Explain the process of breathing

1 Breathing: The technical term is pulmonary ventilation, or the movement of air into
and out of the lungs. (Breathing is also called inspiration and expiration.)

2 Exchanging gases: This takes place between the alveolar cells in the lungs, the blood,
and the body’s cells in two ways:

   • Pulmonary, or external, respiration: The exchange in the lungs when blood
gains oxygen and loses carbon dioxide, transforming it from venous blood into
arterial blood

   • Systemic, or internal, respiration: The exchange within systemic capillaries
when the blood releases some of its oxygen and collects carbon dioxide from the
tissues

3 Adult breathing rate: About 12 to 20 times per minute.

4 Anoxia: Oxygen deficiency in which the cells either don’t have or can’t utilize
sufficient oxygen to perform normal functions.

5 Asphyxia: Lack of oxygen with an increase in carbon dioxide in the blood and
tissues; accompanied by a feeling of suffocation leading to coma.

6 Expiration or exhalation: The diaphragm returns to its domed shape as the
muscle fibers relax, via elastic recoil of the lungs and tissues lining the thoracic
cavity, the external intercostal muscles relax, and the internal intercostal muscles
contract. This movement pulls the ribs back into place, decreasing the volume of
the thoracic cavity and increasing pressure, forcing air out of the lungs.

7 Hypoxia: Low oxygen content in the inspired air.

8 Inspiration or inhalation: When the muscles of the diaphragm contract, its
dome shape flattens; simultaneously, the contraction of the external intercostal
muscles pulls the ribs upward and increases the volume of the thoracic cavity,
decreasing the intra-alveolar pressure. The pressure difference between the
atmosphere and the lungs diffuses air into the respiratory tract.

9 Lung capacity: The vital capacity plus the residual air.

10 Mediastinum: The region between the lungs extending from the sternum ventrally
(at the front) to the thoracic vertebrae dorsally (at the back), and superiorly
(top) from the entrance of the thoracic cavity to the diaphragm inferiorly
(at the bottom).

 11 Minimal air: The volume of air in the lungs when they’re completely collapsed
(150 cubic centimeters in an adult).

12 Phrenic nerve: The nerve that innervates (stimulates) the diaphragm.

13 Residual air: The volume of air remaining in the lungs after the most forceful
expiration (1,200 cubic centimeters in an adult).

14 Respiratory centers: Nerve centers for regulating breathing located in the
medulla oblongata, or brain stem. The centers are influenced by the amount of
carbon dioxide in the blood.

15 Tidal air: The volume of air inspired and expired in the resting state (500 cubic
centimeters in an adult).

16 Vital capacity: The volume of air moved by the most forceful expiration after a
maximum inspiration. It represents the total moveable air in the lungs (4,600
cubic centimeters in an adult).

Here’s what happens as you breathe in and out . Red blood cells use a
pigment called hemoglobin to carry oxygen and carbon dioxide throughout the body
through the circulatory system  Hemoglobin bonds loosely with oxygen, or O2, to
carry it throughout the body; the bonded hemoglobin is called oxyhemoglobin.

After hemoglobin releases its oxygen molecules, it picks up carbon dioxide, or CO2,
to deliver to the lungs for exhalation. The freshly bonded hemoglobin becomes
carbohemoglobin

Blood vessels in human body

The blood vessels in human body,Blood vessels come in three varieties

1 Arteries carry blood away from the heart. The largest artery is the aorta. Small
ones are called arterioles, and microscopically small ones are called metarterioles.

2 Veins carry blood toward the heart; all veins except the pulmonary veins contain
deoxygenated blood. Small ones are called venules, and large venous spaces are
called sinuses.

3 Microscopically small capillaries carry blood from arterioles to venules, but
sometimes tiny spaces in the liver and elsewhere called sinusoids replace
capillaries.

The walls of arteries and veins have three layers: the outermost tunica externa (sometimes
called tunica adventitia) composed of white fibrous connective tissue, a central
“active” layer called the tunica media composed of smooth muscle fibers and yellow
elastic fibers, and an inner layer called the tunica intima made up of endothelium that
aids in preventing blood coagulation by reducing the resistance of blood flow. Arterial
walls are very strong, thick, and very elastic to withstand the great pressure to which
the arteries are subjected. Arteries have no valves.

There are two types of arteries: elastic and muscular. In elastic arteries, found primarily
near the heart, the tunica media is composed of yellow elastic fibers that stretch
with each systole and recoil during diastole; essentially they act as shock absorbers to
smooth out blood flow. In muscular arteries, the tunica media consists primarily of
smooth muscle fibers that are active in blood flow and distribution of blood. The
larger blood vessels have smaller blood vessels, the vasa vasorum, that carry nourishment
to the vessel wall.

While larger in diameter than arteries, veins have thinner walls and are less distensible
and elastic. Veins that carry blood against the force of gravity, such as those in the legs
and feet, contain valves to prevent backsliding into the capillaries. Normally the blood
that veins are returning to the heart is unoxygenated (contains carbon dioxide); the
one exception is the pulmonary vein, which returns oxygenated blood to the heart
from the lungs.

Capillaries are breathtakingly tiny and capable of forming vast networks, or capillary
beds. Their walls are a single layer of squamous endothelial cells. Precapillary
sphincters take the place of valves to regulate blood flow. All exchange occurs at
the capillaries.

Blood from the digestive tract takes a detour through the hepatic portal vein to
the liver before continuing on to the heart. Called the hepatic portal system, this
circuitous route helps regulate the amount of glucose circulating in the bloodstream

What Is Human Anatomy?

Anatomy means the study of structure and human anatomy means the study of structure of human beings. It is one of the three basic medical sciences, which are taught to medical students who are to follow a career related to hospitals.

Human anatomy is purely related to the study of structure. It is not concerned with the study of functions of various parts of human body. In fact, there is another basic medical science, known as Physiology, which is concerned with the study of the function of various parts of human body. Anatomy just describes the structural details.

Yes, it is a fact that structure and function are very much inter-related and one cannot be understood without the other but a distinction has to be made because of the level of details in both fields. The details of human structure are so vast that they cannot be studied along with the vast details of human functions. That is why the study of function and structure is differentiated into two different branches of medical science.

It can be divided into three major categories.

1) Gross anatomy (macroscopic anatomy)
2) Microscopic anatomy (Histology)
3) Basic anatomy

Gross Anatomy: It deals with the study of macroscopic details of human structure. It is not concerned with fine microscopic structural details of human body and is studied with naked eye. It has two approaches of study: Systemic approach and regional approach. In systemic approach, the human body is considered to be composed of different organs systems while in regional approach, human body is considered to be composed of different regions.

Microscopic anatomy: It deals with the study of microscopic details of various structures of human body. Microscopic anatomy depends on an important instrument known as the microscope.
Basic anatomy: It is sometimes not considered as a major subdivision of human anatomy, however, it is very important for medical students who are new to the concepts of anatomy. Basic anatomy explains all the basic concepts of human anatomy so that the different structural arrangements of these basic components can be understood properly.

For more information, please visit the following website where all subdivisions of human anatomy including the body systems are explained in a smart way that makes the learning process very easy.
Human Anatomy

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Study Anatomy

Study Anatomy

There are many different reasons for wanting to study anatomy. Maybe you want to learn human anatomy as a part of an educational program. Or, maybe you need to learn how the human body functions in order to further your career. Amazingly, you might just want to learn about the human body for personal reasons. Whether your reason is academic, business or personal in nature, learning about the human body is very intense, but rewarding.

Definitions

There are many technical and difficult definitions of human anatomy, but basically it is the study of body parts. Many people also learn physiology when they learn anatomy. Physiology explains how the body parts that you learned about in anatomy actually function. In order to understand how physiology works you have to also understand anatomy. It is for this reason that anatomy and physiology are usually taught together at most medical programs.

Considerations

Learning about the human body takes time and should be treated as a serious task. It is the foundation for learning about different facets of the medical profession. Depending on where you intend to specialize, anatomy training involves much more than just reading textbooks.
More advanced training goes beyond textbooks and may involve the use of learning tools such as graphic medical diagrams, anatomy photos and even human cadavers. If you are not comfortable about or strong enough to learn about the human body and its tissues and fluids, then the medical profession may not be a good career choice for you.

Misconceptions

Many people have the misconception that it is too hard to study anatomy. It is a challenge, but it can be done with the right tools. It has often been said that the average anatomy and physiology course is used to get rid of inadequate students that don't possess either the capacity to learn or the stomach to learn about the human body. Although this logic may not apply to you, it is up to the individual as to how and if you are going to tackle and learn anatomy.
Just like with any other challenge, find a strategy for accomplishing the task and stick with it. Human anatomy study guides will help you accomplish your goals. Contrary to belief, you can't rely on riddles, nursery rhymes and other memorization games to get you through anatomy and physiology courses.

Tips

Learning anatomy involves covering a lot of material. In order to be successful, you must have advanced study skills. You will not be able to get by and pass anatomy courses without studying. If you are one of those people that can pass all of your classes without studying, unfortunately, you will not have the same luck with the average anatomy class. Now is the time to purchase one of the best human anatomy study guides that your budget will allow.

These are just a few things that will help you to tackle and study anatomy successfully. Understand that learning about the human body is very challenging. However, all medical professionals must be knowledgeable about the human body. The topic of human anatomy is very challenging, but it can be mastered with the right mindset and learning tools.

As a medical student one needs to Study Anatomy Guide for a good understanding of human skeleton visit my blog to learn more about it.

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Conduction System Of Heart

"Conduction System Of Heart"
The mighty, nonstop heart keeps up its rhythm because of a carefully choreographed
dance of electrical impulses called the conduction system that has the power to produce
a spontaneous rhythm and conduct an electrical impulse. Four structures play
key roles in this dance — the sinoatrial node, atrioventricular node, atrioventricular
bundle, and Purkinje fibers.Each is formed of highly tuned modified cardiac muscle.
Rather than both contracting and conducting impulses as other cardiac muscle does,
these structures specialize in conduction alone, setting the pace for the rest of the heart.
Following is a bit more information about each one:

1 Sinoatrial node: This node really is the pacemaker of the heart. Located at the
junction of the superior vena cava and the right atrium, this small knot, or mass,
of specialized heart muscle initiates an electrical impulse that moves over the
musculature of both atria, causing atrial walls to contract simultaneously and
emptying blood into both ventricles. It’s also called the S-A node, sinoauricular
node, and sinus node.

2 Atrioventricular node: The impulse that starts in the S-A node moves to this mass
of modified cardiac tissue that’s located in the septal wall of the right atrium. Also
called the A-V node, it directs the impulse to the A-V bundles in the septum.

3 Atrioventricular bundle: From the A-V node, the impulse moves into the atrioventricular
bundle, also known as the A-V bundle or bundle of His (pronounced
“hiss”). The bundle breaks into two branches that extend down the sides of the
interventricular septum under the endocardium to the heart’s apex.

4 Purkinje fibers: At the apex, the bundles break up into terminal conducting fibers,
or Purkinje fibers, and merge with the muscular inner walls of the ventricles. The
pulse then stimulates ventricular contraction that begins at the apex and moves
toward the base of the heart, forcing blood toward the aorta and pulmonary artery.

One of the best ways to detect cardiac tissue under a microscope is to look for undulating
double membranes called intercalated discs separating adjacent cardiac muscle
fibers. Gap junctions in the discs permit ions to pass between the cells, spreading the
action potential of the electrical impulse and synchronizing cardiac muscle contractions.
Potential problems include fibrillation, a breakdown in rhythm or propagation of
the impulses that causes individual fibers to act independently, and heart block, an
interruption that causes the atria and ventricles to take on their own rates of contraction.
Usually the atria contract faster than the ventricles.

A healthy heart makes a “lub-dub” sound as it beats. The first sound (the “lub”) is
heard most clearly near the apex of the heart and comes at the beginning of ventricular
systole (the closing of the atrioventricular valves and opening of the semilunar
valves). It’s lower in pitch and longer in duration than the second sound (the “dub”),
heard most clearly over the second rib, which results from the semilunar valves closing
during ventricular diastole. Defects in the valves can cause turbulence or regurgitation
of blood that can be heard through a stethoscope. Called murmurs, these sounds
indicate imperfect closure of one or more valves.


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What is the function of liver

"What is the function of liver"
The largest gland in the body, the liver is divided into a large right lobe and a small left
lobe by the falciform ligament, another peritoneal fold. Two smaller lobes — the
quadrate and caudate lobes — are found on the lower (inferior) and back (posterior)
sides of the right lobe. The quadrate lobe surrounds and cushions the gallbladder, a
pear-shaped structure that stores and concentrates bile, which it empties periodically
through the cystic duct to the common bile duct and on into the duodenum during
digestion. Bile aids in the digestion and absorption of fats; it consists of bile pigments,
bile salts, and cholesterol.

The liver secretes diluted bile through the hepatic ducts into the cystic duct and on
into the gallbladder. Liver tissue is made up of rows of cuboidal cells separated by
microscopic blood spaces called sinusoids. Blood from the interlobular veins and arteries
circulates through the sinusoids with food and oxygen for the liver cells, picking up
materials along the way. The blood then enters the intralobular veins, which carry it to
the sublobular veins, which empty into the hepatic vein, which leads to the inferior
vena cava. Bile secreted from the liver cells is carried by biliary canaliculi (bile capillaries)
to the bile ducts and then to the hepatic ducts.

Considering the number of vital roles the liver plays, the complexity of that process
isn’t too surprising. Among the liver’s various functions are

1 Production of blood plasma proteins including albumin, antibodies to fend off
disease, a blood anticoagulant called heparin that prevents clotting, and bile pigments
from red blood cells, the yellow pigment bilirubin, and the green bile pigment
biliverdin

2 Storage of vitamins and minerals as well as glucose in the form of glycogen

3 Conversion and utilization through enzyme activity of fats, carbohydrates, and
proteins

4 Filtering and removal of nonfunctioning red blood cells, toxins (isolated by
Kupffer cells in the liver) and waste products from amino acid breakdown, such
as urea and ammonia

 Unfortunately, a number of serious diseases can damage the liver. The hepatitis virus
inflames the gland, and cirrhosis caused by repeated toxic injury (often through alcohol
or other substance abuse) destroys Kupffer cells and replaces them with scar
tissue. Also, painful gallstones can develop when cholesterol clumps together to form
a center around which the gallstone can form.


Terms
What is the function of liver

Human anatomy of head and neck

The skull is made up of 19 bones, 12 of which are pairs. You
can see most of these bones in the illustration. Where the
bones join is called a suture. Little fingers of bone interdigitate
with adjoining little fingers to make the joining solid.
The bones shown are: the frontal bone, the nasal bones, the
lacrimal bones, the ethmoid bones, the sphenoid bones, the
zygomatic bones, the maxilla, the mandible, the parietal
bones, the temporal bones, the occipital bone, the palatine
bones (not seen, since they are inside the orbit of the eye),
and the vomer (not seen, since it is inside the nasal cavity).

There are two bones that you cannot see in the illustration,
the palatine and the vomer. The palatine bones are paired
and are buried deep in the skull behind the nose. They make
up the rear part of the palate, part of the base of the nasal
cavity, and a small part of the floor or the orbit. The vomer is
a thin bone which forms part of the nasal septum separating
the two sides of the nasal cavity.

Lacrimal, meaning tear producing, is from the Latin lachrymal,
meaning a small vase, of the kind found in ancient
Roman sepulchers that was used for collecting tears shed in

mourning.(The lacrimal bone forms half of the receptacle,
which holds the lacrimal sac, a structure that receives the
tears and directs them into the nasal cavity. That explains
why we blow our noses in cold weather, or when we cry, we
are blowing out the tears that have drained into the cavity.
The other half of the receptacle for the lacrimal sac is made
from the frontal process of the maxilla.) Ethmoid, so-named
because it is full of holes, is from the Greek ethmo and oiedes,
meaning “formed like a strainer.” Sphenoid is from the Greek
spheno and eidos together meaning wedge-shaped. Zygomatic
or zygoma comes from the Greek zygon, which means yoke,
the kind used to harness oxen. Maxilla is from the Latin mala
meaning jaw, particularly the upper jaw. Mandible derives
from the Latin mandibula, which stems from mandare meaning
to chew and pertains particularly to the lower jaw, which
has most of the chewing motion. Parietal is from the Latin
paries, parietes, meaning “walls of a hollow cavity.” Temporal
indicates the temple, from the Latin tempora, meaning “temple,
the right place, the fatal spot..”(As well as indicating a
place on the skull where death can easily be afflicted, this
word coveys a sense of reverence for life.) Occipital is from
the Latin occiput, meaning “the back of the head.” Palatine is
from the Latin palatum, meaning the hard palate and is the
base for the words palatable and palliative. Vomer is the Latin
word for plowshare.

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