Recording-2025-01-17T18:49:21.667Z anatomy Friday 1/17

Homeostasis in Animals

• Cold-blooded Animals:

  • E.g., lizards use environmental conditions to regulate body temperature.

  • Behaviorally seek shade to cool down without physiological mechanisms.

• Opposite of Cold-blooded:

  • Warm-blooded animals maintain temperature through physiological processes like sweating.

• Dynamic Equilibrium:

  • The body constantly adjusts to maintain a stable internal environment.

  • Negative Feedback Mechanism:

    • A primary method of maintaining homeostasis.

    • When out of range, a response occurs to return to the desired state (e.g., sweating reduces body temperature).

    • Once the desired temperature is reached, the response ceases (e.g. hypothalamus signals to stop sweating).

Feedback Mechanisms

• Negative Feedback:

  • Promotes stability by counteracting changes.

  • Essential for regulating temperature, blood sugar, etc.

• Positive Feedback:

  • Accelerates a response to achieve a significant change (e.g., childbirth, blood clotting).

  • Continual increase until a specific outcome is achieved.

    • Example: Blood clotting involves platelets forming a larger clot until bleeding stops, which if unchecked, leads to excessive clotting.

Consequences of Lack of Homeostasis

• Disease:

  • Acute lack of homeostasis can lead to disease, characterized by rapid onset and short duration.

• Aging:

  • Chronic deviation from homeostasis leads to aging, including physical changes and declining function.

• Death:

  • Failure to maintain homeostasis ultimately results in death.

Cell Chemistry Basics

• Matter:

  • Defined as anything that occupies space and has mass.

• Elements:

  • There are 92 naturally occurring elements, composed of atoms.

• Subatomic Particles:

  • Protons: Positively charged.

  • Neutrons: No charge.

  • Electrons: Negatively charged.

  • Number of protons is equal to the number of electrons in a neutral atom.

• Atomic Number:

  • Indicates the number of protons and thus the identity of the element.

Electron Configuration

• Energy Levels:

  • Electrons are arranged in energy levels around the nucleus.

  • Octet Rule: Atoms tend to combine so that they have eight electrons in their outer shell (to achieve a stable configuration).

  • Elements will either share electrons, accept, or donate them to reach stability.

Ionic and Covalent Bonds

• Ionic Bonds:

  • Formed when electrons are transferred from one atom to another (e.g., sodium and chloride form table salt).

  • Results in charged ions (cations and anions) that attract each other.

• Covalent Bonds:

  • Formed through the sharing of electrons between atoms (e.g., water and methane).

  • Polar covalent bonds occur when electrons are not shared equally, creating molecules with slight charges (e.g., in water).

Hydrogen Bonds and Water

• Hydrogen Bonds:

  • Form between a hydrogen atom of one molecule and electronegative atoms of another (e.g., oxygen).

  • Individually weak but collectively strong, contributing to unique properties of water.

• Water as a Solvent:

  • Water's polar nature allows it to dissolve various substances, making it an essential component in biological systems.