Week 4: Physiology of the Cardiovascular System Flashcards
What are the 11 different body systems?
- Circulatory system, consisting of…
- Cardiovascular system
- Lymphatic system! - Digestive system
- Respiratory system
- Urinary system
- Skeletal system
- Muscular system
7.Integumentary system - Immune system
- Nervous system
- Endocrine system
- Reproductive system
Define homeostasis.
Maintaining a relatively constant internal environment (steady state) in the face of a constantly changing external environment.
What is the average red blood cell concentration for males?
5.4 x 10^6/microlitre
(with a normal range being 4.5-6.5)
What is the average red blood cell concentration for females?
4.8 x 10^6/microlitre
(with a normal range being 3.9-5.6)
What two systems regulate homeostasis?
- Nervous system
- Hard-wired
- Fast acting (milliseconds)
- Rapid response by target cells - Endocrine system
- Hormones transported in blood
- Slower acting (minutes, hours, days)
- Slower and often long-lasting responses of target cells
NOTE! The nervous and endocrine systems often overlap in function (e.g., in blood pressure regulation)!
What is the heart?
A high-pressure pump, essentially the central driver of the cardiovascular system.
What is the function of blood vessels (a.k.a., vasculature)?
Distributes blood to all parts of the body and back to the heart.
What are the 5 types of blood vessels?
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
What is the function of blood?
It is a transport medium in which materials to be transported are dissolved or suspended.
What are the two vascular loops (blood vessel loops)?
- Pulmonary circulation (from the heart to the lungs and back)
- Systemic circulation (from the heart to the other organs and back)
What are the two vascular loops (blood vessel loops)?
- Pulmonary circulation (from the heart to the lungs and back)
- Systemic circulation (from the heart to the other organs and back)
How much of our total body weight (TBW) is made up by the blood?
About 8%.
What is the average volume of blood in…
- Males?
- Females?
Males = 5.5 litres
Females = 5 litres
What is the liquid portion of the blood called? What portion of the blood is liquid?
Plasma, which makes up approx. 55% of the blood.
What are the 3 types of specialised elements that are suspended in the plasma?
- Erythrocytes (Red Blood Cells)
- Important in oxygen transport! - Leukocytes (White Blood Cells)
- Immune system’s mobile defence unit - Platelets
- Important in haemostasis (blood clotting)
What is haemostasis?
Blood clotting.
What portion does each blood component of the blood take up of the whole blood?
Plasma = 55% of whole blood
Erythrocytes = 45% of whole blood
Platelets and Leukocytes = <1%
What is the function of the smooth muscle that is present in the walls of some blood vessels?
Allows the blood vessels to contract (vasoconstriction) or relax (vasodilation) in response to changes in the local environment.
What is achieved through vasoconstriction?
Blood vessels is narrowed, limiting blood flow.
Give an example of when vasoconstriction may be employed.
- When temperature drops, the skin blood vessels will constrict.
- Reduces loss of heat from skin to the environment (i.e., a method of thermoregulation) - Blood vessels serving the kidneys and digestive tract will constrict during exercise.
- Allows us to divert that blood supply elsewhere where it is needed (i.e., skeletal muscles)
What is achieved through vasodilation?
Blood vessels widen, increasing blood flow.
Give an example of when vasoconstriction may be employed.
- When temperature increase, the skin blood vessels will dilate.
- Blood vessels serving the skeletal muscles will widen during exercise (allowing more blood to reach those tissues).
- More oxygen and fuel needed
What are the “receiving chambers” of the heart?
The atria!
- Right atrium receives deoxygenated blood from the systemic circuit
- Left atrium receives oxygenated blood from the pulmonary circuit (the lungs)
What is the name of the vein that brings blood from the body (systemic circuit) back to the heart?
Vena cava.
What valves prevent blood from back-flowing from the ventricles back into the atria?
Atrioventricular (AV) valves.
What valves are present in the arteries of the heart (i.e., the pulmonary arteries and the aorta) that prevent back-flow of blood into the ventricles?
Semilunar valves.
What is the major artery of the heart (where oxygenated blood exits)?
Aorta.
What must pass through the heart to allow the cardiac muscle to contract?
Electrical current.
What property of the heart ensures its uniform beating?
Autorhythmicity - allows the heart to generate its own rhythm.
What is the function of the pacemaker (SA node)?
Coordinates and provides rhythm to the heartbeat.
Where is the pacemaker found?
In the right atrium (near the vena cava).
What do the conduction fibres do?
Rapidly conduct the current initiated by the pacemaker cells to the myocardium (i.e., heart muscle).
What is another name for the heart muscle?
Myocardium.
What is the pathway of the electrical current that is initiated by the pacemaker cells?
- Travels through the internodal pathway to the Atrioventricular (AV) node.
- Then passes down the Bundle of His.
- Finally emerges through the Purkinje Fibres, causing the ventricles to contract.
Where are the Purkinje fibres found?
Throughout the cardiac muscle of the ventricles.
What is another word for the heartbeat (used in physiology)?
The cardiac cycle.
What term do we use to describe the heart chambers contracting?
Systole.
What term do we use to describe the heart chambers relaxing?
Diastole.