Human Respiratory System: Anatomy and Function, Slides of Family and Consumer Science

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Concept 3 Notes

Overview

• Major function: gas exchange; supply the body

with O

2

it needs and dispose of CO

2

• It cannot do this without the help of the cardiovascular (CV) system!!
• Key

structures:

nose,

pharynx,

larynx,

trachea,

lungs,

diaphragm

Functional Zones

• Conducting Zone: warms, humidifies, and filters air

as it travels to the respiratory zone

• Air enters the nose through nostrils and is warmed/moistened as it passes through the nasal cavity
• Air moves through the pharynx, which connects the nasal cavity and mouth to the larynx (voice box) and esophagus - Air travels down the larynx to the trachea (windpipe) - The epiglottis is a piece of cartilage that blocks the larynx when we swallow food. Nostrils in the nose Nasal cavity Pharynx Esophagus Larynx Trachea

Functional Zones

• Conducting Zone: warms, humidifies, and filters air

as it travels to the respiratory zone

• Air travels down the trachea which splits into right and left primary bronchi that enter the lungs - Right lung has 3 lobes (superior, middle, and inferior) - Left lung has 2 lobes (superior and inferior) - Lungs are surrounded by pleurae = serous membranes that line the thoracic wall and diaphragm Left bronchus Left lung Trachea Right bronchus Right lung Diaphragm

Functional Zones

• Respiratory Zone: where gas exchange occurs

in the bronchioles, alveolar ducts and alveoli

• Bronchioles empty into the alveolar ducts,

which dead end in tiny alveolar sacs that contain

alveoli (thin-walled air sacs)

• This is where the bulk of gas exchange occurs! Bronchiole Alveolar duct Alveolar sac Alveoli

Gas Exchange

• Gas exchange = the diffusion of O 2

and CO

2

between the alveoli and blood in the lungs and

then later the blood and body tissues

• Arteries and veins feed into each alveolar sac, with capillaries connecting to each alveoli
• CO 2 moves OUT of the blood and INTO the alveoli
• O 2 moves INTO the blood and OUT of the alveoli Happens across the respiratory membrane

Breathing

• Diaphragm = muscle that moves the lungs
  • Separates the thoracic cavity from the abdominal cavity
• Volume changes in lungs  pressure changes,

which causes air to move

An overview of pulmonary ventilation When we inhale, the diaphragm contracts  room for lungs to expand When we exhale the diaphragm’s contraction is released and the lungs return to their deflated size

Breathing

2 Phases:

1. Inspiration = when air moves into the lungs

• Inspiratory muscles contract and the diaphragm lowers  increased volume in thoracic cavity
• Lungs expand  air flows in An overview of pulmonary ventilation Inspiration

• The intercostal muscles contract  pulling the ribs up, and the diaphragm contracts and moves down  pulling air into the body through the mouth or nostrils.

Breathing

The details

• Air passes through the nasopharynx or oral pharynx to the trachea.
• The trachea filters air using tiny hair-like cilia and mucus.
• Air moves down the trachea and into the right and left bronchi. - Trachea is very stiff so it stays open and doesn’t collapse every time pressure drops when you exhale!
• Air passes into further branching bronchioles.

• Air arrives at alveoli where gas exchange will occur.
• O 2 that has been pulled into the alveoli diffuse through the really thin alveoli membrane and into the pulmonary

Breathing

The details

• CO 2 that has been created by the body through cellular respiration is brought by the capillaries to the alveoli and diffuses into the them.
• The diaphragm relaxes, moving up and causing air (containing CO 2 ) in the alveoli to be exhaled. capillaries to be circulated through the heart and to the rest of the body for cellular respiration.