Overview of the Human BodyChapter 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

RECEPTOR (ie. free

nerve ending in the skin)

CONTROL CENTER(such as the brain)

EFFECTOR(such as a muscle,

or a gland)

Stimulus (input into the system)

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

OrganelleMoleculeAtoms

Chemical level Cellular level

Tissue levelTissues consist of similartypes of cells.

Organ levelOrgans are made up of different typesof tissues.

Organ system level Organismal level

Smooth muscle cell

Smooth muscle tissue

Connective tissue

Blood vessel (organ)

HeartBloodvessels

Epithelialtissue

Smooth muscle tissue

1 2

3

4

56

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

Sodium atom (Na)(11p+; 12n0; 11e–)

Chlorine atom (Cl)(17p+; 18n0; 17e–)

Sodium gains stability by losingone electron, and chlorine becomesstable by gaining one electron.

After electron transfer,the oppositely charged ionsformed attract each other.

Sodium ion (Na+) Chloride ion (Cl–)

Sodium chloride (NaCl)

+ —

Ionic Bonds

Figure 2.6a–b Formation of an ionic bond.

Reacting atoms

Hydrogen atoms Carbon atomFormation of four single covalent bonds:Carbon shares four electron pairs withfour hydrogen atoms.

+

Molecule of methane gas (CH4)

Structural formulashows single bonds.

or

Resulting molecules

Figure 2.7a Formation of covalent bonds.

Covalent Bonds

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

H2OH2

•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

GLYC

EROLH2O

A triglyceride

• Hydrophilic-• Hydrophobic-

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 Reactions1. Synthesis or Anabolic reactions2. Decomposition or Catabolic reactions3. 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?

OGlucose Fructose

SucroseGlucose

Fructose&

Reactant Products

FructoseFructose

A. Synthesis ReactionB. Decomposition ReactionC. Exchange ReactionD. 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

Enzyme (E)

Enzyme-substratecomplex (E-S)

Enzyme (E)

Product (P)e.g., dipeptide

Energy isabsorbed;bond isformed.

Water isreleased.

Peptidebond

1 Substrates bind at active site. Enzyme changes shape to hold substrates in proper position.

2 Internalrearrangements leading to catalysis occur.

3 Product isreleased. Enzyme returns to original shape and is available to catalyze another reaction.

Active site

+

Link- Enzyme animation

Sucrase is the enzyme that catalyzes this decomposition reaction

OGlucose Fructose

Sucrose

GlucoseFructose&

Reactant Products

sucraseFructose Fructose

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. Carbohydrates2. Lipids3. Proteins4. 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

= Fuel

• Glucose is a ‘single’ sugar. • Note that it is a ring structure with 6 carbon atoms. • Other monosaccharides- fructose, galactose

C6H12O6 =

glucose

=

Sucrose is a disaccharide

Other disaccharides- maltose, lactose

OGlucose FructoseFructose

Polysaccharides• Starch/Amylose• Glycogen• Cellulose

Linear chain

(a) Starch

Starch granules inpotato tuber cells

Glucosemonomer

(b) Glycogen

GlycogenGranulesIn muscletissue

(c) Cellulose

Cellulose molecules

Cellulose fibril ina plant cell wall

Polysaccharides

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 lipids1. 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

• Triglycerides are three fatty acids linked to one glycerol molecule.

• Fatty acids are long, linear chains of carbon and hydrogens (hydrocarbon chains).

GLYC

EROL F A T T Y A C I D

F A T T Y A C I D

F A T T Y A C I D

TriglyceridesGL

YCER

OL

• 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.

FATTY ACID #1

Functions and locations of triglycerides in the body

• Functions of triglycerides?

• Where can we find stores of triglycerides?

GLYC

ERO

L

F A T T Y A C I D F A T T Y A C I D F A T T Y A C I D

1.

2.

3.

Steroids• All consist of a complex

ring structure• Cholesterol is the precursor

for all steroid hormones– Estrogen– Testosterone– Cortisol

• Signaling molecules– Sexual function– Tissue metabolism

• Component of animal cell membranes

cholesterol

estrogen testosterone

Eicosanoids

• Non-Steroidal Anti-Inflammatory Drugs(NSAIDs) inhibit prostaglandin synthesis

Cell Cell membranae

• 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

Phospholipids

A triglyceride

A phospholipid

Phospholipids are modified triglycerides. Phospholipids have TWO fatty acids chains, and a phospho-group in place of the third!

GLYCEROL

F A T T Y A C I D

F A T T Y A C I D

F A T T Y A C I D

GLYCEROL

F A T T Y A C I D

F A T T Y A C I D =

PhosphateGroup

Non-lipidGroup

PhospholipidChemist’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?

Yikes!

Phospholipid bilayer

Chemist’s version

Biologist’s version Sesame Street

versionH20

Two layers of phospholipids, stacked on each other, with the hydrophobic tails of each layer

facing one another.Phospholipid animationhttp://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, generalizedamino acid

- + +-

•Amino acids are linked together via peptide bonds. •Two linked amino acids = dipeptide•10-50 linked together = polypeptide•50+ = protein

Heidi’s Protein Cartoon- Each shape in the chain represents

one amino acid

Peptide bonds

Protein FunctionsThe 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 double helix

•RNA is a single stranded nucleic acid; serves as a template for protein synthesis

RNA

DNA

Adenosine

Adenosine Triphosphate- ATP

• Storable “energy packets” for cells

---

Link http://faculty.ccbcmd.edu/biotutorials/energy/adpan.html

Solute

Membraneprotein

Relaxed smoothmuscle cell

Contracted smoothmuscle cell

+

+

+

Transport work: ATP phosphorylates transportproteins, activating them to transport solutes(ions, for example) across cell membranes.

Mechanical work: ATP phosphorylates contractile proteins in muscle cells so the cells can shorten.

Chemical work: ATP phosphorylates key reactants, providing energy to drive energy-absorbing chemical reactions.

(a)

(b)

(c)

Cellular work driven by ATP energy

• Hydrolysis of ATP provides energy for cellular needs

• ATP transfers its terminal phosphate, and ‘energizes’ another molecule