3. Basic Process ofLife.ppt

Subject: Human Anatomy & Physiology-I (HAP-I)
Topic: Basic Life Processes, Homeostasis & Basic
Anatomical Terminology
MR. S. PATHAK
Department of Pharmacy
LECTURE-03

Learning Objectives
1. Know the Demonstrate the anatomical position
2. Know thw human body using directional and regional terms
3. Distinguish between the posterior (dorsal) and the anterior (ventral)
body cavities, identifying their subdivisions and representative
organs found in each
4. Know the difference between metabolism, anabolism, and
catabolism
5. Provide at least two examples of human responsiveness and human
movement
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Learning Outcomes
 On completion of this course, the student will be able to:
1. Describe the Demonstrate the anatomical position
2. human body using directional and regional terms
3. Distinguish between the posterior (dorsal) and the anterior
(ventral) body cavities, identifying their subdivisions and
representative organs found in each
4. Distinguish between metabolism, anabolism, and catabolism
5. Provide at least two examples of human responsiveness and
human movement
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BASIC LIFE PROCESSES
Certain processes distinguish organisms or living things from nonliving things.
Following are the six most important life processes of the human body:
1. Metabolism is the sum of all the chemical processes that occur in the body. One
phase of metabolism is catabolism (catabol- throwing down; ism-a condition),
the breakdown of complex chemical substances into simpler components. The
other phase of metabolism is anabolism (anabol- a raising up) the building up of
complex chemical substances from smaller, simpler components. For example,
digestive processes catabolize (split) proteins in food into amino acids. These
amino acids are then used to anabolize (build) new proteins that make up body
structures such as muscles and bones.
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2. Responsiveness is the body’s ability to detect and respond to
changes. For example, a decrease in body temperature represents a
change in the internal environment (within the body), and turning
your head toward the sound of squealing brakes is a response to
change in the external environment (outside the body). Different
cells in the body respond to environmental changes in
characteristic ways. Nerve cells respond by generating electrical
signals known as nerve impulses (action potentials). Muscle cells
respond by contracting, which generates force to move body parts.
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3. Movement includes motion of the whole body, individual
organs, single cells, and even tiny structures inside cells. For
example, the coordinated action of leg muscles moves your
whole body from one place to another when you walk or
run. After you eat a meal that contains fats, your gallbladder
contracts and squirts bile into the gastrointestinal tract to aid
in the digestion of fats. When a body tissue is damaged or infected,
certain white blood cells move from the blood into the
affected tissue to help clean up and repair the area. Inside the
cell, various parts move from one position to another to carry out
their functions.
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4. Growth is an increase in body size that results from an increase in
the size of existing cells, an increase in the number of cells, or
both. In addition, a tissue sometimes increases in size because the
amount of material between cells increases. In a growing bone, for
example, mineral deposits accumulate between bone cells, causing
the bone to grow in length and width.
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5. Differentiation is the development of a cell from an unspecialized
to a specialized state. As you will see later in the text, each type of
cell in the body has a specialized structure and function that differs
from that of its precursor (ancestor) cells. For example, red blood
cells and several types of white blood cells all arise from the same
unspecialized precursor cells in red bone marrow. Such precursor
cells, which can divide and give rise to cells that undergo
differentiation, are known as stem cells. Also through
differentiation, a fertilized egg (ovum) develops into an embryo,
and then into a fetus, an infant, a child, and finally an adult.
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6. Reproduction refers either to the formation of new cells for tissue
growth, repair, or replacement, or to the production of a new
individual. In humans, the former process occurs continuously
throughout life, which continues from one generation to the next
through the latter process, the fertilization of an ovum by a sperm
cell.
When the life processes cease to occur properly, the result is death
of cells and tissues, which may lead to death of the organism.
Clinically, loss of the heartbeat, absence of spontaneous breathing,
and loss of brain functions indicate death in the human body.
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HOMEOSTASIS
Homeostasis (homeo-sameness; stasis-standing still) is the condition of
equilibrium (balance) in the body’s internal environment due to the
constant interaction of the body’s many regulatory processes.
Homeostasis is a dynamic condition. In response to changing conditions,
the body’s equilibrium can shift among points in a narrow range that is
compatible with maintaining life. For example, the level of glucose in
blood normally stays between 70 and 110 milligrams of glucose per 100
milliliters of blood.* Each structure, from the cellular level to the
systemic level, contributes in some way to keeping the internal
environment of the body within normal limits
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HOMEOSTASIS AND BODY FLUIDS
 An important aspect of homeostasis is maintaining the volume
and composition of body fluids, dilute, watery solutions containing
dissolved chemicals that are found inside cells as well as
surrounding them.
 The fluid within cells is intracellular fluid (intra-inside),
abbreviated ICF. The fluid outside body cells is extracellular fluid
(extra- outside), abbreviated ECF.
 The ECF that fills the narrow spaces between cells of tissues is
known as interstitial fluid (inter-between).
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 As you progress with your studies, you will learn that the ECF differs
depending on where it occurs in the body: ECF within blood vessels is
termed blood plasma, within lymphatic vessels it is called lymph, in and
around the brain and spinal cord it is known as cerebrospinal fluid, in
joints it is referred to as synovial fluid, and the ECF of the eyes is called
aqueous humor and vitreous body.
 The proper functioning of body cells depends on precise regulation of
the composition of the interstitial fluid surrounding them. Because of
this, interstitial fluid is often called the body’s internal environment.
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CONTROL OF HOMEOSTASIS
 Fortunately, the body has many regulating systems that can
usually bring the internal environment back into balance.
 Most often, the nervous system and the endocrine system, working
together or independently, provide the needed corrective measures.
 The nervous system regulates homeostasis by sending electrical
signals known as nerve impulses (action potentials) to organs that
can counteract changes from the balanced state.
 The endocrine system includes many glands that secrete
messenger molecules called hormones into the blood.
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 Nerve impulses typically cause rapid changes, but hormones usually
work more slowly. Both means of regulation, however, work toward the
same end, usually through negative feedback systems
 A feedback system or feedback loop is a cycle of events in which the
status of a body condition is monitored, evaluated, changed,
remonitored, reevaluated, and so on.
 Each monitored variable, such as body temperature, blood
pressure, or blood glucose level, is termed a controlled condition. Any
disruption that changes a controlled condition is called a stimulus.
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 A feedback system includes three basic components—a receptor, a
control center and an effector.
1. A receptor is a body structure that monitors changes in a
controlled condition and sends input to a control center.
Typically, the input is in the form of nerve impulses or chemical
signals. For example, certain nerve endings in the skin sense
temperature and can detect changes, such as a dramatic drop in
temperature.
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2. A control center in the body, for example, the brain, sets
the range of values within which a controlled condition should
be maintained, evaluates the input it receives from receptors, and
generates output commands when they are needed. Output from
the control center typically occurs as nerve impulses, or hormones or
other chemical signals. In our skin temperature example, the brain acts
as the control center, receiving nerve impulses
from the skin receptors and generating nerve impulses as output
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3. An effector is a body structure that receives output from the control
center and produces a response or effect that changes the controlled
condition. Nearly every organ or tissue in the body can behave as an
effector. When your body temperature drops sharply, your brain (control
center) sends nerve impulses (output) to your skeletal muscles
(effectors). The result is shivering, which generates heat and raises your
body temperatur.
 A group of receptors and effectors communicating with their
control center forms a feedback system that can regulate a controlled
condition in the body’s internal environment
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A. NEGATIVE FEEDBACK SYSTEMS
 A negative feedback system reverses a change in a controlled
condition. Consider the regulation of blood pressure.
 Blood pressure (BP) is the force exerted by blood as it presses
against the walls of blood vessels. When the heart beats faster or
harder, BP increases.
 If some internal or external stimulus causes blood pressure
(controlled condition) to rise, the following sequence of events
occurs Baroreceptors (the receptors), pressure-sensitive nerve cells
located in the walls of certain blood vessels, detect the higher
pressure.
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 The baroreceptors send nerve impulses (input) to the brain (control
center), which interprets the impulses and responds by sending
nerve impulses (output) to the heart and blood vessels (the
effectors). Heart rate decreases and blood vessels dilate (widen),
which cause BP to decrease (response). This sequence of events
quickly returns the controlled condition— blood pressure—to
normal, and homeostasis is restored. Notice that the activity of the
effector causes BP to drop, a result that negates the original
stimulus (an increase in BP). This is why it is called a negative
feedback system.
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B. POSITIVE FEEDBACK SYSTEMS
 A positive feedback system tends to strengthen or reinforce a
change in one of the body’s controlled conditions.
 A positive feedback system operates similarly to a negative
feedback system, except for the way the response affects the
controlled condition.
 The control center still provides commands to an effector, but this
time the effector produces a physiological response that adds to or
reinforces the initial change in the controlled condition.
 The action of a positive feedback system continues until it is
interrupted by some mechanism.
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 Normal childbirth provides a good example of a positive feedback
system.
 The first contractions of labor (stimulus) push part of the fetus into
the cervix, the lowest part of the uterus, which opens into the
vagina.
 Stretch-sensitive nerve cells (receptors) monitor the amount of
stretching of the cervix (controlled condition). As stretching
increases, they send more nerve impulses (input) to the brain
(control center), which in turn releases the hormone oxytocin
(output) into the blood.
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 Oxytocin causes muscles in the wall of the uterus (effector) to
contract even more forcefully.
 The contractions push the fetus farther down the uterus, which
stretches the cervix even more.
 The cycle of stretching, hormone release, and ever-stronger
contractions is interrupted only by the birth of the baby.
 Then, stretching of the cervix ceases and oxytocin is no longer
released.
 These examples suggest some important differences between
positive and negative feedback systems.
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 Because a positive feedback system continually reinforces a change in a
controlled condition, some event outside the system must shut it off.
 If the action of a positive feedback system is not stopped, it can
“run away” and may even produce life-threatening conditions in
the body.
 The action of a negative feedback system, by contrast,
slows and then stops as the controlled condition returns to its
normal state. Usually, positive feedback systems reinforce
conditions that do not happen very often, and negative feedback
systems regulate conditions in the body that remain fairly stable
over long periods.
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HOMEOSTATIC IMBALANCES
 As long as all the body’s controlled conditions remain within
certain narrow limits, body cells function efficiently, negative
feedback systems maintain homeostasis, and the body stays
healthy.
 Should one or more components of the body lose their ability to
contribute to homeostasis, however, the normal equilibrium among
body processes may be disturbed.
 If the homeostatic imbalance is moderate, a disorder or disease
may occur; if it is severe, death may result.
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 A disorder is any abnormality of structure or function.
 Disease is a more specific term for an illness characterized by a
recognizable set of signs and symptoms.
 A local disease affects one part or a limited region of the body; a
systemic disease affects either the entire body or several parts of it.
 A person with a disease may experience symptoms, subjective
changes in body functions that are not apparent to an observer.
Examples of symptoms are headache, nausea, and anxiety.
 Objective changes that a clinician can observe and measure are
called signs.
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 Signs of disease can be either anatomical, such as swelling or a
rash, or physiological, such as fever, high blood pressure, or
paralysis.
 The science that deals with why, when, and where diseases occur
and how they are transmitted among individuals in a community is
known as epidemiology.
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Anatomical Terminology/Position
 anatomists standardize the way in which they view the body.
 However, the purpose of this language is not to confuse, but
rather to increase precision and reduce medical errors body.
 By using precise anatomical terminology, we eliminate
ambiguity.
 Descriptions of any region or part of the human body assume
that it is in a specific stance called the anatomical position
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Body Positions
 In the anatomical position, the subject stands erect facing the
observer, with the head level and the eyes facing directly forward.
 The feet are flat on the floor and directed forward, and the
upper limbs are at the sides with the palms turned forward (Figure
1.5).
 In the anatomical position, the body is upright. Two
terms describe a reclining body.
 If the body is lying face down, it is in the prone position.
 If the body is lying face up, it is in the supine position
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REGIONAL TERMS
 The human body’s numerous regions have specific terms to help
increase precision.
 Notice that the term “brachium” or “arm” is reserved for the
“upper arm” and “antebrachium” or “forearm” is used rather than
“lower arm.”
 Similarly, “femur” or “thigh” is correct, and “leg” or “crus” is
reserved for the portion of the lower limb between the knee and
the ankle. You will be able to describe the body’s regions using the
terms from the figure.
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DIRECTIONAL TERMS
 These terms are essential for describing the relative locations of
different body structures.
 Anterior (or ventral): Describes the front or direction toward the
front of the body. The toes are anterior to the foot.
 Posterior (or dorsal): Describes the back or direction toward the
back of the body. The popliteus is posterior to the patella.
 Superior (or cranial): Describes a position above or higher than
another part of the body proper. The orbits are superior to the oris.
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 Inferior (or caudal): Describes a position below or lower than another
part of the body proper; near or toward the tail (in humans, the coccyx, or
lowest part of the spinal column). The pelvis is inferior to the abdomen.
 Lateral describes the side or direction toward the side of the body. The
thumb (pollex) is lateral to the digits.
 Medial describes the middle or direction toward the middle of the body.
The hallux is the medial toe.
 Proximal describes a position in a limb that is nearer to the point of
attachment or the trunk of the body. The brachium is proximal to the
antebrachium.
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 Distal describes a position in a limb that is farther
from the point of attachment or the trunk of the body.
The crus is distal to the femur.
 Superficial describes a position closer to the surface
of the body. The skin is superficial to the bones.
 Deep describes a position farther from the surface of
the body. The brain is deep to the skull.
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BODY PLANES
 There are three planes commonly referred to in anatomy and
medicine
 The sagittal plane is the plane that divides the body or an organ
vertically into right and left sides. If this vertical plane runs
directly down the middle of the body, it is called the midsagittal or
median plane. If it divides the body into unequal right and left
sides, it is called a parasagittal plane.
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 The frontal plane is the plane that divides the body or an
organ into an anterior (front) portion and a posterior (rear)
portion. The frontal plane is often referred to as a coronal
plane. (“Corona” is Latin for “crown.”)
 The transverse plane is the plane that divides the body or
organ horizontally into upper and lower portions.
Transverse planes produce images referred to as cross
sections. Other names for a transverse plane are a cross-
sectional or horizontal plane.
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 An oblique plane, by contrast, passes through the body or an
organ at an angle between a transverse plane and a sagittal
plane or between a transverse plane and a frontal plane.
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BODY CAVITIES
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REFERENCE
 Tortora Gerard J., Derrickson Bryan, “Principles of Anatomy And Physiology”,
twelth edition, John Wiley & Sons, Inc page no. 922-949.
 Bill & Melinda, “Anatomy and Physioogy”, OpenStax College Rice
University, Maxfield Foundation, page no. 1041-1061.
 Robbins & Cotron, “Pathologic basis of Disease”, eight edition, SAUNDERS
ELSEVIER.
 Whiteknigh, “human Physiology”, Wikibooks contributors, page no. 217-235.
 http://www.innerbody.com/
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3. Basic Process ofLife.ppt

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