Trimester Revision Flashcards
What is plasma?
Liquid with sugar, water, proteins, hormones and salt. Proteins establish an osmotic gradient between blood and interstitial fluids to buffer pH.
What is a hematocrit?
The % of total blood volume occupied by cell components (red blood cells)
What are the three proteins within plasma?
- Albumins - contribute to osmotic pressure
- Globulins (alpha,beta,gamma)- transport, help blood clotting, act as antibodies
- Fibrinogen - helps blood clotting
All about erythrocytes:
Red blood cells. Have quaternary structure as they have four hemoglobin chains that carry oxygen. Can play a role in pH buffering as they can also bind with CO2, CO and NO, H+. Do not have any organelles and are biconcave.
Why do RBC have a biconcave shape?
Increases surface area for diffusion of oxygen.
What are leukocytes?
White blood cells.
What are thrombocytes?
Platelets. Plug wounds to stop bleeding and are formed from megakaryocytes in the bone marrow.
Blood life cycle:
Kidney detects low blood oxygen, releases erythropoietin to the bone marrow, stimulating it to make more red blood cells.
List the leukocytes from most to least common:
Use acronym Never Let Monkeys Eat Bananas. Neutrophils, leukocytes, monocytes, eosinophils and basophils.
What is characteristic of anemia?
Reduced oxygen carrying capacity of the blood = lower numbers of RBCs.
Normal hematocrit % for women and men?
Women: 42%
Men: 45%
What happens when we have lower numbers of red blood cells in the body?
A patient may be pale and feel tired. RBC carry oxygen to cells that will use it to make ATP. Less cells = less oxygen = less ATP = less energy for the patient.
Why do bruises change colour?
Impact trauma will cause blood to leak below the skin surface from a damaged blood vessel. Different bruise colours occur as old red blood is engulfed by macrophages, stripping haem of iron and making it into biliverdin, which has a green colour. This will be converted to bilirubin which is orange/yellow. This will then combine with albumin and be transported to the liver where it will be excreted
What are the three steps of haemostasis?
- Blood vessel spasm
- Formation of platelet plug
- Coagulation of blood
Exposing blood to collagen in damaged vessels causes platelets to stick and produce chemicals that promote more platelet aggregation.
Factors that determine blood flow:
- Blood vessel diameter- influences resistance.
2. Blood pressure- blood flows from high to low pressure, larger pressure gradient results in greater velocity of blood
What is MAP?
Mean arterial pressure. The average pressure in the arteries during one cardiac cycle.
What is systole?
Systole, period of contraction of the ventricles of the heart that occurs between the first and second heart sounds of the cardiac cycle (the sequence of events in a single heart beat). Systole causes the ejection of blood into the aorta and pulmonary trunk.
What is diastole?
Diastole is when the heart muscle relaxes. When the heart relaxes, the chambers of the heart fill with blood, and a person’s blood pressure decreases.
How is low MAP countered?
When blood pressure drops, baroreceptors stimulate action potential to the brain stem that cause an increase in sympathetic activity, in order to increase cardiac output and return MAP back to normal.
low MAP causes a cascade that quickly increases sympathetic activation return MAP back to normal, causes increases firing of the SA node and contractility of the heart (higher heartrate) as well as increased venous return which causes a higher stroke volume. Through sympathetic stimulation and increase/decrease of parasympathetic influence MAP is brought back to normal. Sympathetic stimulation causes vasoconstriction which effects total peripheral resistance.
Haematocrit for men and women:
women 42% and men 45%. Men have slightly higher haematocrits due to the hormone testosterone. Testosterone increases the production of erythropoietin (EPO), which is responsible for stimulating red blood cell production.
What happens if there is a reduced number of red blood cells inn the blood?
Erythropoiesis occurs in the bone marrow and is controlled by erythropoietin (EPO). If the kidneys detect a reduced oxygen carrying capacity, which is associated with reduced RBC count, the kidneys will release EPO into the blood stream. EPO increases erythropoiesis, increasing the oxygen carrying capacity of the blood. This is a negative feedback loop
What happens when we go from lying down to standing?
The gravitational force causes blood to pool at the veins in the leg. Decrease in venous return which results in lower blood pressure corrected by baroreceptor reflex. Increased heart rate compensates for lower blood pressure. Cardiac output decreases due to decrease in venous return. MAP will decrease as cardiac output will decrease. Systolic and diastolic pressure increases.
Events occurring in a Wigger’s diagram/ one cardiac cycle?
First, the closing of the atrioventricular (AV) valves. Following the closure of the AV valves is a sharp rise in the ventricular pressure as isovolumetric ventricular contraction occurs.
Second, opening of the pulmonary and aortic semilunar vales. The pressure inside the ventricle is greater than in the aortic arch and pulmonary trunk, causing the semilunar valves to open, allowing blood to exit the heart and enter the pulmonary and systemic circulation.
Finally, isovolumetric ventricular relaxation. Here, all the heart valves are closed - The pulmonary and aortic semilunar valves closed as pressure is greater in the pulmonary trunk and aortic arch than inside the ventricles. The ventricles are relaxing and pressure is decreasing in preparation for re-filling by the atria.
Once pressure inside the atria is higher than that in the ventricles, the AV valves will opens and blood will enter the ventricles.
Finding ultrafiltration:
Pressure out of capillary - pressure into capillary = ultrafiltration pressure
ECG- what happens in each section?
(P wave, QRS, T
P: atrial depolarisation
QRS: ventricular depolarisation
T: ventricular repolarisation
PR segment: AV nodal delay
ST segment: ventricles contracting and emptying
TP interval: ventricles relaxing and filling.
List the leukocytes from most to least common:
Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils (Never Let Monkeys Eat Bananas)
Example calculation- If 38 packed volume units of cells are separated from 51 volume units of plasma from a blood sample find haematocrit.
38+51=89, 38/89 x 100 = 42.6%
What are the symptoms of anemia and why do they occur?
A patient may feel tired and be pale when they have a lower RBC count as the cells contain haemoglobin that will carry oxygen to cells in the bpdy to make ATP. Lower oxygen carrying capacity of the blood gives a pale appearance (less red pigment from haemoglobin). Less oxygen means less ATP available = patient feels tired.
Why do bruises change colour?
A contusion is a bruise- it will change colour as impact trauma will cause blood to leak below the skin surface from damaged blood vessel. When old RBCs are engulfed by macrophages the haem will be stripped of iron and made into biliverdin, which is green in colour. Will convert to bilirubin which is orangey yellow and released to blood, then combines with albumin annd transported to liver where it will be excreted as urine or feces, giving each their colour
What are the three events occurring during haemostasis?
- Blood vessel spasm
- Formation of the platelet plug
- Blood coagulation
Exposing blood to collagen in damaged vessels causes platelets to stick and produce chemicals that promote more platelet aggregation
What can happen if a mother’s blood mixes with her fetuses positive blood type during birth if the mothers blood type is negative?
If a mother with negative blood group gives birth to a baby with positive blood group and is exposed to its blood supply when the placenta falls out (or something) the mother will produce D (Rh) antibodies if not treated. If she has another baby with positive blood type the antibodies will cross the placenta and destroy RBC of the fetus, lowering the hematocrit. Can cause anemia and be fatal
What is the process of a blood transfusion for doping?
Athlete will donate their blood which will be centrifuged. The liquid part will be re-injected and RBC’s stored. Before the comp, RBCs will be re-injected to give more oxygen
What are the consequences of blood doping?
blood viscosity will increase, harder to pump blood. Risk of blood clot, causing stroke, heart attack or pulmonary embolism. Risk of infection if blood comes from someone else. If blood isn’t matched correctly a transfusion reaction (agglutination) may occur.
What are reticulocytes and how do they relate to blood doping?
Reticulocytes are the final stage of RBC before full maturation, if there is a higher level of them in the blood it suggests that the bone marrow is being stimulated to release a higher amount of cells than normal
What is polycythemia?
When more RBC’s are produced than destroyed. This is a primary condition. The secondary condition occurs when this is an appropriate response to a prolonged reduction of O2 delivery to tissues. common in people living at high altitudes.
What is the passage of a red blood cell through pulmonary and systemic circulation?
vena cava into right atrium and through right atrioventricular valve, pumped into pulmonary circulation through pulmonary artery. Pumped back into the heart through the pulmonary vein, enters left atrium and entering the left ventricle which it will then be pumped into systemic circulation by the aorta.
How do valves ensure one way movement of blood?
Valve leaflets point in the direction of blood flow and will open and close due to changes in blood pressure in front and behind the leaflets.
What is the structure of cardiac muscle cells?
Striated with intercalated discs. Discs connect neighboring cells to one another and have desmosomes that anchor. Gap junctions allows action potentials to pass between cells quickly. Allow muscle fibers to contract together. Arranged spirally in the heart allowing contraction and pumping in a wringing motion
What is the function of the pericardial sac?
Prevents friction of the heart against the lungs and prevents overfilling by restricting expansion.
How is electrical activity generated in the heart?
Positively charged ions (Na+) enter the cell, when a threshold crosses -55mv an action potential can occur, allowing lots of positive ions in, depolarizing the cell. After this repolarisation occurs, letting out potassium ions to rebalance. Action potential starts in SA node and spreads in both atria. The AV node is the only place an action potential can spread from atria-ventricle- it has an AV node delay by 0.1sec allowing atria to fully depolarize and contract. This signal moves down bundle of His and through myocardium via Purkinje fiber, which transmits rapidly to allow ventricles to contract as a unit.
How does the SA node work?
SA node = pacemaker potential. Slow depolarisation generated by protein transport pathways. Calcium enters and potassium leaves the channels. Funny sodium channels open during hyperpolarisation allowing sodium into the cell, allowing the cell to begin depolarising. T calcium channels open during depolarisation, allowing potential to cross the threshold, stimulating an action potential and the opening of L channels that allow this. At neutral membrane potential, calcium channels close and potassium channels open.
What happens during cardiac muscle action potentials?
There is no unstable membrane potential = this is a plateau phase. Electrical signal stimulates voltage gated sodium channels to open into the cell , stimulating depolarisation. Sodium channels close at above +30 membrane potential. Potassium channels will open, allowing repolarisation as potassium moves out of the cell.
Function of L type calcium channels in cardiac muscle:
Allow the plateau stage. Calcium moves into the cell, membrane potential stabilises. This increases the refractory period. After this, potassium channels open and let ions out.
L type calcium voltage gated channel will be open by action potentials, allowing calcium into cardiac muscle cells. Entry of calcium stimulates ryanodine calcium channels to then open, increasing calcium concentration in the cardiac muscle cell.
Calcium moves to contraction relaxation units in the muscle, binding to tryponin an actin filaments, enabling cross brisge cycling and contraction to occur. Calcium ions must enter from extracelluar fluid to trigger contraction. This provides 90-95% of calcium for contraction.
What is the refractory period of the heart?
Time period when a recently activated area is non responsive. In cardiac muscle, the refractory period is much longer as compared to skeletal muscle. Because of the refractory period, cardiac muscle cells cannot undergo tetanus, allowing sufficient pumping of blood throughout the body
What is isovolumetric ventricular contraction?
Period in cardiac cycle where there’s a constant volume of blood in ventricles during contraction, resulting in ventricles contracting on fixed volume, increasing pressure. Both valves are closed.
The valves opening and closing during a cardiac cycle:
Ventricular filling occurs when pressure in the atria is greater than pressure in the ventricle, bicuspid AV valve is open and semilunar valve is closed. Isovolumetric contraction is reached when the AV valve closes. When blood pressure in ventricle is greater than in the aorta, the semilunar valve will open and systole will occur. As the process begins again, diastole occurs.
What are the lub dub sounds produced as a result of?
‘lub’ closure of AV valves, ‘dub’ closure of semilunar valves. Blood flow is laminar, which does not produce sound. Closing of the valves makes blood flow turbulent, which produces sound from vibrations
What is the SA node?
SA node is the pacemaker of the heart, influencing heart rate through consistent depolarization. Electric activity in the heart comes from pacemaker cells in the SA node. Heart is affected by the sympathetic and parasympathetic nervous systems. Their nervous systems don’t generate electric activity - they modify it
How do parasympathetic nerves work?
The parasympathetic nerves have a longer preganglionic fiber and shorter postganglionic. The pre ganglionic fiber releases acetylcholine to nicotinic receptors on the postganglionic fiber. Acetylcholine from the post fiber binds to muscarinic receptors on the tissue site. The vagus nerve innervates the SA and AV node, decreases the heart rate and the rate at which the threshold is reaached. Potassium channels are stimulated to open more to counteract the effect of sodium and calcium entering the cell.
How do the sympathetic nerves work?
Sympathetic nerves have a shorter preganglionic fibre and a longer postganglionic fibre. Acetylcholine released from pre ganglionic to nicotinic receptors and adrenaline/noradrenalin released from the postganglionic fibre to bind with alpha or beta receptors. Innervates SA node, AV node and entire myocardium, increases the heart rate. Noredrenalin acts on sodium and calcium channels, stimulating them to open, generating more action potentials faster
What is atrial fibrillation?
Irregular, uncoordinated depolarization of atria. Problem starts in upper chambers of the heart, quivering (fibrillating) rather than beating, meaning that the heart doesn’t pump blood as efficiently as it should. Catheter ablation can burn tissue that connects the pulmonary vein to atria with a laser, causing scar tissue that stops electric signaling from being directed to atria, stopping atrial fibrillation
Function of umbilical vein:
directs oxygen rich blood to the heart, diverting blood from liver and kidneys. A thicker wall is needed as blood pressure will be increased in a fetal circulatory system. This also makes vasoconstriction after birth easier
