Circulatory Systems

Question 1

What are the types of circulatory systems? How does an open circulatory system differ from a closed system?

Answer 1

• Open Circulatory System
  o Blood mixes with internal organs directly
  o Organisms with this type of system do not have a true heart or capillaries, instead of a true hear, there are blood vessels that act as pumps to force the blood along
• Closed Circulatory System
  o Blood is pumped through a closed system of arteries, veins, and capillaries

Question 2

Describe the flow of blood through the mammalian heart. Know the vessels that lead into the heart, the names of the valves, and the vessels leading out of the heart.

Answer 2

See pic

Question 3

Describe the electrical conduction through the heart, know what an EKG is and what each waveform represents.

Answer 3

• Electrically excitable, generate own action potential
• Nervous input can increase or decrease rte
• Sinoatrial Node (SA node): Pacemaker-establishes rhythm
  o Spontaneously and rhythmically generate action potentials
• Action potential spreads due to connections via gap junctions
• AtrioVentricular Node (AV Node), near Right AV valve
• From AV node, impulse travles down AV bundle: Bundle of His
  o Splits into L and R branches
• Signal then to Purkinje Fibers which distribute signal to myocardium of venrticles
• Abnormal Rhythm?
  o Pacemaker: implantable device that uses low-energy electrical impulses to re-establish heart rhythm

Electrocardiogram (ECG or EKG)

• Record of electrical impulses generated during the cardiac cycle
• Monitor electrical activity produced by SA node
• P wave – begins when SA node fires
• QRS complex – 3 waves – AV node excites ventricles
• T Wave – repolarization of ventricles back to resting state

Question 4

What is systole and diastole? What is happening during each?

Answer 4

Cardiac Cycle
2 Phases
- Diastole
o Atria contract and ventricles fill (blood pressure lowest)
- Systole
o Ventricles contract and blood is ejected from the heart (blood pressure highest)
Heart Valves open and shut in response to pressure gradients

Question 5

What is blood pressure? What determines blood pressure? If someone has 120/80 blood pressure, what does this mean?

Answer 5

Blood Pressure – Force exerted by blood on the walls of blood vessels
-Higher in arteries than in veins
Resistance (R) – tendency of blood vessels to slow down the flow of blood
-based on vessel radius, length and blood viscosity

• Change in arteriolar resistance is a major mechanism to control blood flow to a reigon
• Radius is most important factor
• Vasodilation – increase in radius
• Vasoconstriction – decrease in radius
• Controlled by locally produced substances, hormones, and nervous system input
• The greater the cardiac output and the higher the resistance, the higher the blood pressure
• Garden Hose analogy
• Arterial blood pressure is a function of how hard the heart is working and how constricted or dilated the various arterioles are
• Baroreceptors are stretch receptors in certain arteries
• Communicate with brain to signal blood pressure
• Brain and other nerves can act to decrease or increase blood pressure as needed

120/80 blood pressure is ideal blood pressure 120-systolic 80-diastolic pressure

Question 6

What are the components of blood? What is the function of each component?

Answer 6

Blood
4 Components
- Plasma – Water and solutes
o Functions in buffering, water balance and immune cell transport
- Leukocytes – white blood cells
o Defend body against infection and disease
- Erythrocytes – red blood cells
o Oxygen transport using hemoglobin
- Platelets or thrombocytes
o Role in formation of blood clots (fibrin precipitation)

Question 7

What are the anatomical differences between arteries and veins? What features to veins have to ensure that blood goes back to the heart?

Answer 7

Arteries – Away
- Conduct blood away from the heart
- Note: not all arteries carry oxygenated blood
- Layers of smooth muscle and connective tissue around smooth endothelium
Veins
- Conduct blood back to the heart
- Thinner and less muscular than arteries
- Need help returning to the heart
o Smooth muscle contractions help propel blood
o Valves inside veins squeezed by skeletal muscles

Question 8

What is Hypertension? Myocardial Infarction? What are the symptoms and problems associated with each?

Answer 8

Hypertension = high blood pressure

• Many causes - obesity, smoking, aging, et
• Can be treated with diet, exercise, and drugs

Myocardial Infarction (MI) – Heart attack

• Localized regions of the heart muscle die when the blood supply is cut off
• Dead cardiac muscle does not regenerate
• Cardiac angiography can detect narrowing of coronary vessels
• Balloon angioplasty can widen the lumen of narrowed vessels
• Coronary artery bypasses take a healthy blood vessel and use it to replace a blocked coronary artery