CHAPTER 1 ORGANIZATION OF THE HUMAN BODY
Anatomy--study of structure
Physiology--study of function
These are closely related.
TABLE 1.1 P. 2
SUBDISCIPLINES OF A & P
1. Chemical level--includes atoms and molecules essential
for life. Major atoms are:
Carbon C
Hydrogen H
Oxygen O
Nitrogen N
Calcium Ca
Potassium K
Sodium Na
These atoms can combine with each other and certain other
atoms to form molecules such as proteins, carbohydrates, fats, & nucleic
acids.
2. Cellular level--molecules combine to form cells, the
basic structural and functional units of all living things. Cells come in
different kinds.
3. Tissue level--tissues are groups of similar cells and
the substances surrounding them that perform specific functions. 4 basic tissue
types:
Epithelium
Connective
tissue
Muscle tissue
Nerve tissue
4. Organ level (organ-system level)--organs are structures
composed of 2 or more different tissues that have specific functions and
usually recognizable shapes:
Stomach
Kidney
Liver
Heart
5. System level--a system is made up of related organs
with a common function.
6. Organismal level--one living individual as a whole
Learn names of systems and components as given in the
table, functions as follows:
1. Integumentary--protects
the body and helps regulate body temp.
2.
Skeletal--support & protection, assists in body movement
3.
Muscular--brings about movement and produces heat
4. Nervous--one
of the 2 regulatory systems of the body--detects changes both inside the body
and in the environment--responds by sending nerve impulses to muscles and
glands
5. Endocrine--the
other regulatory system--responds by releasing hormones (chemical messengers)
6.
Cardiovascular--major transportation of the body
7. Lymphatic
& immune systems
a. Minor
transportation system
b. Defense
against disease
8.
Respiratory--oxygen in, carbon dioxide out
9.
Digestive--physical and chemical breakdown of food, absorption of nutrients,
elimination of solid wastes
10.
Urinary--elimination of wastes by filtering the blood, regulation of volume and
composition of blood
11.
Reproductive--reproduces the organism
In examination of the body, the following diagnostic
techniques may be used:
Palpation—examination by feeling—lumps, swellings, pulse,
etc.
Auscultation—listening—heartbeat, breathing, bowel sounds
Percussion--tapping
1.
Metabolism--sum of all chemical processes that occur in the body
a.
Catabolism--large molecules are broken down to smaller ones, releasing energy
b.
Anabolism--uses energy and raw materials from food to build the body's
structural and functional components—atoms, ions, or molecules are joined
together
2. Responsiveness--ability to detect and respond to
changes inside and outside the body--different cells respond differently:
Muscle
cells--contract, often directed by nerve impulses
Endocrine
cells--secrete hormones
3. Movement--of whole body, individual organs, single
cells or even just tiny components within cells (organelles)
4.
Growth--increase in size
Increase in
number of cells
Increase in
size of cells
Increase in
amount of substance between cells
5. Differentiation--a cell changes from unspecialized
state to specialized--development of a fertilized egg to a complete individual.
Stem cells are cells that arise in the early divisions of the fertilized egg
and have the potential to become any type of cell. We now know that some of
these cells may remain in the body throughout life.
6.
Reproduction--formation of new cells or production of a new individual
Our bodies are composed of trillions of cells which must
have relatively stable (unchanging) conditions. Homeostasis involves achieving
ideal conditions for all cells of the body and then maintaining these
conditions in spite of changes occur both inside and outside the body:
Outside--temp,
amount of oxygen
Inside--food,
heat from exercising, amount of water taken in
External environment--our
surroundings—where outside changes take place
Internal environment—not just insides in general but
refers specifically to the fluid that surrounds all body cells. To understand
this we must discuss body fluids.
All living cells contain a high % of water inside and also
must be surrounded by fluid and kept moist. All body fluids consist of mostly
water, with various solutes dissolved in it. Different fluids have different
solutes and different concentrations of those solutes. Solutes may include:
Gases
Nutrients
Ions
Proteins
2 major body fluids:
1. Intracellular fluid (ICF)—inside cells, 2/3 of total
body fluid
2. Extracellular fluid (ECF)--outside body cells (but inside
the body), 1/3 of total body fluid
a. Blood
plasma--the liquid part of blood, contained in blood vessels
b.
Interstitial fluid--fills the microscopic spaces between cells and is also
called intercellular fluid or tissue fluid. This is the fluid that makes up the
internal environment.
Components of these fluids constantly move back and forth
from blood to tissue spaces into cells and back.
An organism is said to be in homeostasis when all
conditions in the internal environment are within normal physiological limits.
Proper gases,
nutrients, ions, water, temperature, etc.
CONTROL OF HOMEOSTASIS
When homeostasis is disturbed, illness or death may result. Anything that disturbs homeostasis is called a stress. Stresses may be:
External--heat,
cold, lack of oxygen
Internal--pain,
high BP, low blood sugar, mental upsets
Our bodies are constantly exposed to stresses. We can
never achieve perfect homeostasis and just stay there. It is a constant
balancing act--a certain condition leans one way, we correct that, then it may
lean the other way and have to be fixed again, or another condition gets out of
balance. Controlled conditions (monitored variables):
Heart rate
Blood pressure
Acidity of
blood
Blood sugar
Body temp
Breathing rate
The 2 major regulatory systems act to maintain
homeostasis--the nervous system and the endocrine system.
Nervous--by
detects deviations from homeostasis and sends messages (nerve impulses) to
proper organs that can counteract the stress--this occurs quickly
Endocrine--glands
release hormones--works more slowly
A feedback system (feedback loop) is a continuous cycle in
which information is continually monitored and fed back (reported) to a central
control region. There are 3 major parts:
1. Receptor--this
monitors
2. Control
center—receives information about the state of its condition, evaluates the
input, and is responsible for directing the response that will keep its
condition within normal limits or return it there if it deviates. Many control
centers are in the brain, but control
centers are located in other areas of the body as well.
3.
Effector--receives instructions from the control center (output) and produces a
response (effect).
The response reversed the original stimulus, so this is
called a negative feedback system. If the response had caused the body to heat up
even more, it would have been a positive feedback system. Positive feedback
systems strengthen or reinforce the stimulus.
Negative feedback systems tend to return conditions to
normal when they begin to go wrong. Most beneficial feedback systems in the
body are negative. Positive feedback systems are often harmful and often cause
disorders in the body. Two beneficial positive feedback systems are blood
clotting and labor contractions.
HOMEOSTASIS OF BLOOD PRESSURE--a negative feedback system
HOMEOSTASIS OF LABOR CONTRACTIONS--a beneficial positive feedback system. The hormone
oxytocin is produced in
This positive feedback is OK because it is ended by the birth
of the baby.
If the control systems are unable to keep conditions
within normal limits, an imbalance in homeostasis results:
Moderate-->
Disease or disorder
Severe-->
Death
Disorder---any abnormality of structure or function
Disease---illness with a recognizable set of signs and
symptoms
Local
disease--limited area
Systemic
disease--larger area or whole body
Diseases cause:
Symptoms--not
apparent to an observer--pain, nausea
Signs--can be
observed and measured--swelling, fever, rash
Diagnosis—science
and skill of distinguishing one disease or disorder from another
ANATOMICAL POSITION
In descriptions of the human body, we always assume that the body is in a specific position, standing straight with feet flat on the floor and slightly apart, arms by the sides with palms facing forward. Left and right are the patient's left and right. Other related terms:
Pronation of
the hand means the palm faces backward
Supination of
the hand means the palm faces forward (anatomic position)
Prone is lying face down.
Supine is lying
face up.
Fig.
1.5 page 13—REGIONAL NAMES ---TEST IN LAB ONLY
EXHIBIT 1.1 PAGE 14 (Fig 1.5 P. 13 and Fig 1.6 P. 15 may help with some examples)
These terms are very important and should be learned
thoroughly--be able to define them and also USE THEM. These are used to
describe the location of various body structures in relation to each other
1. Sagittal--divides into right and left parts
a.
Mid-sagittal (median)--divides exactly in half--passes thru the midline
b.
Parasagittal--unequal--NOT on midline
2. Frontal
Divides into front and back
Coronal
3. Transverse
Cross-sectional
Horizontal
Oblique planes go through the body at a diagonal. These
are vague and rarely used in my course.
Fig. 1.7 and 1.8 P. 16
Fig.
1.9 P. 17
Enclosed spaces within the body that contain internal
organs. The body cavities protect, separate and support the organs. Please note
that this edition of the text has left out the dorsal & ventral cavities,
but they are still in the lab book and we will still talk about them.
1. Dorsal body cavity--contains organs that are part of
the nervous system—lined by the meninges
a. Cranial
cavity--formed by skull bones and contains the brain
b. Vertebral
(spinal) canal--formed by vertebrae and contains the spinal cord
2. Ventral body cavity--a thin serous membrane lines this
cavity and covers organs within it. Internal organs in the ventral body cavity
are called viscera.
a. Thoracic
cavity (chest)
1) Right and
left pleural cavities—each contains a lung
2)
Mediastinum--between lungs and contains heart, esophagus, trachea, thymus
gland, blood vessels & lymphatics
a)
Pericardial cavity--contains only the heart
b. Abdominopelvic
cavity--separated from thoracic cavity by the diaphragm
1) Abdominal--contains most of the
digestive organs & spleen
2) Pelvic
cavity--contains urinary bladder, internal reproductive organs and part of the
large intestine
Serous membrane in the thoracic cavity is called pleura.
Lining--parietal
pleura
Covering
organs--visceral pleura
Visceral pleura
of the heart is called the pericardium.
Serous membrane in the abdominopelvic cavity is called peritoneum.
Lining--parietal
peritoneum
Covering
organs--visceral peritoneum
FIGURE 1.9 P. 17
SUMMARY OF CAVITIES & MEMBRANES
The abdominopelvic cavity may be divided into 9 regions
for anatomical study.
Figure
1.11 P. 19 & 1.12 A & B P. 20
|
Right hypochondriac |
Epigastric |
Left hypochondriac |
|
Right lumbar |
Umbilical |
Left
lumbar |
|
Right iliac
“ inguinal |
Pubic
Hypogastric |
Left
iliac
“ inguinal |
1. Epigastric
Liver most of these
Stomach
2. Left hypochondriac
Rest of stomach
Spleen
Most of left
kidney
3. Right hypochondriac
Rest of liver
Part of
gallbladder
4. Umbilical
Transverse colon
Most of small
intestine
5. Left lumbar
Descending
colon
6. Right lumbar
Rest of
gallbladder
Ascending colon
Most of right
kidney
7. Hypogastric
Urinary bladder
Lower large
intestine
8. Left iliac
Portion of
colon
9. Right iliac
Appendix
Loops of the SI may be found in all regions.
The cavity is also frequently divided into 4
regions (quadrants)
(Figure
1.12C P. 20)
|
UR |
UL |
|
LR |
LL |
Figure out some organs in each quadrant.
MEDICAL IMAGING
(Table 1.3 P. 21 – 24
gives examples of images)
1. Conventional radiography
(standard x-rays)---a beam of x-rays passes through the body and strikes
This
technique has been in use for around 100 years and is still the starting point
in most cases.
2.
Magnetic resonance imaging (MRI)---a strong
magnetic field is produced and causes all the hydrogen protons of the area to
line up. Next, radio waves to the same area "reads these ion patterns and
this produces an image. Since bone doesn’t show up much on MRIs, they are often
used for images of parts enclosed in bones, such as the brain, spinal cord and
the insides of joints, but can also be used for other body areas including
study of blood flow, examination of the liver, etc.
3. Computed tomography (CT scan)---Links x-rays and computers (which tells you it is a fairly
new technique). It produces cross-sectional images which can be put together to
give a 3-dimensional view of the whole body or just
4. Sonography
(ultrasound)---sound waves are sent into the body and bounce back off body
tissues. This produces an image called a sonogram. It is a very safe technique,
since no radioactivity is involved. Most of us think of its use in pregnancy
first, but it is also used for other purposes such as study of abdominal and
pelvic organs, blood flow and the heart.
5. Positron emission tomography
(PET)---a substance that gives off positively charged particles (positrons) is
injected or inhaled. As the positrons collide with negatively charged electrons
in tissues, gamma rays are given off. A camera detects these and sends signals
to a computer, where a color image is formed. This shows where the substance is
being used in the body, so it gives
6. Radionuclide scanning—radioactive substance is injected into a vein and carried
in the blood. The more active the tissue, the more of the radionuclide
accumulates, producing more intense color due to more gamma rays being given
off.
7. Endoscopy—instrument called an endoscope with a light & camera
is inserted into the body. An image projected onto a monitor gives a view of
internal parts.