the maintenance of optimal physiological conditions within the body so that vital functions can be performed without deviations or disturbances.

**dynamic (ever-changing and adjusting)

Components of homeostatic feedback loop 

1. Receptor (sensor): monitors a controlled condition

2. Integrating center (Control center): usually the brain--determines next action

3. Effector: receives directions from the control center, produces a response that changes the condition

• original stimulus reversed

• most feedback systems in the body are negative

• used for conditions that need frequent adjustment

• body temperature, blood sugar levels, blood pressure

Homeostasis of Blood Pressure

Pressure receptors in walls of certain arteries detect an increase in BP

nBlood Pressure = force of blood on walls of vessels

nBrain receives input and signals heart and blood vessels

nHeart rate slows and arterioles dilate (increase in diameter)

nBP returns to normal

noriginal stimulus intensified

nseen during normal childbirth, vomiting, blood clotting

nStretch (receptors) in walls of uterus send signals through the nervous system to the hypothalamus (control center), which in turn sends a signal through the nervous system that stimulates pituitary gland

nPituitary gland releases oxytocin (messenger) into bloodstream- binds to receptors on smooth muscle of uterus

nUterine smooth muscle contracts more forcefully (effector)

nMore stretch, more hormone, more contraction etc.

nCycle ends with birth of the baby & decrease in stretch

nChemical messengers:

nHormones: chemical secreted into bloodstream

nNeurotransmitters: chemicals secreted by nerve cells

nSend signals to other nerves, muscles, glands

Mass: amount of matter in an object

weight: force of gravity acting on matter

**on earth, weight and mass are equal

112 elements, 92 occur naturally

26 of naturally occurring elements are in the body

C-Carbon

O-Oxygen

H-Hydrogen

N-Nitrogen

**Make up 96%

Ca-Calcium

P-Phosphorus

K-Potassium

S-Sulfur

Na-Sodium

Cl-Chlorine

Mg-Magnesium

Fe-Iron

**Make up 3.8%

Trace elements: Copper, tin, selenium, zinc

 Molecule containing different kinds of atoms

 number of protons in the nucleus.

Unless the shells are full, the electron will be

Ionic compounds generally exist as

In the body, materials containing ionic bonds are found mainly in

Teeth, bones, blood

nIons in a compound that dissolve in water are called electrolytes

nIonic bonds are easily broken by adding water

Electrolytes:

Why does Your Body Need Them?

Brain, nerves:

1. Powered by electricity

2. Electrochemical energy

Muscles (including heart):

1. Calcium (Ca2+) allows muscles to contract

Digestive system:

1. Hydrogen (H+) major ion of digestion

Regulation of Body Fluids:

1. Blood pressure regulation: (a few examples you need to know)

Sodium (Na⁺)

Potassium (K⁺)

Chloride (Cl-)

Phosphate (PO4^3-)

Hydroxide (OH-)

Calcium (Ca²⁺)

Magnesium (Mg²⁺)

·         Atoms share electrons to form covalent bonds

·         Electrons spend most of the time between the two atomic nuclei

·         Unequal sharing of electrons between atoms.

·         In a water molecule, oxygen attracts the hydrogen electrons more strongly

-Oxygen has greater electronegativity as indicated by the negative Greek delta sign.

Human Body 70% water – medium of chemical reactions

Polarity

·         Uneven sharing of electrons

·         Partial negative charge near oxygen atom and partial positive charge near hydrogen atoms

Hydrogen Bonds

·Formed by the attraction between slightly positive hydrogen atom and a slightly negative atom of another element.

·Gives water unique characteristics

Solvent

Most versatile solvent known – dissolves hydrophilic (polar, water soluble) substances, not hydrophobic (non-polar, oil soluble)

·         Its shape allows each water molecule to interact with neighboring ions/molecules

o   oxygen portion attracts sodium

o   hydrogen portion attracts chloride

o   sodium & chloride separate as ionic bonds are broken

·         Hydration spheres surround each ion and decrease possibility of bonds being reformed

High

·         Can absorb a large amount of heat with only a small increase in its own temperature

o   Large number of hydrogen bonds in water

o   Bonds are broken as heat is absorbed instead of increasing temperature of water

·         Large amount of water in body helps lessen the impact of environmental changes in temperature

·         Evaporation of water from the skin removes large amount of heat

·         Molecules with a hydrophobic region and a hydrophilic region.

o   In water, form clusters with polar regions at the surface, and nonpolar regions in interior of cluster - i.e. Soap

·         Provide specific boundaries for other substances

o   Cell membrane: phospholipids

Water as a Lubricant

·Major component of lubricating fluids within the body

oMucus in respiratory and digestive systems

oSynovial fluid in joints

oSerous fluids in chest and abdominal cavities

oOrgans slide past one another

Free Radicals

·Atom with an unpaired electron in its outermost shell

·Unstable and highly reactive

·Can become stable by giving up electron, or taking one from another molecule

oAntioxidants attach to electrons

oWithout antioxidants free radicals attach to electrons on body cells, especially nerve tissue.

Free Radicals & Your Health

·Produced in your body by

oUV light

ox-rays

oMajority: during normal metabolic reactions (hydrogen peroxide)

·Linked to many diseases

odiabetes

oAlzheimer’s

oatherosclerosis

o arthritis

Dissolve acids in water:

Dissolve bases in water:

Dissolve salts in water:

Neutralization reaction:

pH

As pH increases,

 [H+] decreases

A difference of 1.0 in pH means a 10x difference in [H+]

*A solution of pH 7 has 10x the [H+] of a solution with pH 8

-Always contain carbon and hydrogen

-usually contain covalent bonds

-usually large, unique molecules with complex functions

·         Four major classes of organic compounds (macromolecules or polymers) are

v  Carbohydrates

v  Lipids

v  Proteins

v  Nucleic acids

Carbohydrates

·Diverse group of substances formed from – carbon, hydrogen, oxygen

·Examples

vcarbohydrates

vsugars

vstarches

vsaccharides

vcellulose

·Main function is to produce energy

·Hydrophilic

Three types of carbohydrate molecules

·         Monosaccharides -one molecule

v  Glucose – most abundant monosaccharide in body

§  Stored in liver as glycogen (a polysaccharide)

·         Disaccharides - two molecules

·         Polysaccharides – many molecules

Monosaccharides

·simple sugars

·humans can absorb only three types of monosaccharides

·Glucose, fructose, galactose

Disaccharides

·Formed by combining two monosaccharides: sucrose (fructose + glucose), lactose (galactose + glucose), maltose (glucose + glucose)

·         Lactose Intolerance -

Polysaccharides

·Contain 10 or 100’s of monosaccharides

·In animals

►glycogen –storage in liver

·In plants

►starch and cellulose are large carbohydrate molecules used for energy storage

§rice

§potatoes

§grains

Fats Containing Carbon, Hydrogen

(hydrophobic)

1. Storage lipid

2. Regulatory lipid

3. Structural lipid

1. Storage lipid

►Triglycerides- Common body fat: fatty acids + glycerol (energy)

►Types of Unsaturated Fatty Acids

§cis - fatty acids

·Angular fatty acid chain: more fluid

§trans - fatty acids

·Straight fatty acid chain: more viscous (like saturated fatty acids)

2. Regulatory lipid

►Steroids- Act as hormones

►Cortisol– anti-inflammatory

3.  Structural lipid

Proteins-elements/formation

carbon

hydrogen

oxygen

nitrogen

sulfur

**Constructed from combinations of 20 amino acids, held together by peptide bonds

Structural

Hormones

Oxygen transport (hemoglobin)

Cell receptors/channels

Antibodies

Enzymes

Energy

1. Primary: Sequence of amino acids

2. Secondary: chain of amino acid's spatial arrangement IE beta pleated sheet, alpha helix

3. Tertiary: complex 3D shape

4. Quaternary: shape formed by more than one polypeptide chain joining together IE hemoglobin

**Shape of protein influences its ability to form bonds and function

Protein Denaturation

►   Unique shape facilitates specific function. If proteins unravel, can’t function

►   Heat, acid or salts change (denature) three dimensional shape and destroy protein’s ability to function

Enzymes:

 proteins that are catalysts

1. Speed up the rate of chemical reactions

Lower the activation energy for a reaction

2. Are not permanently altered in the reactions

3. Do not change the nature of the reaction

4. Enzymes catalyze reactions by binding the reactants (substrates)

orient them so that less energy is needed to get the reaction going

Enzymes Catalyze...

Lock and Key Model

-Enzymes have complex structures

-Regions in the structure act as active sites

bind specific substrates

catalyze specific chemical reaction

produce specific products

optimal pH

Nucleic Acids and function

DNA

RNA

Function

-Storage of genetic information for protein synthesis

-Energy

DNA Structure

·         Huge molecules containing

§  carbon

§  hydrogen

§  oxygen

§  nitrogen

§  phosphorus

·         Molecules exist in nucleus of cells

DNA Fingerprinting

In identification

1. criminal

2. victim

3. a child’s parents

-strand of hair

-drop of semen

-spot of blood

1. Only gives probability, not certainty, unlike traditional fingerprinting

2. Can rule out non-paternity, but cannot conclusively prove paternity

adenosine triphosphate (derivative of nucleic acids)

Energy currency of the body

Releases energy when one phosphate is removed from molecule

nCells are Basic, living, structural and functional unit of the body

nCells are the smallest units that perform all vital physiological functions

nEach cell maintains homeostasis at the cellular level

3 Generalized Cell Structures

1. Nucleus

2. Plasma (cell) membrane

3. Cytoplasm

Control center of the cell

-46 human DNA molecules or chromosomes

-Two sets of 23 chromosomes or diploid

ngenes found on chromosomes represent a total of 30,000 genes in every human

nEach gene gives instructions to build a specific protein

Plasma Membrane Functions

-Physical isolation

-Regulation of exchange with the environment nCell to cell communication

-Movement   - microvilli, cilia, flagella

Describes structure of plasma membrane

1. “Sea of lipids in which proteins float like icebergs”

2. Membrane is 50 % lipid and 50 % protein--held together by hydrogen bonds

3. Lipid is a barrier to entry or exit of polar substances

4. Proteins are “gatekeepers”--regulate traffic through the cell membrane via channels and transporters

Two back-to-back layers of phospholipid molecules, with cholesterol and glycolipids scattered on and through the double row

Phospholipids

-Comprises 75% of lipids

-Makes up the Phospholipid bilayer

-Each molecule is amphipathic

Two parallel layers of molecules

Function of Cholesterol

Increases stiffness of membrane

(membranes are usually fluid structures)

Plasma Membrane Projections

1. Microvilli

2. Cilia

3. Flagella

Plasma Membrane Projections

Microvilli

-Fingerlike projections

-Greatly increase surface area for absorption (e.g. small intestine)

Plasma Membrane Projections

Cilia

-Shor hair-like structures

Plasma Membrane Projections

-Long whip-like structures found on mature sperm

*Allows sperm to swim

1. Integral proteins

2. Peripheral proteins

*Receive chemical messengers (hormones)

-Cellular recognition site

-Ligand (chemical signaling molecule) binds to receptor

-Results in reaction in the cell

-Anchor proteins in cell membrane or to other cells

-Allow cell movement

-Cell shape & structure

-Speeds up reactions

-Substrate binds to enzyme, makes products

Membrane Junctions (Linkers)

1. Desmosomes

2. Tight junctions

3. Gap junctions

Membrane Junctions (Linkers)

Desmosomes

-Allow for stretching

-IE Skin

-Like rivets or spot welds

*cell membranes held together by a thin layer and reinforced by a network of filaments for strength

Membrane Junctions (Linkers)

Tight Junctions

-No extracellular space between cells

-Substances must pass through cells

-Epithelial cells of digestive system

-Allows for control of substances

*membranes tightly bound together by membrane proteins via adhesion belt, preventing passage of materials IE Stomach lining

Membrane Junctions (Linkers)

Gap junctions

-Protein channels link cytosol region of two adjacent cells

-Limited exchange of small substances between cells

-Heart muscles

*cell membranes bound together by membrane proteins called channel proteins, allowing small materials to pass through gaps

1. Cytosol

2. Cell organelles

3. Cytoskeleton

Fluid: Contains enzymes for necessary chemical reactions

• 75-90% water with other components

1. Large organic molecules suspended by electrical charges

-proteins

-carbohydrates

-lipids

2. Small dissolved organic molecules

-simple sugars

-ions

3. Site of many important chemical reactions

-Production of ATP

-Synthesis of building blocks for macromolecules

Tiny organs, perform funtions to maintain homeostasis

1. Ribosomes

2. Endoplasmic reticulum

3. Golgi apparatus

4. Protein synthesis

5. Lysosomes

6. Peroxisomes

7. Mitochondria 

Nucleus tells ribosomes which proteins to make via mRNA

1. Packages of ribosomal RNA and protein

-Free ribosomes are loose in cytosol

*synthesize proteins found inside the cell

-Membrane-bound ribosomes

*attached to endoplasmic reticulum

*synthesize proteins needed for plasma membrane or for export

*Processes and packages proteins into envelopes called vesicles, then sends to the Golgi apparatus

-Processes and packages proteins produced by rough ER

-Processes and packages lipids synthesized by smooth ER

(Post office)

Protein synthesis

-Translation

nInstructions for making specific proteins is found in genetic coding in the DNA

Translation: The process of reading the mRNA code to form a specific protein

-Membranous vesicles

-Filled with digestive enzymes

Functions:

-Digest foreign substances

-Autophagy - recycles own organelles

*Clean-up crew

-Membranous vesicles

-Contain enzymes that oxidize organic material

Function:

-Oxidizes products of normal metabolic breakdown

-Oxidizes toxic substances such as alcohol and formaldehyde

*Contains catalase which decomposes H₂O_{2 ( product of metabolism)}

_{Clean-Up Crew}

Double membrane organelle

Function

-Generation of ATP by cellular respiration

-Powerhouse of cell

*Look and function like bacteria

*Made from maternally inherited DNA

Supports and stabilizes cellular structure--made of protein

*Orchestrates cell division

Made of:

1. Microfilaments--7nm diameter--Actin

2. Intermediate filaments--10nm diameter--several proteins

3. Microtubule--25nm diameter--Tubulin

Asexual

Cell growth must balance cell death

(G₀ phase of mitosis)

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase 

Mitosis

1. Prophase

-Chromosomes condense and organize

-nuclear membrane and nucleoli disappear

-Spindle attach to centromeres of duplicated chromosomes

Mitosis

2. Metaphase

Mitosis

3. Anaphase

-Centromere of each duplicated chromosome is separated

-Paired chromatids are pulled apart

Mitosis

4. Telophase

-Chromosomes uncoil

-Nucleoli appear

-Cytokinesis occurs-->two genetically identical daughter cells are produced

Pathological cell death

-Death of cells damages adjacent cells

Homeostatic cell death

-Process where specific cells die off in a controlled fashion that does not damage adjacent cells

1. Glycolysis

2. Citric Acid (Krebs) Cycle

3. Electron Transport Chain

-Splitting of sugar occurs outside of mitochondria

-Process of ten separate reactions in sequence that occur in the cytosol.

- 6-carbon glucose broken down into two 3-carbon molecules

C₆H₁₂O₆  --> 2C₃H₆O₃  + (2 ATP)

*Anaerobic-no oxygen used; functions in almost all living organisms

*Muscular pain from over exercise due to waste product of glycolysis (lactic acid)

Aerobic process

-Takes over where glycolysis leaves off.

-Takes place in mitochondria

-Each 3-carbon molecule loses one carbon atom:

forms 2-carbon molecule

-Makes 2 more ATP, (one per each 3-carbon molecule)

releases more high-energy electrons, & hydrogen ions

(Oxidative Phosphorylation)

Aerobic

-In Mitochondria

-High-energy electrons from previous steps (glycolysis and Krebs Cycle) power the process

-Electrons passed down from areas of higher energy to areas of lower energy.

-Movement of electrons powers the active transport of H⁺ ions out of a mitochondrial membrane.

-When concentration of H⁺ outside of membrane is greater than inside, H⁺ rush back in, fueling a pump that produces ATP.

nThis step produces an additional 26-34 molecules of ATP

OVERVIEW -The Final Equation: (Yes, this is important!)

C₆H₁₂O₆+ 6O₂= 6CO₂ + 6H₂O + (30-38 ATP)

(glucose)

(energy molecules)

How much ATP is produced per glucose molecule

Glycolosis?

Krebs cycle?

Oxidative phosphorylation?

Glycolosis: 2 ATP

Krebs cycle: 2 ATP

Oxidative phosphorylation: 26-34 ATP

TOTAL: 30-38 ATP

1. Food

2. Liver

-Liver stores glycogen

-Enzymes digest glycogen into free glucose

(Don't burn cleanly)

1. Triglycerides (from adipose tissue)

-Fatty acids enter Krebs cycle

ketones are byproducts

2.Protein

-Amino acids enter Krebs cycle

Ammonia and urea (toxic) produced as byproducts

ATP Transported Out of Mitochondria

Used within cell to power cellular functions

1. Muscle Tissue

2. Nerve Tissue

3. Epithelial Tissue

4. Connective Tissue

Cells designed for contraction

 Three Types:

1. Skeletal Muscle

2. Smooth Muscle

3. Cardiac Muscle

-Communication Network

Cell types

1. Neurons

-high-speed communication via electrical signals

2.Neuroglia

-support of neurons

1. Epithelial membranes

-Covers all body surfaces

-Forms barriers, tubes

2. Epithelial glands:

Clusters of epithelial cells that secrete various materials

-Use diffusion, mediated transport, exocytosis to secrete substances

A. Exocrine glands: do not secrete into blood

-Sweat, salivary, glands of digestive system

B. Endocrine glands: secrete into blood

-Hormones, nutrients secreted by liver

Functions

1. Connection

2. Structure

3. Support

General Structure

-Large amounts of extracellular material 

(extracellular matrix)

nMultiple tissue types

nOrganized to perform a specific function