CV Flashcards
What is a Haematocrit
The volume of blood cells in blood, it is also referred to as the packed cell volume, so the normal haematocrit is 0.45
Give a composition of blood with a percentage of its components
Fluid plasma - 55%
Cells - 45% (erythrocytes 44%, white blood cells and platelets 1%)
What causes the red bloods to become bi-concave discs
The loss of the cell nucleus causes the red blood cells to become bi-concave discs
In human, how many red blood cells are there
4 to 6 million erythrocytes per ml of blood
Give the diameter of a red blood cell
7 to 7.5 micrometers (um)
What is a reticulocytes and how much of the circulating red blood cell population does it make up
Reticulocytes are immature red blood cells and make up less than 1% of circulating red blood cells, they usually might have visible ribosomes still in them
Categorise the white blood cells into two groups, describing each type
Granulocytes
Neutrophil (ploymorphonuclear leukocytes) 40 - 75% = most numerous, phagocytotic and multilobar (number of lobes increases with age), can survive in hostile environments like low oxygen, contains myeloperoxidase because they use respiratory burst
Eosinophil (acidophilic leukocytes) about 5% = bi-lobar or tri-lobar with dark pink granules (losenge-shaped with crystalline cores- Charcot-leyden crystals), highest in the morning and numbers change, can phagocytose and associated with parasites, neutralise action of histamine, has receptors for IgE
Basophils (basophilic leukocytes) about 0.5% = contain large blue granules, similar role to mast cells, secretes histamine and vasoactive substances that increase blood flow to the local area, very rare, involved in anaphalactic shock
Agranulocytes
Lymphocytes (T and B) 20-50% = it is not possible to differentiate between T and B lymphocytes by just using a stain but immunohistochemistry can differentiate them
Monocytes 1-5% = kidney shaped (reniform) nucleus, differentiate into tissue macrophages
Give the 3 types of granules within a neutrophil and what they do
Type 1 - lysosomes involved in digestion of phagocytosed material e.g myeloperoxidase and acid hydrolases, most numerous (not unique to neutrophils)
Type 2- secretions from neutrophil involved in inflammatory response (unique to neutrophils)
Type 3 - contains enzymes (gelatinases and adhension molecules) which when secreted by the cell facilitate the insertion of proteins into the membrane of cell surface, this allows the neutrophils to squeeze between cells
What do the four types of platelet granules contain and what are their functions
Alpha granules = contain clotting factors
Delta granules = contains serotonin which is absorbed into them after discharge of clotting factors
Peroxisomes = contains catalase, an enzyme used to eliminate oxygen radicals
What is plasma
Plasma is blood without all the cells, it includes
Water
Salt and minerals
Plasma proteins (albumins, globulins, fibrinogen)
Hormones, signal molecules and other clotting factors
Makes up about 55% of blood
What is serum
Serum is plasma without clotting factors
Where are blood cells produced and destroyed
They are produced in the liver (in a foetus) and in the bone marrow (in adults)
They are destroyed in the liver and the spleen
Give the role of spectrin in red blood cells
Spectrin is an important protein in the endoskeleton of red blood cells
Give the different types of B and T lymphocytes and what they do
B cells - produce antibodies
T Helper (TH) cells - help B cells and activate macrophages
T Cytotoxic (TC) cells - kill previously marked target cells
T Suppressor (TS) cell - suppress TH cells and hence suppress the immune response
Natural Killer (NK) cells - mainly kill virus infected cells
Give the different cells that monocytes differentiate into
Tissue macrophages - everywhere Antigen presenting cells - everywhere Kupffer cells - liver Osteoclasts - bone Alveolar macrophages - lung
What is the progenitor cell for platelets
Megakaryocyte
What is hematopoiesis and where are all blood cells derived from
Hematopoiesis is the formation of the blood cells
All blood cells are derived from a pluripotent (multipotential) hematopoietic stem cell ( a hemacytoblast)
The haemacytoblast gives rise to common myeloid progenitor cells and he common lymphoid progenitor cells
Cardiac and voluntary (skeletal) muscle appear similar in many respects but (a) how do they differ structurally? (b) how do they differ physiologically? Try to think of 3 differences in each category
Structually
- interclated discs in cardiac muscle only
- single nucleus in cardiac muscle instead of syntitium of skeletal muscle
- central nucleus
Physiologically
- cardiac muscles are myogenic so dont need nerves
- secrete atrial natiuretic peptide hormone (NPH)
What does atrial natriuretic peptide do?
Atrial natriuretic peptide hormone is secreted by the atrium, it is released when cells are excessively stretched
It inhibits renin secretion
It increases the excretion of sodium, water and potassium in the kidneys
Which are smaller myocytes in the atrium or the ventricle
Myocytes in the atrium are smaller because of less resistance and workload
What are contained in the electron dense granules and alpha granules of platelets
Electron dense granules
- ADP
- Serotinin
- Calcium ions
Alpha granules
- platelets derived growth factor (PDGF)
- heparin antagonist factor (PF4)
- Von willebrand factor (vWF)
- Fibrinogen
Where are the sino atrial node and atrioventricular node located
The sino atrial node is located on the medial side of the superior vena cava at its junction with the right atrium
The atrioventricular node is located at the base of the inter-atrial septum, anterior to the opening of the cardiac sinus
Where are the purkinje fibres found and give some characteristics they have
They are found under the endocardium in the interventricular septum
They have large vacuoles an large stores of glycogen so stain magenta with a PAS stain
There is a delay between the contraction of the atria and the ventricles. What physical features cause this delay?
Rings of fibrous tissue between the atrium and ventricle prevent direct passage of an electrical signal so signal has to go through only the AV node which delays the signal slightly