Ch. 47 Respiratory System

Larger, complex animals have _______ respiratory systems because they cannot rely on diffusion.

specialized

Cutaneous Respiration(Skin Breathers)

Animals in damp environments can use skin as a gas exchange surface.

Gills

Specialized extensions of tissue that project into water.

External Gills

• Not enclosed within body structures.

• Must be constantly moved to ensure contact with oxygen-rich fresh water.

• Are easily damaged(axolotl)

Lamelle

Composes gill filaments. Serve as their respiratory surface.

Within each lamalle, blood flows _____ (aka countercurrent flow) to direction of water movement.

opposite

Tracheal Systems

consists of air ducts called tracheae, which branch into very small tracheoles.

Tracheoles

are in direct contact with individual cells.

Lungs of mammals are packed with millions of _______ (sites of gas exchange).

alveoli

Alveoli in the lungs of mammals are surrounded by an extensive _________ ________.

capillary network.

Flow of Air:

Nose - pharynx - larynx - trachea - bronchi - bronchioles - alveoli

During inhalation, external intercostal muscles ________ the rib cage.

expand

During exhalation, the diaphragm muscle relaxes and moves back ________.

upward

The diaphragm expands the volumeof the thorax and lungs through ________ movement. (Inhalation)

downwards

The pressure in the diaphragm pushes the air back out and the ribs ______.

relax

Medulla Oblongata

controls respiration

When neurons ____ producing impulses, respiratory muscles relax, and exhalation occurs.

stop

Muscles of breathing are usually controlled __________.

automatically

Neurons are sensitive to changes in blood _______.

Carbon Dioxide(CO2)

Increased production of carbonic acid lowers the blood PH which stimulates _____ neurons in the _______ and ________ bodies.

chemosensitive,aortic,carotid

Hemoglobin consists of __ polypeptide chains: two a and two b

4

(Hemoglobin) Each polypeptide chain is associated with a _____ group.

heme

Each heme group has a _____ _____ _____ that can bind a molecule of O2.

central iron atom

Hemoglobin loads up with oxygen in the lungs, forming _________.

oxyhemoglobin

Hemoglobin’s affinity for O2 is affected by ____ and _______.

Ph, temperature

Disadvantages of external gills:

• Must constantly be moving to ensure contact with oxygen-rich fresh water

• Are easily damaged