Introduction to circulation Flashcards
What are the functions of circulation?
–Carrying O2 glucose nutrients to the cells
–Removing waste: CO2 and heat
–Homeostasis of the extracellular fluid (via the kidneys)
–Distribution of hormones
–temperature regulation
–defence against infections
What is the main function of the cardiovascular system?
–To maintain appropriate levels of perfusion to tissues
What are the functional differences between the systemic circulation and the pulmonary circulation?
Pulmonary: Lungs, low pressure, high flow, low resistance.
Systemic: Multiple organs, high pressure, variable flow, variable resistance
Name the four valves and the regions that they divide?
- Tricuspid – R atrium from R ventricle
- Pulmonary – R ventricle from pulmonary artery
- Aortic – L ventricle from aorta
- Mitral (sometimes called “the bicuspid valve”) – L atrium from R ventricle
What are the two main normal valve sounds AND what causes them?
•S1, First heart sound – produced by the closing of the AV valves.
–Marks the end of ventricular diastole
–Occurs when ventricular pressure increases above atrial pressure
•S2, Second heart sound – produced by the closing of semilunar valves.
–Marks the end of ventricular system
–Occurs when ventricular pressure decreases below arterial (aortic/pulmonary) pressure
What is the key blood pressure equation?
BP = cardiac output (flow) x peripheral resistance
BP = CO x PR
How is blood pressure measured?
By listening for Korotkoff sounds made by the brachial artery as different pressures are applied to the upper arm.
What is the main regulator for blood volume?
Blood volume is set by the kidneys (or its processes of filtration and reabsorption)
–Depends on water intake
–Can also say “GFR”
What are the symptoms of heart murmurs?
Often asymptomatic, possibly pt has low energy
What type of blood vessel is the reservoir for the majority of blood in the body?
veins
What elements of the vascular system have the greatest influence on total peripheral resistance (TPR)?
Resistance arterioles. A generalised contraction in resistance arterioles greatly affects TPR and measured blood pressure.
Name the layers of a large artery (from innermost to outermost) and the type of tissue found in each layer
•Intima
–Endothelium
–Basement membrane
–Lamina propria
- Internal elastic membrane
- Media (smooth muscle)
- Adventitia (connective tissue)
Name some differences in structure and function between the right heart and the left heart
Right heart
- Thin walled
- Crescent X-section
- Sends blood toLungs only
- Low Pressure
- High flow
- Low resistance
- Deoxygenated blood
Left Heart
- Thick walled
- Circular cross section
- Sends blood to the body
- High pressure system
- Variable flow system
- High resistance system
- Oxygenated blood
Name the large blood vessels, the heart chambers, and the valves that plasma must pass through as it goes from the vena cava to the aorta (in order).
•Superior & Inferior Vena cava
–Arrives Deoxygenated
- Right Atrium
- Tricuspid Valve
- Right Ventricle
- Pulmonary Valve
- Pulmonary Arteries
- Lungs
–Oxygenated
- Pulmonary Veins
- Left Atrium
- Mitral (bicuspid) Valve
- Left Ventricle
- Aortic Valve
- Systemic Circulation
What are AV valves in the heart?
- AV valves control fluid movement (making it one-way) between the atria and their ventricles
- The 2 AV valves are the tricuspid valve (between the RA and the RV) and the bicuspid (or mitral) valve (between the LA and the LV)
- The tricuspid valve is made up of three leaflets and the bicuspid valve is made up of 2 leaflets
- Each leaflet is prevented from everting by chordae tendinae, which are connected to the papillary muscle in the appropriate ventricle
- When the AV valves close, they make the sound known as S1
What are semilunar valves in the heart
- Semilunar valves control fluid movement (making it one-way) between ventricles and their output arteries
- They are made up of three flaps that look “moon-like”
- The 2 seminlunar valves are the pulmonary valve (between the RV and the pulmonary arteries) and the aortic valve (between the LV and the aorta)
- When the semilunar valves close, they make the sound known as S2
Explain briefly how the kidneys contribute to setting blood volume.
- The kidneys filter the blood, sending toxins, waste products, water and electrolytes into the urine
- The filtration occurs by sending plasma to a nephron.
- Small molecules are filtered through the glomerulus of the nephron into the tubule system, and necessary molecules (eg water and electrolytes) are absorbed back into the blood, leaving behind other molecules to be excreted.
- The kidney can rapidly decrease blood volume by filtering more fluid and reabsorbing less water, and it can increase blood volume (after drinking) by decreasing filtration and increasing reabsorption
Explain what a portal system is, in the context of the kidney
- A portal system is when a capillary bed pools into another capillary bed through veins, without first going back through the heart. The two capillary beds are IN SERIES with one another.
- Both capillary beds and the blood vessels that connect them are considered part of the portal system.
- Portal systems allow the contents of one capillary system to be “seen” by another capillary system without being diluted by being mixed with blood from the rest of the body
- At the nephron, the first set of capillaries (the glomerular capillaries) reformulate into the efferent arteriole
- Instead of sending blood straight back to the heart, the efferent arterioles rebranch into the peritubular capillaries, where they reabsorb molecules from the tubule system
- In the peritubular capillaries, the blood is osmotically concentrated, which allows it to absorb readily the water and electrolytes during reabsorption
Define (for the nephron) filtration, reabsorption, secretion and excretion.
- Filtration is when a molecule leaves the glomerular capillaries and enters the Bowman’s capsule
- Reabsorption is when a molecule leaves the nephrons tubule system and enters the peritubular capillaries
- Secretion is when a molecule leaves (is sent from) the peritubular capillaries into the tubule system
- Excretion is when a molecule follows the course of the tubule system to its end and ends up in the urinary bladder
Name the blood vessels (in order) that plasma going to a nephron would pass through if the blood was not filtered?
- Afferent arteriole
- Glomerular capillaries
- Efferent arteriole
- Peritubular capillaries
- Venous system back to the heart
What is GFR?
- GFR = glomerular filtration rate
- It is the amount of fluid entering all Bowmans capsules
- In ml / min
- increased GFR leads to fluid loss to urine
What is the difference between hypoxia and ischaemia?
- Hypoxia is when there is insufficient O2 supply to a region or to entire body
- Ischaemia is when there is insufficient blood flow to a region
- Ischemia always results in hypoxia; however, hypoxia can occur without ischaemia if, for example, the oxygen content of the arterial blood decreases
–as occurs with lung disease or anaemia.
What is angina pectoris?
- A symptom
- Of chest pain (and referred chest pain)
- Due to over-exertion of heart muscle
- Typically in the context of ischaemia of heart tissue
–Due to coronary artery disease
What is “reperfusion” in the context of an acute myocardial infarct?
- Reperfusion is the re-establishment of blood supply to an area that has been ischaemic or otherwise deprived of oxygen.
- Usually the initial insult is a plaque or thrombosis that is blocking a blood vessel (eg myocardial infarct), so that plaque or thrombosis must be moved or destroyed.
- The medical procedures used to move or remove the plaque are generally referred to as PCI (percutaneous coronary intervention) such as balloon angioplasty.
- There are also “plaque buster drugs” such as tissue plasminogen activator that can be used instead of PCI.
