Overview of the Human Body
Chapter 1
Overview
•
•
•
•
Anatomy and physiology: definitions
Form and Function
Homeostasis
Levels of organization
What is “Anatomy and Physiology”?
• Anatomy-
• Physiology-
Form (Structure) Fits Function
• Principle of Complementarity-
• You need to understand the parts and how they
are put together before you can truly understand
how they work
• If you know what a body structure does, you can
usually predict how it is organized/structured to do
its job
Homeostasis
• Homeostasis-
• The nervous system and endocrine system
(hormones) play important roles in
communication that promotes homeostasis
throughout the body.
• Every cell of the body must also maintain
homeostasis
Homeostasis and Feedback Loops
• All systems involve three components: a ‘receptor’,
a control center and an effector
Stimulus (input into the system)
RECEPTOR
(ie. free
nerve ending
in the skin)
CONTROL CENTER
(such as the brain)
EFFECTOR
(such as a muscle,
or a gland)
The response to the stimulus leads to
change. The change is ‘fed back’ to the
receptor.
Response
(system’s
output)
Homeostasis and Feedback Loops
• In negative feedback a stimulus causes a response
which works to reduce/counteract the stimulus
– Examples?
• In positive feedback a stimulus
causes a response which further
increases the stimulus, so that
output is accelerated
– Examples?
Levels of Organization
• How big is an atom?
~ 10,000,000 atoms
lined up side by side
to measure 1 mm
Atoms
Molecule
Organelle
Smooth muscle cell
2 Cellular level
1 Chemical level
Smooth muscle tissue
Heart
Blood
vessels
3 Tissue level
Tissues consist of similar
types of cells.
Blood vessel (organ)
Smooth muscle tissue
Connective tissue
Epithelial
tissue
4 Organ level
Organs are made up of different types
of tissues.
6 Organismal level
5 Organ system level
Chemistry
Chapter 2
Chemistry Basics
• Element: unique substance that cannot be
broken down into a more simple substance by
ordinary chemical methods.
Chemistry Basics
• Atom: building block of an element
– Proton
– Neutron
– Electron
• Atomic Number
• Atomic Mass
Chemistry Basics
• Isotope: different # of neutrons (from a
standard atom of the same element)
• Ion: different # of electrons (from the
standard atom of the same element)
Chemical Bonds
• Chemical bonds: energy relationships between
electrons of reacting atoms
• Electrons in valence shell (outermost electron shell)
– chemically reactive electrons
• Octet rule (rule of eights)
– Except for the first shell (full with two electrons) atoms
interact to have eight electrons in their valence shell
• 3 major bond types
– Ionic
– Covalent
– Hydrogen
Ionic Bonds
+
Sodium atom (Na)
(11p+; 12n0; 11e–)
Chlorine atom (Cl)
(17p+; 18n0; 17e–)
Sodium gains stability by losing
one electron, and chlorine becomes
stable by gaining one electron.
Figure 2.6a–b Formation of an ionic bond.
Sodium ion (Na+)
—
Chloride ion (Cl–)
Sodium chloride (NaCl)
After electron transfer,
the oppositely charged ions
formed attract each other.
Covalent Bonds
Reacting atoms
Resulting molecules
+
or
Structural formula
shows single bonds.
Carbon atom
Hydrogen atoms
Formation of four single covalent bonds:
Carbon shares four electron pairs with
four hydrogen atoms.
Figure 2.7a Formation of covalent bonds.
Molecule of methane gas (CH4)
Types of Covalent Bonds
• Non-Polar: Electrons shared equally
– Produces electrically balanced, nonpolar
molecules
• Polar: unequal sharing of electrons produces
polar
– Atoms in bond have different electron-attracting
abilities
Electrons and chemical bonds
H2
H2O
•Which molecule above is polar? Non-polar? How do you know?
•Which molecule above has covalent bonds? Polar covalent bonds?
•Are either of these molecules ions?
Other important terms
• Hydrophilic• Hydrophobic-
A triglyceride
H 2O
pH- Acids and Bases
• Acids
– Have a sour taste
– Release hydrogen ions, protons (H+) into
solution
– HCl, HC2H3O2, H2CO3
• Bases
– Have a bitter taste, feel slippery
– Are proton acceptors (they take up H+s from
solution)
– NaOH, HCO3-, NH3
pH- Acid-Base Concentration
• The concentration of H+ ions in solution is
measured in units of pH
• The pH scale is logarithmic and runs from 0 to 14,
with a pH value of 7 indicating a neutral solution
– Acidic solutions have pH values
from 0-6
– Neutral solutions = pH 7
– Basic (alkaline) solutions
have pH values from 8-14
• The more hydrogen ions in a
solution, the more acidic it is,
but the lower its pH value.
Thought Question
• The presence of hydrogen ions
stimulates the brain to increase
respiration rate.
• Johnny’s blood pH is 7.25. Normal
blood pH is 7.4.
• Will Johnny likely be breathing faster
or slower than normal? Why?
Chemical Reactions
1. Synthesis or Anabolic reactions
2. Decomposition or Catabolic reactions
3. Exchange reactions (swapping
partners)
Chemical Reactions
• Synthesis or Anabolic reactions
A + B → AB
• Decomposition/Catabolic
Reactions
AB → A + B
• Exchange reactions
AB + CD → AD + CB
What type of reaction is this?
Sucrose
Glucose
Glucose
O
Fructose
Fructose
Reactant
A.
B.
C.
D.
&
Fructose
Fructose
Products
Synthesis Reaction
Decomposition Reaction
Exchange Reaction
All of the above
Chemical Reactions, Energy & Enzymes
• Most chemical reactions do not occur
spontaneously, or they occur so slowly that they
would be of little value to cells
• Activation energy-
• Enzymes promote chemical reactions by
lowering activation energy
• Enzymes are biological catalysts, they are
usually protein molecules
Mechanism of enzyme action
Substrates (S)
e.g., amino acids
+
Product (P)
e.g., dipeptide
Energy is
absorbed;
bond is
formed.
Water is
released.
Peptide
bond
Active site
Enzyme (E)
Enzyme-substrate
complex (E-S)
1 Substrates bind
2 Internal
at active site.
rearrangements
Enzyme changes
leading to
shape to hold
catalysis
substrates in
occur.
proper position.
Link- Enzyme animation
Enzyme (E)
3 Product is
released. Enzyme
returns to original
shape and is
available to catalyze
another reaction.
Sucrase is the enzyme that catalyzes this
decomposition reaction
Sucrose
Glucose
sucrase Glucose
O
Reactant
Fructose
Fructose
&
Fructose
Fructose
Products
What do you think?
-Does the reverse reaction ever occur?
-Is sucrose ever formed (synthesized) from glucose
and fructose?
What are organic compounds?
• In chemistry, an organic compound
must contain carbon and hydrogen
• Most biologically relevant, organic
compounds are soluble in water
– Why?
– What group might be the exception?
• Many are polymers (large molecules)
built from monomers (small subunits)
What are examples of inorganic
compounds in the body?
What are some examples of these
organic compounds in the body?
1.
2.
3.
4.
Carbohydrates
Lipids
Proteins
Nucleic acids
Can you identify an example of each?
Carbohydrates
• Group of molecules that includes sugars,
starches and fiber
• Account for less then 1-2% of body weight
• In the body, primary function is as a
readily usable energy source (glucose)
– Also as energy storage (glycogen)
– Cellular surface markers
• Forms of carbohydrates
– Monosaccharides, Disaccharides,
Polysaccharides
Glucose is a monosaccharide
C6H12O6 =
=
= Fuel
glucose
• Glucose is a ‘single’ sugar.
• Note that it is a ring structure with 6 carbon atoms.
• Other monosaccharides- fructose, galactose
Sucrose is a disaccharide
Glucose
O
Fructose
Fructose
Other disaccharides- maltose, lactose
Polysaccharides
• Starch/Amylose
• Glycogen
• Cellulose
Linear chain
Polysaccharides
Glucose
monomer
Starch granules in
potato tuber cells
(a) Starch
Glycogen
Granules
In muscle
tissue
(b) Glycogen
Cellulose fibril in
a plant cell wall
Cellulose molecules
(c) Cellulose
Monomer + Monomer + Monomer = Polymer
Lipids
• Lipids, as a class, are a very diverse group of
molecules
– What do you think is the unifying
characteristic of lipids?
• Lipids are important energy stores
• Lipids form essential structures in cells
Major types of lipids
1. Triglycerides
- Comprised of fatty acids and glycerol;
what we usually call ‘fats’ or ‘oils’
2. Steroids
-Cholesterol derivatives
3. Eicosanoids
-Cell signaling molecules
4. Phosopholipids
- Amphipathic molecules that form cell
membranes
Triglycerides
FATTY ACID
FATTY ACID
FATTY ACID
• Triglycerides are three fatty acids linked to one
glycerol molecule.
• Fatty acids are long, linear chains of carbon and
hydrogens (hydrocarbon chains).
Triglycerides
FATTY ACID #1
• In different triglycerides, the glycerol is the same, but
the fatty acid chains vary, resulting in different types
of fats and oils.
• All fatty acid (hydrocarbon chains) are non-polar.
Functions and locations of
triglycerides in the body
• Functions of triglycerides?
1.
FATTY ACID
2.
FATTY ACID
3.
FATTY ACID
• Where can we find stores
of triglycerides?
Steroids
• All consist of a complex ring
structure
• Cholesterol is the precursor
for all steroid hormones
– Estrogen
– Testosterone
– Cortisol
cholesterol
• Signaling molecules
– Sexual function
– Tissue metabolism
• Component of animal cell
membranes
estrogen
testosterone
Eicosanoids
• Diverse group of lipids
derived from fatty acids of
cell membranes
– Prostaglandins
• Powerful signaling
molecules, synthesized
by nearly all tissues of
the body
• Tend to act locally
• Pain/inflammation
• Labor
Cell
• Non-Steroidal Anti-Inflammatory Drugs
(NSAIDs) inhibit prostaglandin synthesis
Cell
membranae
Phospholipids
Phospholipids are modified triglycerides. Phospholipids have
TWO fatty acids chains, and a phospho-group in place of the third!
A triglyceride
Non-lipid
Group
Phosphate
Group
A phospholipid
=
Phospholipid
Chemist’s version
Anatomist/Biologist’s
version
Phospholipid molecules are amphipathic. One part of the
molecule is polar, while the other end is non-polar.
Which end interacts readily with water?
Phospholipid bilayer
Chemist’s
version
Biologist’s version
H20
Sesame Street
version
Two layers of phospholipids, stacked on each
other, with the hydrophobic tails of each layer
facing one another.
Phospholipid animation
http://telstar.ote.cmu.edu/biology/MembranePage/index2.html
All cell membranes are a
phosophlipid bilayer
• Forms the boundary between a cell and its
environment
• Hydrophobic core, with hydrophilic ends
Proteins
• Proteins are polymers (chains)
of amino acids (AA)
• A single,
generalized
amino acid
Heidi’s Protein CartoonEach shape in the chain represents
one amino acid
Peptide bonds
-
+
-
+
•Amino acids are linked together via
peptide bonds.
•Two linked amino acids = dipeptide
•10-50 linked together = polypeptide
•50+ = protein
Protein Functions
The over 2 million proteins in our bodies do an
amazing variety of tasks
•
•
•
•
•
•
•
•
Enzymes (control metabolism)
Support
Movement
Transport
Cell Receptors for communication
Buffering
Hormonal Regulation
Defense
The 20
Amino
Acids
Protein Structure
The hydrogen bonds
between amino acids
(not the peptide
bonds) are easily
disrupted by changes
in temperature and pH.
What happens to
protein structure when
pH is abnormal?
LINK
Nucleic acids
• DNA- deoxyribonucelic acid and
RNA- ribonucleic acid
-Store and process information
-Your genetic code
-Provide the directions for building
proteins
• DNA is a double stranded molecule
that resides in the cell nucleus
• RNA is single stranded molecule
that is found mainly outside of the
nucleus, usually serving as a
‘copy’ of DNA
Nucleic Acids are Polymers, too!
• The monomers/units of nucleic acids are
nucleotides
• A nucleotide consists of
– Sugar
– Phosphate group
– Nitrogenous base (A, C, T, G or U)
Phosphate
Base
Sugar
Nucleotide monomer
DNA and RNA
•DNA is two long strands of nucleotides, held together
by hydrogen bonds between the nucleotide bases
-Exhibits complementary
base pairing along
DNA
double helix
•RNA is a single stranded nucleic acid; serves as a
template for protein synthesis
RNA
Adenosine Triphosphate- ATP
• Storable “energy
packets” for cells
- -
-
Adenosine
Link http://faculty.ccbcmd.edu/biotutorials/energy/adpan.html
Cellular work driven by ATP energy
Solute
+
• Hydrolysis of
ATP provides
energy for
cellular needs
• ATP transfers
its terminal
phosphate, and
‘energizes’
another
molecule
Membrane
protein
(a) Transport work: ATP phosphorylates transport
proteins, activating them to transport solutes
(ions, for example) across cell membranes.
+
Relaxed smooth
muscle cell
Contracted smooth
muscle cell
(b) Mechanical work: ATP phosphorylates
contractile proteins in muscle cells so the
cells can shorten.
+
(c) Chemical work: ATP phosphorylates key
reactants, providing energy to drive
energy-absorbing chemical reactions.