Unit 4.1: Overview of the Cardiovascular System & the Heart Flashcards
What do we require from the environment?
Nutrients and oxygen
How do we overcome the diffusion limitation of oxygen and nutients?
1) cardiovascular system for transport of substances through the body
2) transported by flow of blood through circulatory system
3) bulk flow rather than diffusion
What is transported from the external environment to tissues?
Nutrients, water, gases (especially O2)
What is transported between tissues of body?
Wastes, nutrients and hormones
What is transported from tissues to external environment?
Metabolic wastes, gases (especially CO2), heat
What are the components of the cardiovascular system?
Heart (pumps)
Blood vessels (vasculature)
Blood cells & plasma (fluid)
What is the pericardium?
A tough membranous sac surrounding the heart
What is the structure of the pericardium?
Made up of 2 layers with a small amount of fluid between them that acts as lubricant
What do the coronary arteries do?
Nourish the heart muscle
What happens when there’s a lack of supply to the heart?
Leads to a heart attack (myocardial infraction)
What are the components of the internal anatomy of the heart?
- Left Atrium
- Left ventricle
- Right Atrium
- Right Ventricle
- Valves
What is the course of blood in the heart?
Venae cavae > Right atrium > Right ventricle > Lungs > Pulmonary veins > Left atrium > Left ventricle > sends to body via aorta
What is the function of valves?
They ensure that the flow of blood is unidirectional (one-way)
Where are valves found?
At the entrance to the left and right ventricles
Not found at the atrium due to weak atrial contraction relative to ventricular contraction
Why are there no valves at the atrium?
Atrial contraction compresses the veins at the entry to the heart which closes the exit to the heart and reduces backflow
What are the different valves found in the heart?
AV valves (tricuspid -right and bicuspid/mitral - left) Semilunar valves (aortic and pulmonary)
Where are AV valves attached?
They are attached on ventricular side to collagenous cords (chordae tendinae) - prevents valves from being pushed back into atrium
Where are semilunar valves?
Just inside aorta and pulmonary arteries (prevents backflow into ventricles)
Why don’t semilunar valves need cords like AV valves?
Because of their shape
What are the 2 divisions of the cardiovascular system?
- Pulmonary circuit: blood vessels in the lungs and those that connect the lungs to the heart
- Systemic circuit: encompasses the rest of the blood vessels in the body
What is the path of blood in the pulmonary circuit?
Right atrium > Right ventricle > pulmonary arteries > Lungs > lungs have many small capillaries to increase O2 transfer (increases resistance and decrease pressure of blood) > oxygenated blood as low pressure so it returns to the heart with the help of pulmonary veins to left atrium
What is the path of blood in the systemic circuit?
Left atrium > left ventricle > pumped to aorta that branches into smaller arteries and then to capillary networks throughout the body > O2 diffuses from the blood into the tissues in the capillary beds > flow to small venules and then larger veins > oxygen poor blood has low pressure so it need help to return to heart (via superior/inferior vena cava to right atrium)
