Fundamental Concepts in Anatomy & Physiology: Homeostasis, Body Systems, and Atomic Structure

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Homeostasis and Pathological Conditions

Homeostasis

Homeostasis refers to the maintenance of stable internal conditions in living organisms. It is essential for normal physiological function and survival.

Definition: The state in which internal conditions are maintained by living things.
Mechanism: The body monitors its internal state and takes actions to correct disruptions that threaten normal function.
Example: Regulating blood sugar levels.

Pathological Condition

A pathological condition arises when homeostasis fails, leading to disease or illness.

Also called: Disease state.
When compensation fails: Disease or illness occurs.
When compensation succeeds: Wellness is maintained.
Mechanism: If the body fails to maintain critical variables, normal function is disrupted.

Diabetes Mellitus

Diabetes mellitus is a metabolic disorder characterized by abnormally high glucose concentrations due to problems with insulin production or response.

Type 1: Body doesn’t make insulin (autoimmune destruction of pancreatic beta cells).
Type 2: Body’s cells don’t respond properly to insulin (insulin resistance).
Complications: Kidney failure, vision loss, etc.

Feedback Mechanisms in Physiology

Positive Feedback

Positive feedback intensifies a change in the body’s physiological condition rather than reversing it.

Definition: Only normal when there’s a defined endpoint.
Example: Childbirth – the first contraction of the uterus triggers stretch-sensitive nerve cells in the cervix, which send signals to the brain to release oxytocin. Oxytocin causes stronger contractions, pushing the baby further down the birth canal, which causes more oxytocin release, and so on, until delivery.
Another example: Blood loss – the body responds to severe blood loss by accelerating clotting processes.

Negative Feedback

Negative feedback restores balance and maintains homeostasis by reversing deviations from a set point.

Function: Stabilizes the regulated variable and aids the system in maintaining homeostasis.
Example: If blood glucose rises, insulin lowers it; if body temperature rises, sweating cools it.

Components of Negative Feedback

Stimulus: Change in the environment (e.g., glucose, temperature).
Receptor (sensor): Detects the change (thermoreceptors, baroreceptors, chemoreceptors).
Control center: Processes information and determines the response (often the brain or a specific gland, e.g., hypothalamus for temperature, pancreas for glucose).
Effector: Organ/system that carries out the response (muscles, glands, insulin release).

Functions of Each Component

Stimulus: Triggers imbalance.
Receptor: Monitors and sends information to control center.
Control center: Processes information, decides correction.
Effector: Makes the change to restore balance.

Detailed Steps in Negative Feedback

Input Signal: Initial stimulus that indicates a change in the system.
Integrating Center: Receives and processes the input signal, determines the appropriate response.
Output Signal: The response generated by the integrating center.
Effector/Target: Executes the response to adjust the system back to its normal state.

Body Systems and Their Functions

Major Body Systems

The human body consists of several organ systems, each with specific functions essential for survival.

Circulatory: Heart, blood vessels, blood – transport of materials.
Digestive: Stomach, intestine, liver, pancreas – breakdown and absorption of food.
Endocrine: Glands (thyroid, adrenal, etc.) – hormone production and regulation.
Immune: Thymus, spleen, lymph nodes – protection from external environment.
Integumentary: Skin – protection.
Musculoskeletal: Muscles, bones – movement and support.
Nervous: Brain, spinal cord – coordination of body functions.
Reproductive: Ovaries, testes, uterus – reproduction.
Respiratory: Lungs, airways – gas exchange.
Urinary: Kidneys, bladder – waste removal and water balance.

Atomic Structure and Chemical Bonds

Structure of an Atom

An atom is the smallest unit of matter, composed of a nucleus (center) and an electron cloud (orbitals/energy levels).

Nucleus: Contains protons (positively charged) and neutrons (neutral).
Electrons: Negatively charged particles that orbit the nucleus.
Atoms are electrically neutral when the number of protons equals the number of electrons.

Location of Subatomic Particles

Protons: In the nucleus.
Neutrons: In the nucleus.
Electrons: Orbit the nucleus in energy levels.

Charges of Subatomic Particles

Proton: Positive charge
Electron: Negative charge
Neutron: Neutral

Chemical Bonds

Covalent Bonds

Covalent bonds form when atoms share electrons.

Nonpolar covalent bond: Electrons are shared evenly (e.g., O2 gas).
Polar covalent bond: Electrons are shared unevenly, creating partial charges (e.g., water molecule).

Ionic Bonds

Ionic bonds form when one atom donates an electron and another atom accepts it, creating ions.

Electrostatic attraction: Between oppositely charged ions.
Example: Sodium chloride (NaCl) – sodium donates an electron to chlorine.

Hydrogen Bonds

Hydrogen bonds are weak attractions between a slightly positive hydrogen atom and a slightly negative atom (oxygen or nitrogen).

Importance: Stabilize structures like DNA and proteins; water molecules stick together via hydrogen bonds.

Ions and Their Classes

Ions are charged particles formed when atoms gain or lose electrons.

Cation: Positively charged ion (e.g., Na+, K+, Ca2+).
Anion: Negatively charged ion (e.g., Cl-, HCO3-, PO43-).

Role of Ions in Physiology

Muscle contraction: Ca2+ is essential.
Blood clotting: Involves several ions.
Fluid balance: Na+, Cl- help regulate.

Summary Table: Subatomic Particles

Particle	Location	Charge
Proton	Nucleus	Positive
Neutron	Nucleus	Neutral
Electron	Orbitals/Energy Levels	Negative

Summary Table: Types of Chemical Bonds

Bond Type	How It Forms	Example
Covalent	Atoms share electrons	H2O (water)
Ionic	One atom donates, another accepts electron	NaCl (table salt)
Hydrogen	Weak attraction between H and O/N	DNA, water molecules

Summary Table: Types of Ions

Ion Type	Charge	Examples
Cation	Positive	Na+, K+, Ca2+
Anion	Negative	Cl-, HCO3-, PO43-

Key Equations

Atomic neutrality:
Ionic bond formation:
Covalent bond:

Additional info: Academic context and examples have been expanded for clarity and completeness.