Transport in Animals (Heart, Vessels, T.Fluid ft. ECG)

Question 1

What is the main function of the transport system in animals?

Answer 1

The main function of the transport system in animals is to transport oxygen, nutrients, hormones, and waste products throughout the body.

It also plays a crucial role in maintaining homeostasis, regulating temperature, and protecting the body against pathogens.

Question 2

What are the key differences between open and closed circulatory systems?

Answer 2

Open circulatory system: Blood is pumped into open spaces (hemocoel), where it bathes organs directly (common in arthropods and mollusks).

Closed circulatory system: Blood is confined to vessels and pumped by the heart (found in vertebrates like mammals, and some invertebrates like earthworms).

Question 3

What are the advantages of a closed circulatory system over an open circulatory system?

Answer 3

Faster transport of materials due to the pressure in the vessels.

More efficient because blood can be directed exactly where it’s needed.

It allows for higher metabolic rates, which is important for larger, more active organisms.

Question 4

What are the key components of blood and their functions?

Answer 4

Plasma: The liquid portion of blood, consisting mainly of water, that transports nutrients, hormones, proteins, and waste products.

Red Blood Cells (Erythrocytes): Contain hemoglobin to carry oxygen from the lungs to tissues and bring carbon dioxide back to the lungs for exhalation.

White Blood Cells (Leukocytes): Part of the immune system, these cells protect the body against infection.

Platelets (Thrombocytes): Involved in blood clotting by aggregating at the site of injury to form a clot and prevent excessive bleeding.

Question 5

How do red blood cells (RBCs) adapt to their function?

Answer 5

Biconcave shape increases surface area for gas exchange.

Lack of a nucleus maximizes space for hemoglobin to carry oxygen.

Contain hemoglobin that binds to oxygen, allowing efficient oxygen transport.

Question 6

Describe the structure of the heart in mammals.

Answer 6

The mammalian heart is divided into four chambers: two atria and two ventricles.

Right atrium: Receives deoxygenated blood from the body via the superior and inferior vena cava.

Right ventricle: Pumps deoxygenated blood to the lungs via the pulmonary artery.

Left atrium: Receives oxygenated blood from the lungs via the pulmonary veins.

Left ventricle: Pumps oxygenated blood to the rest of the body via the aorta.

Question 7

Explain the difference between the left and right sides of the heart.

Answer 7

The right side pumps deoxygenated blood to the lungs for oxygenation (pulmonary circulation).

The left side pumps oxygenated blood to the rest of the body (systemic circulation).

The left side has a thicker myocardium (muscle layer) to generate higher pressure for pumping blood throughout the body.

Question 8

What is the cardiac cycle and what are its phases?

Answer 8

The cardiac cycle refers to one complete heartbeat, during which the heart goes through two main phases:

Systole: The contraction phase, where the heart pumps blood out (ventricular systole pumps blood into the pulmonary artery and aorta).

Diastole: The relaxation phase, where the heart chambers fill with blood.

Question 9

What are the heart valves and what is their role?

Answer 9

Atrioventricular (AV) valves: The tricuspid valve (right side) and bicuspid valve (left side) prevent the backflow of blood into the atria when the ventricles contract.

Semilunar valves: The pulmonary valve (between the right ventricle and pulmonary artery) and the aortic valve (between the left ventricle and aorta) prevent the backflow of blood into the ventricles after systole.

Question 10

How is the heart rate controlled?

Answer 10

The Sinoatrial (SA) node acts as the heart’s natural pacemaker, generating electrical impulses that trigger atrial contraction.

These impulses pass through the Atrioventricular (AV) node, then spread to the Bundle of His and Purkinje fibers, causing ventricular contraction.

Question 11

How does the heart’s electrical conduction system ensure efficient pumping?

Answer 11

The SA node generates electrical impulses that cause the atria to contract.

The AV node delays the impulse briefly to allow the ventricles to fill with blood from the atria.

The impulses then travel through the Bundle of His and Purkinje fibers, stimulating ventricular contraction to pump blood to the lungs and body.

Question 12

What are the three main types of blood vessels?

Answer 12

Arteries: Carry blood away from the heart at high pressure. They have thick, muscular walls to withstand pressure and help push blood forward.

Veins: Carry blood back to the heart at low pressure. They have thinner walls than arteries but contain valves to prevent backflow of blood due to gravity.

Capillaries: Microscopic vessels where gas exchange, nutrient, and waste exchange occur between blood and tissues. Their walls are one cell thick to facilitate diffusion.

Question 13

How does blood flow through the arteries, veins, and capillaries?

Answer 13

Arteries: Blood flows under high pressure due to the force from the heart, and the elastic walls allow for recoil to maintain blood pressure.

Veins: Blood flow is aided by skeletal muscle contractions and valves, preventing backflow.

Capillaries: Blood flows slowly, allowing time for the exchange of oxygen, carbon dioxide, nutrients, and waste products with tissues.

Question 14

What is the importance of the elasticity in artery walls?

Answer 14

The elasticity in artery walls helps maintain blood pressure by allowing the arteries to stretch when blood is pumped into them and recoil to help propel blood forward.

Question 15

What factors affect blood flow and blood pressure in the circulatory system?

Answer 15

Cardiac output (volume of blood pumped by the heart per minute).

Resistance in blood vessels: Influenced by factors such as vessel diameter, length, and blood viscosity.

Elasticity of the arteries and the presence of valves in veins also contribute to the regulation of blood flow and pressure.

Question 16

What is tissue fluid?

Answer 16

Fluid that surrounds cells in tissues

Formed from plasma that leaks out of capillaries

Supplies cells with oxygen, glucose, amino acids, and nutrients

Allows waste removal like CO₂ and urea

Acts as a medium for exchange between blood and cells

Question 17

How is tissue fluid formed?

Answer 17

At the arteriole end of capillaries, hydrostatic pressure is high

This forces plasma (minus proteins) out of the capillaries into spaces around cells

Process is called ultrafiltration

Fluid that leaves forms the tissue (interstitial) fluid

Question 18

Why do plasma proteins remain in the blood during tissue fluid formation?

Answer 18

Plasma proteins (like albumin) are too large to pass through capillary walls

This retains osmotic pressure within the capillaries

Helps to draw water back in at the venule end

Question 19

What forces determine tissue fluid movement?

Answer 19

Hydrostatic pressure (pushes fluid out of capillaries)

Osmotic pressure from plasma proteins (pulls water back in)

Net filtration pressure = hydrostatic pressure − oncotic pressure

Question 20

What happens at the venule end of the capillary bed?

Answer 20

Hydrostatic pressure drops due to fluid loss

Osmotic pressure from plasma proteins draws water back into capillaries

Allows reabsorption of water and some solutes

Question 21

What is oncotic pressure?

Answer 21

A form of osmotic pressure due to plasma proteins (mainly albumin)

Pulls water into the capillaries from the tissue fluid

Maintains blood volume and prevents fluid loss

Question 22

What happens to tissue fluid that is not reabsorbed?

Answer 22

Drains into the lymphatic system

Eventually returned to the circulatory system via the subclavian vein

Question 23

How is the lymph system involved in tissue fluid drainage?

Answer 23

Blind-ended lymph capillaries collect excess tissue fluid

Fluid becomes lymph

Lymph vessels contain valves and are aided by muscle contraction

Lymph nodes filter pathogens

Question 24

What causes oedema (tissue swelling)?

Answer 24

Excess tissue fluid accumulation

Caused by:

High blood pressure (increased hydrostatic pressure)

Low plasma protein levels (reduced oncotic pressure)

Lymphatic blockage

Fluid is not reabsorbed properly

Question 25

Why does the hydrostatic pressure drop along the capillary?

Answer 25

Due to loss of fluid from the blood at the arteriole end Also due to friction with capillary walls Leads to lower pressure at the venule end, allowing reabsorption

Question 26

What is ultrafiltration? (In the context of Tissue Fluid)

Answer 26

Movement of fluid and small solutes out of capillaries into tissue spaces Driven by high hydrostatic pressure at arteriole end Larger molecules (e.g., proteins) remain in blood

Question 27

What is the role of tissue fluid in homeostasis?

Answer 27

Provides stable environment for cells Supplies nutrients and removes waste Maintains constant pH, temperature, and osmotic balance

Question 28

What role do capillary walls play in tissue fluid formation?

Answer 28

Thin, one-cell thick walls allow easy diffusion Fenestrations (pores) allow small molecules through Semi-permeable, so large molecules stay in the blood

Question 29

What is an electrocardiogram (ECG)?

Answer 29

A recording of the electrical activity of the heart. Generated using electrodes on the skin. Measures changes in voltage caused by depolarisation and repolarisation of heart muscle.

Question 30

What are the key waves and intervals on an ECG trace?

Answer 30

P wave: Atrial depolarisation (contraction). QRS complex: Ventricular depolarisation (contraction) and atrial repolarisation (masked). T wave: Ventricular repolarisation (relaxation). PR interval: Time from atrial depolarisation to ventricular depolarisation (AVN delay). ST segment: Time between ventricular depolarisation and repolarisation.

Question 31

How is heart rate calculated from an ECG?

Answer 31

Measure time between two R waves. Use formula: Heart rate = 60 / time interval (in seconds).

Question 32

What is the significance of the P wave, QRS complex, and T wave?

Answer 32

P wave: Shows atrial contraction; initiated by SAN. QRS complex: Shows ventricular contraction; initiated by AVN → Bundle of His → Purkyne fibres. T wave: Shows ventricular relaxation (repolarisation).

Question 33

What is the Bohr effect and how does it affect oxygen transport?

Answer 33

Increased CO₂ or decreased pH causes hemoglobin to release oxygen more readily. Shifts the oxygen dissociation curve to the right, ensuring oxygen is delivered to tissues during exercise.

Question 34

What are common abnormalities seen on an ECG?

Answer 34

Tachycardia: Heart rate >100 bpm; shorter intervals between R waves. Bradycardia: Heart rate <60 bpm; longer intervals between R waves. Atrial fibrillation: Irregular rhythm; no clear P waves, irregular QRS complexes. Ectopic heartbeat: Extra or early heartbeat; irregular pattern.

Question 35

What is the relationship between ECG and heart conditions?

Answer 35

ECGs help diagnose arrhythmias, heart attacks, and heart failure. Can show abnormal rhythms, damage to the heart muscle, or conduction problems.

Question 36

How do changes in pressure, temperature, or pH affect oxygen release from hemoglobin?

Answer 36

Higher CO₂, lower pH (Bohr effect), or higher temperature reduce haemoglobin’s affinity for oxygen, ensuring oxygen is released to tissues in need.

Question 37

What are the three types of blood vessels and their function?

Answer 37

Arteries: Carry oxygenated blood away from the heart. Veins: Carry deoxygenated blood back to the heart. Capillaries: Exchange gases, nutrients, and waste products between blood and tissues.

Question 38

What are the three layers of blood vessels and their function?

Answer 38

Tunica intima (inner layer): Smooth endothelium reduces friction and allows smooth blood flow. Tunica media (middle layer): Smooth muscle and elastic fibres that help with contraction/dilation and withstand pressure. Tunica externa (outer layer): Collagen for structural support and strength.

Question 39

How is the structure of arteries suited to their function?

Answer 39

Thick muscular walls with elastic fibres to withstand and maintain high pressure from the heart. Small lumen to keep blood pressure high and ensure efficient transport of oxygenated blood.

Question 40

How is the structure of veins suited to their function?

Answer 40

Thinner walls and wider lumen to accommodate lower pressure and larger volume of blood. Valves to prevent backflow, ensuring blood moves toward the heart.

Question 41

How is the structure of capillaries suited to their function?

Answer 41

One-cell-thick walls for efficient gas and nutrient exchange. Narrow lumen forces red blood cells to flow single file, increasing exposure for exchange. No muscle or elastic fibres, as capillaries don’t need to withstand pressure.

Question 42

How does the elasticity of arteries help with blood flow?

Answer 42

Elastic fibres in arteries allow them to stretch during systole (heart contraction) and recoil during diastole (relaxation). This maintains continuous blood flow and helps to keep blood pressure steady between heartbeats.

Question 43

How do veins ensure blood flow back to the heart?

Answer 43

Valves prevent backflow of blood, ensuring it flows toward the heart, especially when fighting gravity. Wide lumen and thin walls help reduce resistance to flow under low pressure.

Question 44

What is the role of the smooth muscle in arteries and veins?

Answer 44

In arteries, smooth muscle enables vasoconstriction (narrowing) and vasodilation (widening), regulating blood flow and pressure. In veins, smooth muscle aids in pushing blood back to the heart, although it is less pronounced than in arteries.

Question 45

Why do arteries have thicker muscular walls compared to veins?

Answer 45

Arteries carry blood under high pressure from the heart and need thicker walls to withstand this pressure. The elastic fibres allow arteries to stretch and recoil to maintain pressure during the cardiac cycle.

Question 46

How does the structure of capillaries aid in nutrient and gas exchange?

Answer 46

One-cell-thick walls shorten the diffusion distance for gases and nutrients to move in and out of the blood. Narrow lumen ensures that blood is in close contact with tissues, facilitating efficient exchange.

Question 47

How does the structure of blood vessels vary based on pressure and function?

Answer 47

Arteries have thick walls with elastic fibres and a small lumen to withstand high pressure and maintain efficient flow. Veins have thin walls, wide lumen, and valves to allow low-pressure blood flow and ensure blood moves toward the heart. Capillaries have thin walls for effective exchange of gases and nutrients at the tissue level.