The Respiratory System

for student copy

Functions of the Respiratory System

• Gas Exchange

Organs of the Respiratory System

• Upper Respiratory Tract– Nose– Pharynx– Larynx

• Lower Respiratory Tract– Trachea – Bronchi– Lungs

Nose

• framework composed of bone & cartilage• 2 nostrils called: external nares– where air enters the nasal cavity– rt & lt separated by nasal septum• site of nose bleeds@ internal edge: internal nares

Pharynx

• throat • 3 divisions:1. Nasopharynx– begins @ internal nares end of soft palate

2. Oropharynx– edge of soft palate hyoid bone

3. Laryngopharynx – hyoid bone upper edge of esophagus

3 Parts of the Pharynx

Larynx

• “voice box”• Cartilage• Parts:– Epiglottis– Glottis– Thyroid cartilage– Cricoid cartilage

Larynx

• moves upward when you swallow – tips epiglottis over the glottis (opening of trachea)– allows food esophagus (--/ down trachea to lungs)– if not swallowing: glottis is open allowing air lungs

– http://www.linkstudio.info/images/portfolio/medani/Swallow.swf

Trachea• rings of cartilage maintain its shape to prevent it

from closing• forks into 2 bronchi

Bronchus

• each enters a lung where it branches into smaller & smaller bronchioles resembling an inverted tree

Bronchioles

• fine tubes that allow passage of air• smooth muscle surrounds them when

contracts airways constrict• epithelium covered with cilia & mucus

• mucus traps dust, particulates• cilia beat upward removing trapped particles from

airways (moves particles ~1-3 cm/hr)

Bronchioles

Gas Exchange in Lungs

Pulmonary Function Tests

• “PFTs”• subject breathes into a closed system in which

air is trapped w/in a bell floating in water• bell moves up when patient exhales / down

when they inhale

Pulmonary Function Tests

• Tidal Volume:– amt of air expired

• Vital Capacity:– max amt of air that can

forcefully exhaled after a max inhalation

Spirogram

Anatomical Dead Space• not all inspired air will get into the lungs • exhaling does not force all air out of the body

Hemoglobin

• helps transport oxygen, carbon dioxide, & buffer blood

• as carbon dioxide leaves cells & diffuses thru interstial fluid then into capillary it combines with water to form carbonic acid

Hgb Loading & Unloading Oxygen

Respiratory pH Balance

Respiratory Acidosis

• hypoventilation • accumulation of CO2 in

tissues• pH decreases• plasma HCO3- increases

Respiratory Alkalosis

• hyperventilation• excessive loss of CO2

• pH increases• plasma HCO3- decreases• CO2 in blood increases