The Cardiovascular System

Question 1

The Heart

Answer 1

• Four chambered structure with two pumps
  
  • Right side pumps deoxygenated blood ( pulmonary circulation)
  • Left side pumps oxygenated blood (systemic circulation )
  • atria receives from vena cava or pulmonary vein
  • Atria contracts their muscles
  • Ventricles are more muscular
  • Atrioventricular valve: separates atrium and ventricles
  • Semilunar valves:

Question 2

Semilunar valves

Answer 2

• separates ventricular blood from vessels and atrium
• Prevents back flow
  - Types:
  - Tricuspid valve: Right atrioventricular (RAT)
  - Mitral / bicuspid valve: left atrioventricular (LAB)
  - Pulmonary valve: right ventricle from pulmonary
  - Aortic valve: left ventricle from aorta

Question 3

Left ventricle is very muscular, but if the right were as muscular,______would occur

Answer 3

lung damage

Question 4

Electric conduction of the heart

Answer 4

• Impulse pathway travels through the following structures in order: SA node, AV node, AV bundle, the Purkinje fibers.
• SA node generates 60-100 beats per minute
• Once the impulse initiates, both atria contract
  - Atria systole: contraction resulting from increased pressure
• Signal goes to AV node and waits for ventricle to fill
• Signal then goes from bundle of His and purkinje fiber to ventricular muscle.
• Intercalating discs in the muscles allow for coordinated contractions
• Neurological autonomic input to the heart is important in speeding up and slowing down the rate of contraction, but not generating it in the first place.
  - Parasympathetic signals are provided by vagus nerve.

Question 5

Contraction

Answer 5

• Two phases to a heart beat
  - Systole: ventricular contraction, pressure ↑, “LUB”
  - Diastole:ventricles relax and fill with blood, pressure ↓ “DUB”
• Elasticity of arteries maintains the diastolic pressure
• Cardiac output of both ventricles: CO = HR x SV
  - Normally 5L per min.

Question 6

Types of vessels

Answer 6

arteries, veins, and capillaries

Question 7

Function of arteries

Answer 7

• Arteries take blood away from heart and towards tissues

Question 8

Order of vascular throughout the body

Answer 8

• Arteries → Arterioles → Capillaries → venules → veins

Question 9

Endothelial lining

Answer 9

• Release blood clot chemicals
  - Release vasodilators and vasoconstrictors
  - Allow paracellular movement

Question 10

Arteries

Answer 10

• Highly muscular and elastic
  - Moves blood away from heart
  - Carries oxygenated or deoxygenated blood

Question 11

Capillaries

Answer 11

• Small and single layered (endothelium only) vessels

- Diffuses gases, nutrients, Hormones, and waste

Question 12

Veins

Answer 12

• Thin walled and inelastic venules
• Veins have low elasticity due to muscle amount
• They contain 3/4 of the body’s blood.
• Venous blood in lower body have high pressure
  - Valves prevent back flow
  - Broken valves leads to varicose veins(large veins with pooled blood)
• No lower extremity movement → blood pooling → increased risk of blood clotting

Question 13

Pathway of blood flow

Answer 13

• Right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery→ lungs → pulmonary veins → left atrium → mitral valve → left ventricle → aortic valve → aorta → arteries → arterioles → capillaries → venules → veins → venae cavae → right atrium

Question 14

Portal systems ( blood travels through TWO capillary bed before returning to heart)

Answer 14

• Hepatic: gut wall to liver
  - Hypophyseal: hypothalamus to anterior pituitary
  - Renal : glomerulus to nephron

Question 15

Composition of blood

Answer 15

• Plasma @ 55% volume
• Cells (erythrocytes, leukocytes, and platelets) 45% volume
• Serum is plasma without clotting factors and fibrinogen.

Question 16

Erythrocyte-Red blood cells

Answer 16

• Designed for oxygen transport
• Since oxygen is non polar; not dissolvable in cytoplasm; hemoglobin carries it.
• Benefit of shape: large surface area, easier travel through capillaries, and increase oxygen transport.
• Don’t contain mitochondria and other organelles; no oxygen metabolism, more space for hemoglobin, no cellular division
• A blood count of RBCs gives hematocrit (% RBC in sample) and hemoglobin (# of hemoglobin) measurements.

Question 17

Leukocytes-White blood cells

Answer 17

• <1% of volume
  - Defender of immune system
  - Only cells in blood to contain nuclei

Question 18

5 types of leukocytes

Answer 18

• Granulocytes ( toxic granules involved in inflammation, allergies, pus formation
  - NEUTROPHIL, EOSINOPHIL, BASOPHIL
• Agranulocytes
  - Lymphocytes:
  - initiates extrinsic pathway to apoptosis.
  - Function as specific immune response
  - First responders to repeat infections
  - sometimes trained by vaccination
  - Types based on maturation site
  - B -Cell: from bone marrow → Plasma cells
  - T-Cell: from thymus → Cytotoxic and helper T cells
• monocytes
  - Phagocytize pathogens
  - in blood they are known as monocytes
  - In the organs they are known as macrophages
  - i.e Microglia (CNS), Langerhans cell (skin), osteoclasts (bone)

Question 19

Thrombocyte-Platelets

Answer 19

• Released form megakaryocytes
• Assist in blood clotting
• Made in bone marrow in process called hematopoiesis; stimulated by thrombopoietin

Question 20

Types of blood antigens

Answer 20

• ABO Antigens
  - Three alleles are possible (A, B or O)
  - A and B are co-dominant; simultaneously expressed.
  - Individuals with both are “universal recipients”
  - Antibodies for A and B antigens are initially made because E. Coli protein has similar composition.
  - O is recessive
  - O blood type individuals are “universal donors” because there isn’t an anti-O antibody.
  - These proteins determine naming system for blood types
  - Matching these proteins between individual is critical for transfusion
  - Anti-AB, A or B are IgM; does not cross placenta.
• Rh Factor
  - First described in Rhesus monkeys
  - Individuals either have the antigen (Rh+) or don’t (Rh-)
  - Autosomal dominant gene
  - Erythroblastosis fetalis stems from this antigen exposure.
  - Anti-Rh are IgG

Question 21

Purpose of cardiovascular system

Answer 21

Maintain blood pressure, gas, and solute exchange, coagulation, and thermoregulation.

Question 22

Blood Pressure

Answer 22

• Speaks on the effectiveness of this system
  
  • It is measured by a sphygmomanometer
  • It is expressed as ratio of systolic and diastolic pressures.
  • Largest drop in pressure occurs in arterioles due to thinned Walled capillaries
  • A pressure gradient across the system ( much like emf during electric resistance) drive cardiac output
    
    • ΔP = CO x TPR
  • Arterioles and capillaries resist blood flow due to ↑length and ↓cross-sectional area

Question 23

Blood pressure too low?

Answer 23

• Baroreceptors (stimulate vasoconstriction)
  - chemoreceptors (senses concentration → ADH secreted → ↑blood volume/ pressure)
  - low perfusion to the juxtaglomerular cells ( aldosterone secreted→ ↑sodium conc. → blood pressure.)

Question 24

Blood pressure too high?

Answer 24

• Vascular relaxation stimulated

- ANP (diuretic) secreted by atrial cells

Question 25

Gas and Solute exchange

Answer 25

• Facilitated by concentration gradients

Question 26

Oxygen

Answer 26

• Low solubility in plasma
• Carried by hemoglobin within one of its 4 heme subunits
• Measurements
  - Arterial partial pressure (70-100 mmHg) (not easy way)
  - Oxygen saturation using finger probe ( easy way)
• Its binding and dissociation to hemoglobin happens by cooperative binding that produces sigmoidal curve.
• During exercise : ↑oxygen dissociation from hemoglobin

Question 27

Carbon dioxide

Answer 27

• Low solubility in plasma
• Low affinity to hemoglobin
• Therefore its transported in plasma as Bicarbonate (HCO3)
• CO2 + H2O ⇔ H2CO3 ⇔ H+ HCO3 (Bicarbonate buffer system)
  - Carbonic anhydrase catalyzes this reaction
• Causes of right shift (lower affinity) of oxyhemoglobin dissociation curve:
  - If ↑CO2 produced → ↓ blood pH / ↑[H+] → protons interfere with Hemoglobin-Oxygen affinity → dissociation curves shift right → ↑oxygen dissociation from hemoglobin
  - Increased temperature
  - Increased 2,3 BPG (glycolysis)
• Bicarbonate buffer system also link respiratory and renal systems
  - Hyperventilation → ↓ [H+] / ↑pH. → kidney secretes HCO3 → ↓pH

Question 28

Nutrients, waste, and Hormones

Answer 28

• After consuming carbs and amino acids → enter blood through hepatic portal system
• After consuming fats → enter blood through thoracic duct.
• Hormones are usually near the organ or transported in plasma
• Entering or exiting tissue occurs mostly by Concentration gradients.

Question 29

Fluid Balance occurs in blood due to pressure gradients

Answer 29

• Hydrostatic pressure
  - Generated by heart contractions
  - Measure as blood pressure
  - Pushes fluid ,against endothelium, from blood into tissue
• Osmotic pressure
  - Type of sucking pressure
  - Generated by plasma protein
  - Pulls fluid from tissue into blood.
  - A.K.A oncotic pressure

Question 30

Coagulation

Answer 30

• Clots are composed of coagulation proteins and platelets
• Damaged endothelium → coagulation cascade → prothrombin activation → thrombin → fibrinogen → fibrin
  - Coagulation cascade starts by exposure of collagen.
  - Prothrombin is activated by thromboplastin to become thrombin
  - Thrombin converts fibrinogen to fibrin
  - Fibrin aggregates in damaged area

Question 31

where does the greatest drop in blood pressure occur.

Answer 31

Arterioles.