Describe the flow of blood through the heart (2)
Right atrium -> Right Ventricle -> Pulmonary Artery
Pulmonary Vein -> Left Atrium-> Left Ventricle
What are the types of valves in the heart and where are they located? (4)
Mneumonic: LAB RAT
1. Atrioventricular Valves: Triscuspid (right atrium) and Bicuspid (left atrium)
- Semilunar Valces: Pulmonary Valve (Right Ventricle) and Aortic Valve (Left ventricle)
How are intrinsic contractions generated and controlled in the heart? (3)
The autonomic nervous system generates contractions in the heart.
- The Parasympathetic: decreases heart rate. This is controlled by the VAGUS nerve.
- Sympathetic: Increases heart rate.
What are the 3 layers of the heart wall? (3)
- Epicardium - Thin outer layer
- Myocardium - thickest layer (cardiac muscle)
- Endocardium - innermost layer that lines chambers.
What is the structure of the cardiac muscle? (3)
- Striated and branching
- Intercalated discs: Fascia adherens, desmosomes, Gap Junctions
- 1 nucleus per cell.
What are the structures of the left and right Lungs? (4)
Left Lung: 2 lobes, a cardiac notch and lingula, Oblique fissures.
Right Lung: 3 lobes, horizontal and oblique fissures.
What is the respiratory tree in order?
Trachea -> Main bronchi -> Secondary (lobar) bronchi -> Tertiary (segmental) bronchi -> Bronchioles -> Alveoli
Atherosclerosis: Narrowing of arteries or rupture of plaque causing a thrombus
Thrombosis: A bloodclot
Embolism: A stray blood clot
What is the microstructure of blood vessels, what are their functions? (3)
- Tunica Intima - Lined by endothelium and connective tissue. Function: Reduces friction of blood flow.
- Tunica Media: Smooth Muscle layer, has collagen and elastin fibres.
Function: Controls size and shape of artery.
- Tunica Adventitia: Primarily Collagenous. Can contain Nerves and vessels (VASA VASORUM).
Function: Connects artery to surrounding structures.
What are the different sizes of Arteries?
What is their size and function? (3)
Large Elastic Arteries (Conducting): >10mm. Lots of Elastin. Accomodates surges in blood
Medium Arteries (Disturbing) 0.1mm-10mm. Thick layer of smooth muscle. Function: Vasoconstriction and Vasodilation, pulsatile contractions.
Small Arteries/Arterioles (Resistance): < or = 0.3mm. Tonus dictates degree of filling of capillary beds.
What is the structure of capillaries?
How does exchange occur in capillaries (4)
Capillaires are microscopic and have just endothelial layer.
Continuous - Uninterrupted endothelium
Fenestrated - have pores. Seen in secreting organs such as pancreas and kidney.
Hydrostatic pressure forces fluid out of blood into extracellular fluid and osmotic pressure drives fluid is reabsorbed.
Describe the structure of Venules (3)
They are microscopic and drain capillary beds.
No elastin, very thing tunica externa and media.
Describe venous valves
What causes varicose veins? (3)
- Inward projections if intima layer strengthened by collagen and elastic fibres.
- Absent in thorax and abdomen.
- When the vein dilates, the valves may not close, resulting in varicose veins.
How do arteries and veins relate to one another? Why is this important?
Large Arteries have a single vein
Smaller arteries are flanked by 2 veins. Pulsation of the artery helps venous return.
Superficial veins do not have any arteries
It is important for countercurrent mechanism to heat regulation.
What factors help return blood against gravity? (2)
2. Pumps - Arteriovenous pump, Musculovenous pump and respiratory pump
What is anastamosis (2)
Connection of blood vessels. End arterioles have no anastomosis.
How does the Venous Portal system work? (3)
- Venous blood high in products of digestion
- Veins from the spleen, stomach and intestines drain into the liver via the hepatic portal vein
- Filtered by the liver, blood then drains into the hepatic veins and into Inferior Vena Cava to be returned to the heart.