Section 1 Flashcards
What is the purpose of the circulatory system?
To transport agents around the body
What type of agents are transported via the Circulatory System?
- Oxygen which is attained through respiration and is picked up in the lungs
- Waste products such as CO2 that is produced by the organs due to metabolic activities
- Hormones from an organ to an effector organ
- Nutrients such as fuel substrates (glucose or fatty acids via albumin)
- Metabolites
What is the difference between Glycolysis and Glucose Oxidation?
Glycolysis takes place in the cytosol of the cell under anaerobic conditions(the absence of Oxygen) and produces 2 ATP molecules.
Glucose Oxidation takes place in the mitochondrion of the cell under aerobic conditions and produces 30 ATP molecules. It consists if two phases (the Krebs cycle and Oxidative Phosphorylation)
How are fatty acids transported in the blood stream?
In the form of Non Esterified Fatty Acids (NEFA) or free fatty acids (FFA)
Tell me about fatty acid as fuel substrates
- Fatty Acids are largely stored in adipose tissue as triglycerides or triacylglycerides (TAGs).
- Here it can be broken down by lipoprotein lipase to form glycerol and NEFA’s.
- NEFAs can enter circulation and are transported by albumin to the liver or heart
- Specific Fatty Acid Transporters accommodate NEFA uptake into the heart cells.
- They are modified in the cytosol by the addition of CoA
- The transporter Carnitine Palmitoyltransferase 1 (CPT 1) transports it into the mitochondria where it is metabolised to produce ATP
- Fatty acids are preferred as they are easier to break down, readily available and have a higher energy yield.
Define hypoxia and its types
Hypoxia is the lack of oxygen experienced by tissues.
Physiological hypoxia is an adaptation to low oxygen levels at high altitudes. It offers cardioprotection and shows metabolic remodelling. This is exhibited by the Andean Quecha Population.
Pathophysiological hypoxia occurs when oxygen deficiency causes several damaging effects to tissues
Compare glucose metabolism to FA metabolism
- Fatty Acids produce approximately 105 ATP molecules while Glucose produces 32 ATP molecules
- If oxygen is not limiting, FA would be ideal for cardiac tissue to use
- However, glucose produces more ATP molecules per Oxygen molecule compared to FA (2,6 ATP/O2 vs. 2,3 ATP/O2). Glucose can also be metabolised under glycolysis which produces ATP in anaerobic conditions.
- Therefore under hypoxic conditions, glucose would be the more efficient fuel.
Define Myocardial Ischaemia
Ischaemia refers to reduced blood supply to tissues. Since blood flow is reduced, oxygen supply is also reduced. Thus hypoxia is a component of ischaemia.
Myocardial refers to the heart muscle. Thus Myocardial Ischaemia refers to the reduced blood supply to the heart/cardiac tissue.
Differentiate between pulmonary and systemic circulation
Pulmonary Circulation refers to the portion of the Circulatory System that transports deoxygenated blood from the right ventricle of the heart via the pulmonary arteries to alveoli in the lungs to be oxygenated. It returns this oxygenated blood to the left atrium of the heart via the pulmonary veins.
Systemic Circulation refers to the portion of the circulatory system that transports oxygenated blood from the left ventricle of the heart via the Aorta to the physiological components of the rest of the body. It then returns the deoxygenated blood from these components to the right atrium of the heart via the superior and inferior Vena Cava
What does Portal Circulation refer to?
Portal circulation is the portion of the circulatory system of which blood vessels connect two organs (not including the heart). This is often for the transport of metabolites and hormones.
Eg. the hypothalamic hypopheseal portal system connects the hypothalamus and the anterior hypophysis. Hormones secreted by the hypothalamus are released into this portal system and stimulate the anterior hypophysis to secrete its own subsequent hormones.
What is meant by the parallel supply of blood?
Blood supply to the different organs and physiological components of the body takes place parallel to each other. Blood is supplied to each organ and returns from each organ. Thus if supply was stopped to a certain organ, the other organs would not be affected.
Discuss the differences in the muscularity of the Heart
Muscular bundles or tissues are arranged in a spiral form around each of the chambers of the heart. However, there is a difference in the muscularity between the right and left side of the heart. The left ventricle of the heart has more muscles around as the blood from here needs to be pumped to the rest of the body. The right ventricle has less muscle as it pumps blood to the lungs only.
Clinical complications of muscularity
The thickness of the ventricular walls may changed due to disease states. Smoking can cause right ventricular hypertrophy by causing vasoconstriction of pulmonary vessels. The RV needs to pump harder and thus it packs on more muscle. May lead to heart disease
Define striated muscle
In striated muscle, contractile fibrils (cardiac myocytes) in the cells are aligned in parallel bundles.
What is the functional synctium?
The network of heart cells with continuous interlinkages. Gap junctions and desmosomes occur and this allows for easy communication between the cells. The Synctium ensures easy communication between all the different cells that make up cardiac tissue to ensure it pumps as one.
