Topic 14 - Cardiovascular and Circulatory Systems Flashcards
Learning Objectives
- Explain why blood flows continuously around the body
- List the key differences between the three main types of blood vessels.
- Trace a red blood cell arriving at the right atrium through the heart, listing each chamber and structure that it passes on its way to the aorta.
- Explain physiologically why you can feel a pulse when pressing your fingers to an artery.
- Describe the composition of blood and how red blood cells are produced during hypoxia
- Describe why fluid is lost from the blood to the interstitium when exchange takes place at the capillaries
Human Circulatory System
Closed Circ. System:
- Physically seperated from rest of body
- Consists of vessels and pumps
Different types of blood vessels
Artery:
- Endothelium, elastic, smooth, fibrous tissues
- 0.1-10+mm diameter
Arteriole:
- endothelium, smooth muscle tissue
- 10-100um diameter
Capillary:
- endothelium
- 4-10um diameter
Venule:
- Endothelium, fibrous tissues
- 10-100um diameter
Vein:
- Endothelium, elastic, smooth, fibrous tissues
- 10-100mm diameter
Order of blood flow starting at superior/ inferior vena cava
- Deoxy blood into superior/ inferior vena cava1
- into the right atrium
- Through tricuspid valve
- Into right ventricle
- Through pulmonary valve to lungs
- Oxy. blood though pulmonary vein into left atrium
- Through bicuspid valve into left ventricle
- Through aortic valve
- Into aorta and rest of body
Steps of pulmonary circulation
- Deoxy blood from right ventricle
- Through pulmonary valve to lungs
- Blood is oxygenated in lungs
- Returns to heart via pulmonary vein into left atrium
Blood
- Connective tissue made up of cellular and fluid elements
- 92% water, 7% protein (fibrin & transporters), 1% dissolved organic molecules
Plasma
- ~1/4 of extra cellular fluid
- Acts as a buffer between cells and external environment
Erythropoiesis
- RBC production
- Negative feedback loop
1. Controlled by glycoproetein (Erythropoitin/ EPO) and some cytokines
2. Hypoxia triggers release of EPO
3. EPO then triggers the maturation process of RBC in bone marrow
4. Oxygen carrying capacity then increases and production of EPO stops
Blood Doping
- EPO often used
- Blood transfusion
- EPO injection
- Injection of synthetic O2 carriers
Heart
- Composed of cardiac muscle predominantly
- Creates Psi to force blood around the body
- LHS of atiral wall is thicker to create a higher Psi to pump blood further
4 Chambers:
- Right atrium: - Atrioventricular & tricuspid valves
- Right Ventricle - Pulmosary semilunar valve
- Left Atrium - Bicuspid & Mitral valve
- Left Ventricle - Aortic Valve
Heart Diagram lable [Heft]
[Heft]
Heart Contraction
- Heart contains Autorythmic cells to allow the heart to contract by generating an electrical signal coordinating contraction
- Autorythmic cells depolarise the cell membrane, spreading rapidly through conductive pathways
- ECGs show the electrical activity
Mechanical events of the Heart
- Heart is Diastole (not contract)
- Sinoatrial node creates an electrical impulse, e- activity spreads across the atrium chambers.
- Atria undergo systole and force blood into the ventricles
- Atria diastole and atrioventricular node creates e- signal
- e- spreads down Bundle of His to the Perkinjie Fibres
- Ventricles then undergo systole
- Blood is forced out of the heart through the pulmonary artery and aorta
[Heft]
Alterations to HR
- At rest ~65ml blood is left in heart after beating
Stroke Volume (SV):
- Amount of Blood pumped in one beat
Cardiac Output (CO):
- Performance of the heart over 1min
- SV x HR = CO
HR
- Altered by autonomic NS by changing the depolarisisation of the autorhythmic cells
- Sympathetic NS = Adrenaline
- Parasympathetic NS = Acetylchline
Blood Flow Psi
- Arteries contain elastic tissue allowing them to expand and take on loads from heart into blood vessels
- When heart relaxes, arteries compress down to maintain blood psi flowing foward
- Flows from high to low Psi gradient
- Arteriole system under high Psi
- Venous system under low Psi
- Recorded as Systolic/ Diastolic (120/80mmHg)
