2. Introduction
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• Anatomy – the study of the structure of the human body
• Physiology – the study of the function of the human body
“The complementary relation of structure and function.”
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Anatomical Terminology:
Orientation and Directional Terms
• Terms of Relative Position (based on anatomical position):
• Superior versus Inferior (Cranial vs. Caudal)
• Anterior versus Posterior (Ventral vs. Dorsal)
• Medial versus Lateral
• Ipsi-lateral versus Contra-lateral
• Proximal versus Distal
• Superficial versus Deep
• Internal versus External
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Body Sections or Planes
• Sagittal or Median – divides body into left and right portions
• Mid-sagittal – divides body into equal left and right portions
• Transverse or Horizontal – divides body into superior and inferior
portions
• Coronal or Frontal – divides body into anterior and posterior portions
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Body Sections
A section along a frontal
plane
A section along a transverse
plane
A section along the
median plane
Transverse
(horizontal)
plane
Frontal
(coronal)
plane
Parasagittal
plane
Median
(midsagittal)
plane
11. Levels of Organization
•Subatomic Particles – electrons, protons, and neutrons
• Atom – hydrogen atom, lithium atom, etc.
•Molecule – water molecule, glucose molecule, etc.
•Macromolecule – protein molecule, DNA molecule, etc.
•Organelle – mitochondrion, Golgi apparatus, nucleus, etc.
• Cell – muscle cell, nerve cell, etc.
• Tissue – epithelia, connective, muscle and nerve
• Organ – skin, femur, heart, kidney, etc.
• Organ System – skeletal system, digestive system, etc.
• Organism – the human
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12. Levels of Organization
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Subatomic particles
Atom
Molecule
Macromolecule
Organelle
Cell
Tissue
Organ
Organ system
Organism
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The body and it constituents
• The basic organizational structure of the human body is the cell.
• There are 50-100 trillion cells in the human body.
• Differentiation is when cells specialize.
• As a result of differentiation, cells vary in size and shape due to their
unique function.
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Chemical Constituents of Cells
Organic v. Inorganic Molecules
Organic molecules
• Contain C and H
• Usually larger than inorganic molecules
• Dissolve in water and organic liquids
• Carbohydrates, proteins, lipids, and nucleic acids
Inorganic molecules
• Generally do not contain C and H
• Usually smaller than organic molecules
• Usually dissociate in water, forming ions
• Water, oxygen, carbon dioxide, and inorganic salts
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Cell Membrane
• Outer barrier of the cell
• Controls what moves in and out of the cell
• Selectively permeable
• Phospholipid bilayer
• Water-soluble “heads” form surfaces (hydrophilic)
• Water-insoluble “tails” form interior (hydrophobic)
• Permeable to lipid-soluble substances
• Cholesterol stabilizes the membrane
• Proteins:
• Receptors
• Pores, channels and carriers
•Enzymes
• CAMS (Cell Adhesion Molecules)
• Self-markers
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Transport across the cell membrane
Passive (Physical) Processes
• Require no cellular energy and
include:
• Simple diffusion
• Facilitated diffusion
• Osmosis
• Filtration
Active (Physiological) Processes
• Require cellular energy and
include:
• Active transport
• Endocytosis
• Exocytosis
• Transcytosis
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Active Transport
• Primary Active Transport
Carrier molecules transport substances across a membrane from regions of lower
concentration to regions of higher concentration (Sugars, amino acids, sodium ions,
potassium ions, etc.)
• Secondary Active Transport
Symporters are secondary active transporters that move two substances in the same
direction.
Conversely, antiporters are secondary active transport systems that transport substances
in opposite directions.
26. Bulk Transport Across the Cell Membrane
• The movement of large particles (or large quantities of smaller particles) across the cell
membrane.
•These mechanisms involve enclosing the substances to be transported in their own small globes
of membrane, which can then bud from or fuse with the membrane to move the substance
across.
•This include:
• Endocytosis
• Exocytosis
• Transcytosis
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39. How Do Cells Communicate?
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• Cells typically communicate using chemical signals.
• Sending cells secrete and release proteins or other molecules into the extracellular space.
• Target cells which have the right receptor for that signal can hear the particular chemical message.
• When a signaling molecule binds to its receptor, it alters the shape or activity of the receptor,
triggering a change inside of the cell. Signaling molecules are often called ligands.
• The message carried by a ligand is often relayed through a chain of chemical messengers inside the
cell. Ultimately, it leads to a change in the cell, such as alteration in the activity of a gene or even the
induction of a whole process, such as cell division. Thus, the original intercellular (between-cells)
signal is converted into an intracellular (within-cell) signal that triggers a response.
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Characteristics of Life
• Movement – change in position; motion
• Responsiveness – reaction to a change
• Growth – increase in body size; no change in shape
• Reproduction – production of new organisms and new cells
•Respiration – obtaining oxygen; removing carbon dioxide; releasing energy from foods
•Digestion – breakdown of food substances into simpler forms
• Absorption – passage of substances through membranes and into body fluids
•Circulation – movement of substances in body fluids
•Assimilation – changing of absorbed substances into chemically different forms
• Excretion – removal of wastes produced by metabolic reactions
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Maintenance of Life
• Life depends on five (5) environmental factors:
• Water
• Food
• Oxygen
• Heat
• Pressure
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Requirements of Organisms
• Water
- most abundant substance in body
- required for metabolic processes
- required for transport of substances
- regulates body temperature
• Food
- provides necessary nutrients
- supplies energy
- supplies raw materials
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Requirements of Organisms
• Oxygen (gas)
- one-fifth of air
- used to release energy from nutrients
• Heat
- form of energy
- partly controls rate of metabolic reactions
• Pressure
- application of force on an object
- atmospheric pressure – important for breathing
- hydrostatic pressure – keeps blood flowing
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Homeostasis
Maintaining of a stable internal environment
• Homeostatic Control Mechanisms – monitors aspects of the internal
environment and corrects as needed. Variations are within limits. There
are three (3) parts:
• Receptor - provides information about the stimuli
• Control Center - tells what a particular value should be (called the
set point)
• Effector - elicits responses that change conditions in the internal
environment
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• There are two (2) types:
• Negative feedback mechanisms
• Positive feedback mechanisms
Homeostatic Control Mechanisms
Negative feedback summary:
• Prevents sudden, severe changes in the body
• Corrects the set point
• Causes opposite of bodily disruption to occur, i.e. the ‘negative’
• Most common type of feedback loop
• Examples: body temperature, blood pressure & glucose regulation
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Positive feedback summary:
• Increases (accelerates) the actions of the body
• short-lived
• do not require continuous adjustments
• Examples: blood clotting and child birth
Homeostatic Control Mechanisms
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Organization of the Human Body
Thoracic cavity
Abdominal
cavity
Diaphragm
Pelvic cavity
Cranial cavity
Vertebral canal
(a)
Abdominopelvic
cavity
Abdominal
cavity
Pelvic cavity
Right pleural
cavity
Mediastinum
Left pleural cavity
Pericardial
cavity
Diaphragm
Vertebral canal
Cranial cavity
Thoracic
cavity
(b)
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Life span Changes
Aging occurs from the microscopic level to the whole-
body level.
Can you think of some examples?
55. FLUID, ELECTROLYTE, AND ACID-BASE
BALANCE
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• Human beings are mostly water, ranging from about 75 percent of body mass in infants to
about 50–60 percent in adult
• men and women, to as low as 45 percent in old age. The percent of body water changes
with development, because the proportions of the body given over to each organ and to
muscles, fat, bone, and other tissues change from infancy to adulthood
• Your brain and kidneys have the highest proportions of water, which composes 80–85
percent of their masses. In contrast, teeth have the lowest proportion of water, at 8–10
percent.
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FLUID, ELECTROLYTE, AND ACID-BASE
BALANCE
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Fluid Compartments
• Body fluids can be discussed in terms of their specific fluid compartment, a location that is
largely separate from another
• compartment by some form of a physical barrier. The intracellular fluid (ICF) compartment is the
system that includes all
• fluid enclosed in cells by their plasma membranes. Extracellular fluid (ECF) surrounds all cells in
the body. Extracellular
• fluid has two primary constituents: the fluid component of the blood (called plasma) and the
interstitial fluid (IF) that
• surrounds all cells not in the blood
FLUID, ELECTROLYTE, AND ACID-BASE
BALANCE
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FLUID, ELECTROLYTE, AND ACID-BASE
BALANCE
59. Composition of Body Fluids
• The compositions of the two components of the ECF—plasma and IF—are more
similar to each other than either is to the ICF
• Blood plasma has high concentrations of sodium, chloride, bicarbonate, and protein.
• The IF has high concentrations of sodium, chloride, and bicarbonate, but a relatively
lower concentration of protein. In contrast, the ICF has elevated amounts of
potassium, phosphate, magnesium, and protein. Overall, the ICF contains high
concentrations of potassium and phosphate ( HPO4 2 − ), whereas both plasma and
the ECF contain high concentrations of sodium and chloride.
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FLUID, ELECTROLYTE, AND ACID-BASE
BALANCE
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FLUID, ELECTROLYTE, AND ACID-BASE
BALANCE
61. Fluid Movement between Compartments
Hydrostatic pressure, the force exerted by a fluid against a wall, causes movement of fluid between
compartments. The
hydrostatic pressure of blood is the pressure exerted by blood against the walls of the blood vessels by
the pumping action of the heart. In capillaries, hydrostatic pressure (also known as capillary blood
pressure) is higher than the opposing “colloid osmotic pressure” in blood—a “constant” pressure
primarily produced by circulating albumin—at the arteriolar end of the capillary.
This pressure forces plasma and nutrients out of the capillaries and into surrounding tissues. Fluid
and the cellular wastes in the tissues enter the capillaries at the venule end, where the hydrostatic
pressure is less than the osmotic pressure in the vessel. Filtration pressure squeezes fluid from the
plasma in the blood to the IF surrounding the tissue cells. The surplus fluid in the interstitial space
that is not returned directly back to the capillaries is drained from tissues by the lymphatic system,
and then re-enters the vascular system at the subclavian veins.
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FLUID, ELECTROLYTE, AND ACID-BASE
BALANCE
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FLUID, ELECTROLYTE, AND ACID-BASE
BALANCE
63. Electrolytes
Serum Electrolyte Normal Range
Sodium 136–145 mEq/L
Potassium 3.5–5.0 mEq/L
Chloride 96–106 mEq/L
Calcium in adult 8.5–10.8 mg/dL
Magnesium 1.5–2.2 mEq/L
Phosphate
Bicarbonate:
2.6–4.5 mg/dL
22-30 mmol/L
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67. Hypomagnesemia
Serum magnesium < 1.5 mEq/L
Causes
Decreased absorption or increased loss of magnesium
Alterations in thyroid hormone function
Alcoholism
Medications
◦ Amphotericin B
◦ Diuretics
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68. Hypermagnesemia
Causes
Renal failure (most common cause)
IV Mg therapy for refractory asthma or pre-eclampsia
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Serum [Mg]
Severity
2.5 - 4 mg/dl
Mild
4 - 12 mg/dl
Moderate
> 13 mg/dl
Severe
71. Acid base homeostasis
Acid-base balance must be tightly controlled to maintain a normal extracellular pH
of 7.4 (normal 7.35 to 7.45)
Acid-base balance is regulated by:
◦ Buffers
◦ Intracellular (proteins & phosphate)
◦ Extracellular (bicarbonate & ammonia)
◦ Lungs
◦ Adjusts within minutes to changes in acid-base balance
◦ Kidneys
◦ Slower to compensate
◦ Reclaim and regenerate all the filtered HCO3
- back to blood
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