Ch 7 - Cardiovascular

Question 1

Circulation Pathway

Answer 1

• right atrium - tricuspid valve - right ventricle - pulmonary valve - pulmonary arteries - lungs - pulmonary veins - left atrium - mitral valve (bicuspid) - left ventricle - aortic valve - aorta - arteries - arterioles - capillaries - venules - veins - superior/inferior vena cava - right atrium
• pulmonary circulation - pumped by right heart
• systemic circulation - pumped by left heart

Question 2

Cardiac Valves

Answer 2

• prevent backflow of blood
• atrioventricular valves - tricuspid and bicuspid (mitral)
  
  • seperate ventricles from atrium
• semilunar valves - aortic and pulmonary valves
  
  • seperate ventricles from vasculature
• LAB RAT mneumonic
  
  • left atrium - bicuspid
  • right atrium - tricuspid

Question 3

Electric Conduction in Heart

Answer 3

• Impulse initiation at SA node (sinoatrial)
  
  • no neurological input required
• atria contract and force small amount of blood into ventricals (atrial systole)
  
  • atrial kick (5-30% cardiac output)
• Signal reaches AV node (atrioventricular)
  
  • center junction of atrium and ventricles
  • delay signal so ventricles can fill
• signal to bundle of His and branches in interventricular septum to purkinje fibers that distribute the electrical signal to ventricular muscle
• intercalated discs connect the cardiac cells via gap junctions to allow coordinated contraction

Question 4

myogenic activity

Answer 4

• heart contracts without neurological input
• SA node 60-100 bpm even with all innervation cut off
• neuro input to speed up and slow down but not to generate the contraction

Question 5

Neurological control of cardiac

Answer 5

• autonomic control
• sympathetic - speed up
• parasympathetic - slow down
  
  • Vagus nerve

Question 6

heart contraction

Answer 6

• Systole - centricular contraction and close AV valves
• diastole - heart relaxed, semilunar valves closed
  
  • blood fills ventricles
• cardiac output - total blood pumped by a ventricle per minute
  
  • CO = HR * stroke volume (blood pumped per beat)

Question 7

Vasculature

Answer 7

• all lined with epithelial cells
  
  • chemically controlled to vasodilate and vasoconstrict
  • allow WBC to enter tissue for inflam response
  • release chemicals to help clot formation
• vein vs. artery
  
  • artery has much more smooth muscle
  • vein is oval, artery is circular
• arteries - highly muscular and elastic to maintain pressure
  
  • left ventricle must fight pressure to move blood
  • arterioles are smaller arteries
• capillaries - single endothelial layer, wide enough for singl RBC
  
  • allow for easy diffusion
• veins - thin walled and inelastic
  
  • venules - smaller veins
  • large veins contain valves to prevent backflow in legs due to gravity
    
    • valve failure causes varicose veins
  • also assisted by skeletal muscles in legs to push blood back to heart

Question 8

Portal systems

Answer 8

• hepatic portal system - capillaries in gut go to hepatic portal vein then liver capillary beds
• hypophyseal portal system - leaves capillary beds in hypothalamus and travels to anterior pituitary for release of hormones
• renal portal system - blood leaves glomerulus to efferent arteriole then nephron then vasa recta

Question 9

Blood composition

Answer 9

• plasma - liquid with nutrients, gases, hormones, proteins, salts
  
  • remove clotting factors from plasma to get serum
  • proteins - albumin (osmotic balance, pH), fibrinogen (clotting), immunoglobulins (immune)
• erythrocytes (RBC) - contains hemoglobin, which binds oxygen and carries it thorughout the body
• leukocytes (WBC) - less than 1% of blood volume, immune response
• Thrombocytes (platelets) - cell fragments used for clot formation

Question 10

RBC

Answer 10

• erythrocytes
• contain hemoglobin that binds oxygen
  
  • O2 is nonpolar and would not soluble in blood
• Biconcave
  
  • helps travel in tiny capillaries
  • increase cell surface for binding/gas exchange
• When mature, they do not contain organelles, makes space for hemoglobin
  
  • also cannot metabolize O2 it is carrying
• energy solely from glycolysis via lactic acid
• do not divide to reproduce
• die in the liver and spleen after 120 days
• hematocrit - percentage of blood sample with RBC

Question 11

WBC

Answer 11

• Leukocytes
• less than 1% of blood volume, increases under conditions such as infection
• granulocytes - contain cytoplasmic granules that contain toxins released via exocytosis
  
  • neutrophils
  • eosinophils
  • basophils
• agranulocytes -
  
  • lymphocytes - specific immune response
    
    • learned immunity via vaccinations
    • B cells - mature in bone marrow, antibody generation
    • T cells - mature in thymus, kill virally infected vells and activate other immune cells
  • monocytes - phagocytize foreign matter
    
    • when they leave bloodstream and enter an organ they become macrophages (microglia of the nervous system, Langerhans cells of the skin, osteoclasts in bone)

Question 12

Platelets

Answer 12

• Thrombocytes
• cell fragments released from megakaryocytes in bone marrow
• assist in clotting

Question 13

Hematopoiesis

Answer 13

• Production of blood cells and platelets
• all come from hematopoietic stem cells
  
  • differentiate into lymphoid cell to make NK cell, T cells, B cells (plasma cells)
  • into Myeloid cell to make RBC, platelets, Mast cells, basophil, eosinophil, neutrophil, macrophage, dendritic cell
• erythropoietin - secreted by kidney and stimules production of RBC
• thromnopoietin - secreted by liver and kidney, stimulate platelet production

Question 14

Blood Antigens

Answer 14

• antigens - surface proteins on RBC
  
  • ABO antigens
  • Rh factor
• A and B antigens are codominant, O is recessive to both
  
  • must be homo recessive for type O
• universal donor - type O
• universal recipient - type AB
• body makes antibodies for antigens that are not self
  
  • type A makes anti-B, type B makes anti-A, type O makes anti-B and anti-A
• Only worry about RBC antigens for packed red blood cell transfusion (no platelets)
• Rh factor - allele is dominant, must be homo rec for negative
  
  • In an Rh- person, anti-Rh only produced after exposure to antigens in Rh+ blood
    
    • Rh- pregnant women exposed to Rh+ fetal blood at birth will produce anti-Rh, poses problem for second child if they are Rh+, mother anti-Rh can cross to fetus
    • prevented by giving mother Rh-immunoglobulin (RhoGAM) that absorbs Rh+ fetal cells
    • not a problem for ABO mismatching because maternal antibodies cannot cross to fetus

Question 15

Blood pressure

Answer 15

• measured using sphygmomanometer
• measure pressure above and beyond 1atm
• systolic/diastolic
• gradually drops from arterial to venous circulation
  
  • largest drop in arterioles
• resistance increases with longer vessels and smaller diameters
• regulated by baroreceptors and chemoreceptors (osmolarity)
  
  • ADH released to increase volume and pressure
  • aldosterone release to increase kidney perfusion and increase water retention via sodium retention
  • atrial natriuretic peptide (ANP) - loss in nephron to loss fluid

Question 16

Oxygen diffusion

Answer 16

• carried via hemoglobin
• 4 heme groups on hemoglobin bind 4 O2
• central iron atom changes oxidation state
• oxygen saturation - percent of hemoglobin molecules carrying oxygen
• In lungs, first O2 binds to a heme and this causes conformational change from taut (T) to relaxed (R). Increases affinity for other 3 O2. Affinity increases with each O2 affition (positive feeback)
• Reverse occurs in tissue, one O2 leaves and conformational change to easily remove other 3 O2
• Coorperative binding - a form of allosteric regulation
  
  • sigmoidal oxy-hemoglobin dissociation curve
  • 100% saturation in lungs and 100mmHg partial pressure in lungs
  • 80% saturation during rest, 40mmHg in tissue. 20% of oxygen is in the tissues
  • 30% saturation during exercise, 20mmHg in tissue. 70% of oxygen released into tissues

Question 17

Carbon Dioxide Diffusion

Answer 17

• hemoglobin has much lower affinity fro CO2 then oxygen
• CO2 removed via the bicarbonate buffer system
• carbonic anhydrase in the RBC catalyzes CO2+H2O
• H+ and HCO3- highly soluble in water
• transported to the lungs and the reverse reaction occurs to produce CO2 that is exhaled
• equation controls pH AND CO2 levels

Question 18

Bohr Effect

Answer 18

• increased CO2 leads to lower pH
• excess H+ bind to hemoglobin and decrease affinity for O2
• more O2 released into tissues
• hemoglobin curve shifts right, more O2 delivered to tissues
• exercise - increased O2 demand due to increased CO2 and lactic acid both decrease pH
  
  • increased temperature also cause shift right
  • increased 2,3 bisphosphoglycerate (2,3 - BPG) causes shift right

Question 19

Left shift of Oxyhemoglobin Dissociation curve

Answer 19

• due to decreased CO2, decreased H+, increased pH, decreased temperature, decreased 2,3 BPG
• Fetal hemoglobin (HbF) has higher affinity for O2 than adult hemoglobin (HbA) so shift left compared to adult curve
  
  • due to fetal RBC having to pull O2 off of maternal RBC

Question 20

Respiratory and Renal balance of pH

Answer 20

• bicarbonate buffer system influenced by both
• hyperventilation leads to high pH, kidney will increase excretion of bicarbonate
• renal tubular acidosis type I - kidney cannot excrete acid effectively, metabolic acidosis and respiratory compensates with increased resp rate

Question 21

Nutrients, waste, hormones into circulatory system

Answer 21

• carbs and amino acids via capillaries around small intestine then hepatic portal system
• fats - lacteals of small intestine the via thoracic duct
  
  • from intestinal cells - packaged in lipoproteins (water soluble)
• waste - via conc gradient from tissue to capillary then to kidney
• hormones - in or near organ that produced them, exocytosis
  
  • some via carrier proteins
  • activate cell surface receptors (peptide hormones)
  • dissuse into cell and activate intracellular/nuclear receptors (steroids)

Question 22

Fluid balance

Answer 22

• hydrostatic pressure - force per area exerted against vessel walls
  
  • pushes fluid through capillary walls
• osmotic pressure - sucking pressure from solutes that draw water into bloodstream, mostly plasma proteins
  
  • aka oncotic pressure
• arteriole side is higher hydrostatic and water pushed out
• venule side is higher osmotic and water pulled in
• Starling forces - balance of pressures
• edema - excess fluid in interstitium

Question 23

Coagulation

Answer 23

• clots - contain coagulation factors (proteins) and platelets
• tissue factor - protein in the connective tissue of vessels
• collagen - when exposed in vessels, activates platelets and clump together
• coagulation factors - sense tissue factor and activate complex activation cascade
• endpoint of cascade is prothrombin that leads to thrombin via thromboplastin
• thrombin converts fibrinogen into fibrin
• fibrin forms small fibers to make net and catch RBC anf platelets to make a clot
• clot break down via plasmin (made from plasminogen)