The Cardiovascular and Respiratory Systems

Question 1

The Vascular System

Answer 1

a. Arteries: carry blood away from heart to different organs
b. Arterioles: regulate blood distribution to different tissues
c. Capillaries: responsible for gas and nutrient exchange
d. Veins: returns blood to the heart

Question 2

How blood returns to the heart

Answer 2

a. Skeletal muscle pump: when skeletal muscle contracts blood is pushed back to the heart
b. Thoracic pump: pressure in chest veins decreases while pressure in abdominal cavity veins increases when breath taken→ pressure difference pushes blood from abs to thoracic cavity
c. Nervous system: sends a signal to veins → veins constrict and allows more blood to return to heart

Question 3

Heart’s Electrical Conduction System

Answer 3

• Sinoatrial (SA) node is a specialized region of tissue in the wall of the right atrium is where electrical signals are initiated
• Signals spread through both atria through intermodal pathways then contract
• Atrioventricular (AV) node passes signal into ventricles
• Bundle of His receives signal, then it runs down ventricular septum and splits into right and left bundle
• Signal passed to purkinje fibres then to myocardium
• Myocardium contracts and leads to the ventricles contracting (bottom up) and blood is forces into the aorta and pulmonary arteries

Question 4

Electrocardiogram (ECG) Terms

Answer 4

a. Depolarization: spreading of electrical signal to contract
b. Repolarization: resetting and readying for another contraction
c. Diastole: relaxation
d. Systole: contraction

Question 5

ECG Reading

Answer 5

a. P wave: depolarization through the atria
b. QRS Complex: depolarization through the ventricle
c. T wave: repolarization of the ventricle
d. ** No repolarization of the atria because it happens at the same time as the depolarization of the ventricle

Question 6

Cardiac Output Equation

Answer 6

• Cardiac Output (Q): volume of blood that is pumped out of the left ventricle in one minute
• Q = SV(mL) x HR(beats/min)
• Measured in L/min
• At rest Q is 5-6L/min
• During heavy exercise Q can increase to over 30L/min

Question 7

Stroke Volume and Heart Rate

Answer 7

a. Stroke Volume (SV): volume of blood ejected from left ventricle in one beat
b. Heart Rate (HR): number of times the heart contracts in one minute

Question 8

Oxygen Pathway

Answer 8

• Oxygen enters nasal and oral cavities where the air is moistened, warmed and filtered
• Cilia and mucus filter air and air is warmed and moistened by capillary beds and mucus membranes
• Air enters pharynx which opens into the esophagus and larynx → air goes into larynx but not food because epiglottis covers trachea when swallowing
• Larynx is at the top of the trachea and is made of 9 cartilages and produces sound → contains true vocal cord
• Trachea is a tube allowing the air to pass from the pharynx to the bronchi → made of C-shaped cartilage rings that surround and support it
• Divides into left and right bronchi which lead to the lungs
• Bronchi branch into bronchioles then branch further into alveoli
• Alveoli along with capillaries is where gas exchange occurs
• Oxygen binds to hemoglobin and dissolves within the plasma (2%) then is transported through blood through arteries, then arterioles then to specific tissues

Question 9

Carbon Dioxide Pathway

Answer 9

• Carbon dioxide is dissolved within plasma (5-10%), binds to hemoglobin (20%) or is transported through the bicarbonate system (70-75%)
• Carbon dioxide travels through veins to return to the heart
• CO2 is transported to the lungs where the capillaries exchange the gas into the alveoli
• CO2 exits the body the same way oxygen entered