Circulatory System

Question 1

What does the circulatory system do

Answer 1

• Transport nutrients, gases, hormones, and so on to the rest of the body and collects the metabolic waste for excretion
• Aids in defence against foreign attacks by transporting cells of the immune system to the location of the foreign attack

Question 2

The Heart Structure

Answer 2

• Muscular four chambered organ with two atria and two ventricles
• Rhythmic contraction and relaxation of these chambers pumps blood into arteries and veins throughout all our life

Question 3

Systemic Circulation

Answer 3

Oxygenated blood that travels from the heart throughout the body and returns to the heart as deoxygenated blood.

Question 4

Pulmonary Circulation

Answer 4

Deoxygenated blood that travels from the heart to the lungs and returns to the heart as oxygenated blood

Question 5

Blood Flow throughout the heart and the Valves

Answer 5

1. Right Atrium (Deoxygenated Blood)
2. Right Ventricle (Deoxygenated Blood)
3. Left atrium (Oxygenated Blood)
4. Left Ventricle (Oxygenated blood)

• To prevent back flow there are the valves
  
  • The tricuspid valve (atrioventricular valve)
  • The bicuspid valve (atrioventricular valves)
  • “Try before you Buy”
• Semilunar Valves
  
  • Separate the ventricles and the vasculature
• The opening and closing of the valves create the lub dub sounds

Question 6

Sionartial Node (SA node)

Answer 6

• Generates electrical impulses to cater to the power needs of the heart
• Natural pacemakers

Question 7

Atrioventricular Node (AV), Purkinje fibers and Bundle of HIs

Answer 7

• After the depolarizing wave from the SA node spreads across the atria, the electrical signal travels to the AV node
• From the AV node, the signal then travels down the bundle of HIS to the bottom of the heart
• Then using the Purkinjie fibers the signal travels up the ventricles to distribute the electrical signal throughout the ventricular muscles causing contraction of the ventricles form the BOTTOM UP
• We can record these signals using an electrocardiogram and use it for diagnostic purposes.

Question 8

Systole and Diastole

Answer 8

• Diastole
  
  • Dilation (Heart relaxes, chambers open, and the semilunar valves close, meaning blood cannot leave the heart and filling the atria)
• Systole
  
  • Contraction
  • The blood is contracted through the heart
  • The atria undergo systole first as the blood is squeezed through the AV valves into the ventricles and the AV valves close and the heart experiences ventricular systole where blood is squeezed out of the ventricles and into the vasculature

Question 9

The Vasculature

Answer 9

• Carries blood both away from he heart and then back towards the heart
• Arteries, Veins and capillaries

Question 10

Capillaries

Answer 10

• Made up of a single layer of endothelial cells
• Very thin walls and thus allow easy diffusion of gases, nutrients and waster across the capillary walls
• So small that they can snuggle up into between intercellular pockets
• These connections of capillary beds with out cells help us in thermal regulation
• To prevent heat loss the capillaries constrict and allow us to maintain an internal temperature and vice versa

Question 11

Haemoglobin

Answer 11

• Protein present in red blood cells
• When blood passes through the lungs, where the partial pressure of oxygen is high, oxygen molecules bind to the heme group of hemoglobin
• 2% of oxygen dissolves in plasma
• 98% of oxygen combines with hemoglobin
• Since O2 is consumed for cellular respiration, the partial pressure of oxygen in the cellular region is low, which causes O2 to release from hemoglobin so that the O2 can diffuse into the cells
  
  • The more active the tissue is, the more it will use oxygen the lower the partial pressure of oxygen will drop, and the more oxygen gets released
• Blood delivers more oxygen exactly where that oxygen is most needed.

Question 12

Blood Components

Answer 12

• Red Blood Cells
• Glucose
• Salts
• White Blood cells
• Anti bodies
• Clotting factors
• Platelets
• Hormone
• The components of blood can be separated for diagnostic purposes
  
  • The separation is accomplished by simple centrifugation
• Three layers of blood
  
  • plasma: Water, proteins nutrients, hormones, etc.
  • Buffy Coat: White blood, plateles
  • Hematocrit: Red Blood Cells