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The Red Blood Cell

 

Haemoglobin (Hb)

- A protein designed to carry oxygen from the lungs to the tissues

- Oxygen is given up to participate in respiration - process by which energy is obtained

- Range varies between gender

Women have lower levels that men

Menstruating women have lower levels

Men produce testosterone to stimulate red cell production

Men who lose their testes to disease/accident see their haemoglobin levels fall

 

Red Blood Cell Count (RBCC)

- Red blood cells carry haemoglobin in the blood

- Lack a nucleus - provides flexibility so they can penetrate the smallest capillaries

- Most abundant cell in the blood

- Often called erythrocytes

- RBCC can vary between genders

 

Haematocrit (Hct)

- Haematocrit index expresses that proportion (RBCC) as a percentage/decimal of whole blood, that is taken up by all the blood cells

- Approximately 1000 more red blood cells per unit volume than white blood cells, and 20 times as many platelets, the red cells make up the major proportion of the haematocrit

- Varies with age

 

Red Blood Cell Indices

- Mean cell volume (MCV)

Size of the average (mean) red cell

- Mean cell haemoglobin (MCH)

Reports the average amount (mass) of haemoglobin in the cell

- Mean cell haemoglobin concentration (MCHC)

Average concentration of haemoglobin inside the average size cell

Erythrocyte sedimentation rate (ESR)

- Result is obtained by allowing a thin column of blood to settle down under the influence of gravity

Red blood cells will separate from the plasma

Fall in the level of red cells is then recorded as mm/hour

- An increased ESR can be cause by many factors

○ Cancer

○ Infections

○ Anaemia

○ Inflammation

○ Renal failure

○ Rheumatoid arthritis

○ Multiple myeloma

○ Tuberculosis

- It is increased soon after myocardial infarction

- Heavily influenced by plasma proteins

- Normal range <20 mm/hour especially in elderly

 

Plasma Viscosity

- Index provides an idea of how thick or thin the plasma has become

○ Thinner and more water like - low result <1.5

○ Thicker more treacle like - high result >1.72

- Viscosity records a global property of plasma, not individual molecules

○ Molecules that make up the major component of viscosity include

Fibrinogen

Albumin

Some proteins involved in clotting

○ Also a relationship between plasma viscosity and total plasma protein concentration, and often with the haematocrit and amount of water

 

What are red cells for?

- To carry oxygen

- Needed in process of respiration

○ Where energy is obtained from molecules such as glucose and certain fatty acids

- Muscles require oxygen for energy needed to contract

○ If oxygen is insufficient there may be pain

Intestines - abdominal discomfort/cramps

Muscles of rib cage and diaphragm do not receive enough oxygen - breathing problems and shortness of breath

Insufficient oxygen to brain - forgetfulness, personality changes, symptoms of early Alzheimer's - general symptoms include tiredness and lethargy

○ Insufficient oxygen (HYPOXIA)

○ Can be impaired by diseases of the lung

COPD

Emphysema

Pneumonia

○ May also be cause by the heart not functioning correctly:

Valve disease

Cardiomyopathy

Heart failure (with an inadequate ejection fraction)

Left ventricular aneurysm

Consequences of MI

○ Blood passage around the body may be impaired by atherosclerosis

○ In the tissues movement of oxygen may be impaired by oedema and cellulitis

- If heart and lung function ok and no barrier to blood or oxygen moving into the cells and patient still complains of tiredness, lethargy and SOB - ANAEMIA

 

Anaemia

- A haemoglobin level of e.g. 115g/L - adequate for an elderly person with few physiological requirements and a relatively quiet life

○ A younger more active person this level would be inadequate

- Medical state should be considered

 

Signs and symptoms

Signs

- Pallor (conjunctiva)

- Tachycardia

- Glossitis (swollen and painful tongue)

- Koilonychia (spoon nails)

- Dark urine (sign of red cell destruction)

 

Symptoms

- Decreased work and/or exercise capacity

- Fatigue, lethargy

- Weakness

- Dizziness

- Palpitations

- Shortness of breath (especially on exertion

- Rarely - headaches, tinnitus, taste disturbance

 

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