Lesson I: Functional Organization of the Human Body and Control of the "Internal Environment" Flashcards
goal of physiology
to explain the physical and chemical factors that are responsible for the origin, development, and progression of life
Example of complex control system
✓ hunger makes us seek food
✓ fear makes us seek refuge
✓ Sensations of cold make us look
for warmth.
basic living unit of the body
cell
numbering 25 trillion in each human being, transport oxygen from the lungs to the tissues
red blood cells
the most abundant of any single type of cell in the body
red cells
_____________ being transported from the cells to the __________ to be excreted,
plus other cellular waste products that are being transported to the _______£ for excretion
oxygen
lungs
kidneys
The intracellular fluid differs significantly from the extracellular fluid; for example, it contains large amounts
of;
potassium, magnesium, and phosphate ions
Special mechanisms for transporting ions through the cell membranes maintain the _________________.
ion concentration
maintenance of nearly constant conditions in the internal
environment
homeostasis
__________reacts with ___________, ____, and _________ to release the energy required for cell function.
oxygen
carbohydrate
fat
protein
deliver endproducts of their chemical reactions into the surrounding
fluids
cells
also have the ability to reproduce
additional cells of their own kind
cells
how many percent of the adult human body is fluid, mainly a water solution of ions and other substances
60%
constant motion throughout the body. It is transportedrapidly in the circulating blood and then mixed between the blood and the tissue fluids by diffusion through thecapillary walls
extracellular fluid
are the ions and nutrients needed by the cells to maintain cell life
extracellular fluid
_________ capable of living, growing, and performing their special functions as long as the proper concentrations of ________, _______, ________ , ________, ____________, and
other constituents are available in this internal
environment
cells
oxygen, glucose, different ions, amino acids, fatty substances
The extracellular fluid contains
large amounts of _________, _________, and __________ plus nutrients for the cells, such as _________, ________, ________, and ___________. It also contains carbon dioxide that is
sodium, chloride, bicarbonate ions
oxygen, glucose, fatty acids, amino acids
transported through all parts
of thebody in two stages
extracellular fluid
2 stages in extracellular fluid
✓ movement of blood through the body in the blood vessels
✓ movement of fluid between the blood capillaries and the
intercellular spaces between the tissue cells
A large portion of the bloodpumped by the heart also passes through
the walls
gastrointestinal tract
each time the blood passes through the body, it also flows throughthe lungs. The blood picks up oxygen in the alveoli, thusacquiring the oxygen needed by the cells.
respiratory system
different dissolved nutrients including;
carbohydrates, fatty acids, and amino acids
are
absorbed from the ingested food into the extracellularfluid of the blood.
carbohydrates, fatty acids, and amino acids
How does the musculo -
skeletal system contribute to homeostasis?
✓ the body could not move to the
appropriate place at the appropriate time to obtain the foods required for nutrition
✓ The musculoskeletal system also provides motility for protection against adverse surroundings,
without which the entire body, along with its
homeostatic mechanisms, could be destroyed
instantaneous
Removal of Carbon Dioxide by the Lungs
At the
sametime that blood picks up oxygen in the lungs, carbon dioxide is released from the blood into the
lung alveoli; therespiratory movement of air into and out of the lungs carries the carbon dioxide to the atmosphere
the most abundant of all the end products of metabolism
carbon dioxide
kidney
Passage of the blood through the
kidneysremoves from the plasma most of the other substances besides carbon dioxide that are not needed by the cells.
These substances include different end products of cellular metabolism, such as
urea and uric acid
filtering large quantities of plasma through the glomeruli into thetubules and then reabsorbing into the blood those sub stances needed by the
body, such as glucose, amino acids,appropriate amounts of water, and many of the ions
kidneys
detoxification or removal of many drugs and chemicals that areingested
liver
secretes many of these wastes into thebile to be eventually eliminated in the feces
liver
nervous system is composed of three major parts:
✓ sensory input portion
✓ central nervous system
✓ motor output portion
detect the state of the bodyor the state of the surroundings
sensory receptors
can store information, generate thoughts, create ambition, and determine reactions that the body performs in response to the sen sations
brain
An important segment of the nervous system
autonomic system
It operates at a subconscious leveland controls many functions of the internal organs, includ ing the level of pumping
activity by the heart, movementsof the
gastrointestinal tract, and secretion by many of the
body’sglands
autonomic system
are transported in the extra cellular fluid to all parts of the body to help regulate cellular function
hormones
increases the rates of most chemical reactions in all cells, thus help ing to set the tempo of bodily activity
thyroid hormone
controls glucose metabolism
insulin
control sodium ion, potassium ion, and protein metabolism
adrenocortical hormone
controls bone calcium and phosphate
parathyroid hormone
provide a system for regulation that complements the nervous system
hormones
regulates many muscular and secretory activities of the body, whereas the hormonal system regulatesmany metabolic functions
nervous system
consists of the white blood cells, tissue cells derived from white blood cells, the thymus,
lymph nodes, and lymph vessels that protect the body from pathogens such as bacteria, viruses,
parasites, and fungi
immune system
The immune system
provides a mechanism for the body to;
(1) distinguish its own cells fromforeign cells and
substances
(2) destroy the invaderby
phagocytosis or by producing sensitized lymphocytes orspecialized proteins (e.g., antibodies) that either destroyor neutralize the
invader.
The skin and its various appendages, including the hair, nails, glands, and other structures, cover, cushion, and protect the deeper tissuesand organs of the body and
generally provide a bound ary between the body’s internal environment and the outside world.
integumentary system
integumentary system
important for temperature regulation and excretion of wastes and it provides a sensory interface between the body and the external environment. The skin generally comprises about 12 to 15 percent of body
weight.
not considered a homeostatic function
reproduction
help maintain homeo stasis by generating new beings to take the place of those that are dying
reproduction
that operate in all cells to help control intracellular func tion and extracellular functions
genetic control system
regulates the concentration of carbon dioxide in
the extracellular fluid
nervous system
regulatethe concentration of glucose in the extracellular fluid
liver and pancreas
regulate concentrations of hydrogen,sodium, potassium,
phosphate, and other ions in the extracellular
fluid.
kidney
one of the major substances required forchemical reactions in the cells
oxygen
present in all red blood cells
hemoglobin
Hemoglobin combines with oxygen as the blood passes through the lungs. Then, as the blood passes through the tissue capillaries, hemoglobin, because of its own strong chemical affinity for
oxygen, does not release oxygen into the tissue fluid if too much oxygen is already there. But if the oxygen concentration in the tissue fluid is too low, sufficientoxygen is released to re-establish an adequate concentration. Thus, regulation of oxygen concentration in the tissues is vested principally in the chemical characteristics of hemoglobin itself. This regulation is called?
oxygen-buffering function of
hemoglobin
is a major end product of the oxidative reactions in cells
carbon dioxide
is a simple and excellent example of a
rapidly acting control mechanism
baroreceptor system
which are stimulated by stretch of
the arterial wall
baroreceptors
which in turn decreases the number of impulses transmitted from the vasomotor center through the sym pathetic nervous system to the heart and blood vessels
vasomotor center
a decrease in arterial pressure
below normal relaxes the stretch receptors, allowing the vasomotor center to become more
active than usual, thereby causing?
vasoconstriction and increased heart pumping
Values outside these
ranges are usually caused by
illness
another important factor is the ___________ because whenever it
decreases to less than one-third normal, a person is likely to be paralyzed as a result of the nerves’ inability to carry signals
potassium ion concentration
if the potassium ion concentration increases to two or more times normal, the heart muscle is likely to be
severely depressed
when the calcium ion concentration falls below about one-half normal, a person is likely to experience tetanic contraction of muscles throughout the body because of the spontaneous generation of excess nerve impulses in the peripheral nerves
When the glucose concentration falls below one half normal, a person frequently develops extreme mental
irritability and sometimes even convulsions
a high
concentration of carbon dioxide in the extracellular fluidincreases
pulmonary ventilation
the high concentration of carbon dioxide initiates events that decrease the concentration toward normal, which is ___________ to theinitiating stimulus
negative
if the carbon dioxide concentration
falls too low, this causes feedback to
increase the concentration
ahigh pressure causes a series of
reactions that promotea lowered pressure, or a low pressure causes a series ofreactions that promote an elevated pressure
if some factor becomes excessive or deficient, a control system initiates
negative feedback
which consists of a series of
changes that returnthe factor toward a certain mean value, thus maintaininghomeostasis
negative feedback
The degree of effectiveness with which a control system maintains constant con ditions is determined by the
gain of the negative feedback
Positive Feedback Can Sometimes Cause
Vicious Cycles and death
is caused by positive feedback when
2 liters of blood are removed.
death
the initiating stimulus causes more of the same
positive feedback
is better known as a “vicious
cycle
positive feedback
is an example of a valuable use of positive feedback
blood clotting
When a blood vessel is ruptured anda clot begins to form, multiple enzymes called?
clotting factors
are activated within the clot itself
clotting factors
is another instance in which
positive feed back plays a valuable role
childbirth
positive feedback “childbirth”
When uterine contractions become strong enough for the baby’s head to begin push ing through the cervix, stretch of the cervix sends signal through the uterine muscle back to the body of the uterus, causing even more powerful contractions. Thus, the uterine contractions stretch the cervix and the cervical stretch causes stronger contractions. When this process becomespowerful enough, the baby is born. If it is not powerfulenough, the
contractions usually die out and a few dayspass before they begin again.
Another important use of positive feedback is for thegeneration of nerve signals
That is, when the membrane of a nerve fiber is stimulated, this causes slight leakage of sodium ions through sodium channels in the nerve membrane to the fiber’s interior. The sodium ions entering the fiber then change the membrane potential, which in turn causes more opening of channels, more change of potential, still more opening of channels, and so forth.Thus, aslight leak becomes an explosion of sodium entering the interior of the
lnerve fiber, which creates the nerve action potential. This action potential in turn causes electrical current to flow along both the outside and the inside of the fiber and initiates additional action
potentials. This process continues again and again
until the nerve signalgoes all the way to the end of
the fiber.
the positive feedback itself is part of an overall negative feed back process. For example;
✓ in the case of blood clotting,the positive feedback clotting process is a negative feed back process for maintenance of normal blood volume.
✓ Also, the positive feedback that causes nerve signals allows the nerves to participate in thousands of
negative feedback nervous control systems.
simple feed-
functional structure contributes its share to the
maintenance of homeostatic conditions in the extracellular fluid,which is called?
internal environment
in a sense, is delayed negative feedback.
adaptive control
