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Nervous innervation

Dilation and constriction of the airway are achieved through nervous control by the parasympathetic and sympathetic nervous systems. The parasympathetic system causes bronchoconstriction    , whereas the sympathetic nervous system stimulates bronchodilation    . Reflexes such as coughing, and the ability of the lungs to regulate oxygen and carbon dioxide levels, also result from this autonomic nervous system control. Sensory nerve fibers arise from the vagus nerve, and from the second to fifth thoracic ganglia. The pulmonary plexus    is a region on the lung root formed by the entrance of the nerves at the hilum. The nerves then follow the bronchi in the lungs and branch to innervate muscle fibers, glands, and blood vessels.

Pleura of the lungs

Each lung is enclosed within a cavity that is surrounded by the pleura. The pleura (plural = pleurae) is a serous membrane that surrounds the lung. The right and left pleurae, which enclose the right and left lungs, respectively, are separated by the mediastinum. The pleurae consist of two layers. The visceral pleura    is the layer that is superficial to the lungs, and extends into and lines the lung fissures ( [link] ). In contrast, the parietal pleura    is the outer layer that connects to the thoracic wall, the mediastinum, and the diaphragm. The visceral and parietal pleurae connect to each other at the hilum. The pleural cavity    is the space between the visceral and parietal layers.

Parietal and visceral pleurae of the lungs

This figure shows the lungs and the chest wall, which protects the lungs, in the left panel. In the right panel, a magnified image shows the pleural cavity and a pleural sac.

The pleurae perform two major functions: They produce pleural fluid and create cavities that separate the major organs. Pleural fluid is secreted by mesothelial cells from both pleural layers and acts to lubricate their surfaces. This lubrication reduces friction between the two layers to prevent trauma during breathing, and creates surface tension that helps maintain the position of the lungs against the thoracic wall. This adhesive characteristic of the pleural fluid causes the lungs to enlarge when the thoracic wall expands during ventilation, allowing the lungs to fill with air. The pleurae also create a division between major organs that prevents interference due to the movement of the organs, while preventing the spread of infection.

Everyday connection

The effects of second-hand tobacco smoke

The burning of a tobacco cigarette creates multiple chemical compounds that are released through mainstream smoke, which is inhaled by the smoker, and through sidestream smoke, which is the smoke that is given off by the burning cigarette. Second-hand smoke, which is a combination of sidestream smoke and the mainstream smoke that is exhaled by the smoker, has been demonstrated by numerous scientific studies to cause disease. At least 40 chemicals in sidestream smoke have been identified that negatively impact human health, leading to the development of cancer or other conditions, such as immune system dysfunction, liver toxicity, cardiac arrhythmias, pulmonary edema, and neurological dysfunction. Furthermore, second-hand smoke has been found to harbor at least 250 compounds that are known to be toxic, carcinogenic, or both. Some major classes of carcinogens in second-hand smoke are polyaromatic hydrocarbons (PAHs), N-nitrosamines, aromatic amines, formaldehyde, and acetaldehyde.

Tobacco and second-hand smoke are considered to be carcinogenic. Exposure to second-hand smoke can cause lung cancer in individuals who are not tobacco users themselves. It is estimated that the risk of developing lung cancer is increased by up to 30 percent in nonsmokers who live with an individual who smokes in the house, as compared to nonsmokers who are not regularly exposed to second-hand smoke. Children are especially affected by second-hand smoke. Children who live with an individual who smokes inside the home have a larger number of lower respiratory infections, which are associated with hospitalizations, and higher risk of sudden infant death syndrome (SIDS). Second-hand smoke in the home has also been linked to a greater number of ear infections in children, as well as worsening symptoms of asthma.

Chapter review

The lungs are the major organs of the respiratory system and are responsible for performing gas exchange. The lungs are paired and separated into lobes; The left lung consists of two lobes, whereas the right lung consists of three lobes. Blood circulation is very important, as blood is required to transport oxygen from the lungs to other tissues throughout the body. The function of the pulmonary circulation is to aid in gas exchange. The pulmonary artery provides deoxygenated blood to the capillaries that form respiratory membranes with the alveoli, and the pulmonary veins return newly oxygenated blood to the heart for further transport throughout the body. The lungs are innervated by the parasympathetic and sympathetic nervous systems, which coordinate the bronchodilation and bronchoconstriction of the airways. The lungs are enclosed by the pleura, a membrane that is composed of visceral and parietal pleural layers. The space between these two layers is called the pleural cavity. The mesothelial cells of the pleural membrane create pleural fluid, which serves as both a lubricant (to reduce friction during breathing) and as an adhesive to adhere the lungs to the thoracic wall (to facilitate movement of the lungs during ventilation).

Questions & Answers

what is the name of the two subunits of L chain of a antibody structure
Arshi Reply
The pituitary gland lies in the
Aamir Reply
bony cavity,sella tursica
Arshi
how does endochrondral ossification start in short bones?
Steven Reply
the chondroblast cells forms a cartilaginous bone model which becomes calcified in mid region and is innervated by perosteal capillaries. These capillaris replaces cartilages with bone tissue.
Biplav
what is RH blood group
kuukyile Reply
It is a type of system for classifying blood groups according to the presence or absence of the Rh antigen.
Rakshith
What is the most important organ in the human body?
Gbemi Reply
the heart
Phodiso
or brain
Phodiso
Why?
Gbemi
heart
Kelly
the brain specifically is referred to as the control centre ..all nerve impulses are send to the brain which stimulates other specific parts of the body
Phodiso
please if l am Blood group B+ can l marry a lady with O- blood group?
kuukyile
structure of a serous membrane
Ziyanda Reply
are you asking?
Isa
yes
MOHD
In anatomy, serous membrane (or serosa) is a smooth tissue membrane consisting of two layers of mesothelium, which secrete serous fluid. The inner layer that covers organs (viscera) in body cavities is called the visceral membrane. A second layer of epithelial cells of the serous membrane, called th
Isa
The two layers of serous membranes are named parietal and visceral. Between the two layers is a thin fluid filled space.[2] The fluid is produced by the serous membranes and stays between the two layers to reduce friction between the walls of the cavities and the internal organs when they move with
Isa
a continuation from the 1st one:: A second layer of epithelial cells of the serous membrane, called the parietal layer, lines the body wall. Between the two layers is a potential space, mostly empty except for a few milliliters of lubricating serous fluid that is secreted by the two serous membranes
Isa
Lubricated secretion of skin is called sebum
Jazil
haematopoietic
oyewale
what is the greater tronchanter?
Phodiso
the greater trochanter is  femur is a large, irregular, quadrilateral eminence and a is a part of the system of the skeleton
Jessie
Thanks Jessie...
Phodiso
what is the easiest way to learn labels of Anatomical structures?
Phodiso
Name the two phases of metabolism
Grace Reply
reproduction and growth
Zozo
how about anabolism and catabolism?
Japhar
In Simply Anabolism means formation... Catabolism means breakdown
Jazil
two phases of reproductio?
Japhar
Anabolism indicates potential & catabolism potential converts to kinetic
Doctor
Name the most important life process in the human body in terms of anatomy and physiology
Grace
Nervous system
Nimco
Every system is important for body functions
Jazil
what is the difference between the functions of the adhesion belt and the desmosomes?
Mason Reply
what are the derivatives of the germ layer?
Miriam Reply
zygote
Zozo
Pls explain the atlas of the cervical vertebral column
Ifunanya Reply
why does the material not allow in mri
Simran Reply
what do you mean 'mri'
Nimco
short for magnetic resonance imaging. "the researchers used MRI to record the brain activity" a medical examination performed using magnetic resonance imaging. "he's having an MRI to determine the extent of the injury" an image obtained by magnetic resonance imaging. "after looking at the MRI, the d
Riyaz
what is the meaning of sutures
Ibrahim Reply
i do not know
Nimo
immovable joints btn two bones.eg the skull bones
Japhar
Really,it's true
Nimco
Sutures are immovable junction between two bones e.g those of the skull
Surphy
what should I do to get or to know what to do for me to be excellent in the course of anatomy and physiology
Sandra Reply
study harder
Japhar
Between the heart and the Brain which one is more important to human being... discuss
Faith Reply
well the brain is important for motor skills, the heart is important for involuntary muscle movement supporting body functions. the body can survive without brain involvement, but the body cannot last without the heart
john
granted the heart is important, but the brain gives the body purpose
john
the brain is more important
Kevin
why?
john
brain
tracey
Even though the brain helps the human being to behave normally and purposefully, I think the heart is much more important cos human being cannot live without the heart
Dzifa
why?
john
change the question
Bind
hello guys
Kevin
heart
Kevin
it is difficult to select which organ is more important, now you can replace the heart with a mechanical device and the body could still function, and with technology today brain activity can also be replicated. But life would not be the same
john
there's coordination btn the two..so without any of them no life
Japhar
the heart
The brain is important to humans.
Zozo
what is homeostasis
Rebecca Reply
It is the condition when body feel comfortable
Jazil
Wo feels hungry, thirty due to homeostasis
Jazil
Is the maintenance of the internal environment of all the body cells for normal growth
Komolika

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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