Week 1 Notes

Lecture 1: Intro to Physio 

Physiology 

• The study of functions of organism 

• About the How’s and Why’s 

  • How does the body work?

  • Why does it work the way it does?

Structural Levels of Organization

1. Atoms/ molecules

2. Cells

3. Tissues

4. Organs

5. Organ systems

6. Organism 

External vs Internal Environment

1. External 

   1. Components OUTSIDE the body 

   2. Examples:

      1. Air

      2. Nutrient

      3. Water

      4. Inorganic ions

      5. Urine & feces 

2. Internal

   1. Components INSIDE the body 

   2. Examples:

      1. Cells 

      2. Fluid 

3. THEY ARE SEPARATED BY EPITHELIUM

   1. Examples:

      1. Skin

      2. Lining of lungs

      3. Intestinal tract

      4. Kidney tubules 

4. Major Concept

• Human body requires contact w/ external environment 

• Problem: not all cells are in direct contact 

• Solution: fluid compartments ⇒ allow for cell communication 

Fluid Compartments

• Total Body Water (TBW)

  • Vol. of water contained in all the body’s compartments 

  • Includes: intracellular fluid (ICF) & extracellular fluid (ECF) 

  • INTRACELLULAR FLUID (ICF)

    • Fluid inside cells 

  • EXTRACELLULAR FLUID (ECF)

    • Fluid outside cells 

    • Includes

1. Plasma - liquid (non-cellular) portion of blood

2. Interstitial fluid (ISF) - fluid outside the blood surrounding cells 

Homeostasis 

• Maintenance of a relatively constant internal environment 

• Unifying theme in physio 

• Disruption → disease 

Homeostatic Control Systems

• Regulatory responses to maintain homeostasis

• Classes: 

• Intrinsic/ local controls 

  • On a small scale

  • Inherent in an organ (at organ lvl)

    • EX: blood vessel 

      • Has ability to vasodilate (open up) or vasoconstrict (close up) once detecting chemicals; regulating by itself 

• Extrinsic/ systemic controls 

  • Involving multiple systems

  • Regulatory mechanism initiated outside organ 

    • Involves long distance systems (i.e., endocrine & nervous systems)

      • EX: blood vessels open/close up due to hormone in endocrine or due to electrical impulse by neuron 

        • Vessels not doing it by itself, it’s regulated from outside using other systems 

  • Coordinates response from several organs → common goal 

Regulated Variables

• Conditions regulated by homeostatic control 

• Examples:

1. Temperature

2. pH

3. Salinity 

4. Dissolved gas concentration 

5. Nutrient & waste concentration 

Set Point

• Range for a regulated variable the body wants to maintain

• Examples:

1. Body temp: 37C

2. Blood glucose: 100 mg/dL

3. Blood pH: 7.35-7.45

• WHAT HAPPENS IF YOU GO OUT THE RANGE??

  • ⇒ Error signal (aka deviation from that set point)

Homeostatic Response

• As a result of an error signal 

• Response in which body tries to fix error signal to return to homeostasis

• COMPONENTS:

1. Stimulus - change from set point (error signal)

2. Sensor - detects stimulus 

   1. Specific type of cells that detects the stimulus

3. Integrating center 

   1. Receives input from receptors (takes on info)

   2. Determines needed output to effectors (process info then decides on an output) 

   3. Usually is part of nervous system, BUT sometimes sensor = integrating center, depending on scenario 

4. Effectors - receives output to respond to stimulus 

• EXAMPLE: BLOOD GLUCOSE

• Stimulus - sugar, glucose in blood

• Sensor - beta cells in pancreas

• Integrating center - beta cells 

  • Takes info in that blood glucose lvls are high and determines needed output

    • Needed output = insulin 

      • Releases insulin into blood, then insulin binds to effectors (cells of the body) 

• Effectors - cell of the body 

  • Receives output (insulin) to respond to the stimulus 

Feedback 

• Responses made after change is detected 

• Types:

1. Negative feedback (most common)

   1. Responses moves system in the OPPOSITE direction of initial change 

   2. Stabilizing 

   3. Examples:

      1. Body temperature 

         1. Ex: temp set 37C

            1. Initial change: temp goes up 

            2. Response: to bring temp down (aka moving response in opposite direction to stabilize)

      2. Blood glucose level 

2. Positive feedback 

   1. Response moves system in SAME direction as initial change

   2. Directional 

   3. Less common 

   4. Examples: 

      1. Childbirth 

      2. Ovulation 

      3. Blood clotting 

      4. Ex: temp set 37C

         1. Initial change: temp goes up even more

         2. Response: move system in same direction, so temp goes up and up until something happens, until fever breaks 

Diabetes

• Metabolic disease affecting:

  • Blood glucose levels

  • Urine volume

• Results in:

  • Excessive thirst

  • Excessive fluid loss

  • Eventually all body systems affected 

• Types

1. Diabetes Mellitus Type I

• Inadequate insulin production 

• If immune system starts to attach own Beta cells of pancreas, Beta cells go down ⇒ inadequate insulin production 

• ISSUE: Beta cells 

• Insulin dependent

• Early onset, an autoimmune disease

2. Diabetes Mellitus Types II

• Body cells lose response to insulin 

• ISSUE: effector cells, either decreased or damaged the response to insulin 

• Non-insulin dependent 

• Late onset, most common 

3. Gestational Diabetes

• Temporary loss of sensitivity to insulin due to hormonal changes

• Mimics DM Type II

  • ISSUE: receptors, not the insulin 

4. Diabetes Insipidus 

• Inadequate antidiuretic hormone (ADH) secretion → high urine volume 

  • Inadequate: inadequate ADH secretion causes to not reabsorb water and will turn into urine ⇒ high urine volume

  • ADH: makes you stop urinating, makes you reabsorb fluids more 

  • Diuretic = what causes you to urine, like caffeine 

• Rare 

  • Usually genetically predisposed 

• HOW CAN YOU DEVELOP DIABETES??

  • Obesity 

  • High fat content relative to lean body mass 

  • Body mass index (BMI): 30-39

    • BMI = body weight (kg) / height (m^2)

  • Sedentary lifestyle 

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Lecture 2: Biomolecules and Protein Synthesis 

Chemical Bonding

• Types:

1. Ionic

• Electron is transferred from one element to another 

• Electronegativity: one strong, one weak 

• Between 2 ions w/ opposite charges 

• Ex: NaCl

2. Covalent

• Electrons are shared 

• Electronegativity: relatively equal 

  • Non-polar = equal sharing 

    • Ex: CH4 

  • Polar = unequal sharing

    • Ex: H2O

3. Hydrogen 

• Opposite partial charges on adjacent molecules → attraction 

• Slight + charges (near H) and - charges (near O) → attraction 

• Ex: water molecules binding to each other 

Biomolecules 

• Molecules synthesized by cells 

• Contain C-C covalent bonds

• Often form ring or chain structures 

• HOW DO WE MAKE BIOMOLECULES??

  • Dehydration synthesis 

    • Forming covalent bonds by removal of water 

    • 2 different molecules to form ONE molecule by removing H2O

• HOW DO WE BREAK BIOMOLECULES??

  • Hydrolysis 

    • Breaking covalent bonds by the addition of water 

    • 1 molecule becoming TWO separate molecules by adding H2O 

Types of Molecules 

1. Carbohydrates

2. Lipids

3. Proteins 

4. Nucleic acids

Carbohydrates 

• Contain: C, H, & O 

  • C + H2O = 1C : 2H : 1O

•  Properties

  • Polar → hydrophilic

• Types: 

1. Simple sugars

   1. Function: fast energy  

• Monosaccharide - one sugar

  • Ex: glucose, fructose, galactose    

• Disaccharide - 2 sugars

  • Ex: sucrose, lactose 

• Monosaccharide → disaccharide thru dehydration synthesis  

  • Glucose + fructose → sucrose 

  • Galactose + glucose → lactose

2. Complex carbohydrates

   1. Functions:

      1. Energy storage

      2. Structural support

      3. Component of cell membranes 

• Polysaccharide - chain of sugars 

  • Examples:

    • Starch 

      • For structural support 

    • Glycogen

      • For storing excess glucose 

    • Cellulose

      • Main component of plant cell well 

    • Chitin

      • Structural support ; found in cell wall of different fungi 

Lipids

• Contain: C, H, and O 

• Properties

  • Non-polar → hydrophobic 

• Types:

1. Triglycerides (“fat”)

   1. Structure = glycerol + 3 fatty acid chain 

   2. Functions: 

      1. Energy storage 

      2. Insulation 

      3. Protection 

• Saturated 

  • No double bonds 

  • Tightly packed & forms zig-zags

  • Solid at room temp 

• Unsaturated 

  • Contain double bonds 

  • Can be cis/trans fatty acid 

  • Loosely packed, contains kinks 

  • Liquid at room temp 

2. Phospholipids

   1. Structure = glycerol + (polar) phosphate group + 2 (non-polar) fatty acid tails 

   2. Function: cell membrane structure   

3. Eicosanoids

   1. A type of chemical messenger in your body 

   2. Structure = ring structure + fatty acids 

   3. Function: cellular communication 

   4. Ex: prostaglandin 

      1. An intermediate chemical messenger that’s a signal for pain; needed for pain perception  

4. Steroids

   1. Structure = 4 carbon rings (3 hexagon + 1 pentagon) w/ side chains 

      1. All derived from cholesterol 

   2. Functions:

      1. Membrane fluidity 

      2. Cellular communication 

      3. Others 

   3. Examples:

      1. Cholesterol 

      2. Testosterone 

      3. Vitamin D   

Proteins

• Contain: C, H, O, N

• Structure = chain of amino acids (polypeptide) 

  • Folded 

• Functions:

  • Structural support

  • Enzymatic activity 

  • Chemical messengers

  • Receptors 

• Amino Acid 

• Structure = central C + amino group (NH2) + carboxyl group (COOH) + R group (determines amino acid) 

Levels of Protein Structure

1. Primary 

   1. Sequence of amino acid 

   2. Bonds involved: peptide

      1. Multiple peptide bonds = polypeptide 

2. Secondary 

   1. Folding of protein occurs here

   2. Localized repetitive twisting & folding to:

      1. Alpha helix → spirals

      2. Beta pleated sheets → pleats 

   3. Bonds involved: hydrogen (no R groups) 

      1. H-bonds stabilizes alpha-helix & beta-pleated sheets 

      2. R groups does not participate in H-bonds   

3. Tertiary 

   1. Overall 3D structure 

   2. Bonds involved: hydrogen, ionic, disulfide (R groups involved) 

      1. Disulfide = a type of covalent bond 

      2. R groups start binding w/ each other ⇒ dictates overall 3D structure 

4. Quaternary 

   1. Multiple polypeptide chains binding together 

   2. Bonds involved: hydrogen, ionic, disulfide 

Nucleic Acids

• Contain: C, H, O, N, P

• Properties: polar → hydrophilic 

• Structure = chain of nucleotides 

• Functions:

  • Store genetic information (DNA)

  • DNA expression (RNA)  

• Types: 

1. DNA

2. RNA

Nucleotide 

• Structure = phosphate group + sugar + nitrogenous base 

  • Nitrogenous bases: adenine, guanine, cytosine, thymine (DNA) or uracil (RNA)

• Complementary base pairing:

  • A - T (DNA) or A - U (RNA)

  • G - C

• Pyrimidines = cytosine, thymine, & uracil 

• Purines = adenine & guanine 

DNA vs RNA

1. DNA

   1. Double-stranded helix

   2. Sugar = deoxyribose 

   3. Thymine binds to adenine 

   4. Antiparallel ; strands run in opposite directions 

      1. 5’ end to 3’ end

      2. 3’ end to 5’ end 

2. RNA

   1. Single-stranded 

   2. Sugar = ribose 

   3. Uracil binds to adenine 

   4. 3 Types:

      1. mRNA (messenger RNA) 

• Nucleus → ribosome

• Components to make ribosome is found in cytoplasm since DNA never able to leave nucleus 

2. tRNA (transfer RNA)

•  Important in protein synthesis 

3. rRNA (ribosomal RNA)

   1. Part of the ribosome 

   2. Essential in making protein 

DNA Replication 

• DNA → DNA 

• Location: nucleus 

• Semi-conservative: one old strand, one new strand 

• Bidirectional 

  • Occurs in middle of DNA so it expands in 2 directions 

• Enzymes involved: 

  • Helicase - unwinds double helix 

  • DNA polymerase - adds nucleotides to each unwound string of DNA 

    • Can only add in 5’ → 3’ direction 

Protein Synthesis 

• Central dogma of molecular bio

• DNA —transcription-→ mRNA —translation-→ protein 

Transcription 

• DNA → mRNA (same language of nucleotides)

• Location: nucleus

• Enzymes involved:

  • RNA polymerase - unwinds DNA & makes complementary RNA strand to DNA 

Genetic Code 

• mRNA language are codons (groups of 3 nucleotides)

• Each codon codes for:

1. Amino acid (sense)

2. Stop signal (nonsense)

• 64 possible codons, but only 20 amino acids 

  • Degeneracy = multiple codes for one amino acid 

• Start codon = AUG (methionine)

• Stop codon = UAG, UAA, UGA

  • Stops translation process 

Translation

• mRNA (nucleotides) → proteins (amino acids) 

  • Different “language” so must translate 

• Location: cytoplasm

• Organelle involved: ribosome  

• Process:

1. mRNA becomes associated w/ a ribosome

2. Start codon (AUG) is exposed and tRNA w/ complementary anticodon binds

   1. tRNA have specific anticodon and are attached to an amino acid 

3. Next codon of mRNA exposed and tRNA binds

4. Peptide bond forms between amino acid (when 2 AA bind together) 

5. Ribosome moves along mRNA to expose another codon

6. Process repeats until stop codon (UAG, UAA, or UGA) then polypeptide is released