Comprehensive Module 1 Physiology and Chemical Homeostasis Study Notes

Branches of Physiology

Physiology: The study of the functions of the body.
Cell Physiology: How cells and their parts work.
Organ Physiology: How organs function individually.
Systemic Physiology: How organ systems function as a team.
Pathophysiology: The study of disease's impact on the body.

Subatomic Particles and Atomic Structure

Subatomic Particles:
- Protons:
  - Location and Charge: Located in the atom and carry a positive charge ( $+$ ).
  - Function: Responsible for weight and defining the "name" (identity) of the atom.
  - Rules: The quantity of protons is indicated by the atomic number.
- Neutrons:
  - Location and Charge: Located in the nucleus and carry no electrical charge.
  - Function: Contributes to the weight of the atom.
  - Rules: Calculated by taking the atomic mass and subtracting the number of protons: $N + P = \text{weight}$ $\text{weight} - P = N$
- Electrons:
  - Location and Charge: Found in the orbits/shells surrounding the nucleus and carry a negative charge ( $-$ ).
  - Function: Interacts with the electrons of other atoms.
Orbit and Shell Rules:
- First Shell: Can hold ONLY $2$ electrons.
- Second Shell: Can hold up to $8$ electrons.
- Third Shell: Can hold up to $8$ electrons.
- Valence Shell: The outermost electron shell of an atom.
- Valence Electrons: The electrons located in the outer valence shell.

Chemical Bonds and Ion Formation

Forming Ions (Sodium and Chloride Example):
- Sodium ( $\text{Na}$ ): Has $1$ valence electron, which it wants to give away to another atom.
- Chloride ( $\text{Cl}$ ): Has $7$ valence electrons and needs $1$ more electron to fill its valence shell to become stable.
- Reaction Process: Sodium gives its $1$ valence electron to chloride, creating ions.
- Sodium Ion ( $\text{Na}^+$ ): Possesses more protons than electrons (more positive than negative particles), resulting in a positive charge. It is classified as a cation ( $\text{Na}^+$ ).
- Chloride Ion ( $\text{Cl}^-$ ): Possesses more electrons than protons (more negative than positive particles), resulting in a negative charge. It is classified as an anion ( $\text{Cl}^-$ ).
Ionic Bonds:
- Mechanism: Form due to the attraction of opposing electrical charges ("opposites attract").
- Key Properties:
  - Bonded particles are no longer referred to as neutral atoms.
  - Ions do NOT share electrons.
  - Ionic bonds dissolve rapidly in water due to the polarity of water molecules.
  - Example: Ionic bonds form table salt.
Covalent Bonds:
- Mechanism: Formed by sharing electrons between atoms.
- Nonpolar Covalent Bond:
  - Characterized by equal sharing of electrons.
  - Examples: Oxygen gas, nitrogen gas.
  - Properties: Small, simple, and possess no charges, which means they can diffuse through cell membranes without any help.
- Polar Covalent Bond:
  - Characterized by unequal sharing of electrons.
  - Example: Water. Because water has "poles" (slight electrical charges), it pulls apart ionic bonds and dissolves table salt.
Hydrogen Bonds:
- Form ONLY between already existing polar molecules; they do NOT create new molecules.
- Creates an electrostatic attraction between water molecules.
- Forms surface tension.
- Holds $\text{DNA}$ in the double helix formation.

Homeostasis and Homeostatic Regulation

Homeostasis:
- The body's ability to maintain stable internal conditions even though there is continuous change in the outside environment.
Mechanisms of Homeostatic Regulation:
- Autoregulation:
  - A localized response of organs and tissues to maintain homeostasis.
  - Tissues or receptors send a message (usually a chemical) to themselves.
- Extrinsic Regulation:
  - Requires help from the nervous system or endocrine system to maintain homeostasis.
  - Impact is usually systemic!
  - Nervous System: Provides a rapid, short-term, and specific response.
  - Endocrine System: Uses chemical messengers that affect tissues and organs over longer periods of time, influencing growth and development.
  - Examples of Extrinsic Controls: Pancreas (endocrine system) and Hypothalamus.
Components of a Homeostatic Control System:
1. Receptor: Sensitive to a particular stimulus (analogous to a thermometer).
2. Control Center: Integration center that receives and processes the information sent from the receptor, establishes the set point, and sends out operational commands (analogous to a thermostat).
3. Effector: A cell or organ that responds to the control center command (analogous to an air conditioner turning on).
- Set Point: The range of desired value.
Feedback Loops:
- Negative Feedback:
  - The body's response reverses or negates the original stimulus to maintain normal conditions.
  - Keeps the body in its normal range; any variation outside the set point triggers the response to correct the situation until homeostasis is reached.
  - Has set points, which are usually ranges.
- Positive Feedback:
  - A stimulus causes the initial change to continue, exaggerating the effect rather than opposing it.
  - Homeostasis is achieved eventually, but only when the danger, illness, or stressful situation is alleviated.
  - Has no set point; usually operates toward a specific single goal or job.

Regulation of Blood Sugars, pH Dynamics, and Buffers

Regulation of Blood Sugars:
- Normal blood sugar range: $70 - 120$
- Physiological states vary based on intake, such as consuming Lucky Charms for breakfast versus fasting with no food for $8$ \,hours.
pH Dynamics:
- Hydrogen ion ( $\text{H}^+$ ) concentration determines pH.
- More $\text{H}^+$ : Acidic, resulting in a lower pH value ( $0 - 7$ ).
- Less $\text{H}^+$ : Alkaline/base, resulting in a higher pH value ( $7 - 14$ ).
- Human Blood pH: $7.35 - 7.45$
- Impact of Abnormal pH: Causes a lack of function in the body.
- pH Classifications:
  - Acidic: Characterized by more $\text{H}^+$ .
  - Neutral: Characterized by equal $\text{H}^+$ to $\text{OH}^-$ (hydroxyl groups).
  - Alkaline / Base: Characterized by less to no $\text{H}^+$ .
Neutralizing and Buffers:
- Buffers: Minimize pH changes, keeping pH changes small.
- Neutralization: Combining an acid and a base can neutralize either and/or both.
- Neutralization Reaction Example: Hydrogen Chloride (hydrochloric acid) mixed with Sodium Hydroxide (a base): $\text{HCl} + \text{NaOH} \rightarrow \text{H}_2\text{O} + \text{NaCl}$
- Enzymes: Enzymes "help" chemical reactions happen by speeding them up. More enzymes lead to a higher amount of product formed faster.
Buffer Chemical Reaction Mechanism:
- Acids recombine with bases to produce a salt and a weak acid that breaks down into water and carbon dioxide ( $\text{CO}_2$ ).
- Step 1 (Acid and Base Reaction): $\text{HCl} + \text{NaH}_2\text{CO}_3 \rightarrow \text{NaCl} + \text{H}_2\text{CO}_3$
- Step 2 (Decomposition in Lungs): $\text{H}_2\text{CO}_3 \rightarrow \text{H}_2\text{O} + \text{CO}_2$

Course Deadlines and Academic Guidelines

Integrity Statement:
- Must complete the integrity statement for ALL shells/courses.
Wednesday Deadlines:
- First discussion post due (applicable to asynchronous courses only).
Sunday Deadlines:
- Pre-lesson checkpoint 1 AND 2.
- Module 1 quiz (administered via Respondus).
- Peer response in discussion forum (asynchronous courses).
- Lab quiz (administered via Respondus).
Time Management Strategy:
- Avoid feeling overwhelmed on Sunday by completing something each day, which also leads to better retention of knowledge.