Unit: 5 Physiological Structure And Life Processes

Summary: Physiological Structure and Life Process

1. Choose the correct option for the following questions:

2. Write differences:

(a) Red blood cell (RBC) and White blood cell (WBC)

Feature	Red Blood Cell (Erythrocytes)	White Blood Cell (Leucocytes)
Nucleus	Mature mammalian RBCs do not have a nucleus.	WBCs always possess a nucleus.
Haemoglobin	They contain the red pigment haemoglobin.	They do not contain haemoglobin (colourless).
Shape	They are biconcave and disc-shaped.	They are irregular or amoeboid in shape.
Function	Main function is to transport Oxygen and Carbon dioxide.	Main function is to fight against infection and provide immunity.
Number	They are much more numerous ($4.5 – 5$ million/$mm^3$).	They are fewer in number ($4000 – 11000$/$mm^3$).

(b) Auricle and Ventricle

Feature	Auricle (Atrium)	Ventricle
Position	Located in the upper part of the heart.	Located in the lower part of the heart.
Wall Thickness	They have thinner muscular walls.	They have thick and strong muscular walls.
Function	They receive blood from the body and pump it to ventricles.	They pump blood out of the heart to the lungs and body.
Blood Pressure	Blood pressure is low in auricles.	Blood pressure is high in ventricles.
Valves	Associated with Tricuspid and Bicuspid valves at exit.	Associated with Semilunar valves at exit (Aortic/Pulmonary).

(c) Artery and Vein

Feature	Artery	Vein
Direction of Flow	Carries blood away from the heart to body organs.	Carries blood from body organs towards the heart.
Wall Structure	Walls are thick, muscular, and elastic.	Walls are thin and less elastic.
Lumen	The lumen (internal passage) is narrow.	The lumen is wide.
Valves	They do not have valves (except pulmonary artery base).	They possess valves to prevent backflow of blood.
Blood Type	Usually carries oxygenated blood (except Pulmonary Artery).	Usually carries deoxygenated blood (except Pulmonary Vein).

(d) Pulmonary blood circulation and Systemic blood circulation

Feature	Pulmonary Circulation	Systemic Circulation
Route	Circulation between the heart and the lungs.	Circulation between the heart and all other body parts.
Purpose	To oxygenate the blood (release $CO_2$, pick up $O_2$).	To deliver oxygen/nutrients to tissues and collect waste.
Start Point	Starts from the Right Ventricle.	Starts from the Left Ventricle.
End Point	Ends at the Left Auricle.	Ends at the Right Auricle.
Path Length	It is a shorter circulation path.	It is a longer circulation path.

(e) Systolic blood pressure and Diastolic blood pressure

Feature	Systolic Blood Pressure	Diastolic Blood Pressure
Definition	Pressure exerted on arteries when the heart contracts.	Pressure exerted on arteries when the heart relaxes.
Phase	Occurs during the systole (contraction) phase of ventricles.	Occurs during the diastole (relaxation) phase of ventricles.
Value	It represents the higher number in a BP reading.	It represents the lower number in a BP reading.
Normal Range	Normal range is $100-140$ mmHg (Avg: $120$ mmHg).	Normal range is $60-90$ mmHg (Avg: $80$ mmHg).
Significance	Indicates the maximum strain on arteries.	Indicates the minimum pressure sustained by arteries.

(f) Anaemia and Haemophilia

Feature	Anaemia	Haemophilia
Cause	Caused by deficiency of Iron, Vitamin B12, or RBC loss.	It is a genetic disorder caused by lack of clotting factors.
Main Symptom	Tiredness, pale skin, shortness of breath, weakness.	Prolonged bleeding from cuts, inability to clot blood.
Nature	Usually nutritional or acquired (can be treated with diet/supplements).	Usually hereditary/congenital (life-long condition).
Blood Component	Related to low Haemoglobin or RBC count.	Related to dysfunction/lack of clotting proteins/platelets.
Risk	Causes organs to suffer from lack of oxygen.	Causes risk of excessive blood loss from minor injuries.

(g) Angiogram and Open heart surgery

Feature	Angiogram	Open Heart Surgery
Type of Procedure	It is a diagnostic procedure (imaging test).	It is a therapeutic/surgical treatment procedure.
Invasiveness	Minimally invasive (catheter inserted into artery).	Highly invasive (chest is cut open to access heart).
Purpose	To visualize blood vessels and detect blockages.	To repair heart defects, replace valves, or bypass arteries.
Recovery	Recovery is quick (hours to a day).	Recovery takes weeks to months.
Anesthesia	Often done with local anesthesia and mild sedation.	Done under general anesthesia.

(h) Platelets and White blood cell

Feature	Platelets (Thrombocytes)	White Blood Cells (Leucocytes)
Nucleus	They are non-nucleated fragments.	They have a distinct nucleus.
Function	Essential for blood clotting (coagulation).	Essential for immunity and fighting infection.
Size	They are the smallest blood corpuscles ($2-4$ microns).	They are larger than platelets ($8-20$ microns).
Shape	Irregular or disc-like cell fragments.	Amoeboid or spherical shape.
Production	Produced by fragmentation of megakaryocytes in marrow.	Produced in bone marrow and lymph nodes.

3. Give reason

(a) Blood is red.

Reason: Blood appears red due to the presence of a red pigment called haemoglobin found inside the Red Blood Cells (RBCs). Haemoglobin is an iron-containing protein that binds to oxygen. When oxygenated, it appears bright red; when deoxygenated, it appears dark red.

(b) WBCs are like the soldiers of body.

Reason: WBCs are called the soldiers of the body because they defend the body against foreign invaders like bacteria, viruses, and germs. They do this by producing antibodies to neutralize pathogens or by directly engulfing and destroying them (phagocytosis), just as soldiers protect a country from enemies.

(c) Wall of ventricle is highly muscular or thicker than the wall of auricle.

Reason: Ventricles have to pump blood out of the heart to distant parts of the body (Left Ventricle) or to the lungs (Right Ventricle) against gravity and resistance. This requires high pressure. Auricles only need to pump blood down into the adjacent ventricles. Therefore, ventricles have thicker muscular walls to generate the necessary force.

(d) Wall of left ventricle is thicker than the wall of right ventricle.

Reason: The left ventricle has to pump blood to the entire body (systemic circulation), which requires a very high pressure to overcome the resistance of the systemic vessels and reach all extremities. The right ventricle only pumps blood to the lungs (pulmonary circulation), which are located nearby. Thus, the left ventricle wall is thicker to generate higher pressure.

(e) Arteries do not have valve but veins have valves.

Reason: Blood flows through arteries with high pressure and speed due to the pumping action of the heart, which naturally prevents backflow. Veins, however, carry blood at low pressure against gravity (often moving upward from legs to heart). To prevent the blood from flowing backward due to gravity, veins are equipped with valves.

(f) A person with anaemia feels tired after a short walk.

Reason: Anaemia is the deficiency of haemoglobin or RBCs, which are responsible for transporting oxygen to cells. Oxygen is required for the production of energy (ATP) through cellular respiration. If a person is anaemic, their body cells receive insufficient oxygen, leading to less energy production. Consequently, they feel tired and exhausted quickly even after minor physical activity.

(g) Arteries are deeply seated inside the muscles but veins are superficial.

Reason: Arteries carry blood under high pressure. Being deeply seated protects them from external injuries; a cut in an artery can lead to rapid, life-threatening blood loss. Veins carry blood at lower pressure and are located superficially (just under the skin) to assist in heat regulation and because damage to them is less critical and easier to control than arterial damage.

(h) Blood group should be tested before transfusion.

Reason: Blood groups differ by the antigens present on RBCs (A, B, Rh). If incompatible blood is transfused (e.g., A group given to B group), the recipient’s antibodies will attack the donor’s blood cells, causing them to clump together (agglutination). This can block blood vessels, cause kidney failure, and lead to death. Therefore, matching is essential to prevent this immune reaction.

(i) Blood coagulates slower or does not coagulate in haemophilic person.

Reason: Haemophilia is a genetic disorder where the body lacks specific clotting factors (proteins necessary for the coagulation cascade, such as Factor VIII or IX). Without these factors, the chemical reaction required to form a fibrin mesh (clot) cannot complete properly, causing bleeding to continue for a prolonged time or preventing coagulation entirely.

4. Answer the following questions.

(a) Describe the main parts of the human circulatory system.

Answer: The main parts of the human circulatory system are:

1. Heart: A four-chambered muscular organ that acts as a pump to circulate blood throughout the body.

2. Blood: A fluid connective tissue composed of plasma (liquid part) and blood cells (RBCs, WBCs, Platelets). It transports nutrients, oxygen, waste, and hormones.

3. Blood Vessels: A network of tubes that carry blood. They are of three types:

– Arteries: Carry oxygenated blood away from the heart (except pulmonary artery).

– Veins: Carry deoxygenated blood towards the heart (except pulmonary vein).

– Capillaries: Microscopic vessels connecting arteries and veins where exchange of materials occurs.

(b) Write the main function of blood.

Answer: The main functions of blood are:

1. Transport: Carries oxygen from lungs to tissues and carbon dioxide from tissues to lungs. It also transports digested food, hormones, and waste products (urea).

2. Protection: WBCs in blood fight infection, and platelets prevent blood loss through clotting.

3. Regulation: It helps regulate body temperature by distributing heat and maintains the water and pH balance of the body.

(c) When any part of the body is injured, the bleeding stops after a while. Why?

Answer: Bleeding stops because of a process called coagulation or clotting. When a blood vessel is damaged, platelets rush to the site and rupture to release an enzyme called thromboplastin. This initiates a chain reaction (converting prothrombin to thrombin, then fibrinogen to fibrin) that creates a mesh of fibres. This mesh traps blood cells, forming a clot that plugs the wound and stops bleeding.

(d) Ramila gets tired even after walking a short distance and also feels difficult to breathe? What is the reason for this? Explain.

Answer: Ramila is likely suffering from Anaemia.

Reason: Anaemia is caused by a lack of red blood cells or haemoglobin. Haemoglobin’s job is to carry oxygen to the body’s tissues. When walking, muscles need more energy and oxygen. Due to low haemoglobin, her blood cannot supply enough oxygen to the muscles for energy production, causing tiredness. The difficulty in breathing (shortness of breath) is the body’s attempt to compensate by taking in more oxygen to meet the demand.

(e) A person has blood pressure $130/90$ mmHg. What does this mean?

Answer: This means the person’s blood pressure reading consists of two values:

– $130$ (Systolic Pressure): The pressure in the arteries when the heart beats (contracts). It is slightly higher than the average normal ($120$).

– $90$ (Diastolic Pressure): The pressure in the arteries when the heart rests between beats. It is on the border of high ($80$ is normal).

Interpretation: This reading indicates Pre-hypertension or early stage High Blood Pressure. The person should monitor their diet and lifestyle.

(f) Which device is used to measure blood pressure?

Answer: The device used to measure blood pressure is called a Sphygmomanometer.

(g) Before the transfusion of blood to a patient, blood group of donor and receiver patient is checked by the doctor. Why?

Answer: It is checked to prevent agglutination. If the blood types are incompatible (e.g., Donor has Antigen A and Recipient has Antibody A), the recipient’s immune system will destroy the donor cells. This reaction causes clumping of blood, blockage of vessels, toxic reaction, and potentially fatal consequences.

(h) Sarita’s grandmother shows the symptoms like frequent urination, tiredness, muscular spasm and numbness in hands and legs, and thirst. What is the problem with her?

Answer: Based on the symptoms of frequent urination (polyuria) and excessive thirst (polydipsia), coupled with tiredness, Sarita’s grandmother is likely suffering from Diabetes (High Blood Sugar). The numbness and spasms suggest diabetic neuropathy (nerve damage) or electrolyte imbalance often associated with uncontrolled diabetes.

(i) Mention the effect and preventive measures of high blood pressure.

Answer:

Effects:

– Damage to blood vessels (hardening or atherosclerosis).

– Stroke (brain haemorrhage).

– Heart attack or heart failure.

– Kidney damage (Renal failure).

Preventive Measures:

– Reduce salt (sodium) intake.

– Regular physical exercise and maintaining a healthy weight.

– Avoid smoking and excessive alcohol consumption.

– Manage stress through relaxation techniques.

– Eat a balanced diet low in saturated fats.

(j) Respiratory system, digestive system and circulatory system in human body are interrelated. Explain this statement with reasons.

Answer: These systems rely on each other to keep body cells alive:

– Digestive & Circulatory: The digestive system breaks down food into nutrients (glucose, amino acids). These nutrients are absorbed into the blood (circulatory system) to be transported to all cells.

– Respiratory & Circulatory: The respiratory system brings oxygen into the lungs. The blood (circulatory system) picks up this oxygen and delivers it to cells. It also collects $CO_2$ from cells and brings it back to the lungs to be exhaled.

– Interrelation: Cells need both nutrients (from digestion) and oxygen (from respiration) to produce energy. The circulatory system acts as the “bridge” or transport system connecting the source of fuel (digestive/respiratory) to the destination (cells).

(k) How is high or low blood pressure detected?

Answer: It is detected using a Sphygmomanometer. An inflatable cuff is wrapped around the upper arm. The doctor inflates it to stop blood flow, then slowly releases the air while listening with a stethoscope (or using a digital sensor).

– High BP (Hypertension): If the reading is consistently above $140/90$ mmHg.

– Low BP (Hypotension): If the reading is consistently below $90/60$ mmHg.

(l) What process in the body is represented by the given figure? Which systems are involved in this process? If the organ system shown in figure 3 were absent, how would the medicine ingested in figure 2 still be able to reach the knee? Explain with reasons.

           

Answer:

           

Figure 1 represents the process of ingesting medicine or food.

           

Figure 2 represents the Digestion process.

           

Figure 3 represents the Circulatory process.

           

Figure 4 represents the transport process of nutrients and medicine reaching the specific site (knee).

           

The given figure shows the combined process of digestion and the transport function of the circulatory system in the human body. Both the Digestive System and the Circulatory System are involved in this process.

           

If the system in Figure 3 (Circulatory System) were absent, the medicine ingested in Figure 1 would not be able to reach the knee shown in Figure 4. This is because the transport of all substances in the body (including food, hormones, and medicines) is performed by the blood and the circulatory system.

(m) Answer the following questions on the basis of the information given on the table.

Identification:

X: Red Blood Cell (Biconcave, no nucleus, made in marrow).

Y: White Blood Cell (Irregular, nucleus, made in marrow/lymph).

Z: Platelet (Round/spherical fragments, no nucleus, involved in clotting).

i. Which blood cell deficiency causes anaemia in a person?

Deficiency of cell X (Red Blood Cell) causes anaemia.

ii. What will be the problem when the number of Y blood cells increases beyond normal?

An abnormal increase in Y (White Blood Cells) often indicates an infection (leukocytosis) or, if uncontrolled and malignant, it indicates Leukemia (blood cancer).

iii. If blood coagulates slower or does not coagulate in the injured or cut part of a person, which blood cells are below the normal count in that person? What is this condition called?

The cells below normal are Z (Platelets). This condition is called Thrombocytopenia. (If the failure to clot is genetic despite normal platelets, it is Haemophilia, but based on cell count, it is platelet deficiency).

(n) While Sarita was walking on the road, she saw an old man suffering from chest pain. She rushed him to the hospital. The initial examination suggested that he might have a heart problem. Which test would be appropriate to identify his heart condition? Explain with reason.

Answer: The most appropriate immediate test is an ECG (Electrocardiogram) followed by an Angiogram.

Reason: Chest pain (Angina) indicates reduced blood flow to the heart. An Angiogram is the gold standard to visualize the coronary arteries and identify the exact location and severity of blockage causing the pain/heart attack.

(o) Explain the blood circulation in the human body with a diagram.

Answer: Blood circulation occurs in a double circuit:

Pulmonary Circulation: Deoxygenated blood from the body enters the Right Auricle $\rightarrow$ Right Ventricle. It is pumped to the Lungs via the Pulmonary Artery. In lungs, it releases $CO_2$ and picks up Oxygen. Oxygenated blood returns to the Left Auricle via Pulmonary Veins.

Systemic Circulation: Oxygenated blood moves from Left Auricle $\rightarrow$ Left Ventricle. It is pumped into the Aorta to be distributed to all body parts. Cells use oxygen and release $CO_2$. The deoxygenated blood is collected by veins (Vena Cava) and returned to the Right Auricle.

(p) Write the preventive measures for hyperuricemia.

Answer: Hyperuricemia is high uric acid. Preventive measures include:

– Avoid high-purine foods (red meat, organ meats like liver, shell-fish).

– Avoid alcoholic beverages.

– Drink plenty of water to help flush uric acid from kidneys.

– Maintain a healthy body weight.

– Eat plenty of fruits and vegetables.

(q) Explain the internal structure of the human heart with a neat and labelled diagram.

Answer:

Chambers: The heart has four chambers. Two upper thin-walled Auricles (Right & Left) and two lower thick-walled Ventricles (Right & Left).

Septum: A muscular wall (Septum) divides the right (deoxygenated) and left (oxygenated) sides.

Valves:

– Tricuspid Valve: Between Right Auricle and Right Ventricle.

– Bicuspid (Mitral) Valve: Between Left Auricle and Left Ventricle.

– Semilunar Valves: At the base of the Pulmonary Artery and Aorta.

Vessels: Vena Cavae open into Right Auricle. Pulmonary Veins open into Left Auricle. Pulmonary Artery exits Right Ventricle. Aorta exits Left Ventricle.

(r) Explain the main causes of a heart attack.

Answer: A heart attack (Myocardial Infarction) occurs when blood flow to a part of the heart muscle is blocked. Causes include:

– Atherosclerosis: Deposition of fat, cholesterol, and calcium (plaque) inside coronary arteries, narrowing them.

– Thrombosis: Formation of a blood clot on the plaque, completely blocking the artery.

– Risk Factors: High blood pressure, high cholesterol, smoking, obesity, diabetes, and lack of exercise.

(s) Introduce angiogram and its importance.

Answer:

Introduction: An angiogram is an X-ray imaging test where a contrast dye is injected into the blood vessels (usually via a catheter in the groin or arm) to make them visible on X-ray.

Importance: It is crucial for diagnosing heart conditions. It helps doctors see exactly where arteries are narrowed or blocked. It guides treatment decisions, such as whether a patient needs angioplasty, stenting, or bypass surgery.

(t) Give a brief introduction to open-heart surgery.

Answer: Open-heart surgery is a major surgical procedure where the chest is cut open and surgery is performed on the muscles, valves, or arteries of the heart. During the surgery, the heart may be stopped, and a heart-lung machine takes over the pumping of blood. It is used for coronary artery bypass (CABG), repairing or replacing heart valves, and fixing congenital heart defects.

(u) When Samip’s blood was tested, the number of white blood cells was found to be more than 3000. Which symptom may appear in his body in this situation? Give a reason.

Answer: $3000$ WBCs is below normal (Leukopenia).

Symptoms: Weakened immunity, frequent infections, fever, fatigue.

Reason: WBCs fight infection. Low numbers mean the body cannot defend itself against bacteria/viruses effectively.

(v) The level of fibrinogen was found to be high in the plasma of Harish at the time of the blood test. Does this affect his blood circulation or not? Explain with a reason.

Answer: Yes, it affects circulation.

Reason: Fibrinogen is a clotting factor. High levels of fibrinogen make the blood thicker (more viscous) and “stickier” (hypercoagulable). This increases the risk of blood clots forming spontaneously inside the vessels (thrombosis). These clots can block blood circulation, potentially leading to heart attack or stroke.

(w) Study the given table and answer the following questions.

X: Bleeding continuous, superficial $\rightarrow$ Haemophilia (Lack of clotting).

Y: Deep injury, high pressure, stopped $\rightarrow$ Artery injury (High pressure indicates artery).

Z: Superficial, stopped $\rightarrow$ Normal capillary/vein cut.

i. Which person suffers from haemophilia?

Person X. (Bleeding did not stop even though the wound was superficial).

ii. In which person is the artery injured?

Person Y. (Bleeding was with high pressure, which is characteristic of arterial bleeding).

iii. Which injury, Y or Z is more dangerous? Give a reason.

Y is more dangerous.

Reason: Y involves a deep injury with high-pressure bleeding (Artery). Arterial bleeding results in rapid and massive blood loss, which can lead to shock and death very quickly if not stopped. Z is superficial and stopped on its own.

(x) Study the concept map given below and answer the following questions.

(Map: Left Ventricle $\rightarrow$ Kidney $\rightarrow$ Left Auricle)

i. What type of blood circulation is shown in the concept map?

It represents Systemic Blood Circulation. (Circulation from Heart to Body Organ and back).

ii. In which parts of the concept map do arteries and veins play a role?

– Artery (Renal Artery): Carries blood from Left Ventricle (via Aorta) to the Kidney.

– Vein (Renal Vein): Carries blood from the Kidney back to the heart (Right Auricle via Vena Cava).

(y) Look at the diagram given below and answer the following questions.

           

i. Differentiate the blood vessel 15 and 18.

           

Answer: Vessel 15 (Aorta) carries oxygenated blood from the heart to the rest of the body. Vessel 18 (Superior Vena Cava) carries deoxygenated blood from the upper body back to the heart.

           

ii. Write the function of valves 11 and 13?

           

Answer: Valve 11 (Bicuspid/Mitral Valve) allows oxygenated blood to flow from the Left Auricle to the Left Ventricle and prevents backflow. Valve 13 (Pulmonary Valve) allows deoxygenated blood to flow from the Right Ventricle to the Pulmonary Artery and prevents backflow.

           

iii. What happens in the absence of part 4?

           

Answer: Part 4 is the Pericardium. In its absence, the heart would not be protected from external shocks, mechanical injuries, or friction.

           

iv. Label the part 6, 7, 8 and 9.

           

6: Right Auricle

           

7: Left Auricle

           

8: Right Ventricle

           

9: Left Ventricle

(z) Draw neat and labelled diagram of:

i. External structure of the human heart

ii. Internal structure of the human heart

iii. Arteries, veins, and capillaries

iv. Pulmonary blood circulation

v. Systemic blood circulation