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By the end of this section, you will be able to:
  • List the structures that make up the respiratory system
  • Describe how the respiratory system processes oxygen and CO 2
  • Compare and contrast the functions of upper respiratory tract with the lower respiratory tract

The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help to maintain acid-base balance. Portions of the respiratory system are also used for non-vital functions, such as sensing odors, speech production, and coughing ( [link] ).

Major respiratory structures

This figure shows the upper half of the human body. The major organs in the respiratory system are labeled.
The major respiratory structures span the nasal cavity to the diaphragm.

The nose and its adjacent structures

The major entrance and exit for the respiratory system is through the nose, via the nostrils. The inhaled air enters into the nasal cavity, which is separated into left and right sections by the nasal septum. The wall of the nasal cavity has three bony projections, called the superior, middle, and inferior nasal conchae. Conchae serve to increase the surface area of the nasal cavity and to disrupt the flow of air as it enters the nose, causing air to bounce along the epithelium, where it is filtered, warmed, and humidified. Air exits the nasal cavities and moves into the pharynx.

Several bones that help form the walls of the nasal cavity have air-containing spaces called the sinuses, which serve to warm and humidify incoming air. Sinuses are lined with a mucosa. Each sinus is named for its associated bone: frontal sinus, maxillary sinus, sphenoidal sinus, and ethmoidal sinus. The sinuses produce mucus and lighten the weight of the skull.

Portions of the nasal cavities are lined with mucous membranes, containing sebaceous glands and hair follicles that serve to prevent the passage of large debris, such as dirt, through the nasal cavity.

The conchae and sinuses are lined by respiratory epithelium    composed of pseudostratified ciliated columnar epithelium ( [link] ). The epithelium contains goblet cells, one of the specialized, columnar epithelial cells that produce mucus to trap debris. The cilia of the respiratory epithelium help remove the mucus and debris from the nasal cavity with a constant beating motion, sweeping materials towards the throat to be swallowed. Interestingly, cold air slows the movement of the cilia, resulting in accumulation of mucus that may in turn lead to a runny nose during cold weather. This moist epithelium functions to warm and humidify incoming air. Capillaries located just beneath the nasal epithelium warm the incoming air.

Pseudostratified ciliated columnar epithelium

This figure shows a micrograph of pseudostratified epithelium.
Respiratory epithelium is pseudostratified ciliated columnar epithelium. Seromucous glands provide lubricating mucus. LM × 680. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

Pharynx

The pharynx    is a tube formed by skeletal muscle and lined by mucous membrane that is continuous with that of the nasal cavities. The pharynx is divided into three major regions: the nasopharynx, the oropharynx, and the laryngopharynx ( [link] ).

Questions & Answers

what is the meaning of extended family
Shellyann Reply
extended family is two are more nuclear family living together under one roof
Nordalee
what is genetic engineering
Ebot Reply
good day please what is a cell?
Colota Reply
cell is the basic unit of all living things/organism
Hassan
differenciate b/w cilia and flagellum
Abshira
Cilia: 1. They are smaller in number. 2. Cilia usually occur throughout or major part of the surface of a cell. 3. They beat oar like and in a co-ordinated rhythm 4. Cilia help in locomotion, feeding, circulation, etc.. 5. Example: Paramecium
iti
Flagella: 1. They are larger in size. ADVERTISEMENTS: 2. Flagella are commonly found at one end of the cell. 3. The flagella beat whip-like and independently. 4. Flagella help in locomotion. 5. Example: Euglena
iti
smallest structural and functional unit of an organism!
zidane
cell is the basic unit of all living things
Lukman
what is homeostasis
alex Reply
the ability of an organism to maintain stable internal environment, even when the external environment changes
Bee
what's the function of the hypothalamus
Agyekum
what is homeostasis
Edward Reply
constant maintenance of internal body temperature
Agyekum
What is the function of the Pituitary Gland?
WeNdlovu
how can homeostasis be maintained?
alex
pituitary gland also known as the master gland secretes hormones which triggers other gland to secretes their hormones
Agyekum
what's the full meaning of DNA and RNA
Deborah Reply
DNA is Deoxyribonucleic acid and RNA means Ribonucleic acid
Christian
sha is mitochondria?
Sparrow Reply
what is biology
Femi Reply
biology is the study which deals with the study of the biological components or animal and plants.
Juhi
biology is the study of life.
Roger
biology is the branch of science which deals with study of two parts 1.botany&2zoology these is known as biology....
Chetan
biology is the study of human beings ...
Chetan
Biology is a branch of science that deals with the study of nature
Agyekum
biology is the science of living organism
Abshira
biology is the branch of science that deals with study of living organisms
Lukman
what is neculer cell?
is it nuclear cell?
iti
asthma occur in which part of the body organ?
Festus Reply
Lungs
NICHOLAS
lungs
marian
heart
Cynthia
can you explain to me why you say heart is the answer
marian
what is hemoglobin
Lucky Reply
a protein that carries oxygen, it is found within red blood cells
EmmyOrangePeel
Apart from endocrinology, what other alternative should be done to a D/m client
Deborah Reply
good day please what is excretion
Blaise Reply
excretion is the process by which metabolic wastes and other none-useful materials are eliminated from an organism.
Petrene
its the process of eliminating or removal of metabolic waste and non useful materials from an organ.
eyong
Its the removal of metabolic waste product from the body
Boo
it is the removal from the body of living organisms, toxic waste products of metabolism which if allowed to accurate can cost harm to the body..
Renzo
how are protons formed?
Brian Reply
What is isotopes?
Brian
isotopes is a phenomenon in which atoms of the same element has the same atomic number but different mass number due to a difference in their neutron number or relative abundance in the earth crust
Efosa
give me more mcqs there r just two mcqs
Salma Reply
Define the term Disease in one paragraph.
Sutanya Reply
Disease is any disorders that counteract with the normal performance of the immune system.
Agyekum
what is cell?
Colota
Cell is the basic unit of life It is the building block of an organism
Agyekum
do agree with me that if someone needs to truely be a biologist he should be mathematician physicist & chemist in oreder to acheive the level #biologist
Assila
what is a protoplasm?
Colota
colourless living part of the cell
Jenny
what is protoplasm made up of?
Jack

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Source:  OpenStax, Human biology. OpenStax CNX. Dec 01, 2015 Download for free at http://legacy.cnx.org/content/col11903/1.3
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