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
What is the cardiac cycle?
Cardiac cycle is the heart beat
The sequence of events that occurs in one complete beat of the heart
What is systole?
The pumping phase when the heart muscles contracts is called systole
Atrial systole is the contraction of the Atria which forces the remaking blood into the ventricles
Ventricular systole is when atria relaxes and refills and ventricles contract forcing blood to arteries
How to calculate cardiac output?
Heart rate; is the number of times the heart beats per min
Stroke volume; is the volume of blood forced from a ventricle of the heart with each contraction
Cardiac output is the amount of blood leaving one of the ventricles every minuet
Cardiac output (mL/min) =stroke volume (Ml) x heart rate (beats per min)
Vasoconstriction vs vasodilation
The elastic of the artery wall recoiled when ventricles relax. This done by the muscle of the contract to reduce the diameter of the artery thus reduce blood flow to organ - this contraction is called vasoconstriction
The muscles in the wall of artery relaxes to increase blood flow - vasodilation
CO2 and Lactic acid are waste products if respiration in muscle cells. Theses are the vasodilators which produce a local widening of dilation if arterioles
How does the blood clot?
When injury occurs blood clotting or coagulation is necessary so blood does not seep out of wound and loss of blood occur
Blood clot formation requires large number of chemical substances or clotting factors which are present in the blood plasma.
Complex series of reactions results in the formation of an insoluble protein called fibrin
Fibrin threads from a mesh that traps blood cells, platelets and plasma.
This mesh with the trapped materials = clot
Threads stick to the damaged blood vessels and hold the clot in position
After formation of a clot, a slower process called a clot retraction occurs.
Network of threads contract becoming denser and stronger, pulling he edges of damaged blood vessels together.
As clot restriction occurs, a fluid known as serum is squeezed out.
The clot dries forming a scab over the wound that prevents entry of infecting micro-organisms
What does the lymphatic system consist off?
- a network of lymph capillaries joined to larger lymph vessels
- lymph nodes which are located along the length of some lymph vessels
What is a lymph
At the arterial end of a blood capillary, fluid tends to leak out due to high blood pressure in blood. Some but not all of this fluid returns of the capillary at the venous end. The excess fluid in the tissue is returned to the blood via the lymphatic system. Fluid retuned to the blood via this way is known as a lymph.
What makes up the lymphatic system?
Not a circulating system - only a one way system
- lymph vessels originate at blind ended tubes in the spaces between cells of most tissue
- lymph capillaries are slightly larger than blood capillaries and are more permeable causing proteins and disease causing organisms in the intracellular fluid to easily pass through walls of lymph capillaries to lymph
- network of lymph vessels join up to form 2 lymphatic ducts that empty into large veins in upper chest
Lymph node or lymph glands occur along the intervals of lymphatic vessels
- most numerous in neck, armpits, groin and around alimentary canal
- nodes are bean shaped
- range from 1mm-25mm
- each is surrounded by a capsule of connective tissue that extends into the node forming a framework
- within each framework are LYMPHOID TISSUE (continue cells know as LYMPHOCYTES, MACROPHAGES AND PLASMA CELLS)
- lymph enters convex side of node, filters through the slaves and passes out through vessels in the opposite side
- lymph passes through many nodes before entering circulatory system
What are the two main roles of the lymphatic system
- collect some of the fluid that escapes the blood capillaries and return it to the circulatory system
- defence against diseases
- lymph entering lymph notes contains cell debris, foreign particles and micro organisms which have penetrated through external defences of body - may be causing disease thus must be destroyed.
- in the nodes the phagocytes called macrophages destroy theses particles (ingest vis phagocytosis)
- projections from the macrophages surround the particle and take it into the cell where enzymes destroy it (10-30min process of killing)
- when infections occur formation of lymphocytes increase and the lymph nodes become swollen and sore
Blood transfusion
Blood transfusion is the process of transferring blood or blood products of blood donor to a suffering of excessive blood loss via injection
Leukaemia, anaemia, haemophilia, injury
Blood needs to be matched otherwise the mixing of incompatible blood can cause the clumping of erythrocytes or agglutinate
- immune system will attack foreign cells causing them to clump and disintegrate
- death can occur
ABO Blood group
Antigen - is a substance that is capable of stimulating the formation of a specific protein called an ANTIBODY
Antibodies are produced in response to an antigen and are able to combine with the antigen that initiated the response
Surface of blood cells contain particular antigens that are able to react with the appropriate antibodies in plasma.
BG. RBC. Plasma A - Antigen A - Anti-B B - Antigen B. - Anti A AB - Antigen AandB. Neither O. Neither Both anti A and B
RH Blood group
Based on antigens that occur on the surface of RBC
A person with Rh antigens is said to +
An individual without Rn antigens is able to produce an anti-Rn antibody that reacts against those antigens
Rh positive cannot produce anti-Rh antibody
Types of blood transfusion
Whole blood - blood is taken from donor with a chemical added to prevent clotting (mainly used for severe blood loss)
- red cell concentrates - most widely used
- produced by spinning blood at very high speeds in a centrifuge
- heavier sink to bottom, leaving lighter plasma on top
- concentrate may or may not hAve platelet and WBC removed
- used for patients suffering heart disease
- plasma
- centrifuged
- patients requiring extra clotting factors for control of severe bleeding or liver disease
- platelets con
- abnormal platelets of reduced number of platelets
- Cryoprecipitate
- obtained by freezing plasma and thawing slowly
- when thawed, the cryoprecipitate remains as solid
- contains many substances necessary for blood clotting
- used to treat haemophilia or severe bleeding
- immunoglobins
- group of proteins that act as antibodies
- extracted from blood and used for patient who are deficient in antibodies
- used to treat patients who have no immunity to a particular disease Eg tetanus immunoglobulin
- autologous transfusions is when patients own blood is used
- blood was collected proper to an operation that may require transfusion
- elective sing her and blood is collected 4wks before
- eliminated the risk of transmission of disease and possible side effects of regular transfusion
