Week 6 - Unit 5: Respiratory System Part 1

Question 1

Describe the structure of alveoli

Answer 1

Alveoli have elastic walls which expand during inspiration and recoil (spring back) during expiration

Question 2

what is the role of the diaphragm in inspiration?

Answer 2

Diaphragm moves down (flattens) when diaphragm muscle contracts.

Thorax volume increases and pressure decreases.

Air pushed into the lungs from outside down the pressure gradient

Question 3

Describe the structure of the respiratory system and how each is related to its function.

Answer 3

Each lung contains millions of alveoli which have folded walls. = Large surface area for fast diffusion
Alveolus wall is thin, made of one layer of flattened epithelium cells.= sort diffusion distance for fast diffusion

Capillary wall is thin, made of one layer of flattened endothelium cells.= sort diffusion distance for fast diffusion

Ventilation brings in fresh supplies of atmospheric air and Circulation of blood continually replaces blood high in O2 with blood low in O2 = Maintains a high concentration gradient for fast diffusion

Question 4

Air moves into the lungs. Explain how the diaphragm causes this.

Answer 4

When diaphragm flattens

Volume of thorax increases and pressure decreases
Air moves (into lungs) down pressure gradient / from high to low pressure

Question 5

Describe how oxygen in air in the alveoli enters the blood in capillaries.

Answer 5

Diffusion

Across (alveolus) epithelium / (capillary) endothelium

Question 6

Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli and blood in the capillaries around them

Answer 6

Many alveoli / alveoli walls folded so large surface area;
Many capillaries so a large surface area;
(So) fast diffusion;
Alveoli or capillary walls / epithelium / lining are thin / short distance between alveoli and blood;
(So) short diffusion distance / pathway;
(So) fast diffusion;
Ventilation / circulation;
Maintains a diffusion / concentration gradient;
(So) fast diffusion;

Question 7

Define. Tidal volume (TV)

Answer 7

the volume of air in each breath

Question 8

Define. Ventilation (breathing) rate (VR)

Answer 8

 the number of breaths per minute

Question 9

Define. Pulmonary Ventilation Rate (PVR)

Answer 9

the volume of air exchanged by the lungs per minute, taking into account both the tidal volume and the ventilation rate: PVR = TV X VR

Question 10

Define. Forced expiratory volume (FEV)

Answer 10

the maximum volume of air that can be breathed out in 1 second

Question 11

Define. Forced vital capacity (FVC)

Answer 11

the maximum volume of air that can be breathed out forcefully after a really deep breath in.

Question 12

The rate of diffusion of oxygen is affected by the difference between its concentration in the alveolus and its concentration in the blood.
Circulation of the blood helps to maintain this difference in oxygen concentration. Explain how.

Answer 12

• Replaces it with blood with a low oxygen concentration / removes blood with high oxygen concentration;

Question 13

In healthy lungs, a gradient is maintained between the concentration of oxygen in the alveoli and the concentration of oxygen in the lung capillaries.
Describe how ventilation helps to maintain this difference in oxygen concentration.

Answer 13

• Brings in air containing a high(er) oxygen concentration;

* Removes air with a low(er) oxygen concentration;

Question 14

Give one other way that helps to maintain the difference in oxygen concentration.

Answer 14

• Circulation of blood / moving blood;

Question 15

fill in the blanks. When you breathe in (inspiration), air enters the______ (windpipe) then the two ______(one bronchus leads to each lung).

Air then enters smaller branches of each bronchus called ________ where it is carried to small air sacs called_____.

Answer 15

trachea
bronchi
bronchioles
alveoli

Question 16

fill in the blanks. The ribcage, intercostal muscles and diaphragm all work together to ventilate the lungs. • 2 types of muscle contract to cause inspiration (& relax to cause expiration)
• ________ muscles (in between the ribs).

• _________ (a ring of muscles at the edge of a tough sheet of tissue called the diaphragm.
• A third set of muscles contracts to cause forced expiration (internal intercostal

Answer 16

External intercostal

Diaphragm muscles

Question 17

fill in the blanks.
• _______ diffuses from alveoli into blood capillaries (via the walls of both) down a concentration gradient.

• ______ diffuses in the reverse direction.
• Alveoli are adapted for efficient gas exchange.
• Note: alveoli walls contain an elastic protein called _____.
• Elastin allows alveoli to _____ during inspriration and to recoil (spring back) to their original size during expiration.

Answer 17

oxygen
carbon dioxide
elastin
expand