Respiratory & Circulatory System YR 11

Functions of the Respiratory System

• Obtain oxygen from external environment for cellular respiration

• Remove carbon dioxide from body that was produced during cellular respiration

Relationship between the respiratory and circulatory system.

Respiratory system: takes in oxygen and removes carbon dioxide

Circulatory system: transports oxygen and carbon dioxide around body to/from cells

Nasal Cavity

Structure:

Hairs, lysosomes, mucus membrane

Function:

Warm, humidify (moisten) and filter air

Pharynx

Structure:

Lymphoid tissue, mucous membrane, muscle, submucosal connective tissue

Function:

Passage for both air and food and water to trachea and oesophagus

Epiglottis

Structure:

Flap of elastic cartilage

Function:

Blocks the trachea during swallowing to prevent food and drink entering the trachea

Larynx

Structure:

Cartilage at the top of the trachea

Function:

Contains mucous membrane flaps that vibrate to produce speech (aka voice box)

Trachea

Structure:

Windpipe compose of c shaped rings of cartilage , lined with cilia and mucous membrane.

Function:

Passage of air to the lungs, also filter air

Bronchi

Structure:

Contain c-shaped cartilage that spaces further apart as the bronchi diameter decreases. Increase in smooth muscle and elastin. Contains cilia and mucus membrane.

Function:

Passage of air into each lung, also filters air

Bronchioles

Structure:

Composed of elastin and smooth muscle, lined with mucous membrane and cilia.

Function:

Controls flow of air into the lungs (able to expand), filters air.

Alveoli

Structure:

Sacs at the end of the bronchioles. One cell thick. Covered in capillaries. Moist surface.

Function:

Site of gas exchange

Ribs

Structure:

Bones

Function:

Site for muscle attachment and protection of underlying organs

Intercostal Muscles

Structure:

Skeletal muscle between ribs

Function:

Move ribs to increase / decrease volume during breathing

Diaphragm

Structure:

Skeletal muscle that separates the abdomen and thorax

Function:

Involved in breathing

Ventillation

The movement of air in and out of the lungs

Inspiration

The movement of air INTO the lungs

Expiration

The movement of air OUT of the lungs

What determines the direction of movement of air during ventilation?

Air moves from an area of high pressure to low pressure. During inspiration, the volume of the chest cavity is increased, leading to decreased pressure. During expiration, the volume of the chest cavity is decreased to increase the pressure.

Process of inspiration

• Diaphragm contracts / flattens

• External intercostal muscles contract and move ribs out and up

• This increases the volume of the chest cavity

• This results in a decrease in pressure within the chest cavity

• Therefore, air moves from high (environment) to low (body)

Process of expiration

• Diaphragm relaxes and bulges upwards

• Intercostal muscles relax, moving ribs down and in

• This results in an increase in pressure within the chest cavity

• Therefore, air moves from high (chest cavity) to low (environment)

Difference between relaxed and forced breathing.

• Relaxed (normal) breathing – passive, relaxation of muscles

• Forced (heavy) breathing – contraction of internal ICM to actively lower ribs

5 factors of the lungs that facilitate efficient gas exchange

1. Surface area: Small, round, hundreds of thousands of alveoli resulting in huge surface area = Allows for rapid diffusion

2. Blood supply: Alveoli is well supplied with capillaries = Maintains steep concentration gradient by constantly moving oxygen away from alveoli

3. Thin: One cell thick wall alveoli = Less distance for gas to travel increases rate of diffusion

4. Moist: Lungs are located deep in the chest to avoid evaporation = Gasses need to dissolve before they diffuse

5. Ventilation: Lung volume is changed by respiratory muscles = Maintains concentration gradient for rapid gas exchange

Systemic and Pulmonary circulation.

• PC: blood from R side to L side of the heart which goes to the lungs

• SC: blood flowing from L side to R side of the heart going to the tissue of the body

Eight functions of blood.

• Transport O2 and nutrients to cells

• Remove CO2 and waste from cells

• Transport hormones

• Maintain pH and fluid levels

• Maintain body temp

• Maintain water content and ion levels

• Defend body against disease

Plasma

• 91% water 9% dissolved substances (nutrients, oxygen, waste)

• Function is to transport the components of blood throughout the body

Erythrocytes = RBC

• Biconcave shape, no nucleus, contains haemoglobin

• Originates in bone marrow

• Lifespan of 120 days

• Function is to transport oxygen from the lungs to cells for respiration

Leucocytes = WBC

• Larger than RBC, may contain ribosomes and digestive enzymes

• Originates in bone marrow

• Lifespan of 120 days

• Function is to defend the body against disease causing microorganisms

Thrombocytes = Platelets

• Tiny cell fragments, no nucleus

• Originate in bone marrow

• Lifespan of 5-9 days

• Function is blood clotting and to assist in the repair of damaged tissue

How nutrients and wastes transported in blood

Nutrients:

Inorganic nutrients are transported as ions eg Na+ Ca2+ Organic nutrients dissolve in plasma eg glucose, vitamins, amino acids, fatty acids

Wastes:

Metabolic wastes (substances produced by cells) such as urea, creatine and uric acid are transported in solution in blood plasma

Transport of Oxygen

Dissolved in blood plasma (3%)

Combines with haemoglobin as oxyhaemoglobin (97%)

[Haemoglobin + oxygen → oxyhaemoglobin]

Formation and breakdown oxyhaemoglobin

Formation: Formed around the capillaries around the alveoli - O2 concentration is higher in alveoli than in the blood. O2 form the air in the alveoli diffuses into the blood in the capillaries.

Breakdown: Capillaries around the cells of the body - Body cells continually use O2 -Tissue fluid around body cells have lower O2 concentration than in the blood in the capillaries. O2 diffuses from blood in the capillaries into tissue fluid and then into body cells

Two structural features of erythrocytes that make them suited to their function

One: high SA/V ratio allows for more haemoglobin to bond to oxygen

Two: no nucleus allows for more haemoglobin carrying capacity

Transport of Carbon Dioxide

One: Dissolved in plasma (7-8%)

Two: Combined with haemoglobin to form carbaminohaemoglobin (22%)

Three: In plasma as bicarbonate ions (70%)

Formation and breakdown carbaminohaemoglobin

Formation: Capillaries around the cells of the body - CO2 diffuses from the body cells (High CO2 concentration) into the blood (low CO2 concentration) and binds to haemoglobin in the red blood cell.

Breakdown: Capillaries around the alveoli - CO2 detaches from the haemoglobin and diffuses from the red blood cell (High CO2 concentration) into plasma and then into alveoli (low CO2 concentration) to be exhaled.

Reaction of carbon dioxide and water.

Carbon dioxide + water ↔ carbonic acid ↔ hydrogen ions + bicarbonate ions

CO2 diffuses from body cells into the blood plasma (water), there it reacts to form carbonic acid. Carbonic acid then ionises into hydrogen ions and bicarbonate ions. Near the alveoli, the bicarbonate ions and hydrogen ions combine into carbonic acid which breaks down into carbon dioxide and water (the CO2 will then diffuse across the blood into the alveoli).

Blood clotting

1. Vasoconstriction: the smooth muscle in the walls of the blood vessels contract, making the lumen smaller (constriction) reducing blood flow to the area

2. Platelet Plug: If there is damage to the blood vessel walls, the rough surface allows platelets to stick Sticking platelets attracts other platelets to the area build up of a platelet plug to reduce blood loss Platelets release substances that cause vasoconstriction Sufficient for small capillary tears

3. Fibrin Clot: The platelets at the plug become activated and react with clotting factors (chemical substances) Complex series of events create insoluble protein threads called fibrin Fibrin forms a mesh that traps RBC, plasma and platelets. This is now called a clot or thrombus

4. Clot Retraction: Network of threads contract, becoming denser and stronger, pulling the walls of the damaged vessel together As the clot retracts, a fluid called serum leaks out Clot then dries forming a scab

Antigen

Sugar molecules on the surface of red blood cells that acts as a marker to the immune system

Antibody

Protein produced by the immune system that recognize foreign molecules

Antigen-Antibody complex

Antibodies are specific and will only recognize a certain antigen. If the right antigen and antibody come in contact, a complex form. Like the lock and key of an enzyme and substrate.

Agglutination

The clumping together of erythrocytes when the specific antigen and antibody combine and form a complex.

Describe the Rh blood system.

There is another antigen that may be present on the surface of erythrocytes called the Rhesus antigen, which is a protein. If the antigen is present, the person is Rhesus positive.

Define blood transfusion

It involves blood, or a blood product, from a donor being injected directly into the patient's bloodstream.