Human Anatomy and Physiology BIOL3306 Fall 2024 Lecture Notes PDF

Human Anatomy and Physiology BIOL3306 Fall 2024 Week 11: The Cardiovascular System Blood Professor: Nour Nissan 19.1 Overview of Blood Blood—Fluid connective tissue that always circulates through the heart and blood vessels; About 5 liters and about...

Human Anatomy and Physiology BIOL3306 Fall 2024 Week 11: The Cardiovascular System Blood Professor: Nour Nissan 19.1 Overview of Blood Blood—Fluid connective tissue that always circulates through the heart and blood vessels; About 5 liters and about 8% of the total body weight Composed of: – Plasma—Liquid extracellular matrix – Formed Elements ▪ Erythrocytes or Red Blood Cells (RBC s) ▪ Leukocytes or White Blood Cells (W BC s) ▪ Platelets (cell fragments) Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.1 Overview of Blood Figure 19.1 The three visible layers of blood. When centrifuged, the components of blood separate into three distinct layers – The top layer is plasma, which constitutes about 55% of the total blood volume – The middle layer is the Buffy Coat, which constitutes about 1% of the total blood volume and consists of leukocytes and platelets – The bottom layer constitutes about 44% of the total blood volume and consists of the erythrocytes............................—Percentage of blood composed of erythrocytes Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.1 Overview of Blood Functions Exchanging Gases—Oxygen is transported from the lungs to tissues mostly by erythrocytes; Erythrocytes and plasma transmit carbon dioxide from tissues to the lungs Distributing Solutes—Blood transmits many solutes, including nutrients, hormones, ion, and wastes Performing Immune Functions—Leukocytes and proteins of the immune system use blood to reach all body tissues Sealing Damaged Vessels by Forming Blood Clots—When a blood vessel is broken, platelets and certain proteins form a blood clot that seals the vessel Preserving Acid-Base Homeostasis—The p H of blood is maintained within the narrow range of 7.35–7.45 because blood composition controls many of the body’s most important buffer systems Stabilizing Blood Pressure—Blood volume is a primary factor in determining blood pressure, therefore maintaining blood volume is vital to maintaining a stable blood pressure Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.1 Plasma Plasma Pale yellow liquid consisting of 90% water, which is important in determining the Viscosity, or thickness, of blood About 1% of plasma volume is a variety of small solutes that dissolve in the water and form a solution; Includes glucose, amino acids, nitrogenous wastes, ions, and some oxygen and carbon dioxide Includes Plasma Proteins, that make up about 9% of the volume and are made mostly by the liver Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.1 Plasma Table 19.1 Components of Plasma Plasma Component Function Water 90% of plasma volume; solvent that dissolves and transports many solutes through the body Plasma Proteins 9% of plasma volume; multiple functions (see below) Albumin Maintains osmotic pressure Immune proteins Produced by leukocytes; function in immunity Transport proteins Bind and transport hydrophobic compounds through the blood Clotting proteins Stop blood loss from damaged vessels Other Solutes 1% of plasma volume; multiple functions (see below) Glucose, amino acids Nutrition; used for protein synthesis Ions Electrolyte and acid-base homeostasis Dissolved gases (small amounts Oxygen delivered to the tissues; carbon dioxide delivered to the of oxygen and carbon dioxide) lungs to be exhaled Wastes Delivered to the appropriate organ for excretion Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Erythrocyte Structure Erythrocytes—Biconcave discs, Gives them a large surface- to-volume ratio that is critical to their role in gas exchange Lack nuclei (anucleate) and most other organelles, including mitochondria; Consist of little more than a plasma membrane surrounding cytosol filled with enzymes and one billion molecules of Hemoglobin (Hb) Each red blood cell carries about 1 billion oxygen molecules Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Erythrocyte Structure Erythrocytes (continued) Hemoglobin consists of four polypeptide subunits: two alpha ( ) chains and two beta () chains; Each polypeptide is bound to an iron-containing Heme Group The heme binds to oxygen (O2 ) in parts of the body where oxygen level is high (lungs), forming......................... The heme releases oxygen, forming................................... in parts of the body where oxygen level is low (tissues) Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Erythrocyte Structure Erythrocytes (continued) When all four heme groups are bound to oxygen, the protein is bright red; Conversely, when fewer heme groups are bound to oxygen, the protein is a much darker red; Blood in veins looks “blue” because of light refraction Hemoglobin also binds carbon monoxide (C O), but 200 times more strongly than oxygen and will not release the C O, forming Carboxyhemoglobin, which is often lethal Erythrocytes squeeze through over 100,000 blood vessels under high pressure and enormous shear forces, which damages them Also, they lack the cellular machinery to repair themselves Erythrocyte lifespan is only 100–120 days.............................. —Production of formed elements in the blood from Hematopoietic Stem Cells (HSC s); Occurs in Red Bone Marrow in the spongy bone Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Lifespan of an Erythrocyte Erythropoiesis—Formation of erythrocytes which takes 5–7 days; About 250 billion cells per day are formed HSC s differentiate into progenitor cells called Erythrocyte Colony-Forming Units (CFU s) CFU s then differentiate into Proerythroblasts, which requires Erythropoietin (EP O) hormone, secreted by the kidneys Proerythroblasts develop into Erythroblasts, which synthesize hemoglobin; They mature and eject their nuclei to become Reticulocytes They eject the rest of the organelles and squeeze into the sinusoidal capillary to enter the bloodstream Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Lifespan of an Erythrocyte Figure 19.4 Erythropoiesis: formation of erythrocytes. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Lifespan of an Erythrocyte Regulation of Erythropoiesis—Regulated by a negative feedback loop to maintain hematocrit within normal limits; Regulated by erythropoietin and influenced by the level of oxygen in the blood 1) Stimulus: Blood oxygen level decreases below the normal range of about 104 mm Hg May result from respiratory problems, heart conditions, or reduced availability of oxygen (e.g., high altitudes) 2) Receptor: Kidney cells detect a low oxygen level in blood Chemoreceptor cells are stimulated if oxygen is low 3) Control Center: Kidneys produce more....................... and release it into the blood Erythropoietin communicates with HSC s in bone marrow Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Lifespan of an Erythrocyte Regulation of Erythropoiesis (continued) 4) Effector/Response: Rate of erythropoiesis increases, time of erythrocyte maturations decreases, and hematocrit rises 5) Return to Normal Range: Receptors in the kidneys detect the return of blood oxygen to the normal range, and the kidneys decrease production of erythropoietin As more erythrocytes enter the blood, the oxygen-carrying capacity of the blood increases and kidney cells reduce erythropoietin production to baseline levels Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Lifespan of an Erythrocyte Figure 19.5 Regulation of erythropoiesis. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Lifespan of an Erythrocyte Erythrocyte Death—The plasma membranes of erythrocytes become less flexible, and they are unable to exit the spleen (the red blood cell graveyard) 1) Erythrocytes become trapped in the spleen 2) Spleen macrophages digest erythrocytes – Macrophages are phagocytes that ingest and destroy older erythrocytes and other cells 3) Globin is broken down into amino acids -> goes to......... to be used in formation of new proteins. 4) Iron from the heme group binds to proteins and is stored in the liver or is placed in a new heme molecule 5) heme is turned into bilirubin which is sent to the......... for excretion Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Lifespan of an Erythrocyte Figure 19.6 Erythrocyte death. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Anemia Anemia—Defined as decreased oxygen-carrying capacity of the blood Symptoms include pallor (pale skin, gums, and/or nail beds), fatigue, weakness, and shortness of breath Severe anemia may cause a rapid heart rate as the body is attempting to compensate for impaired oxygenation of the tissues and may be fatal is untreated There are three primary causes: Decreased hemoglobin, decreased hematocrit, and abnormal hemoglobin Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Anemia Abnormal Hemoglobin Sickle-Cell Disease—Most common cause of abnormal hemoglobin Individuals with a single copy of the defective gene have Sickle-Cell Trait, and are usually asymptomatic; Provides protection again the mosquito-born disease Malaria, endemic to tropical locations Individuals with two copies of the gene have Sickle-Cell Disease and produce Hemoglobin S (Hb S); erythrocytes become “sickle” shaped, which get caught in capillaries and are destroyed, leading to anemia Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.2 Anemia Figure 19.7 Erythrocytes in sickle-cell disease. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved White Blood Cells (Leukocytes) Defend the Body Produced by division of stem cells in bone marrow Functions – Protect against infection – Regulate the inflammatory reaction Two major categories – Granular: neutrophils, eosinophils, and basophils – Agranular: lymphocytes and monocytes Most WBCs have a relatively short life span 1-20 days Circulating levels can rise quickly in response to infection May leave the blood for the interstitial fluid or lymph Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.4 Platelet Characteristics Platelets—Involved in blood clotting Lack nuclei and most organelles, but contain microtubules associated with actin and myosin filaments Contain granules with clotting factors and enzymes, some Figure 19.10a Structure and mitochondria, and glycogen to formation of platelets. carry out oxidative catabolism Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved Platelets Are Essential for Blood Clotting Megakaryocytes arise from division of stem cells in bone marrow. Megakaryocytes in bone marrow break into fragments called platelets. Platelets play an important role in hemostasis. – If blood vessel is injured, platelets initiate the clotting process..........................—The process that stops blood loss from an injured blood vessel; Involves a series of events that form a gelatinous Blood Clot to “plug” the broken vessel Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved Hemostasis: Stopping Blood Loss Three stages 1. Vascular spasm: constriction of blood vessels to reduce blood flow 2. Platelet plug formation: sealing of the ruptured blood vessel 3. Coagulation: formation of a blood clot  Blood changes from a liquid to a gel  Complex series of reactions involving at least 12 different clotting proteins in the plasma Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.5 Disorders of Clotting Clotting Disorder—Condition in which clotting in not regulated properly Bleeding Disorders—Blood is unable to clot; Often result from clotting protein deficiencies such as Hemophilia A, caused by shortage of factor VIII and Hemophilia B, caused by inadequate factor IX – Many may be treated by replacing the missing clotting factor or protein with periodic infusions Hypercoagulable Conditions—Formation of an inappropriate clot, called...........................; The clot, can obstruct blood flow through a vessel Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.5 Anticlot Medications Drugs that prevent one step in the clotting process: Heparin (and its derivatives)—Used in hospitals because action is nearly immediate, but must be injected Warfarin (trade name Coumadin)—Inhibits production of the vitamin K-dependent clotting factors by the liver (factors II, VII, IX, and X); Can be given by mouth so preferred in outpatient settings although careful monitoring is required Apixaban and Rivaroxaban—Inhibit factor Xa; Preferred because they require no monitoring Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.5 Anticlot Medications Drugs that act directly on platelets: Aspirin—Inhibits enzymes in platelets that contribute to platelet aggregation Clopidogrel—Blocks platelet receptors and inhibits platelet aggregation Glycoprotein IIb/IIIa Inhibitors—Used commonly in heart attack patients, work by a similar mechanism to clopidogrel Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Typing and Matching Blood Transfusion—Blood is removed from a Donor and given to a Recipient; First done in the 1800s although many recipients died; Discovered the presence of surface markers, or antigens, on erythrocytes in 1901 Blood Groups—Determined by the antigens on erythrocytes made of carbohydrate chains that are genetically determined Over 30 different types of antigens are found on erythrocytes, but two antigen groups are important clinically: AB O Blood Group and the R h Blood Group Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Typing AB O Blood Group—Features two antigens: The A Antigen and the B Antigen; There are four possible AB O types: Type A—Only the A antigen is present on the erythrocytes Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Typing Type B—Only the B Type A B—Both the A and antigen is present on the B antigens are present on erythrocytes the erythrocytes Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Typing Type O—Neither the A nor B antigens are present on the erythrocytes; “O” simply means that both the A and B antigens are absent Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Typing R h Blood Group—Features the R h (D) Antigen; First discovered in rhesus monkeys; Individuals with the R h antigen are R h-.............. (................) and those lacking the R h antigen are R h-.............. (................); The AB O and R h blood groups are combined into eight common blood types Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Transfusions Your immune system recognizes antigens on your erythrocytes as “self” antigens and does not produce antibodies to those antigens It does produce antibodies to foreign antigens; This means antibodies are present in your plasma only if the antigens are normally absent on your erythrocytes Anti-A and Anti-B Antibodies are Pre-Formed, meaning they are present without exposure to those antigens Anti-R h Antibodies are only produced if a person has been exposed to blood containing the R h antigen Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Transfusions Here is an example: Sue has type B- blood, so her erythrocytes have B antigens only; Her immune system cannot make anti-B antibodies, or it would agglutinate her own erythrocytes; However, she can safely produce anti-A and anti-R h antibodies Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Transfusions A patient cannot receive any blood containing antigens that his or her immune system would recognize as foreign; Sue could not receive blood with A or R h antigens, which includes:........................................ Sue could safely receive blood from blood types that do not have A and R h antigens:....................... These are a Match for Sue’s blood type Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Transfusions If Sue donates blood, her blood can be given only to recipients who lack the anti-B antibody including:.......................................... All other blood types have anti-B antibodies that will agglutinate her donated erythrocytes This agglutination is known as a Transfusion Reaction and destroys the donor erythrocytes, possibly leading to kidney failure and death Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Transfusions In another example, Donor Ed has O- blood (Universal Donor), which has none of the antigens of the AB O or R h groups; Recipient Oscar has AB+ blood (Universal Recipient), which has none of the anti-A, anti-B, or anti-R h antibodies Figure 19.20 Matching blood types for blood transfusions. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Transfusions However, if donor Oscar has AB+ blood, with A, B, and R h antigens and recipient Ed has O- blood, with anti-A, anti-B, and possibly anti-R h antibodies; The result would be a transfusion reaction; Type O- blood can only receive type O- blood and type AB+ can only donate to type AB+ Figure 19.20 Matching blood types for blood transfusions. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Typing Table 19.5 The Eight Major Blood Types Blood Prevalence in Antigens Present on May Receive May Type U.S. Population Erythrocyte Surface Antibodies Present in Plasma* From Donate To AB+ 3% A, B, R h None Universal AB+ recipient AB− 1% A, B Anti-R h AB−, A−, AB+, AB− B−, O− A+ 34% A, R h Anti-B A+, A−, AB+, A+ O+, O− A− 6% A Anti-B, anti-R h A−, O− AB+, AB−, A+, A− Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Blood Typing Table 19.5 The Eight Major Blood Types (continued) Blood Prevalence in Antigens Present on May Receive May Type U.S. Population Erythrocyte Surface Antibodies Present in Plasma* From Donate To B+ 9% B, R h Anti-A B+, B −, AB+, B+ O+, O− B− 2% B Anti-A, anti-R h B−, O− AB+, AB−, B+, B− O+ 38% Rh Anti-A, anti-B O+, O− AB+, A+, B+, O+ O− 7% None Anti-A, anti-B, anti-R h O− Universal donor * Anti-R h-antibodies are only present if an R h-negative individual has prior exposure to R h antigens. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 19.6 Hemolytic Disease of the Newborn, or Erythroblastosis Fetalis When an R h-negative mother carries and gives birth to a R h- positive fetus, Hemolytic Disease of the Newborn, or Erythroblastosis Fetalis results During birth, fetal erythrocytes enter the mother’s blood, which stimulates her immune system to produce anti-R h antibodies; Little risk for the first such pregnancy In subsequent pregnancies, maternal anti-R h antibodies can cross the placenta and rupture fetal R h+ erythrocytes If R h-negative, the pregnant woman is given Rh o(D) Immune Globulin, which prevent her leukocytes from producing anti-R h antibodies Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved