Human Physiology Exam 1

Physiology 

How the different parts of the body and systems do what they do.

Anatomy 

The parts of the body and what they do

Homeostasis 

maintain a stable internal environment

• keeps the body in balance so cells can function properly

• Organ systems work together to maintain this balance

• Related to extracellular fluid (circulatory system, cardiovascular system)

Extra-cellular fluid

All body fluid outside the cells, including interstitial fluid and blood plasma.

• Transports nutrients, oxygen, and hormones

Interstitial fluid 

Fluid that surrounds and bathes the cells in tissues. (fluid around tissues)

• Involved in nutrient and waste exchange between blood and cells

Intracellular fluid 

Fluid inside the cells; makes up most of the body’s total fluid

Feedback loop 

A control mechanism in which the output of a system influences its own activity.

 

Regulatory mechanisms that maintain homeostasis

Negative feedback loop

Stabilizes

Reverses the change

Restores balance

Brings body back to normal

Ex:

-           Body temp regulation

-           Blood sugar regulation (insulin/glucagon)

  Blood pressure regulation

Positive feedback loop

Amplifies

Increases the change

Pushes process to completion

Not about balance, about finishing a process

Ex:

-           Labor contractions (oxytocin)

-           Blood clotting

  Milk letdown during breastfeeding

Fluid mosaic model of membranes

Describes the cell membrane as a flexible lipid bilayer with proteins embedded and moving within it.

• Phospholipid bilayer

Carrier proteins 

Membrane proteins that bind specific molecules and move them across the membrane.

• Involved in active and passive transport

Channel proteins

Membrane proteins that form pores allowing ions or water to pass through.

-         Passway way in the cell membrane

• Facilitated diffusion

Tight junctions 

A junction that forms a tight/blocked barrier between cells.

No extracellular space or movement

Gap junctions

A junction that forms an intercellular passageway between cell membranes to move small molecules and ions

Desmosomes 

link between two cells to hold them together/ has cadherin.

Provides strength

Diffusion

Solutes move from high concentration → low concentration

Simple Diffusion

Movement of molecules directly through the membrane from high to low concentration.

-         Small and nonpolar molecules that move through the cell membrane with no energy needed. (passive)

-         Oxygen and carbon dioxide

-         Moves with the concentration gradient (high to low)

facilitated Diffusion

Movement of molecules through carrier or channel proteins from high to low concentration.

-         Doesn’t require energy (passive)

• Ions and glucose

Osmosis 

Movement of water across a semipermeable membrane from low solute (salt/sugar) concentration to high solute (salt/sugar) concentration. ( 💡 Water follows solute.)

-         Water moves to where there is less water/higher particle concentrations are to reach equilibrium

-         Does not occur with penetrating molecules (only non-penetrating solutes)

Ex: Sucrose, potassium, sodium, calcium

Penetrating solutes 

Solutes that can cross the cell membrane

-         Small and nonpolar

-         Oxygen

-         Water

Carbon dioxide

Non-penetrating solutes 

Solutes that cannot cross the cell membrane and affect water movement

-         Sodium

-         Potassium

-         Ions don’t go through the membrane

• Large and polar

Osmotic pressure

The pressure required to prevent water movement across a membrane due to solute concentration.

-         Pressure that forces water across cell membrane

Hydrostatic pressure

The pressure exerted by a fluid against a surface or membrane.

Saturation 

where a system reaches its maximum 

operational capacity

• When all transport proteins are occupied- limiting transport rate

Transport maximum

The maximum rate at which a substance can be transported due to protein saturation

Active transport 

Movement of substances across the cell membranes against their concentration gradient, requiring ATP

Endocytosis 

Process by which cells bring substances into the cell using vesicles. (molecules fusing with the cell membrane)

Exocytosis 

Process by which cells release substances out of the cell using vesicles. (molecules fusing with the cell membrane)

Removes waste and delivers materials

Tonicity

Effect of a nonpenetrating solute on another solution

• -         the ability of solution to cause water to move into or out of a cell by osmosis (where the water is moving)

  -         How a cell responds when placed on a solution

Hypotonic, Hypertonic, Isotonic

Hypotonic

Solution has lower solute concentration than the cell (cell swells).

-         Water is less concentration.

-         More water inside cell

Hypertonic

Solution has higher solute concentration than the cell (cell shrinks).

-         Water is more concentrated

• Less water inside the cell

Isotonic

Solution has equal solute concentration (no net movement/ no change).

-         Equal water inside and outside the cell

Osmolarity

• Relates cell and solution concentrations

• Relates to water and cell, not cell change

• Molarity (#particles)/ #molecules

• Hyperosmotic, Iso-osmotic, Hypo-osmotic

-         Ex: OSM= 1M (2 particles)/ 1 molecule of NaCl

1 M NaCl = 2 Osm NaCl

Hyperosmotic

Higher total solute concentration to solution

Iso-osmotic

Equal total solute concentration to solution

Hypo-osmotic

Lower total solute concentration to solution

Symport 

Transport of two substances in the same direction across a membrane

Antiport 

Transport of two substances in opposite directions across a membrane

Molarity 

The concentration of moles of a substance per liter of solution (moles/L).

list the levels of organization of living organisms from the atom to the organism.

a.     Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism

Epithelial tissue

                                                      i.      Covers surfaces and lines body cavities/ forms glands

                                                   iii.      Protects (skin), absorbs (intestine lining), and secretes (insulin)

                                                   iv.      Avascular/ Rapid regeneration

                                                     v.      Ex: skin, lining of stomach, lungs

Connective tissue

                                                      i.      Supports, storage, cushion, transport, and protects body parts

                                                     ii.      Cells are spread out in a matrix

                                                   iii.      Ex: bone, blood, cartilage, tendons

Highly vascular/ innerved

Muscular tissue

                                                      i.      Contracts to produce voluntary and involuntary movement

                                                     ii.      Types: skeletal, cardiac, smooth

                                                   iii.      Ex: Heart, bicep brachii

Nervous tissue

                                                      i.      Conducts electrical signals/ actions potential

                                                     ii.      Allows communication within the body

                                                   iii.      Made of neurons and neuroglial cells

                                                   iv.      Ex: brain, spinal cord, and nerves

Regulated variables

factors that the body monitors and controls

• Examples include body temperature, blood glucose level, blood pressure, pH, and oxygen concentration

• kept within specific ranges constantly

Set point

constant balance range in homeostasis that the body tries to maintain

Control systems

mechanisms that maintain homeostasis

• Receptors, Control centers, and Effectors

Negative feedback Example

                                                      i.      If your body temperature rises → your body sweats to cool you down
If it drops → you shiver to warm up

                                                     ii.      High blood sugar → insulin released → sugar decreases → normal restored

Positive feedback Example

                                                      i.      Contractions start → oxytocin released → stronger contractions → more oxytocin

Phospholipid bilayer

Forms a selective barrier; hydrophilic heads face out, hydrophobic tails face in (nonpolar/barrier)

Cholesterol (cell membrane)

Stabilizes membrane; controls fluidity

Integral (transmembrane) proteins

Transport, receptors, channels

Peripheral proteins

Support, enzymes, signaling

Glycoproteins

Cell recognition, immune response

Glycolipids

Cell identity and communication

1. Passive transport

      (no ATP, down gradient)                                             

   i.      Simple diffusion

                                                     ii.      Facilitated diffusion

                                                   iii.      Osmosis

Filtration

1. Active transport types

      (requires energy)                                          

      i.      Primary active transport

                                                     ii.      Secondary active transport

                                                   iii.      Vesicular transport (endocytosis, exocytosis)

 

1. Secondary active transport

                                                      i.      Uses energy stored in ion gradient

                                                     ii.      Types:

                                                   iii.      Symport (same direction)

                                                   iv.      Antiport (opposite direction)

1. Vesicular transport

                                                      i.      Endocytosis (phago-, pino-, receptor-mediated)

                                                     ii.      Exocytosis

1. explain Fick’s law of diffusion

1. Rate of= Concentration gradient(membrane permeability)/ distance( molecular weight)

1. The rate of diffusion depends on:

a.      Concentration gradient (steeper = faster)

b.     Surface area (larger = faster)

c.      Membrane permeability

d.     Distance/thickness (thicker = slower)

1. describe the various fluid compartments of the body and the relative amounts of water found within each.

Compartment	% of Total Body Water
Intracellular fluid (ICF)	~66%
Extracellular fluid (ECF)	~33%
— Interstitial fluid	~25%
— Plasma	~8%

a.     chemically regulated (ligand regulated)

                                                      i.      Requires a specific chemical ligand to activate and open or close the channel

                                                    ii.      Ligan can be a neurotransmitter, hormone, or signaling hormone

Ex: Synapses, Acetylcholine

a.     voltage-regulated channels

                                                      i.      Requires a change in membrane electrical charge to cause channels to open or close

                                                    ii.      Depolarization or repolarization in cell membrane

                                                  iii.      No chemical binding required.

                                                  iv.      Ex: Axons and muscle cells

Glycolysis

occurs in the cytosol and produces a net gain of 2 ATP while breaking glucose into pyruvate.

• does not require oxygen.

Pyruvate oxidation

takes place in the mitochondrial matrix; it prepares pyruvate for the Krebs cycle but does not produce ATP directly

Krebs (Citric Acid) Cycle

also in the mitochondrial matrix, generates 2 ATP along with high-energy electron carriers

• require oxygen (directly or indirectly)

electron transport chain

located on the inner mitochondrial membrane, use these electron carriers to produce the majority of ATP (about 26–28 ATP).

• require oxygen (directly or indirectly)