Key words - Topic 3.1

Question 1

Alveoli

Answer 1

Tiny air sacs that serve as the primary gaseous exchange surface. The consist of a in epithelial cell layer, collagen and elastic fibres.

Question 2

Breathing rate

Answer 2

The number of breaths per minute

Question 3

Bronchi

Answer 3

Divisions of the trachea that lead into the lungs. They are small tubes supported by incomplete rings of cartilage.

Question 4

Bronchioles

Answer 4

Many small divisions of the bronchi. They contain smooth muscle to restrict airflow to the lungs but do not have cartilage. They are lined with a thin layer of ciliated epithelial cells.

Question 5

Cartilage

Answer 5

Strong, flexible connective tissue that supports the walls of the trachea and bronchi, preventing collapse. It is found in an incomplete ring shape.

Question 6

Ciliated epithelial cells

Answer 6

Specialised cells with tiny hair-like cilia found in the lining of the trachea that waft bacteria-containing mucus up to the back of the throat to be swallowed.

Question 7

Countercurrent flow

Answer 7

An adaption for gaseous exchange in bony fish. Blood in the gill filaments and water moving over the gills flow in opposite directions, maintaining a steep oxygen concentration gradient.

Question 8

Elastic fibres

Answer 8

Fibres of elastin that allow the alveoli to stretch as air is drawn in and recoil back to normal size, expelling air. They are also found in the trachea, bronchi, bronchioles.

Question 9

Exchange surface

Answer 9

A surface over which materials are exchanged from one region to another. An effective exchange surface has a large surface area, thin layers and a good blood supply, and ventilation to maintain a steep diffusion gradient.

Question 10

Expiration

Answer 10

During expiration (exhalation) the diaphragm relaxes and reverts to a dome. The external intercostal muscles relax, moving the ribs down and in. The volume of the thorax decreases and thoracic pressure exceeds air pressure. Air moves out of the trachea.

Question 11

Gill filaments

Answer 11

The main site of gaseous exchange in fish, over which water flows. They are found in large stacks, called gill plates, and have gill lamellae which provide a large surface area for exchange.

Question 12

Gill lamellae

Answer 12

The fine branches of the gill filaments. They are adapted for gaseous exchange by having a large surface area.

Question 13

Gill plates

Answer 13

Large stacks of gill filaments

Question 14

Gills

Answer 14

The organs of gaseous exchange in fish. They are contained in a gill cavity and are made up of gill lamellae, gill filaments and gill plates.

Question 15

Goblet cells

Answer 15

Specialised cells that secrete mucus onto the trachea lining. The mucus traps harmful substances and microorganisms, preventing their entry into the lungs.

Question 16

Inspiration

Answer 16

During inspiration (inhalation) the diaphragm contracts and flattens and the external intercostal muscles contract, moving the ribs up and out. The volume of the thorax increases and the thoracic pressure falls below air pressure. Air moves into the trachea.

Question 17

Internal intercoastal muscles:

Answer 17

Muscles found between the ribs which are responsible for forced exhalation.

Question 18

Mammalian gasous exchange system

Answer 18

A complex system found in mammals in which oxygen and carbon dioxide gases are exchanged.

Question 19

Operculum

Answer 19

A flap that covers the gills of bony fish. It protects the gills and helps to maintain a constant stream of water over them

Question 20

Smooth muscle

Answer 20

An involuntary muscle found in the walls of the trachea and bronchi. It constricts the lumen of the bronchi by contracting, reducing airflow of the lungs.

Question 21

Spiracles

Answer 21

Small, external openings along the thorax and abdomen of most insects, through which air enters, and air and water leave the gaseous exchange system. Spiracle sphincters open and close the spiracles to control gas exchange.

Question 22

Spirometer

Answer 22

A device used to examine patters of breathing and determine different aspects of lung volume

Question 23

Surface area to volume ratio

Answer 23

The surface area of an object divided by its volume. The larger the surface area to volume ratio, the smaller the object.

Question 24

Tidal volume

Answer 24

The volume of air that moves into and out of the lungs during a normal breath

Question 25

Trachea (mammals)

Answer 25

The primary airway which carries air from the nasal cavity down into the chest. It is a tube supported by incomplete rings of cartilage.

Question 26

Tracheae (insects)

Answer 26

Large tubes that run from the spiracles, into and along an insects body. They are supported by spirals of chitin. The tracheae divide further into smaller tracheoles.

Question 27

Tracheal fluid

Answer 27

A fluid found at the ends of the tracheoles. The amount of fluid affects the surface area available for gaseous exchange and water loss.

Question 28

Tracheoles:

Answer 28

Divisions of the tracheae that run throughout the tissues of an insect, forming a complex network. They are the main site of gas exchange and are completely permeable to gases.

Question 29

Ventilation

Answer 29

The movement of fresh air into the lungs and stale air out of the lungs via inspiration and expiration

Question 30

Vital capacity

Answer 30

The largest volume of air that can be breathed in following the strongest possible exhalation.