Module 4 (blood and immune) Flashcards
Blood volume and circulation
5L in humans; 14,000L through the heart every 24 hours; must be maintained to retain pressure
Blood overall function
Provides a one-way pressurised system for the transport of oxygen, proteins, lipids, glucose and essential ions required for normal cell function; bathes muscles and other organs in an oxygenated environment
Arterial pressure
Maintained by elastic vessel walls that contain lots of smooth muscle; very high pressure because walls expand to carry systolic pressure from the heart
Venous pressure
Lower pressure, veins are not elastic; one-way valves required to prevent back-flow and ensure it if always flowing in one direction
Blood loss
People can withstand up to 20% of blood loss; any more results in pressure and flow being impaired and tissue is starved of oxygen
Hypertension
High blood pressure; can be caused by a narrowing or hardening of the arteries, reducing flow and resulting in unwanted coagulation
Circulatory system components
Heart (L and R ventricles and atria); capillaries (large: high volume/low flow; small: low volume/high flow); veins and arteries
Blood pressure; changes and function
Different depending on the vessel type; normal BP is 120/80 (120mL mercury -systolic blood pressure)
High BP - arteries not expanding and contracting efficiently - something wrong and significant use to thromboses
Low BP: not enough blood pumping through veins to supply muscles and tissue with oxygen
Ensures even and efficient blood flow through the small capillaries; it is low enough to prevent capillary leakage but high enough to avoid coagulation.
Systolic pressure
Blood is at full compression (LV is squeezed at highest and arteries are expanded at greatest); 120/80 BP
Diastolic
The heart is at complete rest
Major components of blood (6)
Cells (erythroid, myeloid and lymphoid)
Proteins (major types: albumin, haemoglobin, fibrinogen, immunoglobulins)
Lipids (bound in lipoproteins; HDL, LDL and VLDL)
Electrolytes (salts and minerals; HCO3-, Na+, Cl-, Ca++, Mg++, K+, creatine, creatinine)
Vitamins, hormones
Glucose
Erythroid cells
Erythrocytes; solely for oxygen transport; don’t have a nucleus so survive radiotherapy much better (no DNA)
Myeloid cells
Neutrophils, monocytes (become macrophages), basophils, eosinophils); all white blood cells which engage in some form of innate immunity (and sometimes phagocytosis); they have a range of receptors that bind immune complexes
Composition of types of cells in the blood
Erythrocytes: 5-6 million/mL
Leukocytes: 10,000/mL
Platelets: 400,000/mL
Lymphoid cells
B-cells (come from bone marrow; provide antibodies/immunoglobulins; adaptive immunity)
T-cells (migrate to the thymus above the heart and become a part of the cellular adaptive response)
Albumin
Most abundant protein (accounts for ~50% of total blood protein); functions mainly to maintain colloidal osmotic pressure (to provide a soak for fluid within the blood - preventing leaking from capillaries) and also binds and transports many small molecules and proteins, maintains hypertonicity
Fibrinogen
Second most abundant protein - cleaved by the enzyme thrombin (in the coagulation cascade) to form cross-linked fibrin that forms the blood clot - prevents leakage; constitutes 7% of total blood protein
Immunoglobulin
(Ig) AKA antibody; found in the gamma fraction in serum electrophoresis), responsible for immunity; produced by plasma cells (a form of B lymphocyte); constitutes ~10% of total blood protein and becomes elevated in diseases such as multiple myeloma; provide us with a vast repertoire of different antigen-binding molecules which provide defence against everything
Complement proteins
A set of 9 plasma proteins that phagocyte and opsonise foreign organisms; innate immunity; most abundant protein is C3; essential for tagging/coating invading organisms so they can be digested
When they encounter bacteria with a surface different enough, it is activated
Coagulation factors
A set of 13 proteins cleaved in an ordered cascade that initiates the cleavage of fibrinogen into fibrin to form the clot; thrombin is the central enzyme that cleaves fibrinogen; Ca++ essential to coagulation
Haemoglobin
The major component of RBCs which carries oxygen from lungs to the heart to tissue; constitutes 96% of RBCs dry weight which makes up ~45% of the blood volume
Each molecule contains 4 haem molecules each containing 1 iron atom (in feris state); can carry 4 oxygen molecules each
Oxygen loaded, transported to the tissue where it dissociates (due to partial pressure of oxygen reducing), picks up a CO2 molecule and removes it
Missing coagulation component
Haemophilia’s result; factor VIII deficiency is the commonest form
Electrolytes
Salts and minerals that maintain isotonicity and buffering; free Ca++ and K+ also tightly maintained - crucial for the regulation of membrane channels, ion pumps and normal nerve and muscle function (such as the heart)
Deviation from any of the normal levels of ions will result in a significant illness
Oxygen transport conditions
Many molecules can displace O2 from Fe++
CO2 - venous blood
CO - carbon monoxide poisoning
CN - cyanide poisoning