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Lecture: Homeostasis
I.
Organization of Life
A.
Structure:Function and Function:Structure
1.
2.
Anatomy - study of the structure of cells, tissues, organs, organisms
Physiology - study of how cells, tissues, organs, organisms function
3. Darwin - Origin of the Species (1858)
a. Structure and Function are intimately linked
b. Structure dictates the Function
1. Finch beaks and food on the Galapagos
c. Evolution "selects" most favorable Functions
1. kidneys/skin of various organisms
a. kangaroo rat – desert
b. human – land
c. sea bass - salty ocean water
d. Environment and competition "naturally" select genes that give rise to Structures that
have favorable Functions to improve the viability of each species
B. Organization of Living Things
1. principles of matter/energy
2. atoms -> molecules
3. complex organic molecules
4. organelles -> cells
5. tissues
6. organs
7. organ/body systems
8. organism
***
(Physics)
(Chemistry)
(Biochemistry)
(Cellular Biology)
(Histology)
(Physiology/Anatomy)
(Physiology/Anatomy)
(Physiology/Anatomy)
all fields overlap and contribute to each other
See Figure 1
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II. Basic Functions of Organisms
A. Maintenance of Boundaries - separation of organism from outside world
a. virus - protein coat around DNA/RNA interior
b. cell - cell membrane (semipermeable - selective)
c. organism - skin
B.
Movement - ability to move self and materials
a. cells - cilia and flagella (sperm)
b. humans - muscle cells (contractility) & bone
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C.
Responsiveness (Irritability) - respond to both Internal and External changes
a. nervous system - quick response to change
b. endocrine system - medium/longer changes
D.
Digestion - breaking down foodstuffs to useable/absorbable form
a. digestive system - breakdown/absorb essential materials
E. Metabolism - all chemical reactions that occur in cells & body
a. anabolism - synthesizing larger molecules
b. catabolism - breaking down larger molecules
c. regulated primarily by endocrine hormones
cellular respiration - breaking bonds of larger molecules for useable energy currency (ATP)
a. digestive system - mainly carbohydrate & fats
b. respiratory system - oxygen and carbon dioxide
c. cardiovascular system - distribution of nutrients and
gases
glucose + oxygen -> carbon dioxide + water + ENERGY (stored in ATP)
F.
Excretion - removing all types of waste from the body
a. digestive system - unused foodstuffs
b. urinary system - nitrogenous wastes (urea) and electrolyte (salt) balance
c. respiratory system - carbon dioxide
G.
Reproduction - creating more organisms of the same species
a. virus - depends on cells for their machinery
b. cells - the process of division (mitosis)
c. human - sexual (sperm and egg)
i.
regulated by hormones (especially female)
H. Growth - increase in size of cell, organ, or organism
a. number of cells can increase (mitosis)
b. size of cells can increase (fat cells)
III.
A.
Basic Biological Needs of Humans
Nutrients - molecules for structure and energy
1. carbohydrates - primary energy source & structural
a. glycogen, sugars (glucose)
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2. proteins - primarily structural & for signaling (hormones and receptors)
a. 20 amino acids are basic building blocks
b.actin and myosin microfilaments of muscle
c. receptors for hormones/neurotransmitters
d.neuropeptides (enkephalins of nervous system)
3. fats (lipids) - insulation, energy, structure
a. major component of membranes (phospholipids)
b. highest energy content by weight (calories)
4. vitamins - act as cofactors for enzyme functioning
5. minerals - essential for signaling and structure
a. nerve signals - Na+, K+, Ca++, Clb. carry oxygen - Fe+ + in hemoglobin
c. bone - Ca++, Phosphates
B. Oxygen - essential for maximum energy gain from food
1. cellular respiration depends on oxygen
2. nervous system alone uses 25% of all oxygen in humans
C. Water - essential for cellular reactions and transport
D. Body Temperature - essential for cellular reactions
1. most human enzymes work best at 37C (98F)
E. Atmospheric Pressure - for proper absorption of oxygen
Physiology is the study of how organisms separate self and non-self; move; respond to internal and
external changes; digest, metabolize, and excrete materials; reproduce; and grow.
This is achieved by maintaining a proper BALANCE both internally and with the outside world.
IV. Homeostasis
A. Homeostasis - maintaining relative constancy in response to internal and external changes
- dynamic process; changing but relatively constant within limits
- concerns all factors relating to well being of organism (see above)
- regards maintaining internal environment of body due to internal and external changes
1. Homeostasis refers especially to maintenance of proper conditions for:
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a. oxygen (02) and carbon dioxide (CO2) levels
b. levels of nutrients in blood (e.g. glucose)
c. electrolyte /salt balance and osmotic pressure (fluid levels)
d. acid-base balance (pH)
e. temperature
f. pressure of body cavities (especially lungs)
Examples of homeostatic mechanisms:
1.
proper nutrient levels in the blood
a. insulin/glucagon - blood glucose levels
2. proper heart rate and blood pressure
a. adrenaline - response to stimuli
3. removing wastes from the blood
a. kidneys - nitrogenous wastes (urea)
b. respiratory - carbon dioxide
4. maintaining proper oxygen levels in blood
a. brain and respiratory - adjust breathing rate
5. body posture and simple muscular reflexes
a. nervous system and muscular system
B. General Characteristics of Homeostatic Control Mechanisms
1. Nervous & Endocrine Systems are general controls
2. Basic Organization of Control Mechanisms
a. receptor - monitors internal/external stimuli sends info to control center via afferent path
b.
control center - analyzes info as it compares to a "set point" for that particular variable
1. variables may include: glucose level, heart rate, blood pressure, urea concentration,
oxygen level, tension on a muscle.
c.
C.
effector - physiological mechanism acting from the
control center via efferent path
Negative Feedback Mechanisms
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1. control mechanism DECREASES intensity of condition to bring back to "set point"
example: regulation of glucose levels in blood
a.
b.
c.
d.
person eats a candy bar with lots of sugar
glucose levels in the blood rise rapidly
receptors sense increase in blood sugar
control center calls for reduced blood sugar insulin is
secreted into the blood stream
e. insulin causes effector cells (liver & muscle) to absorb
glucose and store it as glycogen
g. glucose levels return to normal (0.9 mg/ml blood)
See Figure 2
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D.
Positive Feedback Mechanisms (cascade - like a snowball effect)
1. control mechanism INCREASES intensity of condition - causing a "domino" effect
example: labor contractions during birth
a. baby rotates into cervix causing pressure
b. receptors sense increased muscle tension
c. control center calls for release of oxytocin, causing
muscles (effectors) to contract more
d. increased muscle tension causes receptors to continue
the message to the control center
e. more oxytocin is released
f. loop continues until baby is delivered and the stimulus is
no longer present
See Figure 3
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In Physiology, we study how each of the organ systems work to provide survival needs of organism
and maintain homeostasis of each of the essential variables
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Lecture:
Basic Chemistry
I. Matter and Energy
A. Matter - fundamental building blocks of nature
1. elements - basic units of matter
B. Energy - capacity to do work (put matter into motion)
1. potential energy - energy stored in a structure
a. water stored in a lake uphill
b. chemical bonds of glucose molecule
2. kinetic energy - energy in an object in motion
a. water in a stream - allows mill to grind corn
b. broken glucose bonds -> ATP -> muscles work
3. Forms of Energy
a. chemical energy - energy in chemical bonds
i. ATP (adenosine triphosphate) - stores energy
b. electrical energy - energy of separated charges
i. battery - + pole and - pole separate charge
ii. nervous impulse run just like a battery
c. mechanical energy - energy of matter in motion
i. bowling ball transfers energy to move pins
ii. muscle motion - ATP -> contraction of muscle
d. electromagnetic energy - energy traveling in waves (light, X-rays, UV rays)
i. electromagnetic spectrum - visible light, UV light, radio waves, X-rays
C. First Law of Thermodynamics
1. “Energy can change from one form to another, but it can never be created or destroyed"
(Total Energy In = Total Energy Out)
examples: Car Engine vs. Human Body
a. Car Engine - gasoline used to run motor to move car
Chemical Energy (gas) ---> motion (20%) + heat (79%) + sound (1%)
b. Human Body - food used to move body, digest, think, etc. Chemical Energy
(food/glucose) --> physiology (80%) + heat (20%)
II. Organization of Matter (Atoms - Elements)
A. Atomic Particles
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Mass
proton
neutron
electron
Charge
1
+1
1
neutral
0
-l
Characteristics
defines element
defines isotopes
determines element
bonding properties
See Figure 4
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B. Organization of Periodic Table
1. # protons = atomic number (unique for each element)
2. # protons + # neutrons = atomic mass
3. isotope - same element; different # neutrons
# protons +
Carbon-12 (99%)
Carbon-13 (0.9%)
Carbon-14 (0.1%)
See Figure 5
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4.
6
7
8
12
13
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# electrons - dictates the NET CHARGE of an atom
# protons
1
1
1
H
H+
H-
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6
6
# neutrons = atomic mass
# electrons
1
0
2
NET CHARGE
0
+1
-1
ion – any atom with a positive or negative charge
anion – an ion with a NEGATIVE charge
cation – an ion with a POSITIVE charge
III. Electron Shells, the Periodic Table, and Chemical Bonds
A.
Electron Shells - electrons occupy "shells" as they orbit around the nucleus (2, 8, 8,..)
B.
The Periodic Table of Elements is organized by electron shells
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H1
He2
Li3 Be4 B5 C6 N7 08 F9 Ne10
Na11 Mg12 Al13 Si14 P15
S16 Cl17 Ar18
See Figure 6
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C.
SHELL l
SHELL2
SHELL3
2 e8 e8 e-
Chemical Bonds are formed so that each atom can have the outermost electron shell filled
1. Ionic Bond - one atom donates electron(s) to another
a. Example: Sodium Chloride (table salt) Na+Cl2. Covalent Bond - two atoms share one/more electrons
a. Example: Methane (CH4), Carbon Dioxide (C02), and
Ammonia (NH3)
b. Polar Molecule - electron sharing is unequal in the bonds
Example: Water (H2O)
c. Non-polar Molecule - electron sharing is almost equal Example: Methane (CH4)
IV.
Elements other than C, H, O, N in Humans
Primary Elements (3% of all body weight)
Calcium
Ca
Bones, teeth, muscle and nerve action, blood clotting
Phosphorus P
Bones and Teeth, DNA, RNA, ATP. Important in
energy transfer
Trace Elements (Less than 1 % of body weight altogether)
Potassium
K
Osmotic balance; cell voltage, muscle and nerve
action
Sulfur
S
Component of proteins (cysteine) and other organic
molecules
Sodium
Na
Osmotic balance; cell voltage, muscle and nerve
action
Chlorine
Cl
Osmotic balance; cell voltage, muscle and nerve
action
Magnesium
Mg
Co-factor for many enzymes
Iron
Fe
Hemoglobin and many enzymes
Copper
Cu
Co-factor of many enzymes
Zinc
Zn
Co-factor of many enzymes
Manganese
Mn
Co-factor of many enzymes
Cobalt
Co
Co-factor of many enzymes and vitamin B12
Chromium
Cr
Co-factor of many enzymes and potentiates Insulin
Selenium
Se
Required for normal liver function
Molybdenum
Mo
Co-factor of many enzymes
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Flourine
Tin
Silicon
F
Sn
Si
Vanadium
V
V.
Teeth and bones
Promotes growth (unknown mechanism)
Growth, bone mineralization, connective tissue
synthesis
Promotes growth and reproduction
Chemical Reactions
A.
Patterns of Chemical Reactions
1.
Chemical Equation - # of atoms of each element same for reactants and products
C6H1206 + 602  6H20 + 6C02
2.
Synthesis - smaller molecules form larger molecule
A + B  AB (anabolic process)
amino acid 1 + amino acid 2 + ..........
peptide (protein)
sugar 1 + sugar 2 + sugar 3 + ............ polysaccharide
(glycogen)
3.
Decomposition - larger molecule broken down into smaller molecules
AB  A + B (catabolic process)
glycogen ---> glucose + glucose + glucose +...........
4. Displacement - one part is exchanged
AB + C  A + BC
glucose + adenosine-P- P-P (ATP)  glucose-P + adenosine-P-P
B.
(ADP)
Exergonic vs. Endergonic Reactions
1.
Exergonic - energy is released during the reaction
A + B  C + D + ENERGY
glucose + oxygen ----> water + carbon dioxide +ENERGY (trapped by ATP)
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2. Endergonic - energy required for reaction to proceed
A + B + ENERGY  C
amino acid 1 + amino acid 2 + ... + ENERGY  peptide (protein)
C.
Chemical Equilibrium
1. Reversible Reactions
A + B  AB
and AB  A + B
2. Chemical Equilibrium
A + B  AB
D.
Rates of Chemical Reactions
1. size of reactants species (smaller means faster)
2. temperature (speeds up the particles)
3. concentration (more likely to come together)
4. catalysts (enzymes) - make reacting more convenient
VI. Acid- Base Chemistry and the pH Scale
A.
Water normally exists in an equilibrium reaction with some dissociation
H2O  H+ + OH-
in a beaker of pure water, the ratio of H+ to H20 is about 1/10,000,000
pH = -log10 [H+] = -log10 [10-7] = -(-7) = 7
pH = relative concentration of H+ in a solution of water
B.
Acids - compounds which increase the concentration of H+ (pH = 1 to 6)
C.
Bases - compounds which decrease the concentration of H+ (pH = 8 to 14)
D.
Buffer - compound that prevents large changes in pH of a solution (pH "shock absorber")
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Figure 1
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Figure 2
Figure 3
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Figure 4
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Figure 5
Figure 6
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