exchange surfaces

Question 1

What are the features of a good exchange surface?

Answer 1

large surface area
- more molecules diffuse at once
short diffusion distance
- efficient exchange
rich blood supply
- higher concentration gradient
ventilation
- maintain a concentration gradient

Question 2

what is cartilage?

Answer 2

• rings around trachea
• support but also allows it to move and flex as we breathe

Question 3

what is ciliated epithelium?

Answer 3

• tall cells with hair-like structures
• waft mucus, dust and bacteria away from lungs

Question 4

what are goblet cells?

Answer 4

• scattered in ciliated epithelium
• secrete mucus

Question 5

what is the squamous epithelium?

Answer 5

• lines alveoli walls
• flattened
• very thin for shortened diffusion distance hence faster diffusion rate

Question 6

what is smooth muscle?

Answer 6

• lines bronchi and bronchioles
• regulates airflow by dilating and relaxing

Question 7

what is the trachea?

Answer 7

• funnels air
• strong and flexible to prevent collapse

Question 8

what are bronchi?

Answer 8

• where the trachea splits
• cartilage and smooth muscle
• ciliated and goblet cells

Question 9

what are bronchioles?

Answer 9

• where the bronchi splits
• elastic fibres for stretch and recoil

Question 10

what are alveoli?

Answer 10

• gas exchange
• SA:V ratio
• capillaries for blood flow

Question 11

how are alveoli are adapted for efficient gas exchange?

Answer 11

• large numbers to increase surface area
• elastic fibres to stretch ad recoil and increase surface area
• increasing surface area allows more molecules to pass through (higher diffusion rate)
• thin walls that are 1 cell thick to reduce diffusion distance
• well ventilated and a good blood supply to maintain a steep concentration gradient

Question 12

what happens during inspiration?

Answer 12

• external intercostal muscles cotract to elevate ribs
• diaphragm moves down and contracts
• air pressure in the lungs decreases
• air moves in

Question 13

what happens during expiration?

Answer 13

• internal intercostal muscles contract
• diaphragm relaxes and moves up
• air pressure in the lungs increases
• air moves out of lungs

Question 14

what is vital capacity?

Answer 14

max vol out after max vol in

Question 15

what is tidal volume?

Answer 15

resting breathing rate

Question 16

what is inspiratory reverse volume?

Answer 16

• maximum air in

Question 17

what is expiratory reverse volume?

Answer 17

maximum air out

Question 18

what is residual volume?

Answer 18

volume of air left in lungs after you breathe out completely

Question 19

what is the equation for total capacity?

Answer 19

residual + vital

Question 20

what is the equation for ventilation rate?

Answer 20

breathing rate x tidal volume

Question 21

what is the spiracle?

Answer 21

opening in the exoskeleton of an insect that allows air to enter and closes when inactive or low oxygen demands

Question 22

what are the tracheae?

Answer 22

airways lined with chitin spirals to stay open under pressure

Question 23

what are the tracheoles?

Answer 23

site of gas exchange

Question 24

what is the fluid involved in gas exchange in insects?

Answer 24

tracheal fluid

Question 25

why is a counter current system necessary in fish?

Answer 25

maintains a concentration gradient of oxygen

Question 26

ventilation mechanism in fish

Answer 26

- mouth opens and buccal floor lowers - volume increases so pressure decreases - water flows in and mouth closes - water is pushed into the gill cavity - operculum is forced open and water exits the fish

Question 27

describe how you would carry out the dissection to display maximum detail of gas exchange system in fish and in insects

Answer 27

fish - remove operculum - place underwater and place a pencil in buccal cavity to inspect lamellae insect - cut open exoskeleton - stain tracheoles with methylene blue

Question 28

what is the function of lamellae?

Answer 28

increase surface area to volume ratio for efficient diffusion of gases like oxygen or carbon dioxide

Question 29

how does the insect transport system and fish gills provide a large SA:V ratio?

Answer 29

- many branched tracheae - many lamellae

Question 30

compare normal expiration to forced expiration.

Answer 30

normal - passive - diaphragm relaxes and moves up - volume of lungs decreases and pressure increases - atmospheric pressure is lower so air moves out of the lungs forced - active (requires energy) - contraction of abdominal so diaphragm is forced up - ribs are forced down hard

Question 31

suggest why smaller insects do not need such well-developed exchange surfaces and transport systems

Answer 31

- larger sa:v ratio - smaller diffusion distance - can keep up with insect's metabolic demands - dont have a hard exoskeleton so o2 can diffuse through skin

Question 32

how is the trachea of a mammal different to the tracheae of an insect?

Answer 32

- mammals have one trachea and insects have multiple - mammals trachea have a larger diameter than insects - mammals have cartilage rings whereas insects have chitin - mammals branch into bronchioles whereas insects branch into tracheoles

Question 33

why do goblet cells need mitochondria and lots of golgi apparatus?

Answer 33

- production of lots of ATP - golgi moifiesand packages proteins to be transported out of the cell by exocytosis

Question 34

for each structure of the mammalian exchange system, explain how it increases the efficiency of gaseous exchange

Answer 34

nasal cavity - large surface area and good blood supply to warm the air - goblet cells secrete mucus to trap dust and bacteria trachea - cartilage rings to prevent collapse - cilliated epithelium and goblet cells secrete mucus, trap dust and waft them to the stomach - smooth muscle allows air to move in and out to maintain high conc gradient alveoli - thin epithelial walls that decrease diffusion distance - elastic fibres that recoil to move air out during exhalation - large number to increase surface area and increase rate of diffusion - good blood supply to maintain high concentration gradient

Question 35

how would allergens causing the smooth muscle to contract affect ventilation?

Answer 35

- reduces diameter of bronchi - less air can be exhaled

Question 36

compare the circulations of a frog and a mammal and the relative effectiveness of each type of circulation

Answer 36

- both have double systems - both have 2 atria but frogs only have 1 ventricle - in mammals the oxygenated and deoxygenated never mix which allows for more efficient gas exchange due to the high oxygen concentration - this means mammalian systems are highly effective - in frogs the blood isnt fully separated so lower rate of gas exchange - less effective than mammals but effective enough to meet the metabolic demands of the frog