Circulation and Respiration

Question 1

Circulatory system

Answer 1

The body system that transports blood, nutrients, oxygen, carbon dioxide, and hormones throughout the body. It includes the heart, blood, and blood vessels (arteries, veins, and capillaries).
All organisms have this system with three main components: a central pump, a vascular system (set of tubes) and a circulating fluid.
This system delivers oxygen and nutrients to tissues, removes waste products, regulates body temperature, and supports immune function.

Question 2

Open circulatory system

Answer 2

A circulatory system where blood is not fully contained in vessels but is pumped into body cavities, directly bathing organs and tissues. Found in many invertebrates like arthropods and most mollusks, this system has lower blood pressure and less efficient circulation compared to closed systems. It helps distribute nutrients, remove waste, and support immune functions.

Question 3

Closed circulatory system

Answer 3

A circulatory system where blood is contained within vessels, such as arteries, veins, and capillaries, forming a continuous circuit. The heart pumps blood through these vessels to transport oxygen, nutrients, and waste products to and from cells. Found in vertebrates and some invertebrates, this system allows for higher blood pressure and more efficient circulation, enabling precise regulation of blood flow to different tissues and organs.

Question 4

Arteries

Answer 4

Blood vessels that carry oxygenated blood away from the heart to the body’s tissues and organs.

Question 5

Capillaries

Answer 5

The smallest blood vessels in the circulatory system, connecting arteries to veins. They have thin walls that allow for the exchange of oxygen, nutrients, and waste products between the blood and surrounding tissues. Capillaries facilitate the transfer of oxygen and nutrients to cells and the removal of carbon dioxide and other metabolic wastes

Question 6

Veins

Answer 6

Blood vessels that carry deoxygenated blood back to the heart from the body’s tissues and organs. Veins have thinner walls than arteries and contain valves to prevent backward flow of blood. They function to return blood to the heart against gravity, aided by muscle contractions and breathing movements.

Question 7

Single circulation system

Answer 7

A type of circulatory system found in some lower vertebrates, such as fish, where blood flows through the heart only once during each complete circuit through the body.
Single circulation systems are less efficient than double circulation systems blood pressure drops after passing through, limiting the delivery of oxygen to tissues.

Question 8

Double circulation system

Answer 8

A type of circulatory system found in mammals, birds, and some reptiles where blood flows through the heart twice during each complete circuit through the body. ‘
It consists of two separate circuits:

• The pulmonary circuit, which carries O2 poor blood from the heart to the lungs for oxygenation and then back to the heart.
• The systemic circuit, which carries O2 rich blood from the heart to the body’s tissues and organs, and then returns deoxygenated blood back to the heart.

Double circulation systems are more efficient than single circulation systems, ensuring a higher delivery of oxygen to tissues and enabling higher metabolic rates.

Question 9

Atrium

Answer 9

One of the two upper chambers of the heart that receives blood. The right atrium receives deoxygenated blood from the body through the superior and inferior vena cava, while the left atrium receives oxygenated blood from the lungs through the pulmonary veins.

Question 10

Ventricle

Answer 10

One of the two lower chambers of the heart responsible for pumping blood out to the body and lungs. The right ventricle pumps deoxygenated blood to the lungs via the pulmonary artery, while the left ventricle pumps oxygenated blood to the rest of the body through the aorta.

Question 11

The path of blood

Answer 11

1. Deoxygenated Blood Enters Right Atrium: Blood low in oxygen returns from the body via the superior and inferior vena cava into the right atrium.
2. Right Atrium to Right Ventricle: Blood flows from the right atrium through the tricuspid valve into the right ventricle.
3. Right Ventricle to Lungs: The right ventricle pumps blood through the pulmonary valve into the pulmonary artery, which carries it to the lungs for oxygenation.
4. Oxygenation in Lungs: In the lungs, blood releases carbon dioxide and picks up oxygen.
5. Oxygenated Blood Returns to Left Atrium: Oxygen-rich blood returns to the heart via the pulmonary veins into the left atrium.
6. Left Atrium to Left Ventricle: Blood flows from the left atrium through the mitral valve into the left ventricle.
7. Left Ventricle to Body: The left ventricle pumps oxygenated blood through the aortic valve into the aorta, which distributes it throughout the body.
8. Cycle Repeats: After delivering oxygen and nutrients to the body’s tissues and picking up waste products, the now deoxygenated blood returns to the right atrium, and the cycle begins again.

Question 12

The cardiac cycle

Answer 12

The series of events that occur in the heart during one complete heartbeat, including the periods of contraction (systole) and relaxation (diastole) of the atria and ventricles, resulting in the pumping of blood throughout the body and lungs.

1. During diastole, which lasts about 0.4 sec, blood returning to the heart flows into all four chambers.
2. During the first 0.1 sec of systole, the atria contract, forcing all the blood into the ventricles.
3. In the last 0.3 sec of systole, the ventricles contrac, pumping blood out of the heart and into the aorta and pulmonary artieries.

Question 13

Heart rate

Answer 13

The number of times the heart beats per minute (bpm). It reflects how frequently the heart contracts to pump blood through the body and is influenced by factors such as physical activity, stress, hormones, and overall cardiovascular health.

Question 14

Pulse

Answer 14

The rhythmic throbbing of the arteries as blood is propelled through them by the heartbeats.

Question 15

Diastole

Answer 15

The phase of the cardiac cycle during which the heart muscles relax and the chambers of the heart fill with blood. It occurs between contractions (systole), allowing the ventricles to fill with blood from the atria.

Question 16

Systole

Answer 16

The phase of the cardiac cycle during which the heart muscles contract and pump blood out of the chambers. It follows diastole and occurs in two stages: atrial systole, where the atria contract to push blood into the ventricles, and ventricular systole, where the ventricles contract to pump blood out of the heart.

Question 17

Pacemaker

Answer 17

A specialized group of cells located in the sinoatrial (SA) node of the heart that acts as the heart’s natural pacemaker, generating electrical impulses that regulate the heart’s rhythm and rate.

1. Impulses from the pacemaker spread quickly through the walls walls of both artia, prompting the atria to to contract at the same time.
2. The impulses then pass to a relay point that delays thhe signals by 0.1 sec, allowing the artria to empty before the impulses are passed to the ventricles. Ventricles then contract strongly, driving the blood out of the heart.

Question 18

EKG (Electrocardiogram)

Answer 18

A medical test that records the heart’s electrical activity using electrodes placed on the skin. It provides information about the heart’s rhythm and can help diagnose various heart conditions.

Question 19

Blood vessels

Answer 19

A tubular structure that carries blood throughout the body.
All blood vessels are lined by a thin layer of tightly packed epithelial cells but only arteries and veins have two additional layers: smooth muscle, connective muscle.
There are three main types of blood vessels: arteries, veins, and capillaries.

Arteries carry oxygen-rich blood away from the heart to the body’s tissues, while veins return oxygen-poor blood back to the heart.

Capillaries are tiny vessels where the exchange of gases, nutrients, and waste products occurs between the blood and tissues.

Blood vessels play a crucial role in maintaining blood pressure, regulating blood flow, and delivering nutrients and oxygen to cells while removing waste products.

Question 20

Blood pressure

Answer 20

The force exerted by circulating blood against the walls of blood vessels, primarily arteries, as it is pumped by the heart. It is expressed as two numbers: systolic pressure (the pressure when the heart contracts) over diastolic pressure (the pressure when the heart relaxes). Blood pressure is measured in millimeters of mercury (mmHg). Normal blood pressure is typically around 120/80 mmHg

Question 21

Hypotension and hypertension

Answer 21

Hypotension is low blood pressure, (90/60 mmHg). It can cause symptoms such as dizziness, fainting, blurred vision, and fatigue. Hypotension may result from factors like dehydration, blood loss, heart problems, hormonal imbalances, or neurological conditions.

Hypertension is high blood pressure, (130/80 mmHg or higher). It is a significant risk factor for cardiovascular diseases such as heart attack, stroke, and heart failure, as well as kidney disease and other health problems. Hypertension can result from various factors including genetics, lifestyle choices, stress, and certain medical conditions.

Question 22

Blood flow through capillary beds

Answer 22

The movement of blood through networks of tiny capillaries where the exchange of gases, nutrients, and waste products occurs between blood and tissues. Blood enters the capillary beds from arterioles, passes through the capillaries where oxygen and nutrients diffuse into tissues, and waste products like carbon dioxide are picked up. Blood then exits the capillary beds into venules, which lead to larger veins that return the blood to the heart. This process is essential for maintaining cellular health and overall homeostasis.

Question 23

Blood return through veins

Answer 23

The process by which deoxygenated blood is transported back to the heart from the body’s tissues.
Veins have valves that prevent backflow and rely on muscle contractions and pressure changes from breathing to assist blood flow. This blood returns to the heart through larger veins, such as the superior and inferior vena cava, ensuring continuous circulation.

Question 24

Blood

Answer 24

Vital fluid in the body that transports oxygen, nutrients, hormones, and waste products. It consists of red blood cells (which carry oxygen), white blood cells (which fight infection), platelets (which help with clotting), and plasma (the liquid component).

Question 25

Red blood cells (erythrocytes)

Answer 25

Most abundant cells in the blood. They contain hemoglobin, a protein that binds to oxygen, allowing red blood cells to transport oxygen from the lungs to the body’s tissues and return carbon dioxide back to the lungs for exhalation.
Red blood cells are biconcave in shape, which increases their surface area for gas exchange and flexibility to pass through narrow capillaries.

Question 26

White blood cells (leukocytes)

Answer 26

The contain a nuclei, lack hemoglobin, larger in size.
These cells are a crucial part of the immune system. They help defend the body against infections, diseases, and foreign invaders. White blood cells are produced in the bone marrow and circulate in the blood and lymphatic system. There are several types with different roles such as identifying, attacking, and destroying pathogens, as well as coordinating immune responses.

Question 27

Platelets (thrombocytes)

Answer 27

Cell fragments in the blood that play a key role in blood clotting. When a blood vessel is injured, platelets gather at the site and adhere to the damaged vessel wall through their membranes. They release chemicals that convert fibrinogen, a blood protein, into fibrin, forming a mesh that stabilizes the platelet plug and creates a stable blood clot to prevent excessive bleeding.

Question 28

Cardiovascular disease

Answer 28

A group of disorders affecting the heart and blood vessels. It includes conditions such as coronary artery disease, hypertension, heart failure, arrhythmias, and stroke. Cardiovascular disease is often associated with atherosclerosis (the buildup of plaque in the arteries), which can lead to reduced blood flow and heart attacks.

Question 29

Human respiratory system

Answer 29

The organ system responsible for the exchange of gases (oxygen and carbon dioxide) between the body and the environment.
It consists of the upper respiratory tract (including the nose, nasal cavity, pharynx, and larynx) and the lower respiratory tract (including the trachea, bronchi, bronchioles, alveoli, and lungs).

1. Air enters the body through the nose or mouth and travels down the respiratory tract to the lungs.
2. Transport of O2 from the lungs to the rest of the body via the circulatory system. The blood also carries CO2 from the tissues back to the lungs.
3. O2 diffuses from red blood cells into body cells. The delivered O2 is then used to make ATP from food via cellular respiration and that same process produces CO2 as a waste product that diffuses from the cells to the blood.

Question 30

The path of air

Answer 30

1. Pharynx: Air enters through the nose or mouth and passes through the pharynx, a cavity at the back of the throat where the respiratory and digestive pathways intersect.
2. Larynx: From the pharynx, air moves into the larynx, also known as the voice box, which contains the vocal cords and serves as the passage for air between the pharynx and trachea.
3. Trachea: The trachea, or windpipe, is a tube composed of cartilage rings that carries air from the larynx to the bronchi. It is located in front of the esophagus and is protected by the epiglottis, a flap of tissue that prevents food from entering the airway during swallowing.
4. Bronchi: The trachea branches into the left and right bronchi, which lead to the lungs. Each bronchus enters a lung and branches further into smaller bronchioles.
5. Alveoli: Bronchioles terminate in clusters of tiny air sacs called alveoli, where gas exchange occurs. Oxygen from inhaled air diffuses across the alveolar membrane into the bloodstream, while carbon dioxide moves from the bloodstream into the alveoli to be exhaled.

This pathway ensures that air is filtered, humidified, and warmed as it travels to the lungs, allowing for efficient gas exchange between the respiratory system and the bloodstream.

Question 31

The brain´s control over breathing

Answer 31

During exercise, control centers in the brain send signals to the body that increase breathing rate and depth.

1. During exercise, the cellular respiration produces more ATP for the muscles and raises the amount of CO2 in the blood.
2. The brain senses the higher CO2 level.
3. Breathing control centers send information (nerve signals) to rib cage and diaphragm muscles that contract to increase the breathing rate and depth of ventilation. (Balance).

Question 32

Diaphragm

Answer 32

A dome-shaped muscle separating the chest and abdominal cavities.

When inhaling: rib cage expands as rib muscles contract, diaphragm contracts (moves down).

When exhaling: rib cage gets smaller as rib muscles relax, diaphragm relaxes (moves up)

Question 33

Role of hemoglobin in gas transport

Answer 33

Oxygen cannot dissolve in blood and therefore O2 does not tend to move from the air to the blood independently.
O2 must be loaded into red blood cells before it can be transferred through the blood.

The oxygen binds to hemoglobin, which consists of 4 polypeptide chains. Attached to each polypeptide is a chemical group called heme, at the center of which is an atom of iron. Each iron atom can hold 1 molecule of O2 (each hemoglobin can therefore hold 4 O2). Hemoglobin transports O2.