anatomy & physiology respi & digestive

8/22/2019 Anatomy & Physiology Respi & Digestive

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ANATOMY & PHYSIOLOGY


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The Lungs

` The lungs are paired, cone-shaped organs which take up most of the space in our chests,

along with the heart. Their role is to take oxygen into the body, which we need for our cells to

live and function properly, and to help us get rid of carbon dioxide, which is a waste product. We

each have two lungs, a left lung and a right lung. These are divided up into 'lobes', or big sections

of tissue separated by 'fissures' or dividers. The right lung has three lobes but the left lung has

only two, because the heart takes up some of the space in the left side of our chest. The lungs can

also be divided up into even smaller portions, called 'bronchopulmonary segments'.

These are pyramidal-shaped areas which are also separated from each other by membranes.

There are about 10 of them in each lung. Each segment receives its own blood supply and air

supply.

Air enters your lungs through a system of pipes called the bronchi. These pipes start from

the bottom of the trachea as the left and right bronchi and branch many times throughout the

lungs, until they eventually form little thin-walled air sacs or bubbles, known as the alveoli. The

alveoli are where the important work of gas exchange takes place between the air and your

blood. Covering each alveolus is a whole network of little blood vessel called capillaries, which

are very small branches of the pulmonary arteries. It is important that the air in the alveoli and

the blood in the capillaries are very close together, so that oxygen and carbon dioxide can move

(or diffuse) between them. So, when you breathe in, air comes down the trachea and through the

bronchi into the alveoli. This fresh air has lots of oxygen in it, and some of this oxygen will

travel across the walls of the alveoli into your bloodstream. Travelling in the opposite direction is

carbon dioxide, which crosses from the blood in the capillaries into the air in the alveoli and is

then breathed out. In this way, you bring in to your body the oxygen that you need to live, and

get rid of the waste product carbon dioxide.

Alveoli are the tiny sacs at the farthest end of your smallest airways. The exchange of

oxygen and carbon dioxide occurs here. Alveoli with partial meconium obstruction are thought

to trap air because of a ball-valve mechanism by which gas reaches the alveoli on inflation but is

trapped secondary to reduced airway diameter during expiration. It is challenging to oxygenate

babies with meconium aspiration syndrome because the alveoli where gas trapping occurs may

rupture, leading to air leak. Also, meconium in the alveoli may deactivate surfactant.

Lung is an organbelonging to the respiratory system and interfacing to the circulatorysystem of air-breathing vertebrates. Its function is to exchange oxygen from air with carbondioxide from blood. The process in which this happens is called "external respiration" orbreathing.
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Bronchioles orbronchioli are the first airwaybranches that no longer contain cartilage.

They are branches of the bronchi. The bronchioles terminate by entering the circular sacs calledalveoli.

DIGESTIVE SYSTEM

The human digestive system is a complex series of organs and glands that processes

food. In order to use the food we eat, our body has to break the food down into smaller

molecules that it can process; it also has to excrete waste.

Most of the digestive organs (like the stomach and intestines) are tube-like and contain

the food as it makes its way through the body. The digestive system is essentially a long, twisting

tube that runs from the mouth to the anus, plus a few other organs (like the liver and pancreas)

that produce or store digestive chemicals.
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The Digestive Process:

The start of the process - the mouth: The digestive process begins in the mouth. Food

is partly broken down by the process of chewing and by the chemical action of salivary enzymes

(these enzymes are produced by the salivary glands and break down starches into smaller

molecules).

On the way to the stomach: the esophagus - After being chewed and swallowed, the

food enters the esophagus. The esophagus is a long tube that runs from the mouth to the

stomach. It uses rhythmic, wave-like muscle movements (called peristalsis) to force food from

the throat into the stomach. This muscle movement gives us the ability to eat or drink even when

we're upside-down.

In the stomach - The stomach is a large, sack-like organ that churns the food and bathes

it in a very strong acid (gastric acid). Food in the stomach that is partly digested and mixed with

stomach acids is called chyme.

In the small intestine - After being in the stomach, food enters the duodenum, the first

part of the small intestine. It then enters the jejunum and then the ileum (the final part of the

small intestine). In the small intestine, bile (produced in the liver and stored in the gall bladder),

pancreatic enzymes, and other digestive enzymes produced by the inner wall of the small

intestine help in the breakdown of food.

In the large intestine - After passing through the small intestine, food passes into the

large intestine. In the large intestine, some of the water and electrolytes (chemicals like sodium)

are removed from the food. Many microbes (bacteria likeBacteroides,Lactobacillus

acidophilus,Escherichia coli, andKlebsiella) in the large intestine help in the digestion process.The first part of the large intestine is called the cecum (the appendix is connected to the cecum).

Food then travels upward in the ascending colon. The food travels across the abdomen in the

transverse colon, goes back down the other side of the body in the descending colon, and then

through the sigmoid colon.

The end of the process - Solid waste is then stored in the rectum until it is excreted via

the anus.

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