Unit 1 - Lecture 1-3 (Human Phys)

Who coined the term “homeostasis”?

Walter Cannon

Walter Cannon’s 4 Postulates

1. role of nervous system in preserving “fitness” of internal environment

2. tonic level of activity

3. antagonistic controls for same parameters

4. chemical signals have diff. effect on diff. tissues

Tonic Level of Activity

postulate 2; means always a background level of activity; ex. engine in car still runs when car is in park

Antagonistic Controls for Same Parameters

postulate 3; need something to raise or lower a parameter; ex. insulin and glucagon

Homeostasis

body has methods that keep it in living limits; does not involve keeping conditions static but instead keeps them within tightly regulated physiological tolerance limits; can also be maintained by up- and down-regulation of receptors

Blood Parameter

5L/body (half plasma)

BPM Parameter

60-80; avg. 70

BP Parameter

120/80 MMHG

pH Parameter

7.35-7.45

Respiratory Rate (RR) Parameter

12-15/min

BLGLU Parameter (blood sugar)

100 MG/DL

O2 Parameter

98% saturated

Temperature Parameter

97 degrees F

Hypo-

lower than normal in EXTRACELLULAR concentration

Hyper-

higher than normal in EXTRACELLULAR concentration

Normo-

normal in EXTRACELLULAR concentration

-Emia

concentration in in EXTRACELLULAR fluids

Upregulation

lower signals so more receptors

Downregulation

a lot of signals so reduce receptors

Basic Principles

govern physiological interactions and the maintenance of homeostasis

Basic Principles Examples

1. shape controls function

2. move water, move solute first

3. blood pressure = blood volume

4. loss of compartment integrity = disease/death

5. bircarb eqn

Loss of Compartment Integrity

fluids should stay in their compartments; ex. blood out of blood vessels

Bicarb Equation

H₂O + CO₂ ←> H₂CO₃ ←> HCO₃^- + H⁺; happening all the time; shifts pH; more CO₂ = more H⁺

Epithelial

border things/liners; minimal matrix; no direct blood supply; have microvilli and cilia; covers body surface; lines cavities and hollow organs, and tubes; secretory glands; variable # of layers (1 to many); cells flattened, cuboidal, or columnar

4 Types of Mammal Tissues

Connective Tisues

most diverse; in a matrix; ex. blood (liquid), fat (adipose), and bone

Tendons

connect muscle to bones

Cartilage

flexible; cells are chondrocytes

How do fluid compartments differ?

conc. of major ions and proteins; proportions within the body fluids

Na⁺

[outside] > [inside]; rushes in as first step of AP

K⁺

[inside] > [outside]; wants to leave inside of cell

What side of a cell is more -?

the inside

Are DNA and proteins charged?

yes (negatively)

Pathology (disease)

what happens when fluid volume and distribution are in conflict

Osmo-

relates to water

Osmotic Pressure

in mmHG or atm; amount of force required to prevent movement of water across a barrier; solute in high conc., water in low conc.

Osmolarity

comparative measure of the total # of dissolved particles per liter of soln.; always compare iso, hypo, and hyper-osmotic

Tonicity

determined by the relative concentrations of non-penetrating solutes across the membrane; what is going to happen to a cell (in real life - shrink, swell, or stay the same)

What happens if solutes can’t cross the membrane?

water will move to reach equilibrium

NaCl

solute; dissociates; neither one changes net conc. across membrane; when measuring in osmoles, assume already dissociated so count them separately

Urea

solute; freely penetrates membranes

Glucose

crosses according to conc. but disappears bc as soon as it crosses the membrane, it gets phosphorylated

Tonicity of Solutions

Relative Osmolarity

likelyhood that water will move

Rules for Osmolarity and Tonicity

1. assume all intracellular solutes are nonpenetrating

2. compare osmolarities before cell is exposed to soln.

3. tonicity of soln. describes vol. change of cell at eq.

4. determine tonicity by comparing non-penetrating solute conc. in cell and soln.; net water movement is into compartment w/ higher conc. of non-penetrating solutes

5. hyposmotic solns. always hypotonic

Plasma Membrane

semi-permeable; allows cells to maintain conc. gradients

4 Major Functions of Membrane Proteins

structural, enzymatic, receptor, and transport

Channel Proteins

allow material through the membrane; flips between open and closed

Carrier Proteins

move material across the membrane; like a revolving door (can only move sm things at a time); ex. glucose/larger things are moved by these

Do O₂ and CO₂ require proteins to move across the membrane?

no; they move freely across the membrane

Secondary Active Transport

uses PE of a conc. gradient of 1 substance to move another; enhances movement of materials

What is membrane equilibrium determined by?

electrical and chemical gradients; Na (sodium) in and K (potassium) out

Depolarization

Na⁺ (sodium) in

Repolarization

K⁺ (potassium) out

Glucose Transport

across epithelial cells it requires diff. mechanisms for apical and basolateral membranes

Lumen

way you measure light; the open space

Apical

brings glucose in

Basolateral

pushes glucose out

Chemical Signals

can be used for local or long-distance communication; gap junctions, autocrines, paracrines, endocrines, and neurotransmitters; can be hydrophilic or hydrophobic

Gap Junctions

openings that allow ions and things to pass between cells; form direct cytoplasmic connections between adjacent cells; important in the heart

Autocrines Signals

act on same cell that secreted them

Paracrine Signals

secreted by one cell and diffuse to adjacent cells; local in nature (anything that can be reached w/o using the vascular system - no traveling through the blood)

Endocrines

released by glands and use the vascular system to get to its destination; ex. hormones

Neurotransmitters

chemicals secreted by neurons that diffuse acrosss a small gap to the target cell

Water and Lipid Soluble Signals Differ

in how they move through the blood and cell membrane (or not)

What happens once a signal reaches its target cell?

message is transduced and amplified

Transduction

transferring a signal from outside to inside the cell

Hydrophilic Signals

have a rapid response rate; short half life; ex. insulin

Enzyme Cascades

fast and large responses through condurction caused by membrane reception

Arachidonic Acid

derived from membrane phospholipids; precursor for important inflammatory molecules; paracrine

Eicosanoids

fatty acid derived paracrines; lipogenase and cyclooxugenase pathways

Lipoxygenase Pathway

leukotrienes - chemotaxis of leukocytes, mediates inflammation, asthma

Cyclooxygenase Pathway

Prostaglandins and thromboxane

Prostaglandins

cox 1 - gastric protection; helps produce things that protect the stomach lining; smooth muscle contraction

cox 2 - inflammation, fever, and pain; produces things that are involved in these

Thromboxane

in the cyclooxygenase pathway; blood vessel constriction; increased platelet activation

Steroidal Anti-Inflammatory Drugs

can’t use them to treat chronic pain bc get immune to it; ex. cortisone

Non-steroidal Anti-Inflammatory Drugs (NSAIDs)

cox 1 and 2 inhibitors → ex. aspirin; cox 2 only inhbitors (celebrex and vioxx)

What effects signal efficacy?

function of receptor specificty and competition

Agonist

also activates the receptor

Antagonist

blocks receptor activity

Same Signal, Different Effects

one of Cannon’s postulates; applies to signal specifity

What does up/down regulation allow for?

modification of response based on signal frequency

too much signal → down reg (less receptors)

too little signal → up reg (more receptors)

Endrocine Disrupters

chemicals that mimic endocrine structure; may enhance or reduce an endocrines response

Obesogens

endrocrine disrupters that may specifically affect cortisol activities

Cortisol

long-term stress hormone; increase in this increases fat cells (adipose) (more energy)

Silphion/Silphium

contained an endocrine disrupter that prevented pregnancy or early term abortions; natural bc; important for the Greeks/Romans and would only grow in Cyrene; hunted into extinction

Estrogen System

demonstartes both Cannon’s postulate/evidence of predator-prey adaptation

How do plants fight?

w/ secondary compounds that they don’t use for their own metabolism

Vasopressin

helps to maintain BP

Signaling Systems

exhibit both tonic and antagonistic controls

What happens when a signal rate descreases?

blood vessel relaxes and opens up (increased diameter)

What happens when a signal rate increases?

blood vessel constricts

What does tonic signaling do?

maintain blood vessel diameter; therefore controls speed of fluid moving through it

Antagonistic Controls

speed up/slow down heartrate