AP Unit 1 - Bio185 A&P1 Homeostasis, Chemistry and the Cell...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Page 1 of 16 Homeostasis Homeostasis = maintenance of a relatively constant (stable) internal body environment Homeostatic regulation = adjustments in physiological systems to preserve homeostasis A. Feedback systems: 1. Components: 1. Receptor – 2. Control center (integration center) – 3. Effector – 2. Two types of feedback systems: a. Negative Feedback — response opposes or reverses the original stimulus e.g. thermoregulation, blood pressure regulation 1. Dynamic equilibrium Set point – Normal range – 2. Action slows and stops as condition returns to normal. 3. Typically regulate conditions that remain fairly stable over long periods b. Positive Feedback — response strengthens or reinforces the stimulus (change in conditions) e.g. Normal childbirth 1. Continues until outside event breaks cycle (event outside of cycle) 2. Typically reinforce conditions that do not happen often 3. Points to Note a. System integration: b. Failure to maintain homeostasis malfunction symptoms = disease Chemistry Matter – A. Atoms = smallest unit of an element
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 2 of 16 1. Contain 3 major types of Subatomic particles: Protons: (+) charge, located in nucleus Neutrons: neutral charge, located in nucleus (see isotopes) Electrons: (-) charge, located in cloud surrounding nucleus; arranged in shells number of electrons in outer electron shell determines chemical properties of that element only outer electrons can react & create bonds with other atoms 2. Isotopes = same element, different number of neutrons e.g. radioactive elements All matter is composed of atoms in various combinations. Their interactions establish the foundations of physiology at the cellular level. B. Chemical Bonds Atoms gain stability by gaining, losing or sharing electron through chemical reactions. (NEVER gain/loss of protons!) 1. Ionic Bonds Ions = Charged atoms — through gain or loss of electrons e.g. sodium chloride 2. Covalent bonds electrons (in outer shells) are shared between two atoms. a. Nonpolar covalent bonds – electrons shared equally between atoms b. Polar covalent bonds electrons tend to spend more time around one atom than the other The slight difference in charge between the two ends of the molecule enable weak attractive forces between neighboring molecules. e.g. H 2 O C. Hydrogen bonds most important of weak attractive force slightly (+) H, attracted to slightly (-) oxygen or nitrogen between molecules (or between parts of a large molecule) e.g. water surface tension, DNA basepairing
Background image of page 2
Page 3 of 16 Compounds Nutrients -- essential elements and molecules obtained from the diet Metabolites -- molecules synthesized or broken down by chemical reactions inside the body. Broadly classified into two 2 categories:
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/03/2008 for the course BIOL 185 taught by Professor Harms during the Fall '07 term at Messiah.

Page1 / 16

AP Unit 1 - Bio185 A&P1 Homeostasis, Chemistry and the Cell...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online