structure and function (gas exchange in humans)

5 features of exchange surfaces and what they do

1. many molecules can diffuse across at the same time → faster diffusion, more space for diffusion

2. very thin → short diffusion distance → faster diffusion

3. permeable → allows substances to cross exchange surface

4. (in animals) - good blood supply → maintains steep concentration gradient

5. good blood supply of external media → maintains steep concentration gradient

label body diagram

*where is nasal cavity, pleural cavity + fluid inside, bronchiole

	definition and why
ribs
intercostal muscles
diaphragm
trachea
larynx
bronchi
bronchioles
alveoli
pleural cavity	and why its there

	definition
ribs	bones that protect internal organs like the lungs/heart
intercostal muscles	muscles between the ribs that control their movement (for inhalation/exhalation)
diaphragm	sheet of connective tissue and muscle at the bottom of the thorax to help change volume of thorax to allow for inhalation/exhalation (is a muscle)
trachea	windpipe that connects mouth/nose to the lungs
larynx	voice box, air passes through and makes a sound
bronchi	2 tubes branching off trachea into lungs
bronchioles	many smaller tubes branching off bronchi to connect to alveoli
alveoli	tiny air sacs where gas exchange occurs
pleural cavity	fluid-filled space between pleural membranes - reduces friction so lungs can move freely

what are the cilia and mucus

• passages down to lungs have ciliated epithelial cells - ells have tiny hairs that beat and push mucus up the passages towards the nose and throat where it can be removed

• The mucus is made by goblet cells

• mucus traps particles, pathogens, and dust and prevents them from getting into the lungs and damaging the cells there

muscles can only _____ on bones, not _____ on them

muscles can only pull on bones, not push on them

External intercostal muscles, pull the rib cage _____

Internal intercostal muscles pull the ribcage ______

External intercostal muscles, pull the ribcage UP

Internal intercostal muscles pull the ribcage DOWN

even simpler definition of diaphragm, without breathing

it separates the ___ cavity from the _______

domed thin sheet of muscle that separates the chest cavity from the abdomen

label lungs

why does trachea have rings of cartillage

to prevent trachea from collapsing during inhalation

where are the internal vs external intercostal muscles

There are 2 sets of intercostal muscles: the external, on the outside of the rib cage, and the internal, on the inside of the rib cage

what is ventilation

the process of moving air into and out of the lungs

what happens during inhalation (5)

1. external intercostal muscles and diaphragm contract.

2. external intercostal muscles pull ribs up and out, diaphragm flattens.

3. volume of thorax increases

4. air pressure decreases inside lungs

5. air is drawn into lungs

why is inhalation an ____ process?

active process

involves muscle contractions, so energy is required

describe the process of exhalation (5)

1. diaphragm relaxes (upwards) into original domed shape

2. external intercostal muscles relax - ribs drop down and in

3. volume of thorax decreases

4. increased air pressure inside lungs

5. air is forced out

during regular breathing, exhalation is a _____ process. why?

passive process

external intercostal muscles relax, and diaphragm relaxes, returns to domed shape

when is exhalation not a passive process, why

during intense exercise, forceful/strong exhales

internal intercostal muscles contract, pull ribs down and inwards, forcing air out of the lungs. external intercostal muscles relax (antagonistic pair - work in different directions to each other))

volume increase = pressure _______

volume decrease = pressure ________

volume increase = pressure DECREASE

volume decrease = pressure INCREASE

oxygen, co2, nitrogen in air vs what is exhaled

what that shows

don’t use nitrogen

produce co2

use oxygen (but not all)

how are alveoli adapted for gas exchange (5)

think wet

• Moist walls/layer of moisture - gases dissolve in the moisture helping them to pass across the gas exchange surface, faster diffusion.

• many alveoli so a massive surface are for gas exchange

• alveoli walls are one cell thick - short diffusion distance, faster diffusion

• good supply of external medium (of air via ventilation - inhalation/exhalation)- so steep concentration gradient maintained

• good blood supply - steep concentration gradient maintained

3 specific diseases smoking causes

• COPD - chronic obstructive pulmonary disease

• coronary heart disease

  • lung cancer - increased risk

3 main bad chemicals from cigarettes

Tar - carcinogen (a substance that causes cancer)

Nicotine - an addictive substance which also narrows blood vessels

Carbon monoxide - reduces the oxygen-carrying capacity of the blood

why is nicotine bad

addictive

• narrows blood vessels → increased blood pressure

• also increases heart rate

• Both of these effects can cause blood clots to form in the arteries leading to heart attack or stroke

why is carbon monoxide bad (3)

binds to ____

puts strain on ____ as ______ ______ and ____ need to increase to get the same amount of _______ into the blood

also puts strain on ____ ___ to pump the blood ______ around the body. This increases the risk of _____ and _______

binds irreversibly to haemoglobin - reduces capacity of blood to carry oxygen

strain on the breathing system as breathing frequency and depth need to increase in order to get the same amount of oxygen into the blood

also puts strain on circulatory system to pump the blood faster around the body. This increases the risk of CHD and strokes

two diseases basically caused by tar

• Chronic bronchitis is caused by tar which stimulates goblet cells and mucus glands to enlarge, producing more mucus

  • It destroys cilia and mucus (containing dirt, bacteria and viruses) builds up blocking the smallest bronchioles and leading to infections

  • A smoker's cough is the attempt to move the mucus

effect of Exercise on Breathing rate

CORMMS

• Change - change whether the student has exercised or not

• Organisms - same age, gender, size and general fitness

• Repeat - repeat the investigation several times to ensure our results are reliable

• Measurement 1 - measure the change in breathing rate

• Measurement 2 - ...immediately after exercise and each minute for the subsequent 5 minutes

• Same - type of exercise carried out, temperature of the environment, food intake of the students prior to the investigation

effect of exercise on breathing results and WHY

what about after exercise has finished, what happens to breathing rate, WHY

• Frequency of breathing increases when exercising

  • This is because muscles are working harder and aerobically respiring more and they need more oxygen to be delivered to them (and carbon dioxide removed) to keep up with the energy demand

  • If they cannot meet the energy demand they will also respire anaerobically, producing lactic acid

• After exercise has finished, the breathing rate remained elevated for a period of time

  • This is because the lactic acid that has built up in muscles needs to be removed as it lowers the pH of cells and can denature enzymes catalysing cell reactions

  • It can only be removed by combining it with oxygen - this is known as ‘repaying the oxygen debt’

  • This can be tested by seeing how long it takes after exercise for the breathing rate to return to normal

  • The longer it takes, the more lactic acid produced during exercise and the greater the oxygen debt that needs to be repaid