chapter 1 Flashcards
how much blood will a person with a body mass of 70kg usually have?
around 5.5 litres.
what is blood made up of in vertebrates? include percentages.
approximately:
- 53.3% plasma
- 45% erythrocytes (red blood cells)
- 0.7% leucocytes (white blood cells)
- 1% thrombocytes (platelets)
what is plasma made up of?
mostly water and proteins, glucose, mineral ions, hormones and carbon dioxide
give 8 functions of the blood:
- delivery of oxygen to tissues
- delivery of nutrients to tissues
- removal of waste from tissues
- immunological protection
- clotting
- transport of cell signalling molecules, for example, hormones
- acting as a buffer to regulate body pH (acidity)
- distribution of heat to regulate core body temperature
what is the technical term for red blood cells?
erythrocytes
what is the function of erythrocytes?
to deliver oxygen from the lungs to the body and carry carbon dioxide from the tissues to the lungs
where do erythrocytes develop, and how long do they circulate in the blood stream for?
they develop in the bone marrow and circulate in the blood stream for about 100-120 days
how big are erythrocytes? (give their approximate diameter and thickness)
they have a diameter of approximately 6.2-8.2 μm and are approximately 2-2.5 μm thick at their thickest point.
what is haemoglobin?
an iron-containing protein that can bind reversibly with oxygen to form oxyhaemoglobin.
give three properties of mature erythrocytes in humans, and explain what this enables them to do
- flexible
- oval biconcave disk
- lack a cell nucleus and most organelles
in erythrocytes, what does the lack of a cell nucleus and most organelles enable them to do?
- have a large surface area to volume ratio
- become biconcave - enabling them to be flexible and squeeze through the capillaries
how are new erythrocytes produced? What is the name of this process, how is it stimulated, and how long does it take?
new erythrocytes are produced in the bone marrow from erythropoietic stem cells. This process is called erythropoiesis and is stimulated by a hormone produced by the kidney called erythropoietin (EPO). Erythropoiesis takes approximately seven days.
what are immature erythrocytes (red blood cells) known as? Do they have a nucleus?
reticulocytes - as well as mature erythrocytes they do not have a nucleus.
can reticulocytes (immature red blood cells) be identified in a blood smear?
yes, when they are stained using methylene blue.
what is the technical term for platelets?
thrombocytes
how big are thrombocytes (platelets)? (give an approximate diameter)
thrombocytes are approximately 2-3 μm in diameter
describe the structure of thrombocytes (platelets)
they are biconvex (opposite to biconcave - sticking out not sticking in) disks of cytoplasm fragments surrounded by a cell surface membrane.
where are platelets produced?
in the bone marrow
do platelets have a nucleus?
no
how do thrombocytes (platelets) appear on a stained blood smear? (what do they look like)
they appear as dark purple spots
what is the main function of thrombocytes?
to contribute to blood clotting and clot formation.
how long do thrombocytes (platelets) live?
about 6-7 days
what is the technical term for white blood cells?
leucocytes
how many different types of leucocytes (white blood cells) are there?
at least 5
are erythrocytes or leucocytes bigger? Which is more abundant?
leucocytes are larger in size than erythrocytes, but they are less abundant
describe the two categories that leucocytes can be divided into
- granulocytes - granulocytes contain granules (usually lysosomes) in their cytoplasm, which all stain differently.
- agranulocytes - these either have an absence of granules in their cytoplasm, or the granules are too fine to see.
give an example of a granulocyte
neutrophils
give 3 examples of agranulocytes
lymphocytes, monocytes and macrophages
what do neutrophils do?
they help the body to defend against fungal or bacterial infections - they engulf and break down bacteria in a process known as phagocytosis.
which distinguishing feature of a neutrophil can be seen in a blood smear?
a multi-lobed nucleus
where are neutrophils present in large amounts?
in the pus of wounds.
what are neutrophils unable to do? What does this mean for them?
they are unable to renew their lysosomes and therefore die after breaking down a few pathogens (usually after about 5 days).
what do neutrophils have the ability to do? What makes this possible?
neutrophils have the ability to leave the capillaries by squeezing through the fenestrations in the capillary wall. This is made possible by having a lobed nucleus, which gives the neutrophil greater flexibility
what are lymphocytes characterised by?
their large, deeply stained nucleus which is surrounded by a relatively small amount of cytoplasm
which two groups can lymphocytes be categorised into?
B lymphocytes and T lymphocytes
what do B lymphocytes do?
produce immunoglobulins, also known as antibodies.
there are several different types of T lymphocyte. Give examples, and explain what they do
- helper T cells - produce cytokines and help co-ordinate the immune response
- cytotoxic T cells - bind to antigens on virus infected cells or tumour cells and destroy them
- natural killer cells
is there any way to distinguish B and T lymphocytes on blood smears? If so, how?
despite their different functions, both B and T cells look the same on blood smears
what is the largest kind of leucocyte?
monocytes
what do monocytes do?
like neutrophils, they carry out phagocytosis, but they live for much longer. Eventually, monocytes, which remove dead cell debris and attack microorganisms.
where are macrophages found?
in the lungs, lymph nodes, and liver
can monocytes replace their lysosomes?
unlike neutrophils, monocytes are able to replace their lysosomes
what shaped nucleus do monocytes have?
a kidney-bean shaped nucleus
what 7 things should you remember to do when making biological drawings?
- complete all drawings in pencil - a sharp 2H pencil will give the best lines but HB is also acceptable
- use a single, clear, continuous line (no ragged lines) - join up lines to form a continuous structure
- accurately record exactly what is observed - do not rely on memory
- add correct labels - these are just the names of structures that are visible. Label lines drawn with a ruler
- add annotations - details such as size and colour
- add the total magnification used for a reminder of how to calculate total magnification
- there must be no shading or colouring on any part of the drawing
