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Cells > Cells 2- Blood and Blood Cells > Flashcards

Cells 2- Blood and Blood Cells Flashcards

(43 cards)

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1
Q

What are the major functions of blood

A 
Connective Tissue
Transport
Heat Distribution
Immunity
Haemostasis
Maintain Homeostasis
Blood Volume ( 5 litres Male, 3.5 litres Female)
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2
Q

What is Haemostasis

A

The physiological process through which the body reduces blood loss.

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3
Q

Examples of substances the blood delivers to cells

A

Products of digestion (fatty acids, amino acids, glucose)
Hormones
Vitamins
Oxygen

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4
Q

Examples of substances the blood removes from cells

A

Metabolic Waste ( Lactic acid, Urea)
C02
Heat
Water

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5
Q

Describe the roles of red blood cells

A

Respiratory transport:
O2 from the lungs to the body (oxyhaemoglobin)
C02 from body to lungs ( carbonic anhydrase)

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6
Q

How exactly is CO2 transported in the blood

A

C02 diffuses out of cells into plasma- where it combines with water to form carbonic acid. Carbonic Anhydrase catalyses the break down of carbonic acid into H+ and HC03-. HCO3- acts as a buffer, H+ combines with haemoglobin to form haemoglobinic acid. In the lungs- reverse process.

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7
Q

What are the adaptations of a red blood cell

A

Biconcave disk- maximum SA for haemoglobin and for a faster rate of diffusion
Flexible- hence can squeeze easily through capillaries
No nuclei or organelles- more space for haemoglobin
Antigens on the surface confer blood group.

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8
Q

Describe the regulation of erythrocyte production.

A

Kidney responds to low O2- stimulates the bone marrow stem cells to produce the hormone erythropoietin, which stimulates eryrhropoiesis ( the production of erythrocytes). This increase Blood Hb, and hence blood o2- creating a negative feedback loop.
Testosterone also causes this.

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9
Q

Describe the life cycle of an erythrocyte.

A

They are produced in the bone marrow form precursors which produce Hb and then lose their organelles. Immature erythrocytes contain ribosomes and these are known as reticulocytes. They have a short life span of around 120 days due to having no nuclei- hence they cannot synthesise proteins. Red blood cells are normally removed by the reticulo-endothelial system where they are ingested by phagocytic macrophages in the spleen.

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10
Q

What are high levels of reticulocytes diagnostic of

A

Anaemia or Chemotherapy- sign of an Iron deficiency.

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11
Q

Describe the basic structure of Hb

A

4 polypeptide chains- with a haem group ( ferrous iron Fe2+) bound to each chain.

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12
Q

Describe the role of Hb

A

Transports oxygen around the body. Each Fe2+ binds to one o2 molecule. Follows cooperative binding- initially the conformational shape of globin molecules makes it difficult for o2 to bind- however when one binds- it breaks the conformational shape- opening up the structure- increasing the affinity of Hb for o2. This allows more oxygen to be carried.

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13
Q

What is methaemoglobin

A

An oxidised from of Hb- Fe3+- hence cannot carry o2.

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14
Q

Describe the formation of oxyhaemoglobin

A

Hb + O2 — HbO2

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15
Q

Describe the interaction between CO and Hb

A

CO has a x200 greater affinity- reducing O2 binding- it is a reversible process.
CO + Hb — COHb- Carboxyhaemoglobin.

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16
Q

What is the haematocrit

A

Packed cell volume- volume of blood that contains cells.

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17
Q

How do we measure the haematocrit

A

Fill a tube with blood- centrifuge it.- layers will form.

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18
Q

What is MCH

19
Q

What is MCHC

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A

Mean cell Hb concentration

20
Q

What is MCV

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A

Mean Cell volume

21
Q

Define Anaemia

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A

Low blood Hb concentration.

22
Q

What is microcytic anaemia.

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A

Small MCV- due to failure of Hb synthesis- normally caused by and Iron deficiency, gradual loss of blood- menstruation. Also it can be caused by gastrointestinal lesions or cancers or by parasitic infections. Blood is not recycled by reticulo-endothelial system hence Hb synthesis is low.

23
Q

What does Normocytic mean.

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A

Normal MCV- Hb synthesis is fine- but acute blood loss lowers quantity of red blood cells- replaced by blood transfusion

24
Q

What is Macrocytic Anaemia

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A

Failure of DNA synthesis and cell division, as well as a reduced division of progenitor cells- hence we have fewer but larger erythrocytes- giving a large MCV. This can be due to pregnancy- folic acid deficiency ( required for thymine deficiency)- Vit B12 ( needed for the actions of folic acid) deficiency- autoimmune disease which destroys B12 uptake in gut, or pernicious anaemia- in vegans and vegetarians.

25
What are leukocytes
White Blood Cells Use Blood for transport Travel near capillary wall and invade tissue space to fight infection Classified by structure and dye binding.
26
What are the types of leukocytes
Polymorphonuclear granulocytes- multilobed nuclei, many granules, phagocytic, abundant: neutrophils, eosinophils ( allergy), basophils ( produce histamine). Lymphocytes- produces antibodies Monocytes- phagocytic
27
Describe polymorphonuclear granulocytes
Lobed nucleus- full of cytoplasmic granules- arrive first on scene- adhere to blood vessels in infected area and migrate to tissue- engulf, kill and digest microorganisms, release inflammatory mediators, toxic oxygen products, digestive enzymes, vasodilators, and chemotaxins- chemicals which attract other immune cells to propagate the immune response
28
Describe the B-lymphocytes
Mature in Bone Marrow- involved in humoral (antibody-mediated) immunity. Foreign antigen stimulates immunoglobulin ( antibody) production- IgM, IgG, IgA, iGd, IgE. Antigen-antibody reactions- agglutination, assist phagocytosis by agglutination, coat in antibody opsonisation- prevent attachment of microorganism to tissues- neutralisation. Involved in primary immune response- first exposure- antibodies appear after latency period- levels peak then fall. The secondary response is quicker, greater and longer due to memory cells.
29
What is passive immunity
An immune response where the antibodies are not made by the host organism- they have been transferred from one organism to another, i.e through the placenta.
30
Where and how do T lymphocytes develop
Produced in bone marrow, migrate to thymus where they are exposed to antigens and acquire surface antigenic molecules becoming immunologically competent.
31
Describe the role of T lymphocytes
They are involved in cellular immunity- no antibodies involved- circulate- bind to complementary foreign antigen- blast transformation- progeny (offspring) have receptors for antigen. These activated T-lymphocytes produce chemotaxins which attract macrophages- lymphotoxin- which kills cells and interferon which kills viruses.
32
Describe monocytes
Large, single horse-shoe nucleus.
33
Describe the role of monocytes
Appear after granulocytes, become macrophages in tissue, engulf microorganisms- tissue debris and dead polymorphs- they also secrete inflammatory mediators and stimulate angiogenesis- and so are involved in the repair process.
34
What is leukocytosis
Raised leukocyte count- due to infection or cancer.
35
What is leukopenia
Low leukocyte count- due to chemotherapy or HIV.
36
What are platelets derived from
Megakaryocytes in the bone marrow.
37
Describe the structure of platelets
2-3 micrometres in diameter, 8-10 day life span, granulated, many organelles but no nucleus.
38
Describe the role of platelets in haemostasis
Platelets express surface receptors for platelet activators- such as exposed collaged in damaged blood vessels- or thrombin from the coagulation cascade. This causes adhesion to exposed collagen- where the platelets then release granules which promote platelet aggregation. Cycloxygenase enzyme catalyses the breakdown of arachidonic acid into thromboxane A2- forming a clot or thrombus.
39
What does aspirin do
Inhibits cyclooxygenase and hence is anti-platelet.
40
How does the vascular endothelium regulate blood clotting
Produces prostacyclin and nitric oxide which inhibit platelet activation.
41
What is the plasma
The fluid component of blood which carries all the components of the blood.- organic and inorganic substances dissolved in water.
42
What is the function of plasma proteins
Exert osmotic pressure to maintain blood volume- albumin and globulins Carrier molecules such as hormones bile salts, water insoluble drugs Fibrinogen- clotting- platelet aggregation.
43
What is the serum
Plasma with the proteins removed due to clotting.

Cells (5 decks)

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