Year 11 ATAR Human Biology Circulatory and Respiratory System

What is the primary role of the circulatory system?

To link the cells inside the body with the environment outside the body.

What are the main components of the circulatory system?

The heart, blood vessels (veins and arteries), and blood.

Where is the heart located in the body?

In the middle of the chest cavity, between the two lungs and slightly to the left.

What is the function of the pericardium?

It encloses the heart, holding it in place while allowing movement as it beats.

What type of muscle makes up the heart?

Cardiac muscle.

What is the primary function of the heart?

To pump blood and oxygen around the body and deliver waste products back to the lungs.

What are the main valves of the heart?

Tricuspid, Mitral, Atrioventricular, Aortic, Pulmonary, and Semi-lunar valves.

How do heart valves function?

They ensure blood flows only in one direction by sealing off the artery when blood tries to flow back into the ventricle.

What is blood made of?

Blood is made of plasma (55%) and formed elements (45%).

What do carotid arteries supply?

Oxygenated blood to the brain, head, and neck.

What is the function of coronary arteries?

To supply oxygenated blood to the heart muscle.

What do renal arteries supply?

Oxygenated blood to the kidneys for filtration and waste removal.

What is the role of mesenteric arteries?

To supply oxygenated blood to the intestines for digestion and nutrient absorption.

What does the hepatic portal system do?

Transports nutrient-rich blood from the digestive organs to the liver for processing.

Why is the hepatic portal system important?

It allows the liver to process nutrients, store glucose, detoxify harmful substances, and regulate blood sugar levels.

What is the main function of erythrocytes (red blood cells)?

To carry oxygen using hemoglobin.

Which type of blood vessel carries blood away from the heart?

Arteries.

Which chamber of the heart pumps oxygenated blood into systemic circulation?

Left ventricle.

What is the purpose of pulmonary circulation?

To carry blood to and from the lungs for gas exchange.

What is the function of plasma in blood?

To transport nutrients, hormones, and waste products.

What are formed elements in blood?

Components such as erythrocytes, leukocytes, and platelets.

What is the significance of the cardiac cycle?

It refers to the sequence of events in one heartbeat, including contraction and relaxation phases.

What is the general direction of blood flow in systemic circulation?

From the left side of the heart to the body and back to the right side of the heart.

What is the general direction of blood flow in pulmonary circulation?

From the right side of the heart to the lungs and back to the left side of the heart.

What is the main function of the circulatory system?

To distribute oxygen-rich blood to the body, remove carbon dioxide from the lungs, carry blood to and from the lungs for gas exchange, and deliver nutrients to the liver.

What is the main function of plasma in the blood?

To transport nutrients, hormones, and waste.

Which arteries supply blood to the brain and head?

The carotid arteries.

What is the function of coronary circulation?

To supply oxygen and nutrients to the heart muscle.

Which blood vessel carries blood from the digestive organs to the liver?

The hepatic portal vein.

What are the main structural differences between arteries, veins, and capillaries?

Arteries have thick, muscular walls and carry oxygenated blood at high pressure; veins have thinner walls with valves to prevent backflow and carry deoxygenated blood at lower pressure; capillaries have one-cell-thick walls for the exchange of oxygen, carbon dioxide, and nutrients.

What are the key steps of the cardiac cycle?

Atrial systole (atria contract to push blood into ventricles), ventricular systole (ventricles contract to push blood into arteries), and diastole (heart relaxes, filling phase).

What is the function of renal circulation?

To filter waste from the blood in the kidneys and maintain fluid balance.

How are oxygen and carbon dioxide exchanged between blood and tissues in systemic circulation?

Through diffusion, where oxygen moves from high concentration in blood to low concentration in tissues, and carbon dioxide moves from high concentration in tissues to low concentration in blood.

Why is the hepatic portal system necessary for digestion and metabolism?

It transports nutrient-rich blood from the intestines to the liver for processing and reducing harmful substances before entering general circulation.

What is the role of capillaries in the circulatory system?

Capillaries have thin walls that allow efficient diffusion of substances, providing a large surface area for the exchange of oxygen, nutrients, and waste products.

What distinguishes pulmonary circulation from systemic circulation?

Pulmonary circulation carries deoxygenated blood from the heart to the lungs for gas exchange, while systemic circulation carries oxygenated blood from the heart to the body.

What happens during atrial systole?

The atria contract, pushing blood into the ventricles.

What occurs during ventricular systole?

The ventricles contract, pushing blood into the arteries.

What is the significance of diastole in the cardiac cycle?

It is the relaxation phase of the heart, allowing the atria and ventricles to fill with blood.

What is the importance of the renal circulation for homeostasis?

It filters waste from the blood and maintains fluid balance, which is crucial for homeostasis.

What is the process of gas exchange in the lungs?

In the lungs, blood releases carbon dioxide and absorbs oxygen during gas exchange.

What is the function of the hepatic portal vein?

To carry nutrient-rich blood from the digestive organs to the liver.

How does the structure of capillaries facilitate their function?

Capillaries have thin walls that are one-cell thick, allowing for efficient diffusion of substances.

What is the role of valves in veins?

To prevent backflow of blood as it returns to the heart.

What is the significance of the aorta in systemic circulation?

The aorta carries oxygenated blood from the heart to the rest of the body.

What is the primary function of arteries?

To carry blood away from the heart.

What happens to blood pressure in arteries during ventricular contraction and relaxation?

Blood pressure increases during contraction and decreases during relaxation.

What are the structural characteristics of arteries?

Arteries have thick, muscular, elastic walls made of smooth muscle and no valves.

What are arterioles?

Small arteries that transport blood to the capillaries.

How do arteries react to ventricular contractions?

They stretch when ventricles push blood into them and recoil when ventricles relax, maintaining blood pressure.

What is the primary function of veins?

To carry blood towards the heart.

What structural features do veins have?

Veins have thin walls and valves that direct blood flow to the heart and prevent backflow.

What are venules?

Tiny veins that carry blood away from the capillaries.

How do veins assist in returning blood to the heart?

Muscles surrounding veins contract to squeeze blood forward, and valves prevent backflow.

What are capillaries and their primary function?

Microscopic blood vessels that form a network carrying blood to nearly every cell in the body.

Why are capillary walls suited for their function?

They are one cell thick, allowing efficient diffusion of substances.

What advantages do capillaries have for material exchange?

Their small size and extensive network provide a large surface area for exchange.

What is vasodilation?

An increase in the diameter of blood vessels allowing for an increase in blood flow.

What is vasoconstriction?

A decrease in the diameter of blood vessels restricting blood flow.

What is the cardiac cycle?

The sequence of events that occurs in one complete beat of the heart.

What is systole?

The pumping phase of the heart when it contracts.

What is diastole?

The filling phase of the heart when the muscle relaxes.

Describe the phases of the cardiac cycle.

1. Both atria and ventricles are in diastole, filling with blood. 2. Atrial systole forces blood into the ventricles. 3. Ventricular systole forces blood into the arteries.

How do the left and right sides of the heart operate during the cardiac cycle?

They operate together; both atria contract together and both ventricles contract together.

What factors determine cardiac output?

The heart rate and the stroke volume.

Define heart rate and stroke volume.

Heart rate is the number of times the heart beats in one minute; stroke volume is the volume of blood forced from the ventricle with each contraction.

What is cardiac output?

The amount of blood leaving the ventricle each minute.

What is the equation for calculating cardiac output?

Stroke volume (ml) x heart rate (beats/min)

What regulates the heart's rhythm and how can it be modified?

The heart has an inbuilt rhythm controlled by the sinoatrial node (SA node), which can be increased or decreased by nervous stimulation from the cardiac center in the brain.

What is the function of the sinoatrial node (SA node)?

The SA node acts as the pacemaker of the heart.

How do hormones affect blood vessel diameter during exercise?

Hormones like adrenaline cause vasoconstriction in most arterioles but induce vasodilation in skeletal muscles and the heart.

What happens in skeletal muscles with inadequate blood flow?

Waste accumulates, stimulating vasodilation to increase blood flow.

What are the percentages of oxygen transport in the blood?

3% is carried in blood plasma, and 97% is combined with hemoglobin to form oxyhaemoglobin.

How does oxygen combine with hemoglobin?

Oxygen combines with hemoglobin in high oxygen concentration areas, such as capillaries in the lungs.

What happens to oxyhaemoglobin in low oxygen concentration areas?

Oxyhaemoglobin breaks down to release oxygen, which then diffuses into surrounding tissues.

What color is oxygenated blood and why?

Oxygenated blood is bright red due to a high proportion of oxyhaemoglobin.

What color is deoxygenated blood and why?

Deoxygenated blood is dark red/purplish due to a lower oxygen content.

What are the percentages of carbon dioxide transport in the blood?

7-8% is dissolved in plasma, 22% is combined with globin in hemoglobin forming carbaminohemoglobin, and 70% is carried as bicarbonate ions.

What occurs to carbon dioxide in the capillaries of the lungs?

Carbon dioxide dissolved in plasma and from carbaminohemoglobin diffuses into the alveoli.

How is carbonic acid formed and what happens to it in the lungs?

Hydrogen ions and bicarbonate ions recombine to form carbonic acid, which breaks down into carbon dioxide and water in the lungs.

What happens to carbon dioxide when it diffuses into the alveoli?

Carbon dioxide is exhaled from the alveoli.

What is the role of the cardiovascular regulating center in the brain?

It sends nerve signals to speed up or slow down the heart rate.

What is the effect of exercise on blood flow?

Exercise increases blood flow to meet the oxygen demands of muscles.

What is the process of dissociation of oxyhaemoglobin?

Oxyhaemoglobin releases oxygen in low oxygen concentration areas, allowing it to diffuse into tissues.

What is the significance of vasodilation during exercise?

Vasodilation increases blood flow to active muscles, enhancing oxygen supply and waste removal.

What is the relationship between oxygen concentration and hemoglobin affinity?

Hemoglobin has a higher affinity for oxygen in high concentration areas and releases it in low concentration areas.

What is the primary method of carbon dioxide transport in the blood?

The majority of carbon dioxide is transported as bicarbonate ions in the plasma.

What happens to oxygenated blood in the body?

It delivers oxygen to tissues and organs while removing carbon dioxide.

What is the physiological response to increased carbon dioxide levels in the blood?

Increased carbon dioxide levels stimulate the respiratory center to increase breathing rate.

What are the two main types of nutrients transported in blood plasma?

Inorganic ions (e.g., sodium Na+, Calcium Ca2+, Potassium K+, Chloride Cl-) and organic substances (e.g., glucose, vitamins, amino acids, fatty acids, glycerol).

What are the metabolic wastes transported in blood?

Urea, creatinine, and uric acid.

What are the primary functions of blood?

Transport oxygen and nutrients to cells, transport carbon dioxide and waste products away, distribute hormones, maintain pH and water content, regulate body temperature, and protect against disease.

What percentage of blood is plasma and what is its main composition?

55% plasma, composed of 91% water and 8% dissolved substances including nutrients, ions, gases, hormones, and waste.

What is the main role of plasma in the blood?

To transport nutrients, hormones, and proteins to cells and remove wastes.

What are the formed elements of blood and their approximate percentage?

45% formed elements, including erythrocytes (red blood cells), leucocytes (white blood cells), and platelets (thrombocytes).

What is the shape of erythrocytes and why is it important?

Biconcave shape, which increases surface area for oxygen exchange and allows for more hemoglobin.

What is the lifespan of erythrocytes and where are they produced?

Lifespan of 120 days, produced in the bone marrow.

What is the primary function of leucocytes?

Involved in immunity, removing dead or injured cells and invading microorganisms.

What are the two main types of leucocytes?

Granulocytes (with granular cytoplasm and lobed nucleus) and agranulocytes (monocytes and lymphocytes with spherical nucleus).

What are thrombocytes and their role in the blood?

Thrombocytes (platelets) are small cell fragments important for normal blood clotting.