Blood Transfusion Reasons | Blood Transfusion Side Effects and Symptoms

What is Blood Transfusion?
Blood transfusion is the process of transferring blood or blood components from one person (the donor) into the bloodstream of another person (the recipient). 
Blood transfusion procedure
Fig: Blood transfusion procedure
Indications of Blood Transfusion:
Major indications of blood transfusion have pointed out in the below:
  • Anemia, bleeding disorders (e.g. Hemophilia, thrombocytopenia),
  • Hemorrhage (blood loss is greater than 30% of blood volume),
  • Trauma,
  • Burns,
  • Surgery,
  • Cancer patients requiring therapy,
  • Women in childbirth and newborn babies in certain cases.
Hazards of Mismatched Blood Transfusion:
Hazards of mismatched blood transfusion mean reactions due to transfusion of incompatible blood.

The severity of Transfusion Reactions:
The severity of transfusion reactions maybe-
  • Mild: Fever and chills,
  • Severe: Acute renal failure, shock, and death.
Severity depends upon the amount of blood transfused, type of reaction and general health of the patient.

Sign and Symptoms of Mismatched Blood Transfusion Reactions:
All the sign and symptoms of mismatched blood transfusion reactions have presented in the below:

1. Non-hemolytic transfusion reaction:
It includes-
  • Fever,
  • Difficulty in breathing,
  • Itching.
2. Hemolytic transfusion reaction:
It includes immediate effects and delayed effects.

a. Immediate effects or hazards:
It includes-
  • Fever,
  • Chills,
  • Increased heart rate,
  • Low blood pressure,
  • Shortness of breath,
  • Bronchospasm,
  • Nausea,
  • Vomiting,
  • Red urine,
  • Chest pain.
  • Rigor,
  • Pulmonary oedema and congestive cardiac failure (may be developed in some patients).
b. Delayed effects or hazards:
It includes-
  • Haemolysis of red blood cells,
  • Jaundice,
  • Haemoglobinaemia,
  • Haemoglobinuria (hemoglobin in the urine),
  • Renal shutdown: Uremia, Anuria, and acute renal failure.
Hazards or Effects of Blood Transfusion:
Hazards or effects of blood transfusion are four types:

1. Reactions are due to a mismatched (incompatible) blood transfusion- transfusion reaction.


2. Reactions due to massive blood transfusion:
It includes-
  • Circulatory shock,
  • Hyperkalaemia,
  • Hypocalcemia leading to tetany (due to massive transfusion of citrated blood),
  • Haemosiderosis (increased deposition of iron in the form of haemosiderin).
3. Reactions due to faulty techniques during blood transfusion:
It includes-
  • Thrombophlebitis,
  • Air embolism.
4. Transmission of infections:
Blood transfusion without screening leads to the transmission of blood-borne infections as follows:
  • HIV (AIDS),
  • Syphilis,
  • Glandular fever,
  • Hepatitis B, C,
  • Malaria,
  • Herpes.
More questions related to this article:
  1. What is the definition of blood transfusion?
  2. Define blood transfusion.
  3. What are the hazards of mismatched blood transfusion?
  4. What are the indications of blood transfusion?
  5. Write down the hazards of blood transfusion.
  6. What are the effects of mismatched blood transfusion?
  7. What are the hazards of mismatched blood transfusion?
  8. What are the important hazards of blood transfusion?
  9. List down the key effects of blood transfusion.
  10. Mention the severity of transfusion reactions.
  11. What are the symptoms of a mismatched blood transfusion?
  12. What is mismatched transfusion?

Blood Pressure | Factors Maintaining Blood Pressure

What is Blood Pressure?
When your heart beats, it pumps blood around your body to give it the oxygen and energy it needs. It pushes against the sides of the blood vessels as the blood moves. The strength of this pushing is termed as your blood pressure. It puts extra strain on your arteries (and your heart) if your blood pressure is too high. Remember, this may lead to strokes and heart attacks.  There are some key factors that affect blood pressure.
Blood pressure measurement process
Fig: Blood pressure measurement process
Factors Controlling Blood Pressure:
There are some key factors which control or maintain blood pressure, those are listed in the below:

Central Factors:
It includes-
  • Cardiac output,
  • Heart rate.
Peripheral Factors:
It includes-
  • Peripheral resistance,
  • Blood volume,
  • Venous return,
  • The elasticity of blood vessels,
  • The viscosity of blood flow,
  • The diameter of blood vessels,
  • The viscosity of blood.
All the above factors have discussed in the following:

1. Cardiac Output:
Systolic pressure is directly proportional to cardiac output. This means when cardiac output increases, the systolic blood pressure is increased and when cardiac output is less, the systolic blood pressure is reduced.

2. Heart Rate:
Marked alteration in the heart rate affects the blood pressure by altering the cardiac output.

3. Peripheral Resistance:
Diastolic pressure is directly proportional to peripheral resistance. This means, when peripheral resistance increases, diastolic pressure increases and when peripheral resistance decreases diastolic pressure decreases.

4. Blood Volume:
Blood pressure is directly proportional to blood volume. If the blood volume increases, there is an increase in venous and cardiac output, resulting in elevation of blood pressure.

5. Venous Return:
Blood pressure is directly proportional to venous return. When venous return increases, there is an increase in ventricular filling and cardiac output, resulting in an elevation of arterial blood pressure.

6. The elasticity of Blood Vessels:

Blood pressure is inversely proportional to the elasticity of blood vessels. This means when the elasticity of blood vessels is reduced (as in atherosclerosis) blood pressure increases.

7. The velocity of Blood Flow:
Blood pressure is directly proportional to the velocity of blood flow within blood vessels. If the velocity of blood flow increases, the resistance is increased. So, blood pressure is increased.

8. The diameter of Blood Pressure:
Blood pressure is inversely proportional to the diameter of the blood vessel. If the diameter decreases, the peripheral resistance increases, leading to an increase in blood pressure.

9. The viscosity of Blood:
Blood pressure is directly proportional to the viscosity of blood. When the viscosity of blood increases, the functional resistance is increased and this increases blood pressure.

More questions related to this article:
  1. Define blood pressure.
  2. What is the definition of blood pressure?
  3. What do you mean by blood pressure?
  4. Name the factors controlling blood pressure.
  5. Describe the key factors in maintaining blood pressure.

Heart Structure | Blood Flow through the Heart Step by Step

Position of Heart:
The heart is situated in the middle mediastinum of the thoracic cavity. It is placed obliquely behind the sternum and adjoining parts of the costal cartilages. So, one-third of it lies to the right of the median plane and two-thirds to the left of the median plane. 
Human heart
Fig: Human heart
Shape and Measurement of heart:

Shape: pyramidal or conical,
Length: 12cm,
Width: 9cm.
Weight:
Adult males: 280-340gm,
Adult females: 230-280gm.

Order of Blood Flow Through the Heart:
Blood flow process through the heart has presented in the below:
  • Through the two largest veins of the body, the superior vena cava, and inferior vena cava, the right atrium receives deoxygenated blood from the whole body.
  • This blood flows from the right atrium into the right ventricle through the right atrioventricular orifice.
  • From the right ventricle, blood is pumped into the pulmonary trunk (pulmonary arteries).
  • Finally, the left and right pulmonary arteries carry the deoxygenated blood to the lungs where blood is oxygenated (exchanges of gases: Carbon dioxide is excreted and oxygen is absorbed).
  • Two pulmonary veins from each lung carry oxygenated blood back to the left atrium.
  • The blood from the left atrium flows into the left ventricle through the left atrioventricular orifice.
  • From the left ventricle, the blood is pumped into the ascending aorta and then into the systematic circulation.
(Note: from the sequences of events just described above it can be seen that the blood passes from the right to the left side of the heart via the lungs or pulmonary circulation).

Blood Supply of the Heart:
It is discussed in the following:

Arterial Supply:

The heart is supplied with arterial blood by the two coronary arteries (right and left) which arise from the ascending aorta immediately above the aortic valve. The right and left coronary arteries from a vast network of arteries and capillaries throughout the heart.

Blood Drainage:
Most of the venous blood is collected into several small veins that join to form the coronary sinus, which opens into the right atrium.

More questions related to this article:

  1. What is the position of the heart?
  2. What is the size of the heart?
  3. What is the weight of the heart?
  4. What is the shape of the heart?
  5. What is the flow of blood through the heart in order?
  6. How does a heart work step by step?
  7. How does blood flow through the 4 chambers of the heart?
  8. How does the blood flow through the heart step by step?

Blood Pressure | Factors that Affect Blood Pressure

What is Blood Pressure?
It is known as the measurement of pressure or force of blood against the blood vessels. Generally, blood pressure is written as two numbers. The first number or top number indicates the systolic pressure and the second number indicates the diastolic pressure. The ideal or normal blood pressure for non-pregnant people with diabetes is 130/80mmHg or lower. You may follow this to know how to measure blood pressure?
Blood pressure measurement methods
Fig: Blood pressure measurement methods
Physiological Factors Affecting Blood Pressure:
There are some physiological factors which are pointed out in the below:
  1. Age,
  2. Sex,
  3. Body built,
  4. Meal,
  5. Sleep,
  6. Diurnal variation,
  7. Emotional condition,
  8. After exercise.
All the above physiological; factors have explained in the following:

1. Age:
Arterial blood pressure increases as age advances.

Systolic pressure in different age:
  • Newborn- 70mmHg
  • After 1 month- 85mmHg
  • After 6 month- 90mmHg
  • After 1 year- 95mmHg
  • At puberty- 120mmHg
  • At 50 years- 140mmHg
  • At 70 years- 160mmHg
Diastolic Pressure in different age:
  • Newborn- 40mmHg
  • After 1 month- 45mmHg
  • After 6 month- 50mmHg
  • After 1 year- 55mmHg
  • At puberty- 80mmHg
  • At 50 years- 85mmHg
  • At 70 years- 90mmHg
  • At 80 years- 95mmHg
2. Sex:
In females, up to the period of menopause, blood pressure is 5mmHg less than in males of the same age. After menopause, the pressure in females becomes equal to that in males of the same age.

3. Body Built:
In the case of obese persons, the pressure is more than in lean persons.

4. After Meals:
Blood pressure increase for a few hours after meals due to an increase in cardiac output.

5. Sleep:
During deep sleep, there is a fall in blood pressure by 15-20mmHg.

6. Diurnal Variation:
Normally blood pressure is slightly low in the early morning. It slowly increases and reaches the maximum level at noon. It becomes low in the evening.

7. Emotional Conditions:
During excitement or anxiety, blood pressure is increased due to the release of adrenaline.

8. After Exercise:
Systolic pressure increases by 20-30mmHg after moderate exercise. Normally diastolic pressure is not affected in moderate exercise. After severe exercise, systolic pressure rises by 40-50mmHg above the normal level. But, the diastolic pressure decreases in severe exercise.

Regulation of Blood Pressure:
The body has four regulatory mechanisms to maintain blood pressure within normal limits:
  • Nervous mechanism or short term regulatory mechanism,
  • Renal mechanism or long term regulatory mechanism,
  • Hormonal mechanism,
  • Local mechanism.
Hormones Involved in Regulation of Blood Pressure:
Some hormones regulate blood pressure are pointed out in the below:

Hormones which increase blood pressure:
It includes-
  • Adrenaline,
  • Noradrenaline,
  • Thyroxin,
  • Aldosterone,
  • Vasopressin (ADH),
  • Angiotensin,
  • Serotonin.
Hormones which decrease blood pressure:
It includes-
  • Bradykinin,
  • Vasoactive intestinal polypeptide (VIP),
  • C-type natriuretic peptide,
  • Atrial natriuretic peptide,
  • Prostaglandin,
  • Brain natriuretic peptide,
  • Histamine,
  • Acetylcholine.
More questions related to this article:
  1. Define blood pressure.
  2. What do you mean by blood pressure?
  3. What are the psychological factors affecting blood pressure?
  4. Name the hormones that regulate blood pressure.
  5. Mention the factors which affect blood pressure.
  6. Write a short note on blood pressure.

Different Heart Chambers and Valves

Chambers of the Heart:
The heart has four chambers. Those are listed in the below:
  1. Right atrium,
  2. Right ventricle,
  3. Left atrium,
  4. Left ventricle.
The two atria are separated from each other by a vertical septum is called interventricular septum. The right atrium communicates with the right ventricle through the right atrioventricular orifice, which is guarded by three cusps. The left atrium communicates with the left ventricle through the atrioventricular orifice, which is guarded by two cusps. 
Human heart chamber and valves
Fig: Human heart chamber and valves
1. Right Atrium:
The right atrium is the right upper chamber of the heart. It receives venous blood from the whole body through three veins:

Superior vena cava and inferior vena cava: Together these veins deliver blood from the body to the heart.

Coronary sinus, that returns blood from the walls of the heart itself.

The right atrium pumps blood to the right ventricle through the right atrioventricular or tricuspid opening.

Internal Features of Right Atrium:
All the internal features of the right atrium have presented in the below:
  • The interior of the right atrium is divided into two continuous spaces: smooth-walled posterior part and rough-walled anterior part. Internally, this division is marked by the crista terminals, which is a smooth, muscular ridge. It corresponds to sulcus terminals externally.
  • The rough anterior part presents musculi pectinati, which fan out from the crista terminals like the: teeth of the comb”.
  • The interatrial septum that separates the right atrium from the left atrium, presents fossa ovalis. It is a depression just above the orifice of the inferior vena cava.
2. Right Ventricle:
The right ventricle is a triangular chamber that receives blood from the right atrium and pumps it to the lungs through the pulmonary trunk and pulmonary arteries.

Internal Features of Right Ventricle:
It includes-
  • The outflow tract of the right ventricle that leads to the pulmonary trunk is the conus arteriosus (Infundibulum). This area is smooth.
  • Trabeculae carnae are irregular muscular ridges.
  • Papillary muscles. The three papillary muscles are lying among the trabeculae carnae. These are- anterior, posterior and septal.
3. Left Atrium:
The left atrium is a quadrangular chamber which is situated posteriorly. It receives oxygenated blood from the lungs through four pulmonary veins and pumps it to the left ventricle through the left atrioventricular orifice (mitral orifice).

4. Left Ventricle:
The left ventricle is a conical chamber. It is longer than the right ventricle and has the thickest layer of the myocardium.

Internal Features of Left Ventricle:
It includes-
  • Trabeculae carnae,
  • Two papillary muscles- Anterior and posterior,
  • Two orifices- left atrioventricular or mitral orifice and aortic orifice.
Valves of the Heart:
The valves of the heart include-

1. Atrioventricular valves: Right atriventricular valve (tricuspid valve) and left atriventricular valve (Bicuspid or mitral valve),

2. Semilunar valves: Aortic valve and pulmonary valve.

There are 4 (2 pairs) valves in the heart:
  • A pair of atrioventricular valves- In between atria and ventricles.
  • A pair of semilunar valves- At the opening of blood vessels arising from the ventricles, namely aorta and pulmonary artery.

How to Measure Blood Pressure? | Blood Pressure Measurement

What is Blood Pressure?
It is the pressure of circulating blood on the walls of blood vessels. Most of the pressure is due to work done by the heart by pumping blood through the circulatory system. Blood pressure generally refers to the pressure in large arteries of the systemic circulation. It is expressed in terms of the systolic pressure over diastolic pressure. It is measured in millimeters of mercury (mmHg). 
Blood pressure measurement procedure
Fig: Blood pressure measurement procedure
How to Take Blood Pressure Step by Step:
Blood pressure measurement method has discussed in the following:

Requirements:
To measure blood pressure the following instruments have to require-
  • Sphygmomanometer,
  • Stethoscope.
Method of Measuring Blood Pressure:
All the process of blood pressure measurement have explained in the below in step by step-
  • The subject should be physically and mentally relaxed, free from excitement.
  • The subject should lie down or sit comfortably. If he sites, he should place the arm on a table at the level of the heart.
  • The “zero” of the sphygmomanometer and the cuff should be at the level of the heart.
  • The arm is exposed up to the shoulder.
  • The cuff is wrapped around the upper arm just above the elbow (Middle of the cuff lies over the brachial artery).
  • The brachial artery is palpated in the cubital fossa, just medial to the tendon of the biceps brachii muscle, a little below the cuff.
  • The radial artery is palpated at the wrist by placing the middle three fingers over it.
  • The cuff is rapidly inflated by the hand pump, raising the pressure 30mmHg above the level at which the radial pulsation disappears.
  • The diaphragm of the stethoscope is placed lightly on the brachial artery and then the pressure in the cuff is gradually lowered using the release valve, keeping the earpieces of the stethoscope in the ears.
  • As the pressure is lowered slowly (2mm/sec), at a particular level in the mercury column, a tapping sound is heard. The level at which the sound is first heard is regarded as the systolic pressure.
  • The pressure in the cuff is further reduced gradually and the character of the sound changes; and finally, at a particular level the sound disappears. The level at which the sound disappears is regarded as the diastolic pressure.
  • The cuff is deflated and the procedure is repeated three times.
Observation:

Reading No.
Systole (mmHg)
Mean Systole (mmHg)
Diastole (mmHg)
Mean Diastole (mmHg)
1
115
120
80
80
2
120
80
3
125
80

Result:
Systolic blood pressure: 120mmHg,
Diastolic blood pressure: 80mmHg,
Age of the person: 24 years.

Comment:
The blood pressure of the person is within the normal physiological limit.

Precautions:
It includes-
  • The subject should be mentally and physically relaxed.
  • The size of the cuff should be proportionate to the circumference of the arm of the subject.
  • The arm, with the cuff wrapped around it, should be at the level of the heart to avoid the influence of gravity.
  • The zero levels of the mercury should be checked.
  • The cuff should not be left inflated for excess time, because the discomfort may cause generalized vasoconstriction that results in higher blood pressure.
  • The pulse rate should be checked at the same time because blood pressure is affected to some extent by the heart rate.
  • The cuff pressure should be decreased to the zero levels between the successive measurements of blood pressure.
  • While taking the reading, the eye should be at the level of the mercury column to avoid parallax.
  • If coarctation of the aorta is suspected, blood pressure should also be recorded in the thigh.

Blood Group List | Importance of Blood Group | Basis of Blood Group

What is Blood Group?
Based on the presence or absence of various antigens, blood is categorized into different groups known as blood groups. 
Blood group list
Fig: Blood group list
Before transfusion of blood to a person, it is necessary to determine the the blood type of the recipients’ blood and the blood type of the donor so that the blood can be appropriately matched. This is known as blood groups.


Different Types of Blood Group:
Classical or principal blood groups are listed in the below:

ABO Blood Groups:
It includes-
  • A,
  • B,
  • AB,
  • O.
Rh Blood Groups:
It includes-
  • Rh +ve,
  • Rh –ve.
Basis of Blood Groups:
Blood groups are determined by the presence or absence of genetically determined antigens or agglutinogens on the surface of RBCs.

A, B, and Rh are the most clinically significant blood antigens present in the RBC membrane.
  • Type A blood has A antigen on the surface of RBCs.
  • Type B blood has B antigen.
  • Type AB blood has both A and b antigens.
  • Type o blood has neither A nor B antigen.
  • Blood with Rh antigen is Rh (+) positive.
  • Blood without Rh antigen is RH (-) negative.
ABO System of Blood Grouping: Antigens, Antibodies, and Compatibility:

Blood Group
Antigen+ antibody (ies) present
As donor, is
As the recipient, is
A
Antigen A makes Antigen B
Compatible with: A and AB
Incompatible with: B and O, because both make antigen-A antibodies that will react with A antigens.
Compatible with: A and O
Incompatible with: B and AB, because type A makes antigen-B antibodies that will react with B antigens.
B
Antigen B makes Antigen A
Compatible with: B and AB
Incompatible with: A and O, because both make antigen B antibodies that will react with B antigens.
Compatible with: B and O
Incompatible with: A and AB, because types b makes antigen- A antibodies that will react with A antigens.
AB
Antigen A and B makes neither Antigen A nor Antigen B
Compatible with: AB only
Incompatible with: A, B and O, because all three make antibodies that will react with AB antigens.
Compatible with all groups “Universal Recipient”
AB makes no antibodies and therefore will not react with any type of donated blood.
O
Neither A nor B antigen makes both Antigen A and Antigen B
Compatible with all groups “Universal Donor”,
O red cells have no antigens and will therefore not stimulate antigen A or antigen B antibodies.
Compatible with: O only
Incompatible with: A, AB and b, because type O makes antigen A and antigen B antibodies.

Importance of Blood Group:
All the key importance of knowing blood group are-
  • To know the blood group of individuals,
  • Blood transfusion and tissue transplants,
  • Certain blood disease,
  • Paternity test and other medico-legal cases.

External Features of Heart | Heart Surface Anatomy

What is Heart?
The heart is a rough cone-shaped hollow muscular organ situated in the middle mediastinum of the thoracic cavity that pumps blood to the body. 
Human heart features
Fig: Human heart features
External Features of Heart:
The heart presents the below external features:
  • Apex,
  • Base,
  • Three surfaces: Stern costal, diaphragmatic and left.
  • Three borders: Right, left and inferior.
The Apex of the Heart:
It includes-
  • It is a conical area formed by the left ventricle.
  • It is directed, forward and to the left in the 5th intercostal space.
  • Location: It lies in the 5th intercostal space, about 9cm from the midline and slightly below and medial to the left nipple.
The Base of the Heart:
It includes-
  • The base (or posterior surface) of the heart is the most fixed part of the heart.
  • It is formed by two atria: Two-thirds by the left atrium and one-third by right atrium.
  • The great veins enter the base of the heart- four pulmonary veins enter the left atrium, and superior and inferior venae cavae enter the right atrium.
The Surface of the Heart:
The surface of the heart has explained in the below:

1. Sternocostal (or anterior) Surface:
It includes-
  • It is formed mainly by the right atrium and right ventricle which are separated from each other by the anterior part of the atrioventricular groove.
  • It is also partly formed by the left auricle and left ventricle.
2. Diaphragmatic (or inferior) surface:
It includes-
  • This surface is flat and faces downward and backward.
  • It is formed by the left ventricle (two-thirds) and right ventricle (one-third) which are separated from each other by the posterior interventricular groove.
3. Left Surface:
It includes-
  • It is directed upward, backward and to the left.
  • It is formed mainly by the left ventricle and partly by the left atrium and left auricle.
Borders of the Heart:
Borders of the heart have explained in the following:

1. Right Border:
It includes-
  • Rounded and convex, formed only by the right atrium.
  • It extends from the right side of the opening of superior vena cava to that of inferior vena cava.
  • The right border separates the base from the stern coastal surface.
2. Left Border:
It includes-
  • It is formed mainly by the left ventricle and partly by the left auricle.
  • It extends from the left auricle to the apex of the heart.
  • It separates the stern coastal surface from the left surface.
3. Inferior Border:
It includes-
  • It is nearly horizontal and extends from the opening of the inferior vena cava to the apex of the heart.
  • It separates the stern coastal surface from the diaphragmatic surface.

Blood Pressure Types | Hormones and Blood Pressure Relation

Blood Pressure Definition:
Blood pressure is defined as the lateral pressure exerted by the column of blood on the wall of the arteries while blood flows through it. Normally, Blood Pressure refers to arterial blood pressure.

What Is Normal Blood Pressure?
Blood pressure is usually expressed with the systolic pressure written above the diastolic pressure as follows-

Blood pressure (BP) = 120/80mmHg (Systole/Diastole). 
Blood pressure measurement
Fig: Blood pressure measurement
Different Types of Blood Pressure:
There are various types of blood pressure which are listed in the below:
  1. Systolic blood pressure,
  2. Diastolic blood pressure,
  3. Pulse pressure,
  4. Mean arterial blood pressure.
All the above blood pressure types have discussed in the following:

1. Systolic Blood Pressure (Systolic Pressure):
It is the maximum pressure by the blood on the arterial wall during the systole of the heart.

Normal systolic pressure: 120mmHg (Range: 110-140mmHg).

2. Diastolic Blood Pressure (Diastolic Pressure):
It is the minimum pressure exerted on the arterial wall during diastole of the heart.

Normal diastolic pressure: 80mmHg (Range: 60-80mmHg).


3. Pulse Pressure:

It is the difference between the systolic pressure and diastolic pressure.

Normal pulse pressure: 40mmHg (Range: 30-40mmHg).

4. Mean Arterial Blood Pressure (Mean Pressure):
This type of blood pressure is the average pressure existing in the arteries. Mean arterial blood pressure is the diastolic pressure plus one-third of pulse pressure.

Normal mean pressure: 93mmHg (80+13=93)

Hormones Involved in Regulation of Blood Pressure:
Those hormones which regulate blood pressure have listed in the following:

Hormones which increase blood pressure:
It includes-
  • Noradrenaline,
  • Vasopressin (ADH),
  • Serotonin
  • Adrenaline,
  • Angiotensin,
  • Aldosterone,
  • Thyroxin.
Hormones which decrease blood pressure:
It includes-
  • A vasoactive intestinal polypeptide (VIP),
  • Bradykinin,
  • Prostaglandin,
  • Histamine,
  • Acetylcholine,
  • The atrial natriuretic peptide,
  • Brain natriuretic peptide,
  • C-type natriuretic peptide.
Importance of Blood Pressure:
There are some key importance’s of blood pressure which are pointed out in the below:
  1. Blood pressure is essential for the flow of blood through blood vessels.
  2. This type of blood pressure provides the motive force for filtration at the capillary bed which is necessary for-
  • Tissue nutrition,
  • Formation of lymph,
  • Formation of urine,
  • Venous return.
More questions related to this article:
  1. What is meant by blood pressure?
  2. What is the definition of blood pressure?
  3. What is normal blood pressure?
  4. Define the term “Blood Pressure”.
  5. Mention the names of hormones that regulate blood pressure.
  6. Name the different types of blood pressure with their normal values.
  7. What are the types of blood pressure?
  8. Mention the classification of blood pressure.

Functions of Blood | Composition of Blood | Properties of Blood

What is Blood?
Blood is a specialized fluid connective tissue. It is composed of cells which are called formed elements and the liquid portion known as plasma. 
Blood cells
Fig: Blood cells
Characteristics of Blood:
There are some key characteristics of blood which are listed in the below:
  • Color: Red (Due to hemoglobin).
  • Volume: The average volume of blood in a normal adult is 5L.
  • pH: 7.4
  • Specific gravity: of total blood is 1.052 to 1.061
  • Viscosity: Blood is generally 5 times more viscous than water. 
Main Functions of Blood:
Blood performs several functions as follows-

1. Transportation or Distribution:
It includes-
  • Transport of oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs.
  • Transport of nutrients absorbed by the digestive tract to all the body cells.
  • Transport of metabolic waste products to the kidneys, lung, skin, and intestines for removal.
  • Transport of hormones from the endocrine glands to their target organs and tissues.
  • Transport of enzymes.
2. Regulation:
It includes-
  • Maintenance of normal pH (acid-base balance) in the body tissues.
  • Maintenance of appropriate body temperature.
  • Maintenance of body fluid or water content of the body.
  • Regulation of blood pressure.
  • Regulation of colloidal osmotic pressure.

3. Protection:

It includes-
  • Prevention of infection by the WBC and circulating antibodies.
  • Prevention of blood loss by initiating coagulation when blood is damaged.
Components of Blood or Plasma:
Compositions of blood or plasma have presented in the below:

Whole blood consists of formed elements (45%) and plasma (55%).


1. Formed Elements (45%):

It includes-
  • Red blood cells (RBC) or Erythrocytes,
  • White blood cells (WBC) or leukocytes,
  • Platelets.
White Blood Cells (WBC) or Leukocytes:
It includes-
  • Neutrophils (60-70%),
  • Eosinophil (2-4%),
  • Basophils (0-15%),
  • Lymphocytes (20-25%),
  • Monocytes (3-8%).
2. Plasma (55%):
It includes-
  • Solids (10%): Organic electrolytes and inorganic electrolytes.
  • Water (90%),
  • Gases: Oxygen, carbon dioxide and nitrogen.
Organic Electrolytes:
It includes-
  • Proteins: Albumin, globulin and fibrinogen.
  • Nutrients: Glucose, amino acids, fatty acids, glycerol, triglycerides, cholesterol, and vitamins.
  • Non-protein Nitrogenous Substances: Urea, uric acid, creatine, creatinine, ammonium, and xanthine.
  • Others: Metabolic enzymes, antibodies, complement, and hormones.
Inorganic Electrolytes:
It includes-
  • Cations: Na+, k+, ca++, Mg++,
  • Anions: Cl-.
More questions related to this article:
  1. What do you mean by blood?
  2. Define blood.
  3. What are the characteristics of blood?
  4. Mention the key properties of blood.
  5. What are the functions of blood?
  6. Discuss all the functions of blood.
  7. What are the compositions of blood?
  8. Write down the compositions of blood.
  9. Write a short note on blood.

Definition and Structure of Cell Membrane

What is Cell Membrane?
The cell membrane, also known as the plasma membrane, is a thin, flexible and double layer of lipid and proteins that surrounds the cytoplasm of cell. The basic function of cell membrane is to separate cytoplasm (the contents of the cell) from its surrounding environment. It is semipermeable membrane surrounding the cytoplasm of a cell. 
Cell membrane
Fig: Cell membrane
Major Components of the Cell Membrane:
The principal components of the plasma membrane are lipids (phospholipids and cholesterol), proteins (integral protein and peripheral protein), and carbohydrate groups that make a semipermeable barrier surrounding the cell.
  • Protein: 55%,
  • Lipid: 42%,
  • Phospholipid: 25%,
  • Cholesterol: 13%,
  • Other lipids: 4%,
  • Carbohydrates: 3%.
All the above compositions of cell membrane have discussed in the following:

1. Phospholipid:
Phospholipids are mainly built up the basic structure of a cell membrane. The phospholipids of a cell membrane are organized in a double layer called the lipid bilayer. The lipid bilayer is semi-permeable (controls what gets in and out), allowing only certain ions and organic molecules to diffuse across the membrane. Watery fluids are found both inside a cell (intracellular fluid) and outside a cell (extracellular fluid), cell membrane keeps the balance between those watery fluids. The plasma membranes save the intracellular components from the extracellular environment.

A single phospholipid molecule has two different ends:
  • Head ( hydrophilic),
  • Tail (hydrophobic).
2. Hydrophilic:
The head end contains a phosphate group and is hydrophilic. The hydrophilic or water-loving areas of these molecules are always contacted with the aqueous fluid both inside and outside the cell. Its head (the phosphate-containing group) has a polar character or negative charge and it tends to form hydrogen bonds with water and other polar molecules on both the exterior and interior of the cell. This means that it likes or is attracted to water molecules.

3. Hydrophobic:
The tail end is made up of two strings of hydrogen and carbon atoms called fatty acid chains. These chains are hydrophobic or do not like to mingle with water molecules. The hydrophobic tail has no charge (non-polar character) and they interact with other non-polar molecules in chemical reactions. The hydrophobic tails of membrane phospholipids are arranged in a manner that keeps them away from water.

4. Proteins:
Proteins are the second key element of plasma membranes. The cell membrane contains two types of associated proteins such as-

Peripheral protein (Peripheral membrane proteins are exterior to and connected to the surfaces of the lipid bilayer).

Integral protein (Integral membrane proteins are inserted into the membrane and most passes through the membrane. Portions of these transmembrane or integral proteins are exposed on both sides of the membrane).

5. Carbohydrates:
Carbohydrates are the third key element of plasma membranes. In general, they are always found on the exterior surface of cells and are bound either to proteins (forming glycoproteins) or to lipids (forming glycolipids). Along with peripheral proteins, carbohydrates make a specialized site on the cell surface that allows cells to recognize each other. This recognition function is very important to cells, that help the immune system to differentiate between body cells (called “self”) and foreign cells or tissues (called “non-self”).

Functions of Lysosome | Lysosomal Enzymes and Their Functions

What is Lysosomes?
Lysosomes are small sac-like structures surrounded by a single membrane and containing strong digestive enzymes that can break down food and engulfed viruses or bacteria. Lysosomes are membrane-bound organelles found within cells. Lysosomes are also known as a suicide sac in the cell.
Lysosomes
Fig: Lysosomes
Shape and Size of Lysosomes:
Lysosomes are like the stomach of the cell and they digest waste and superfluous cell fragments. Lysosomes are usually a small sac-like spherical structure. It measures about 0.5-1.0 ┬Ám in diameter.

Number of Lysosomes:
Number of lysosome present in a cell- 

Range → 50 to 1,000 Lysosomes/cell
There are 50 to 1,000 lysosomes per mammalian cell, but a single large lysosome called the vacuole in fungi and plants.

Different Lysosomal Enzymes and Their Functions:
Lysosomes contain so many digestive enzymes and they digest nutrient molecules. They contain about 45 enzymes that are grouped into six main categories:

1. Nucleases:
Nucleases are important enzymes that hydrolyze nucleic acids.

2. Proteases:
Proteases include enzymes like collagenase and peptidases that convert protein into amino acid.

3. Glycosidases:
Glycosidases convert polysaccharides into monosaccharides. For instance, they convert lactose into glucose and galactose.

4. Phosphatases:
Phosphatases are enzymes that act on organic phosphate compounds to release phosphate.

5. Lipase:
Lipases that act on lipids to produce acids and alcohol.

6. Sulphatases:
Sulphatases are enzymes that act on organic compounds to release sulfates.

Main Functions of Lysosome:
All the functions of lysosome have pointed out in the following:
  • The main function of lysosomes is to help with cell metabolism by ingesting and dissolving unwanted parts of the cell, cell debris or foreign substances that have entered the cell.
  • Acts as autophagic vesicles of the cell.
  • Acts as scavengers of the cell.
  • The digestive enzymes of their acidic interior break down large structures and molecules into simple components, and they then return the products to the cell for further use or disposal.
  • Lysosomal enzymes are synthesized by Endoplasmic Reticulum (ER).
  • The enzymes are passed on to the Golgi apparatus where the lysosomes are produced.
  • Lysosomes use the acid hydrolases from the endoplasmic reticulum to digest complex proteins and organelles that are no longer needed.
  • The lysosomes essentially act as the cell's digestive system.