exchange surfaces and breathing

Question 1

how do insects carry out gaseous exchange?

Answer 1

• because insects have a rigid exoskeleton with a waxy coating gaseous exchange has to occur via the tracheal system
• air enters the insect through there spiracles.
• the air travels across tubes called the tracheae that divide into smaller tubes called tracheoles
• -

Question 2

the need for specialised exchange surfaces

Answer 2

• larger organism have a smaller SA:V
• oxygen cannot diffuse in quick enough to their metabolic needs
• There is a longer diffusion distance
• higher metaabolic activity

Question 3

features of an efficient exchange system

Answer 3

• Large surface area- provides more space for molecules to pass through e.g. root hair cells
• Short diffusion distance (thin) e.g. alveoli
• Good blood supply- maintains concentration gradient. e.g. gills, alveolous
• ventilation mechanism- replaces used air with fresh air, bringing in more oxygen and removing CO2.

Question 4

adaptations that reduce the distance have to diffuse

Answer 4

• alveolus and capillary walls are one cell thick
• consisted of squamous (flattened) cells so are thin
• capillaries are in close contact with alveolus walls
• red blood cells are squeezed against the capillary wall making them closer to the air in the alveoli

Question 5

the role of ciliated epithelial tissue and goblet cells that line the airways

Answer 5

• goblet cells secrete mucus which traps the dirt and pathogens
• the ciliated epithelial wafts the mucus to the top of the trachea where it is swallowed.

Question 6

what happens to the lungs during inspiration

Answer 6

• diaphragm contracts becoming flatter
• external intercostal muscles contact to raise the ribs
• volume in chest cavity is increased
• pressure in chest cavity drops below atmospheric pressure.

Question 7

what happens in the lungs during expiration

Answer 7

• diaphragm relaxes
• external intercostal muscles relaxes and the ribs fall. During exercise or coughing and sneezing the internal intercostal muscles contract to push air out more forcefully
• volume of chest cavity is decreased
• pressure in the lungs increases and rises above atmospheric pressure
• air mov es out along the pressure gradient

Question 8

tidal volume

Answer 8

the volume of air that is breathed in or out during normal breathing (at rest)

Question 9

breathing rate

Answer 9

the number of breaths taken in one minute (one breath = taking air in and breathing it back out again)

Question 10

oxygen uptake

Answer 10

the volume of oxygen used up by someone in a given time

Question 11

residual volume

Answer 11

the volume of air that remains in the lungs after forced expiration

Question 12

Describe ventilation in bony fish

Answer 12

• When the fish open their mouth they lower the floor of the buccal cavity. This causes the volume inside the buccal cavity to increase, which causes a decrease in pressure within the cavity
• The pressure is higher outside the mouth of the fish and so water flows into the buccal cavity
• The fish then raises the floor of the buccal cavity to close its mouth, increasing the pressure within the buccal cavity along the presure gradient
  -Water flows from the buccal cavity (high pressure) into the gill cavity (low pressure)
  -As water enters pressure begins to build up in the gill cavity and causes the operculum (a flap of tissue covering the gills)to be forced open and water to exit the Fish
  The operculum is pulled shut when the floor of the buccal cavity is lowered at the start of the next cycle

Question 13

Countercurrent flow

Answer 13

• when water flows over the gills in the opposite direction to the blood flow in the capillaries
• ensures that an equilibrium is not reached
• ensuring a diffusion gradient is maintained across the entire length of the gill lamellae

Question 14

How does a spirometer work

Answer 14

• persons breath in through the mouth piece of the spirometer inhaling medical-grade oxygen
• as a person breaths the lid chamber moves up and down
• movements are recorder by a pen that wrties on a rotating drum creating a spirometer trace.
• soda like absorbes carbon dioxide

Question 15

Precautions taken when using a spirometer

Answer 15

• subject should be healthy, free from asthma
• soda lime should be fresh and functioning
• no leaks in the apparatus as this would give invaild or inaccurate results
• mothpiece should be sterilised
• wtaer chamber must not be overfilled as watwr may enter the air tubes
• chamber filled with pure oxygen

Question 16

Why do we have water in a spirometer chamber

Answer 16

-it provides air tight seal so no air can enter the system or leave without being resistered on the graph

Question 17

How to calculate tidal volume

Answer 17

• calculate the difference between the peak and the trough of the trace

Question 18

How to measure oxygen uptake

Answer 18

• count the number of peaks pear minute

Question 19

Gas exchange in Inscets

Answer 19

• air enters through the spiracles which open when the insect is active allowing O2 to diffuse up and close when the insect is at rest to stop water lost.
• the air travels through the trachea which is lined with chitin making it impermeable to gases and supports the trachea from collapsing
• the trachea branches into tracheloles which are individual enlogated cells that increase the surface area.
• at rest the tracheoles are surrounded by tracheal fluid limiting air penetrating
• when active the fluid diffused by osomisis into the respiring cells which have a lower water potential due to the build up on latic acid. This increases the surface area for diffusion of gas in the tracheole to the surrounding cells.

Question 20

Ventilation in insects

Answer 20

• air sacs in the tracheal system can be squeezed by flight muscles to push air in and out
• some insects movements of the wings alters the volume of the thorax. When the volume decreases air in the tracheal system is put under pressure and is pushed out. When volume increases the presure drops and air is pushed into the tracheal system from outside.
• some insects such as locus have a specialised breathing movement. When the abdomen explands spiracles at the front end open and air ejters the tracheal system. When it reduces in volumr spiracles at the back open and air leaves the tracheal system

Question 21

What is the role of elastic fibres

Answer 21

-recoil to their original shape:
expel air: and prevent the lungs from bursting..

Question 22

The role of smooth muscle

Answer 22

-controls diameter of airways
- constricts the airways
-relaxes during exercise making the tube wider

Question 23

The role of cartilage

Answer 23

-This provides strength and support for the trachea and bronchi, keeping them open.
- It helps prevent collapse: during breathing in; as the chest volume increases: there will be a
Lower pressure in the trachea;

Question 24

What cells make up the trachea

Answer 24

• large C-shaped cartilage
  -smooth muscle
• elastic fibres
  -goblet cells
  Cillated epithelium

Question 25

What cells make up the bronchi

Answer 25

• smaller pieces of cartilage
  -smooth muscle
  -elastic fibres
  -goblet cells
  -epithelium

Question 26

What cells make up the bronchiole

Answer 26

• smooth muscle
  -elastic fibre
  -squamous epithelium

Question 27

What cells make up the alveoli

Answer 27

• Elastic fibres
• squamous epithelium

Question 28

inspiration

Answer 28

-Diaphragm contacts and flatterns
-external intercostal muscles contract and internal relax
-volume in the thorax increases
-pressure in the thorax decreases
-air moves along the pressure gradient

Question 29

vital capacity

Answer 29

-maximum volume of air a person can breath in and out in one breath

Question 30

tidal volume

Answer 30

-the volume of air braathed in and out in a single breath at rest
-aproxamialty 500cm at rest
-increases with exersize

Question 31

breathing rate

Answer 31

-the number of breaths per minute

Question 32

oxygen uptake

Answer 32

-the air breathed into the spirometer one the carbon dioxide has been removed by the soda lime the oxygen is used for aerobic respiration

Question 33

pulmonary ventilation equation

Answer 33

=tidal volume x breath rate

Question 34

Adaptation in body fish for gas exchange

Answer 34

-Have many lamella so there is a large surface area for gas exchange;
- Presence of secondary
Tamella on primary lamella;
- There is a short distance between blood and water;
- To maintain the concentration gradient;
for faster diffusion;

Question 35

Dissection of fish

Answer 35

• remove the operculum

Question 36

Dissection of insects

Answer 36

• remove the exoskeleton