Chapter 7 - Circulatory System Flashcards
Define what the circulatory system is
It is the body’s main internal transport system consisting of the heart, blood, blood vessels, lymph and lymph vessels.
Circulation is the movement of blood through the heart and blood vessels
What are the functions of blood
The blood is the transport link between cells of all systems of the body
- it transports nutrients and oxygen to all cells of the body
- it transports carbon dioxide and other waste products away from cells
- transports chemical messengers called hormones to cells
- mains the optimal pH of body fluids
- distributes heat and maintains body temperature
- maintains water content and ion concentration of the body fluids
- protects against disease causing micro-organisms
- clotting when vessels are damaged, thus prevent blood loss
What does the blood contain?
Blood contains a liquid part called plasma ( 55% of blood - within that 91% is water and the rest is dissolved substances such as glucose, AA’s lipids, and vitamins and minerals Eg K, Na, oxygen and carbon dioxide, hormones, plasma proteins and wastes urea ).
Formed elements (45%) and are called erythrocytes (RBCs), leucoytes (WBCs) and cell fragments known as thrombocytes (platelets)
Leucocytes
WBC fewer in number
Two types
- Granulocytes - granular cytoplasm, lobed nucleus
- monocytes and lymphocytes - spherical nucleus and a-granular cytoplasm
Removed dead or injured cells and invading micro organisms
Minutes (infections) - years (no infection)
Erythrocytes
RBC
- no nucleus
- 120 days alive
- has haemoglobin
- Produced in bone marrow and destroyed in spleen and liver
Thrombocytes
Platelets are very small cell fragments
1/3 of RBC
Last 7 days
Important for blood clotting
Transport of Oxygen
O2 not soluble so only 3% in solution of blood
Haemoglobin in blood combines with O2 to become oxyhemoglobin
Oxyhemoglobin forms in high concentrations of O2 and breaks down when cont is low
Hb +O2 HbO2
Haemoglobin present increases the oxygen carrying capacity of blood by 60-70x
Oxygenated blood vs deoxygenated blood
Oxygenated = high proportion of oxyhemoglobin ( in artery) (bright red).
Deoxygenated = low proportion of oxyhemoglobin (in veins) ( purple red col)
Why is RBC suited for oxygen transport
- contains haemoglobin which is able to combine with O2 for transport
- has no nucleus so there’s more room for haemoglobin molecules
- biconcave disc shape - increasing TSA, thicker edges more volume for HbO2
Transport of CO2
7-8% in solution in plasma
22% combines with globin part of haemoglobin to form a compound called carbaminohaemoglobin
70% as bicarbonate ions in plasma HCO-3
CO2 +H2O H2CO3 H+ + HCO-3
The carbaminohaemoglobin breaks down and CO2 molecules released diffuse in alveoli
Hydrogen ions and bicarbonate ions recombine to form carbonic acid, which breaks down under enzyme action into water and CO2- diffuse into alveoli
Transport of wastes + nutrients
Metabolic wastes are substances produced by cells that cannot be used or harmful to body if Accumulated (urea, creatinine and uric acid)
Nutrients include minerals, vitamins, AAs, ions (Ca, Na, K,Cl), fatty acids and glycerol
All are dissolved in solution in he blood plasma
What is the great made up off?
Heart is the organ which pumps and pushes blood out into the body
Located left part of chest, middle of lungs
Size of human fist
Around the heart and completely enclosing it is a membrane called PETRICARDIUM which holds the heart in place but allows movement to beat, but stops over stretching
The wall of the heart itself is made up of strongest muscle known as CARDIAC MUSCLE
What is circulation
The same continuous blood flow through the heart is called circulation
Explain types and features of blood vessels
Blood vessels are the transport tubes of heart which tunnels the blood all over the body
Arteries carry blood away from the heart
- have high blood pressure that increases as the ventricles contract and decreases as the ventricles relax
- thick muscular walls
- have no valves
- within body
Veins carry blood towards the heart
- constant relatively low blood pressure
- thin, relatively inelastic walls with little muscles
- have valves
Capillaries are tiny vessels that carry blood between cells
Heart - artery - arterioles - capillaries- venules - veins -heart
Explain the circulation of blood in the heart
Lungs bring in oxygen
Superior and inferior vena cava bring in blood to heart
Right Atria collect deoxygenated blood
Atrioventricular valves separates and prevents back-flow of blood from ventricles to Atria
Left ventricle fills and pumps blood to Lungs
Semilunar valves prevent backflow of blood from arteries to ventricles
The pulmonary trunk divides to 2 pulmonary arteries that carry deoxygenated blood to each lung
Oxygenated blood comes back to heat via pulmonary vein
Left Atrium - atrioventricular valve - left ventricle (thick muscular wall for pumping blood into aorta and put to body)
Aorta - largest artery takes blood everywhere expect lungs