gas exchange + transport

How are the airways kept clean?

- Goblet cells secrete mucus

- Mucus traps the dirt/bacteria

- Cilia (cells with hairlike structures) waft mucus up to mouth

- Mucus is swallowed and destroyed by hydrochloric acid in stomach

What is ventilation?

Movement of air into and out of the lungs

Describe the process of breathing in (inhalation)

-External intercostal muscles contract

- Ribs move up and out

- Diaphragm contracts and flattens

- Volume inside thorax increases

- Pressure decreases

- Air is sucked into the lungs

Describe the process of breathing out

• Internal intercostal muscles contract

• Ribs move down and in

• Diaphragm relaxes and become dome shaped

• Volume inside thorax decreases

• Pressure increases

• Air is forced out of the lungs

Compare inhaled and exhaled air

- Inhaled air contains more oxygen and less carbon dioxide than exhaled air

How are the alveoli adapted for gas exchange?

• Large surface area

• Good blood supply

• Thin walls - short diffusion pathway

• Moist - dissolve gases

Describe the effects of smoking on the body

• Cilia are paralysed → build up of mucus and pathogens → smoker’s cough → bronchitis

• Smoke damages alveolar walls → walls break down → decreased surface area for gas exchange → emphysema

• Carcinogens → tumour growth → lung cancer

• Carbon monoxide combines irreversibly with haemoglobin in red blood cells → forms carboxyhaemoglobin → less oxygen transported → reduced respiration rate

Why can unicellular organisms (e.g. amoeba) rely on diffusion for movement of substances into and out of the cell?

• Large surface area to volume ratio

• Short diffusion distance

Why do animals need circulatory systems?

- Surface area to volume ratio is too small

- Diffusion is too slow

- Circulatory system needed to transport oxygen

What is the role of the phloem?

Transports sugars from leaves to growing regions/roots for storage i.e. Both up and down the shoot

Describe the structure of phloem

• Sieve tubes with sieve plates in between

• Companion cells contain lots of mitochondria for release of energy

What is the role of the xylem?

- Transports mineral ions and water from roots to flowers i.e. Up the shoot only

Describe the structure of xylem

Hollow forming a continuous column - no cytoplasm

Lignin gives the xylem strength and support

List the components of the blood

Plasma- White blood cells (phagocytes and lymphocytes)

Red blood cells- Platelets

What does the blood transport?

Oxygen from the lungs to other parts of the body-

Carbon dioxide from other parts of the body to the lungs

Nutrients from the gut to all parts of the body

Urea from liver to kidneys

List substances transported in the plasma

Carbon dioxide- Urea- Glucose- Amino acids- Hormones

How are red blood cells adapted for their function?

Biconcave disc shape - large surface area for transport of oxygen

Haemoglobin binds to oxygen forming oxyhaemoglobin

No nucleus - more space for haemoglobin

How does the body prevent pathogen entry?

Skin acts as a barrier

HCl in stomach destroys pathogens

Hairs prevent entry

Platelets clot the blood at the site of a wound

How do white blood cells attack invading pathogens?

Phagocytes engulf pathogens

Lymphocytes recognise antigens and produce antibodies which destroy pathogens

Antitoxins made

How do lymphocytes destroy pathogens?

Recognise antigens

Make antibodies (proteins) which destroy pathogens by: Causing bacteria to stick together Label pathogen so it’s easily recognisable by phagocytes Produce antitoxins Cause bacteria to burst

Explain how the body usually responds to foreign proteins

• White blood cells recognise antigens

• Ingest foreign proteins by phagocytosis

• Antibodies produced

• Memory cells produced

  • Provide faster response upon reinfection

Describe the movement of the blood around the body starting at the right atrium

• Deoxygenated blood enters the right atrium via the vena cava

• Right atrium contracts forcing blood through tricuspid valve into right ventricle

• Blood enters the right ventricle and leaves via the pulmonary artery

• Blood flows to the lungs and becomes oxygenated

• Blood returns to the heart and enters the left atrium via the pulmonary vein

• Left atrium contracts forcing blood through bicuspid valve into the left ventricle

• Left ventricles contracts forcing blood into the aorta

• Oxygenated flows around the body and is used in respiration

How is our heart rate increased?

Adrenaline increases heart rate

When we exercise, muscles produce carbon dioxide

Receptors in aorta and carotid artery detect increase in carbon dioxide

Electrical impulses sent to medulla

Accelerator nerve raises heart rate

What is the coronary artery?

Blood vessel that supplies the heart with oxygen

What factors contribute to coronary heart disease?

Heredity

- High blood pressure

- Diet - high levels of saturated fat and cholesterol

- Smoking

- Stress

- Lack of exercise

Explain how coronary heart disease can cause death

• A lot of cholesterol can block coronary artery

• Less oxygenated blood to heart muscle cells

• Less aerobic respiration, more anaerobic respiration

• Lactic acid build up causes heart attack

What does single circulation mean?

Blood is pumped from the heart to the lungs and then to rest of the body

What does double circulation mean?

Blood flows twice into the heart for every once around the body

What does the circulatory system consist of?

-Heart

- Arteries, veins and capillaries

- Blood

Why is the wall of the ventricles thicker than that of the atria

The ventricles have to pump the blood further

Why is the wall of the left ventricle thicker than that of the right ventricle?

- Blood from the right ventricle is only pumped to the lungs

- Blood from the left ventricle is pumped much further - around the whole body

Describe the structure of arteries

-Thick muscle and elastic fibre walls

- Narrow lumen

- High blood pressure

Why are the artery walls so thick?

To withstand the high pressure of the blood flowing inside

Describe the structure of the veins

- Thin muscle and elastic fibre walls

- Large lumen

- Lower blood pressure

- Semi-lunar valves prevent the back flow of blood

Describe the structure of the capillaries

-Thin walls - one cell thick

- Short diffusion distance
- Narrow lumen

Name the blood vessel that takes oxygenated blood to the kidney

Renal artery

Name the blood vessel that takes deoxygenated blood from the kidney

Renal vein

Name the blood vessel that takes oxygenated blood to the liver

Hepatic artery

Name the blood vessel that takes deoxygenated blood from the liver

Hepatic vein