Anatomy sem 1_ week 8-13.docx
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Anatomy notes Week 8: The shape of a RBC is unique it is concave on both sides thin central region, thick outer region No nucleus Gets broken down before entry into the bloodstream Has a life span of less than 120 days A greater exchange rate of oxygen can occur due to a large surface...
Anatomy notes Week 8: The shape of a RBC is unique it is concave on both sides thin central region, thick outer region No nucleus Gets broken down before entry into the bloodstream Has a life span of less than 120 days A greater exchange rate of oxygen can occur due to a large surface area They can form stacks like dinner plates that allow them to travel through small vessels They are flexible, they can squeeze through capillaries smaller than their diameter Recycling of hemoglobin: RBC formed within the bones Before RBCs die (120 days) macrophages break down to convert iron in the body, to then make new RBCs Globular proteins are broken into amino acids Iron is extracted from heme molecules Stored in macrophage, or released into the blood and bound to transferrin, which transports iron back to red bone marrow to synthesize new RBCs The remaining heme is converted to green biliverdin Biliverdin is converted to orange-yellow bilirubin The liver absorbs bilirubin and releases it within bile In the large intestine, converted to urobilin and stercobilins Gives feces a brown color Some are absorbed into the bloodstream and excreted in the urine Gives urine a yellow colour Origins and differentiation of blood cells: Hormone converting stem cells to red blood cells -> erythroblasts Key stages named by hematologists, or blood specialists Embryonic cells differentiate into multipotent stem cells, called hemocytoblasts Hemocytoblasts, or hematopoietic stem cells (HSCs), produce myeloid stem cells Erythroblasts are immature and synthesize Hb When the nucleus is shedding they become reticulocytes Reticulocytes enter the bloodstream to mature into RBCs within about 24 hours The red bone marrow and RBCs are developing, you can see there is the ejection of the nucleus and the reticulocyte enters the bloodstream The reticulocyte becomes a RBC and the average life is 120 days. In the bloodstream, the RBC may rupture (hemolyze) Macrophages are constantly monitoring the condition of the circulating RBCs and will engulf them and then recycle the RBC Heme gets stripped of iron and becomes bilirubin, it is transported to the liver where it gets excreted in the bile and eliminated in the feces Irons get released into the bloodstream, to be reused in RBC formation Kidneys excrete some hemoglobin - hematuria Blood types: antigens and antibodies We have proteins on our cell membranes that allow us to recognize which cells are ours and which are foreign. (called antigens) There are 4 blood types based on the presence of absence of the A and B surface antigens Type A (has only surface antigen A) - contains anti-B antibodies in plasma - your immune system will attack type B surface antigens Type B (has only surface antigen B) - contains anti-A antibodies in plasma Type AB (has both A and B surface antigens) - no anti-A or B antibodies Type O (has no A or B surface antigens) - has both anti-A and anti-B antibodies in plasma Type A can only accept Type A and O. Can donate to Type A and AB Type B can only accept Type B and O. Can donate to Type B and AB Type AB can accept Type A, B, AB, and O. Can donate to Type AB Type O can accept Type O. can donate to types A, B, AB, and O. Blood type testing: Clumping is a reaction to the antigens Neutrophils: Makeup 50-70 percent of circulating WBCs Usually, the first WBC to arrive at the injury site Very active phagocytes, attacking and digesting bacteria Neutrophils: They make up about 60% of WBCs Eosinophils: fight off parasites, fungi, infections, etc Monocytes: Migrate into tissues and become macrophages Aggressive phagocytes About twice the size of a typical RBC Usually 2-8% of circulating WBCs Lymphocytes: Large numbers migrate in and out of peripheral tissues Some types attack foreign cells, others secrete antibodies into the circulation Slightly larger than typical RBC About 20-40% of circulating WBCs The coagulation phase is the third phase: In this phase, factors released by platelets and endothelial cells interact with clotting factors through either the extrinsic or intrinsic pathway (or the common pathway) to form a blood clot. This process involves the conversion of fibrinogen to fibers of fibrin Extrinsic: outside of the blood vessel - tissues, cells outside vessel - trigger release of chemicals Intrinsic: inside cells send out chemicals that trigger coagulation Calcium is important in blood clotting. Many clotting factors - hemophilia lack of one or more clotting factors Common pathway: plasma protein fibrinogen is converted to fibres of fibrin Coagulation or blood clotting Beings 30 seconds or more after damage Involves complex sequence of steps, or cascade End result is the conversion of fibrinogen to insoluble fibrin Fibrin network grows Traps blood cells and more platelets Forms a blood clot Liquids blood plasma is converted into gel Seals damaged portion of blood vessel The clotting process: Requires clotting factors Calcium ions, vitamin K, and 11 different plasma proteins Proteins are converted from inactive proenzymes to active enzymes involved in reactions The liver synthesizes most of these clotting proteins Clotting factors interact in a sequence or cascade The product of the first reaction is an enzyme that activates the second reaction, etc Blood clot forms as a result of extrinsic, intrinsic, and common pathways The common pathway of blood clotting Beings when enzymes from either extrinsic or intrinsic pathways activate factor X Factor X activates prothrombin activator Which converts prothrombin into thrombin Which converts fibrinogen into fibrin, and stimulates tissue factor and platelet factors A positive feedback loop accelerates clot formation and rapidly prevents blood loss Calcium ions and vitamin K affect almost all aspects of the clotting process All 3 clotting pathways require Ca2+ ions Lowered blood Ca2+ levels impair clotting The liver requires vitamin K to synthesize 4 clotting factors A deficiency of vitamin K leads to the breakdown of common pathways and inactivates the clotting system Week 10: Anterior surface of the heart: right atrium and right ventricle are most visible Heart is rotated slightly toward the left The left ventricle and left atrium towards the back Posterior surface of the heart: left ventricle and left atrium more visible When not filled with blood, the outer portion of each atrium deflates into a lumpy, wrinkled flab This exanadable extension of an atrium is called an auricle The heart has 3 layers The outer layer is called the epicardium. It secretes a slippery fluid - it is a serous membrane that covers the outer surface of the heart. It is also called the visceral peridcardium The middle layer is called the myocaridum (myo=muscle, cardium=heart). This is the thickest layer The inner layer is called the endocardium - it cover the inner surface of the heart. It is made of simple squamous epithelial tissue Atrioventrucular valves (AV Valves) allow blood to flow only one way (from the atrium into the ventricles) The right atrium receives deoxygenated blood from the superior and inferior vena cava Left atrium receives oxygenated blood from the pulmonary veins Blood travels from the right atrium into the right ventricle through the right AV valve (tricuspid valce) - this prevents backflow of blood into the atrium when the ventricle contracts With contraction blood exits through the pulmonary valve (pulmonary semilunar valve) into the pulmonary trunk The left ventrice has a much thicker wall than the right ventricle It receives vlood from the left atrium the left AV valve (bicuspid or mitral valve) - it prevents backflow of blood to the atrium during contraction of the ventricle When the left ventricle contracts blood exits through the aortic valve (aortic semilunar valve) Differences between the ventricles Right ventricle Thinner myocarium and wall, half-moon shape in cross section Lower pressure Only needs to propel blood the short distance to the lungs Left ventricle Very thick myocardium and wall Produces 4-6 times as much pressure as right ventricle Propels blood to entire systemic circuit The atrioventricular (AV) Valves Located between atrium and ventricle on each side The right AV valve, also called the tricuspoud valve Has three flaps or cusps The left AV valve, also called the bicuspid valve or mitral valve Has two flaps or cusps Blood flowing from the left atrium to the left ventricle flows through the left AV valve, also known as bicuspid or mitral valve Coronary circulation The coronary arties originate at the base of the ascending aorta There are right and left coronary arteries - they branch off The cardiac cycle The cardiac cycle is the period between the start of one heartbeat and the beginning of the next There are two phases: Systole: which is the contraction phase - blood is being pushed either into the adjacent chamber or the arterial trunk Diastole: which is the relaxation phase when the chaber fills with blood - period between start of one heartbeat and start of the next Includes alternating periods of contraction (systole) and relaxation (diastole) During diastole the chambers are filling with blood During systole the chambers are ejecting blood The atris contract as a pair pushing blood into the ventricles, nect the ventricles contract pushing blood into the pulmonary and systemic circuits and atria are relaxed and filling Atrial systole: Atria contract, pushing blood into ventricles AV valves are open Atrial diastole: Atria relax AV valves pushed closed (1st heart sounds) by higher pressure in ventricles Semilunar valves still closed due to lower arterial pressure Volume in ventricles does not change Ventricular systole: Pressure in ventricles rises higher then arteries Semilunar valves open (AV valves have closed previously) Blood is ejected from ventricles = stroke volume Ventricular distole: Early diastole, semilunar valves close (2nd heart sound), AV valves still closed Once ventricular pressure drops below atrial pressure, AV valves open, ventricles fill passively Heart sounds and the cardiac cycle: First sound is produced as the AV valves close and the semilunar valves open Stethoscopes are used to listen for nomal heart sounds First heart sound (“lubb” or S1) Produced as AV valves close Second heart sound (“dupp” or S2) Produced as the semilunar valves close Third and fourth heart sounds Usually very faint Associated with atrial contraction and blood flow into ventricles Conducting system of the heart: Signal from SA node causes all atrial cells to contact together Signal is delayed at AV node Ensures atria contract before ventricles Action potential travels to: AV Bundle Left and right bundle branches Purkinje fibers The 2 ventricles will then contract simultaneously Heart dynamics: Stroke volume (SV) Volume of blood ejected by a ventricle in one beat Caridac output (CO) Volume of blood ejected from left ventricle in one minute Indicator of blood flow through peripheral tissues The pulmonary circuit: Blood leaves right ventricle, flows through: Pulmonary valve (pulmonary semilunar valve) Pulmonary trunk Right and left pulmonary arteries Respiratory capillaries (where gas exchange occurs) Right and left pulmonary veins Flows into left atrium The systemic circuit: Blood leaves left ventricle, flows through: Aortic valve (aortic semilunar valve) Ascending aorta and aortic arch Descending aorta Numerous branches to capillary beds in the tissues Inferior and superior vena cava, coronary sinus Flows into right atrium The function of the atrium is to collect blood returning to the heart Vascular pathway of blood flow: arteries Carry blood away from the heart, to body organs including te lungs Branch into smaller vessels called arterioles arterioles Arise from arteries and branch into capillaries Capillaries Smallest vessels of the cardiovascular system Arise from arterioles and drain into venules Chemical and gaseous exchange occur here Venules Transport blood between capilaries and veins Veins Return blood to the atria of the heart Comparison of artery and vein: innermost layer the tunica intima – this layer includes the endothelial lining. In arteries, there is a thick layer of elastic fibres called the internal elastic membrane The middle layer is the tunica media – this layer is made of smooth muscle and you can also see elastic fibres. When they contract it is called vasoconstriction, dilation is called vasodilation. There is also an external elastic membrane present in arteries. The outermost layer is called the tunica externa and is a connective tissue sheath. Arteries have: Smaller lumen than veins Greater wall thickness than veins Thicker tunica media with more elastic fibers and smooth muscle Smooth muscle regulates vessel diameter Contraction causes vasoconstriction or decrease in size of the lumen Relaxation causes vasodilation or increase in size of the lumen Elastic fibers provide elasticity to accommodate changes in flow, without increasing pressure in the vessel Veins have thinner walls – they don’t need to withstand much pressure Structure of types of blood vessels: There are 5 general classes of blood vessels – Arteries Arterioles Capillaries Venules veins. Blood is carried away from the heart in arteries, they get smaller as they move away from the heart they branch and become arterioles. Blood then moves to capillaries, where diffusion between blood and interstitial fluid occurs. Then blood enters venules and the larger veins. 1. Arteries Elastic arteries Large vessels close to the heart that stretch and recoil when heart beats include pulmonary trunk, aorta, and branches Muscular arteries Medium-sized arteries Distribute blood to skeletal muscles and internal organs 2. Arterioles Poorly defined tunica externa Tunica media is only 1–2 smooth muscle cells thick 3. Capillaries Only blood vessels to allow exchange between blood and interstitial fluid Very thin walls allow easy diffusion 4. Venules Small veins – smallest don’t contain a tunica media Collect blood from capillaries Medium-sized veins Large veins Function of valves in venous system: Blood pressure in peripheral venules is less than 10 percent of that in the ascending aorta (largest artery). Mechanisms are needed to maintain flow of blood in veins against force of gravity Valves Ensure one-way flow of blood toward heart Contraction of skeletal muscles squeezes veins (and the blood within them). Any contraction of the surrounding skeletal muscles squeezes the blood towards the heart Valves permit blood flow in one direction and prevent backflow of blood toward capillaries If valves do not work properly, blood can pool in veins causing distention and a range of effects Mild discomfort and cosmetic problems as with varicose veins (in thighs and legs) Painful distortion of adjacent tissues as in hemorrhoids (form in the venous networks of the anal canal) The pattern of circulation: Pulmonary circuit Composed of arteries and veins that transport blood between the heart and lungs Beings at the right ventrice, ends at the left atrium Systemic circuit Transports oxygenated blood to all organs and tissues Beings at left ventricle, ends at right atrium The pulmonary circuit Deoxygenated blood exits right ventricle through pulmonary trunk Branches into left and right pulmonary arteries Enter lungs abd branch repeatedly Smallest pulmonary arterioles provide blood to capillary networks surrounding small air pockets, or alveoli Thin walls of alveoli allow gas exchange between alveolar capillaries and inhaled air Oxygenated blood returns to the left atrium through left and right pulmonary veins (two from each lung) Systemic circuit Supplies oxygenated blood to all parts of the body, not in the pulmonary circuit Oxygenated blood leaves left ventricle through aorta Returns deoxygenated blood to right atriym through superior and inferior vena cava and coronary sinus Contains about 84% of total blood volume The aorta: Aorta is the first systemic vessel and largest artery Ascending aorta Begins at aortic semilulnar valve Left and right coronary arteries branch off near base Aortic arch curves across superior surface of heart Descending aorta proceeds downward through mediastinum Arteries of chest and upper limb: Ascending aorta Aortic arch Brachiocephalic trunk, Right subclavain artery Axillary artery Brachial artery Week 11: Components of the lymphatic system: Lymphatic vessels, or lymphatics Carry fluid from peripheral tissues to veins Fluid called lymph Flows through lymphatic vessels Lymphocytes Specialized cells that function in defending the body Lymphoid tissues are lymphoid organs Lymph fluid: Flows through lymphatic vessels Similar to plasma but lower concentration of proteins Components of the lymphatic system: The main cells of the lymphatic system are lymphocytes. Lymphocytes are a type of white blood cell These cells provide defense against specific pathogens or toxins. In the lymphatic system, the lymphocytes in lymphatic vessels are surrounded by lymph – this is interstitial fluid that has entered a lymphatic vessel. Main functions of the lymphatic system: The lymphatic system carries fluid back to the bloodstream. The fluid that comes out of the bloodstream in the tissues needs to be brought back to the bloodstream. Gases, oxygen, water, WBCs, and proteins leave the blood at the capillaries. Water goes into the tissues but we need to retain it – the lymph system brings the fluid back to the bloodstream. Tissues and organs of the lymphatic system filter out and phagocytose pathogens. The organs include the tonsils, thymus, spleen, appendix, and mucosa-associated lymphoid tissue (MALT) in tracts that communicate with the external environment and the red bone marrow. Produce lymphocytes in the red bone marrow and the thymus Areas that don’t have lymphatic vessels are the cornea of the eye, the bone marrow, and the CNS The major chains of lymph nodes that can be palpated with different illnesses – cervical, axillary, inguinal Immunity innate (nonspecific defenses): Do not distinguish between threats Include Physical barriers Phagocytes Immune surveillance Interferons Complement Inflammation Fever In response to injury, mast cells in connective tissue and basophils and platelets in blood release histamine. Histamine causes vasodilation and increased permeability of blood vessels The body's innate defenses: Immunity is your body's defense against pathogens. There are 2 types: innate and adaptive. Innate is the immunity you are born with Physical barrier: prevents the approach of and denies access to pathogens Phagocytes: removes debris and pathogens Immune surveillance: destroys abnormal cells Interferons: increase the resistance of cells to viral infections Slow the spread of disease Complement system: Attacks and breaks down surfaces of cells, bacteria, and viruses Attacks phagocytes Stimulates inflammation Inflammation (multiple effects) fever: Mobilizes defenses Accelerates repairs Inhibits pathogens Origin and distributions of lymphocytes: All of the lymphocytes are initially generated in the red bone marrow One group migrates to the thymus for maturation and they are called T cells (T for Thymus) Travel through the bloodstream to lymphoid tissues and organs The rest develop further in the red bone marrow and are the B cells (B for Bone marrow) and the natural killer cells The B cells move into lymph nodes, the spleen, and other lymphoid tissues The NK cells migrate throughout the body, patrolling peripheral tissues Fever: Defined as body temp >37.2 Celsius Mild fever is beneficial, increasing metabolism A high fever, of>40.0, can damage physiological systems Forms of immunity: Adaptive immunity is the body’s specific immunity. Unlike your innate immunity which is nonspecific and attacks anything it recognizes as foreign, damaged or unknown adaptive immunity is very choosy. Adaptive immunity will only attack specific threats. It is our most powerful defense. Adaptive immunity is carried out by two types of lymphocytes, the B cells and the T cells. Adaptive immunity has 3 underlying traits it is specific, it recognizes and attacks only specific pathogens. it is systemic, this is a widespread reaction, not limited to a localized region of the body. adaptive immunity has memory. In many cases, once you are exposed to an antigen, your body remembers and you become resistant to reinfection. Adaptive immunity: Antigens either infect cells or are “processed” by phagocytes Antigens or antigenic fragments are then displayed on the plasma membrane called antigenic presentation Triggers an immune response Presentation of specific antigens stimulates: Cell-mediated defenses (T cells) Antibody-mediated defenses (B cells) There are 2 types of adaptive immunity – cell-mediated and antibody-mediated (or humoral) When you are infected with a virus, the virus is floating around in the fluids of your system. When the virus isn’t inside the cell it is antibody-mediated. B-lymphocytes are responsible for antibody-mediated immunity T-lymphocytes are responsible for the cell-mediated immunity. The B cells and the T cells also have to work together. Some of the antigens are inside and some outside Five classes of antibodies: Antibodies also called immunoglobulins (lgs) lgG is the largest class Can cross the placenta for passive immunity for the fetus lgM is the first antibody produced Responsible for cross-reactions of blood types lgA is found in exocrine secretions like tears, saliva lgE is involved in inflammatory and allergic response Stimulates basophils and mast cells to release histamine lgD attaches to B cells, aiding in sensitization Immunity and aging: T cells become less responsive to antigens Fewer cytotoxic T cells to respond to infection This may be due to shrinkage of the thymus and reduction in thymic hormones B cells become less responsive Slower production of antibodies Increase in susceptibility to viral and bacterial infections Increase in incidence of cancer due to less effective tumor cell destruction Week 12: We breathe in 21% of oxygen Structures of the respiratory system: Can be divided based on anatomical structures into: Upper respiratory system Includes nose, nasal cavity, paranasal sinuses, and pharynx - shared space with the digestive tract Structures filter, warm, and humidify incoming air lower respiratory system Includes larynx, trachea, bronchi, and lungs Lungs contain bronchioles (air conduction) and alveoli (gas exchange) The respiratory mucosa: The system traps particulates to protect the membrane between blood and air Mucous cells secrete mucous which is sticky - dust particles, etc clean the air with the mucous Cilia sweep mucous upward towards the back of the throat (mucous escalator) where either swallowed (digestive tract destroys pathogens) or coughed out In CF, a defective gene causes problems with the glands that produce mucous. Secretions are thick and sticky, mucous isn’t transported by the cilia, it blocks the smaller passageways, making breathing difficult The nose, nasal cavity, and the pharynx: Air coming from the external nares travels past the nasal vestibule which contains the coarse hairs that filter debris, then the nasal cavity which contains conchae that swirl the incoming air, trapping debris, warming and humidifying the air, and assisting with the sense of smell. The nasal vestibule is a space enclosed by flexible tissues of the nose The nasal septum divides the cavity into right and left sides The pharynx is a chamber shared by the digestive and respiratory systems. It can be divided into the nasopharynx, oropharynx, and laryngopharynx Back of nasal cavity – air moves to the pharynx (throat) – nasopharynx –region behind the nasal cavity, oropharynx behind oral cavity, laryngopharynx behind larynx (first part of the lower respiratory tract) Nasal cavity cleared and flushed by: Mucus produced by the respiratory mucosa Mucus produced in the paranasal sinuses Tears flowing through the nasolacrimal duct Exposure to dust, debris, allergens, or vapors increases mucus production The esophagus is posterior – air turns to the larynx The glottis is the opening to the larynx, the larynx surrounds and protects the glottis and the trachea conducts air towards the lungs. Anatomy of the larynx: The larynx is called the voice box. It has 3 large cartilages and 3 small cartilages. The large cartilages: Epiglottis - during swallowing it folds back over the glottis preventing solids and liquids from entering the respiratory tract Thyroid cartilage - also called the Adam's apple Cricoid cartilage - it is a complete ring of cartilage Anatomy of the vocal cords: The glottis is the opening into the trachea - also known as the vocal cords. When we breathe the glottis opens up to allow air into the lungs. Also makes a sound, when we talk we are pushing air through vocal folds and they vibrate and that gives us our voice When we swallow the glottis closes so that food or drink does not get into the trachea Vocal folds vibrate to make sounds - when air pushes through the glottis, it causes it to vibrate Anatomy of the trachea: The trachea (or windpipe) runs from the larynx to the bronchi. Held open by 15-20 c-shaped tracheal cartilages. They prevent the trachea from collapsing and dont completely encircle as it allows for expansion of the esophagus during swallowing On this picture you can see the larynx - the thyroid and cricoid cartilage and the trachea. Cross section shows the espohagus and the incomplete cartilage The trachea branches into the right and left primary bronchi. The right is larger than the left and is at a steeper angle and tends to be the location that a foreign object might get lodged if aspirated Bronchial branching: We have primary bronchi, secondary bronchi which go to each lobe, territory bronchi, bronchioles, terminal bronchiole, and respiratory bronchiole where the alevoli are Structure of a lobule of the lung: Capillary beds wrapped around the alveoli Alveolar organization: GAS EXCHANAGE This is a big clump of alveoli, Each lung has over 150 million alveoli. Each ball represents and alveola or air sac, they are surrounded by elastic fibres (look like pink rubberbands) that help push air out of the lungs, capillary beds help us to receive oxygen and get rid of CO2. Each lung is highly vascular Pneumocyte type 1 – squamous epithelial cells, they are very thin Pneumocytes type II – produce surfactant Surfactant is an oily secretion, they reduce the surface tension so they won’t collapse, if babies born too premature – main concern that they haven’t produced surfactant which is necessary to keep the alveoli open. Simple squamous epithelium is the lining of the alveolus, surrounded by capillaries. Surfactant is an oily secretion, reduces surface tension of water, allows bubbles to stay open. they reduce the surface tension so they won’t collapse, if babies born too premature – main concern that they haven’t produced surfactant which is necessary to keep the alveoli open. You can see the alveolar macrophages – they patrol the epithelial tissue of the alveoli looking for any particles that could cause infection and will phagocytose them The blood air barrier of the alveoli: Also called the respiratory membrane Site of gas exchange (diffusion) Diffusion occurs quickly because the distance is very short Respiratory membrane is about 0.5 um (mircometers) The surfactant plays a key role in keeping the alveoli open Gross anatomy of the lungs: Lower resp system The right lung has 3 lobes, left has 2 lobes with a cardiac notch (room for the heart) Each lobe is separated by fissures Quietly breathing, what is happening to the muscles in the lungs Muscles contract during inspiration Muscles relax during expiration Respiration control: Respiratory control has both voluntary and involuntary components Involuntary: medulla oblongata and pons of brain stem Voluntary: cerebral cortex or motor neurons Carbon dioxide levels have a much more powerful effect on respiratory activity than do oxygen levels In some people COPD, low oxygen levels are the main stimulus for breathing and giving too much oxygen will decrease the stimulus to breathe Pulmonary ventilation: “Breathing” Movement of air into and out of the resp system Occurs by changing the volume of the lungs Skeletal muscles contract Gas transport and exchange: We have external and internal respiration External resp: exchange of oxygen and carbon dioxide between lungs and external environment Internal resp: absorption of oxygen into the tissues and the release of carbon dioxides from tissues then back into the bloodstream CO2 is responsible for the respiratory activity that happens under normal activities If CO2 is too high, the body will expel it by breathing faster
