9b. gas exchange in mammals and plants

tissue

group of similar cells in one or more different types, where are specialised to carry out particular function

organ

structural and functional unit composed of a collection of tissues working totters to perform a particular function

epithelial tissue

tissue that line surfaces

connective tissue

tissue that holds structures together and provides support eg bone, blood and cartilage

muscle tissue

tissue that is able to contact to move parts of the body

nervous tissue

tissue that converts stimuli to electrical impulses and conducts impulses

squamous epithelium

single layer of flattened cells resting a basement membrane, gives smooth lining surface to reduce friction in blood vessels and heart chamber and provides a short diffusion dunce in alveoli and capillaries

ciliated epithelium

columnar epithelial cells extending from surface, interspersed with goblet cells to produce mucus, to trap dirt and bacteria in trachea, and beat with ATP to move mucus

trachea

A, has a large lumen, lined with ciliated epithelium, supported by rings of cartilage

bronchus

B, one goes to each lung, narrower lumen, lined with ciliated epithelium, supported by rings of cartilage 

Bronchioles

C, smaller and more branched, may in each lung

alveoli

D, small pockets where gas exchange occurs

diaphragm

E, contracts and moves down when you inhale

Ribs

F, protects the lungs

pleural fluid

G, acts as a lubricant and protects lungs during ventilation

pleural membranes

H, forms an airtight cavity

intercostal muscles

I, antagonistic muscles that move the ribcage

C rings of cartilage

to prevent collapse of trachea during inhalation, allow back to bend and allow passage of food down oesophagus

smooth muscle

contacts to narrow lumen of bronchioles to reduce airflow an rent airborne particles entering lungs

electric fibres

recoil to original length when smooth muscle relaxes so widens lumen

short diffusion distance

due to alveoli walls been composed of one cell thick of squamous epithelium

expel air

elastic fibres recoil in alveolar walls

surfactant

secreted by alveoli walls to reduce surface tension of water to prevent alveoli collapsing during expiration

phagocytic cells

in the alveoli to engulf bacteria/foregin articles that reach there

efficient gass exchange surface

features include, large surface area, thin to allow a short diffusion distance, steep concentration gradient maintained by a fresh supply of molecules on one side and removal on the other

pulmonary ventilation

moment of diaphragm and ribcage during breathing

inspiration

movement of air into lungs by:

* diagram contracting and flattening
* external intercostal muscles contract to move rib cage upwards and outwards
* volume of chest vanity increases
* pressure in chest cavity decreases below atmospheric pressure

forced expiration

mount of air out lungs by:

* diaphragm relaxing and returning to domed shape,
* internal intercostal muscles contact to move ribcage downwards and inwards
* volume of chest cavity decreases
* pressure in chest cavity increases above atmospheric pressure

punctured lung

causes the chest cavity to no longer be airtight so pressure cannot change relative to external pressure, preventing ventilation

tital volume

volume of air inhaled in one breath during steady regular breathing typically 05.dm3.

breathing rate

number of breaths per minute

residual volume

volume of air that always remains in lungs after expiration, typically 1.5dm3

vital capacity

maximum volume of air exhaled after a deep breath in typically 5dm3, depends on age sex and fitness

total lung capacity

volume of lungs equals vital capacity plus residual volume

pulmonary ventilation rate

volume of air passing though lungs in one minute. breathing rate x tidal volume dm3 min-1

dead space

air present in trachea, branch and bronchioles where no gas exchange takes place with the blood

forces expiration volume (FEV1)

volume of air that can be breathed out in the first second of forced exhalation

= (4.3 x height (in mm) - 0.029 x age (in years)) - 2.49

peak expiratory flow rate PEFR

maximum rate of forcing air out the mouth measured with a peak flow meter, influenced by height, sex and age, greater at about 30-35 years old, effected by asthma or COPD

respiratory arrest

when a person stops breathing

causes of respiratory arrest

obstruction of airway blocking the trachea or bronchi

drug overdose that results in nervous system an the breathing system being depressed sufficiently to stop

asthma attack, sever pneumonia, severe shock, or heart attack

near drowning

expired air resuscitation

emergency first aid procedure used if someone suffers respirator arrest

mechanical ventilation

used to assist or replace spontaneous breathing, may involve use of ventilator to push air into lungs or suck air out lungs (iron lung)

8, 1, 3, 4, 2, 6, 5, 7, 9

order statements for process of expired air resuscitation:


1. Roll person onto back
2. Pinch nostrils closed and make a tight seal over the patient’s mouth with your own
3. Remove any obstruction visible in mouth with finger
4. Push forehead back and tilt chin to open airway
5. Wait for chest to fall then blow again
6. Blow gently into mouth and watch chest rise
7. After two breaths check pulse
8. Call for help, wear sterile gloves and mask if available
9. If there is a pulse continue blowing through mouth. If there is no pulse perform CPR.

EAR resuscitate unconscious person

as expired air still contains about 16% oxygen and a higher level of carbon dioxide in expired air also stimulates breathing

EAR with a small child

don’t tilt head back as far

make a seal with mouth and nose

reduce volume of breaths but increase frequency

lenticels or stomata

where most gas exchange happens in plants

cuticle

A, waterproof to reduce water loss by evaporation

upper epidermis

B, transparent to allow light through

palisade mesophyll cel

C, many chloroplast to carry out photosynthesis

xylem

D, bring water and mineral ions from the roots

phloem

E, take the products of photosynthesis to other parts of the plant

spongy mesophyll cell

H, air spaces to allow circulation of gases

guard cell

I, open or close stoma

lower epidermis

F, transparent to allow light through, on underside

stoma

J, allow gases to diffuse in and out of leaf

stomata

pores in leaves which allow carbon dioxide in and oxygen out during the day

leaf adaptations

thin/cell have thin cell walls so short diffusion distance

large surface area for gas exchange

many stomas an large air spaces in spongy mesophyll to allow diffusion of gases

steep concentration gradient maintained by using carbon dioxide

transpiration

loss of water by evaporation from aerial parts of a plant, as water evaporates from cell walls of mesophyll into air spaces in leaf, then lost down water vapour potential gradient

prevent water loss

waxy cuticle- limits where can be lost

guard cells can close stomata

turgid

state where stomata open as the are vacuoles full

flaccid

state when stomata are closed as stomata aren’t full

cellulose microfibrils

arranged in hoops around cell so cell only increase in length when it becomes turgid

chloroplast

absorb light to produce ATP to open stoma

thick inner cell wall

compared to thin outer cell wall so guard cell bend more result to become banana shaped to open stoma

2, 3, 1, 4

order steps of stomata opening:


1. Water enters guard cell by osmosis down its water potential gradient
2. Active transport of K+ into the guard cells (using ATP produced in photosynthesis)
3. This lowers the water potential of the guard cell
4. Guard cell becomes turgid and stoma opens

nail polish imprint

used to reveal distribution of stomata in upper and lower epidermis of plants, can be viewed under microscope

1, 6, 2, 4, 5, 7, 8, 3a

order steps for process of nail polish implant


1. Paint clear nail varnish onto the surface of a leaf
2. Examine using a light microscope at high magnification
3. Calculate the density of stomata per mm2
4. Count the number of stomata in the field of view
5. Repeat count at least five times and calculate mean
6. Peel off the dried layer of nail varnish
7. Measure the diameter of the field of view using a stage micrometer and calculate the area of the field of view
8. Calculate the area of the field of view

advantage of high density of stomata

treated has exchange for photosynthesis

disadvantage of high density of stomata

greater water loss by transpiration