pressure, and Resistance 1. *Blood Flow (F) = if the entire body: then blood flow = Cardiac Output Amount to particular Organs varies with organ’s activity and needs 2. *Blood Pressure (BP) = *For largest arteries near heart, BP = *Pressure Gradient = - *Purpose? Blood flows from _______________ pressure to ________________pressure Resistance NEXT SLIDE
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F = P/R 3. *Resistance = Factors Affecting Peripheral Resistance:
Definition of Terms … 3. *Resistance = Factors Affecting Peripheral Resistance: a) *Blood Viscosity = - Mostly away from Heart b) *Total Blood Vessel Length & Relationship = c) * Blood Vessel Diameter & Relationship to Resistance - most important - In small-diameter arteries F = P/R Volume Velocity Arteries Capillaries Veins
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c) Blood Vessel Diameter ….
A change in diameter of the blood vessels or protruding portions of blood vessel wall create turbulence which increases resistance Relationship between Flow, Pressure, and Resistace = Change in P = Pressure Gradient = difference in pressure between two points in the vessels If P increases-Flow ________ If R increases-Flow ________ Velocity volume F = P/R Arteries Capillaries Veins
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B. Systemic Blood Pressure
*Arterial Blood Pressure: Due to what two factors? a) GRAPH: *Greatest Pressure in what Vessels? Why? *Lowest Pressure is in what type of Vessels? Why? What is the relationship? b) *Pulse Pressure & Pulse = 93mm = MAP Systolic Pressure: Diastolic Pressure:
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B. Systemic Blood Pressure …
c) Mean Arterial Pressure: is the actual pressure that propels blood throughout the vessels - Because pressure varies and the blood remains longer in Diastole, then: MAP = diastole + 1/3 pulse pressure Both MAP and Pulse Pressure decline with increased distance from the hear - Arterioles: many & small Have the Steepest Pressure drop, actually loose pulse 93mm = MAP
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e) Pressure Points in taking BP
1. Arterial Pressure … d) Vital Signs e) Pressure Points in taking BP Capillary Blood Pressure = 35 – 15mm Hg Venous Blood Pressure = 15mm to 0mm Hg (entering right atrium) b) Muscular Pump a) Respiratory Pump
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C. Maintaining Blood Pressure OVERVIEW:
∆P = CO X R Interaction between heart and Blood Vessels 1. SHORT-TERM Autonomic N.S. (EXTRINSIC) Via Baroreceptors Vasomotor & Cardiac Centers Via Chemoreceptors “ “ “ HORMONAL (EXTRINSIC) Sym. Adrenal Medulla: Epinephrine and NE Kidney: Renin Angiotensin II Heart: Atria Natriuretic Peptide 2. LONG-TERM-- KIDNEY DIRECT: amount of urine produced (INTRINSIC) INDIRECT (EXTRINSIC) Renin Angiotensin Aldosterone ADH thirst 3. BLOOD VESSELS OF A PARTICULAR ORGAN
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C. Maintaining Blood Pressure OVERVUEW– INTRODUCTION
Three Main Variables: Cardiac Output (Blood volume) Peripheral Resistance Blood Volume Organs Involved: Heart, Blood Vessels, Kidneys, Nervous System & Endocrine system For Entire circulation: Blood Flow (F) = CO = ∆P/ R and rearrange to ∆P = CO X R Also from Heart: CO = SV x HR Homeostasis: factors affecting Cardiac Output interact with those affecting Mean Arterial Pressure– if one variable changes blood pressure is compensated by changes in other variables Regulation of Heart functions and Blood Vessels interrelated
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C. Maintaining Blood Pressure … Mechanisms
Mechanisms OVERVIEW: Short-term: Normal Regulation via autonomic NS and Hormones Long-term: via mostly kidneys in unhealthy people, emergency states.
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Maintaining Blood Pressure …
∆P = CO X R 1. Short-term–Neural Controls a. Purpose: i) Maintain Mean Arterial Pressure (MAP) so as to maintain Systemic Blood Pressure altering vessel diameter to change Resistance ii) Specific organ demands altering blood distribution via diameter changes & vascular shunts b. Mechanism–Cardiovascular Center in Medulla: Vasomotor (Sym), Cardioinhibitory (Para), Cardioacceleratory (Sym): Affects Resistance and CO i) Baroreceptor-Initiated Reflexes most important - Location: in Carotid Sinus (Internal Carotid A) & Aortic Arch - If BP increases ↑ stretch of Baroreceptors
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*Vasomotor Center: inhibited Results in what?
Short Term Neural Controls … Mechanism … b) Baroreceptors and Vasomotor Center … ∆P = CO X R ii) If BP increases increased stretch of Baroreceptors sends messages to the Cardiovascular Center in Medulla: *Vasomotor Center: inhibited Results in what? Cardioaceleratory: inhibited: Results in what? Cardioinhibitory stimulated Results in what? *If BP decreases decrease in stretch of Baroreceptors Then what? iii) Baroreceptor Problems with Sustained increase in pressure: they adapt in Long-term especially in those with chronic high blood pressure - Then Long-term mechanisms are used-- Renal
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Maintaining Blood Pressure … Short-term Neural Controls
iv) Short-term Chemical Reflexes: for O2, CO2, & H+ Mainly in response to breathing changes Via Chemoreceptors Autonomic NS Short-Term Mechanisms: Hormonal Controls - Alters RESISTANCE by changing vessel diameter Adrenal Medulla Hormones-- produced during stress i) Norepinephrine (NE) mostly constriction of vessels But, Vasodialation in skeletal & cardiac muscle ii) Epinephrine affects mostly the Heart Angiotensin II: produced in kidney using Renin - Causes Intense Vasoconstriction ∆P = CO X R
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Control of Blood Pressure … 3. Long-Term Mechanisms: Renal Regulation
Via changing: BLOOD VOLUME a. Direct (intrinsic) independent of hormones ↑ BP in renal arteries more urine less blood volume ↓ BP b. Indirect (extrinsic) renin-angiotensin mechanism (Same as Short term mechanism) Angiotensin II: affects on blood volume (CO) ↑ Aldosterone: reabsorbs Na+, and water follows ↑ ADH: reabsorbs H2O ↑ Thirst via Hypothalamus ∆P = CO X R Figure 19.10
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REVIEW: Systemic BP Regulation
∆P = CO X R Interaction between heart and Blood Vessels 1. SHORT-TERM– affects vessel diameter Autonomic N.S. (EXTRINSIC) Via Baroreceptors Vasomotor & Cardiac Centers HORMONAL (EXTRINSIC) Sym. Adrenal Medulla: Epinephrine and NE Kidney: Renin Angiotensin II 2. LONG-TERM– KIDNEY affects blood volume DIRECT: amount of urine produced (INTRINSIC) INDIRECT (EXTRINSIC) Renin Angiotensin Aldosterone ADH thirst
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III. Blood Flow To Specific Body Tissues
A. Blood Flow to particular tissues Capillaries have greatest affect Independent of MAP (systemic pressure) Flow = ∆P X R To specific Organs: Flow is right for proper function B. Autoregulation INTRINSIC Modifies via diameter of arterioles Mechanisms next slide Brain Heart Skeletal muscles Skin Kidney Abdomen Other Total blood flow at rest 5800 ml/min Total blood flow during strenuous exercise 17,500 ml/min
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Metabolic: INTRINSIC To ↑ Flow to Active Tissues
B. Autoregulation … Metabolic: INTRINSIC To ↑ Flow to Active Tissues Active Tissues: have increased CO2, H+, NO trigger dilation Precapillary Spincters open Inflammatory chemicals (tissue damage) dilation 2. Myogenic: INTRINSIC To protect against inadequate perfusion and high of pressure that would rupture vessels ↑ Pressure ↑stretch damage to small vessels: so compensate by constricting to reduce flow to organ ↓ Pressure ↓stretch tissue not adequately oxygenated: so compensate by dilating Long-term Regulation Angiogenesis: ↑ blood vessels
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C. Blood Flow in Specia Areas
1. Blood Flow: Lungs Pulmonary circuit is short and Arteries/arterioles structurally like veins/venules Arterial resistance and pressure are low (24/8 mmHg) Autoregulation opposite of most tissues at capillaries Low O2 levels = blocked/damaged air sacs bypass with vasoconstriction; High O2 levels means that air sacs are functional, so send blood to them dilation
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D. Blood Flow Through Body/Tissue Capillaries and Capillary Dynamic
1. Capillary Exchange of Respiratory Gases and Nutrients– how they get from blood to tissues Gases Diffusion of O2 and CO2 TO TISSUES: FROM TISSUES: a. Lipid-soluble molecules diffuse directly through membranes b & c. Water-soluble solutes pass through clefts/fenestrations d Larger molecules, such as proteins, actively transported SEE NEXT SLIDE FOR DIAGRAM
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IV Disorders of the Blood Vessels
Students Do Following: Atherosclerosis Types of Circulatory Shock Hypo- and Hypertension
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PART 3 CIRCULATORY PATHWAYS: BLOOD VESSELS OF THE BODY
Two Main Circulations V. Systemic Arteries & Veins Arteries: Left Ventricle AORTA Arch Thoracic Aorta Abdominal Aorta Pelvic Cavity: Common Iliac Arteries Figure 11.12
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Veins: entering Right Atrium
V. Systemic … … Veins: entering Right Atrium Superior Vena Cava - Circle of Willis (a.k.a. cerebral arterial circle) keeps blood flowing to brain Figure 11.13
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2. Inferior Vena Cava a) Digestive organ Veins do not directly take blood back to Inferior Vena Cava, but to Liver: food eaten may have toxins in it, so must be processed by Liver before toxins are spread to the rest of the body
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b. Hepatic Portal System Digestive Organ Capillaries drain into
Veins: entering Right Atrium … 2. Inferior Vena Cava b. Hepatic Portal System Digestive Organ Capillaries drain into Digestive Organ Veins: Superior & Inferior Mesenteric and Splenic Do not directly empty into the Inferior Vena Cava Hepatic Portal Vein drains into Liver Sinusoids for processing of digested food Hepatic Veins then take processed blood Inferior Vena Cava Figure 11.13
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b. Hepatic Portal System …
Digestive Arteries Digestive Capillaries Digestive veins Hepatic Portal V. Liver sinusoids Hepatic Veins Inferior Vena Cava Right Atrium
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VI. Pulmonary Arteries & Veins
Arteries– Pulmonary Trunk from Right Ventricle Left and Right Pulmonary Arteries B. Veins– 4 Pulmonary Veins enter Left Atrium
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END PPT Review Questions Extra Slides
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precapillary sphincters
Review Questions What type of capillaries are found in the liver and bone marrow? What type of vessel maintains the lowest pressure and highest blood volume? One mechanism of blood flow control through capillary beds is via __________ ___________ that can bypass beds by routing blood through vascular shunts. Sinusoid Veins precapillary sphincters
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Review Questions Alternative routs for blood flow that develop from interconnecting vessels are known as _____________. What type of vessel provides the major source of resistance to blood flow? Blood pressure depends on what 3 major variables? anastomoses Arterioles CO, R, and Blood Volume
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Baroreceptors and Chemoreceptors
Review Questions Short term neural control of BP is controlled by reflex arcs involving what types of receptors? ________ is the only hormone that reduces blood volume and is produced by the __________ Which short term hormonal control is initiated by renin release from the kidneys? Baroreceptors and Chemoreceptors ANP heart Angiotensin II
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CO, Resistance, and Blood Volume Blood Volume – which is regulated by?
Review Questions … Blood pressure depends on what 3 major variables? Short term control of BP is regulated by which of the above? Long term control is regulated by changing which variable? CO, Resistance, and Blood Volume Resistance (and CO) Blood Volume – which is regulated by?
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Via intercellular clefts or fenestrations
Participate Localized adjustments made to ensure blood flow according to tissue needs = __________________ _________ autoregulation occurs when arterioles are stretched if systemic BP increases How do water soluble solutes pass through capillary walls? autoregulation Myogenic Via intercellular clefts or fenestrations
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Net Filtration Pressure
Review Questions What does NFP stand for? When net hydrostatic pressure (HP) is less than net osmotic pressure (OP), which way do fluids flow? What vein delivers blood TO the liver? Net Filtration Pressure Into capillaries Hepatic portal vein
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