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.

Explain why it is necessary to match the blood groups of the donor and the recipient.

• If a person receives red blood cells with an antigen that is different to their own

• Their complimentary antibodies will form an antigen-antibody complex

• Resulting in agglutination and potential health complications/death

Which blood type is often referred to as the universal donor.

O+, as there are no antigens on the surface of red blood cells, no antigen-antibody complex (resulting in agglutination) will result even if given to blood types containing anti-A or anti-B.

Which blood type is often referred to as the universal recipient

With AB blood have blood with both antigen A and antigen B present. Therefore there is no Anti-A or Anti-B in their plasma. Therefore regardless of the antigen on the surface of the RBC’s they are donated, no antigen-antibody complex will form therefore no agglutination.

Define circulation

Continuous movement of blood through the heart around the body. Carried by blood vessels.

Artery

Function:

Carry blood AWAY from the heart

Structure:

Thick wall of smooth muscle + elastic tissue, Small lumen, No valves

Pressure:

High pressure Pressure not constant - alters between ventricle contractions

Pulse:

Present Elastic artery wall stretches to accommodate blood. Then will recoil to keep blood moving and maintain pressure

Aorta, Pulmonary artery

Vein

Function:

Carry blood TOWARD the heart

Structure:

Thin wall of little smooth muscle + elastic tissue, Large lumen, Valves present (blood flow in one direction)

Pressure:

Low constant pressure

Pulse:

Absent

Inferior & superior vena cava, Pulmonary vein

Capillary

Function:

Site of gas exchange

Structure:

Microscopic Walls are 1 cell thick

Pressure:

Medium / low

Pulse:

Absent

Vasodilation

Smooth muscle relaxes, increasing lumen size, increase blood flow to area

Vasoconstriction

Smooth muscle contracts, decreasing lumen size, decreasing blood flow to area

Carbon dioxide and lactic acid as vasodilators

Carbon dioxide is produced during aerobic respiration, lactic acid is produced during anaerobic respiration. This means that there is a demand for oxygen as there is an increase in cellular respiration. Vasodilation allows more blood to be taken to the area of production of these waste products, increasing oxygen supply and also removing the wastes produced

Right Atrium

Structure:

Thin walled chamber

Receives deoxygenated blood from vena cava

Function:

Passes blood to right ventricle

Right Ventricle

Structure:

Thick walled chamber

Receives deoxygenated blood from atrium

Function:

Pumps blood to lungs

Left Atrium

Structure:

Thin walled chamber

Receives oxygenated blood from pulmonary vein

Function:

Passes blood to left ventricle

Left Ventricle

Structure:

Very thick walled chamber

Receives oxygenated blood from atrium

Function:

Pumps blood to body

Vena Cava

Structure:

Superior from upper body

Inferior from lower body

Function:

Carries deoxygenated blood to the right atrium

Pulmonary Artery

Structure:

The only artery in the body that carries deoxygenated blood

Function:

Carries blood from right ventricle to lungs

Pulmonary Vein

Structure:

The only vein in the body that carries oxygenated blood

Function:

Carries blood from lungs to left atrium

Aorta

Structure:

Very thick wall

Function:

Carries blood from left ventricle to the body

Atrioventricular Valves

Structure:

Thin flaps of tissue held by chordae tendinea which are pulled by papillary muscles

Function:

Prevent backflow of blood into the atria

Papillary muscles

Structure:

Composed of cardiac muscles

Function:

Contract to close the A-V valve

Chordae Tendineae

Structure:

Tendons that attach cusp to papillary muscles

Function:

Pull cusp closed when papillary muscles contract

Pulmonary valve (semilunar)

Structure:

When blood flows in, the cusps are pushed against the artery wall

Function:

Prevent backflow of blood into the right ventricle

Aortic valve (semilunar)

Structure:

When the ventricle contracts and blood tried to flow back, the cusps fill out and seal off the artery

Function:

Prevent backflow of blood into the left ventricle

Septum

Structure:

Muscle that separates left and right sides of heart

Function:

Prevents oxygenated and deoxygenated blood from mixing

Apex

Structure:

Pointed tip of heart

Left ventricle muscle

Pericardium

Structure:

Membrane that encloses the heart

Function:

The pericardium holds the heart in place and prevents the heart from overstretching

Atrioventricular valves

Location:

Between atriums and ventricles

Structure:

• Atrioventricular valves are flaps of thin tissue

• Edges held by the chordae tendineae

• Attach to the heart on papillary muscles

How they prevent backflow:

When the ventricles contract, blood catches behind the flaps and they billow out like a parachute, sealing off the opening between the atria and the ventricles. Blood must then leave the heart through the arteries and not flow back into the atria.