Bio 225

Exam 1

Animal Physiology

studying the structure and function of the various parts of an animal and how these parts work together to allow animals to perform their normal behaviors and respond to the environment

Evolution

Random processes, natural selection all play a role in producing traits that are best for reproductive success and behaviors for the particular environment and conditions - ultimate cause for diversity

Phenotype

both the genotype and how the organism interacts with its environment to progress development to produce the phenotype of an organism

Physiological Traits

1. all animals are multicellular eukaryotes (nuclei & organelles)
2. locomotion
3. heterotrophic (nutrition from other sources)
4. consume organic material
5. require oxygen - required to maintain homeostasis
6. reproduce sexually and asexually
7. do NOT have cell walls (amorphous cell membrane that controls what goes in and out of a cell)

Adptation

changes in population over evolutionary time as a result of natural selection that improve the survivability or reproductive fitness of the species

Unifying Themes in Physiology

1. physiology is integrative
2. physiological processes obey the laws of physics and chemistry
3. physiological processes are shaped by evolution
4. physiological processes are usually regulated

Reductionism

Can learn about a system by studying the function of its parts

Emergent Properties

New properties that arise with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases.

Carnivores have a much smaller digestive system than herbivores

Fick's First Law

- Substances diffuse from high to low
- Concentration, charge, temperature, or pressure will equalize within a system unless energy is added to maintain this difference

Concentration Gradient

A difference in the concentration of a substance across a distance. A source of potential energy that can be used to drive diffusion

Voltage Gradient

Source of electrical potential energy and can drive movements of substances based on charge difference.
- Signaling in neurons, muscle cells, and active transport of materials into cells

Brownian Motion

Random movement of particles in a solution

Electric Potential

Cells establish a charge difference across biological membranes by moving ions and molecules to create ion and electrical gradients.
- Changes in electric potential sends signals between and within cells

Scaling relationship

relationship between anatomical or physiological traits and body size

Isometric

Morphology or physiology change in direct proportion to body mass
- Bones of larger animals are proportionally thicker than smaller animals

Allometric

Body shape or physiology changes disproportionally as body size increase

Endotherms

Mammals that maintain a constant body temperature by metabolic heat

Proximate Cause

Immediate physiological or biochemical basis of a trait

Ultimate Cause

Example: Whether or not a giraffe's long neck is useful

Regulation and Homeostasis

- Homeostasis does NOT equal equilibrium
- Required for environmental variation
- Temperature, food availability, physiochemical environment around an animal can change
- Animals alter their heart rate and ventilation to rapidly adjust to changing oxygen demand from rest to exercise
LONGER TIME SCALES:
- Adjust rates of transcription, translation, and protein degradation to adjust protein amounts, resulting in functional changes

Conformers

allow internal conditions to change with external conditions

Regulators

maintain relatively constant internal conditions regardless of external conditions

Homeostasis

An animal initiates specific responses to control or regulate a vital variable

Allostasis

The process of achieving homeostasis through physiological or behavioral change
- Northern animals shed their brown summer fur and grow a thicker winter white fur

Feedback loops

To maintain homeostasis, animals must detect external conditions and if necessary initiate compensatory responses that keep vital areas buffered against unfavorable change

Reflex control pathway

a change in the internal or external environment provides a stimulus, the stimulus then causes a response

Antagonistic controls

independent regulators that exert opposite effects on a step or pathway

Negative feedback

A type of regulation that responds to a change in conditions by initiating responses that will OPPOSE the stimulus. Maintains a steady state.

Positive feedback

A type of regulation that responds to change in conditions by initiating responses that will AMPLIFY the change. Takes organism away from a steady state. Begins slowly but rapidly increases in intensity

Set point

Preferred physiological state defended through feedback loops

Feed forward action

anticipation of stimulus

Acclimation

change in response to a controlled environmental variable in a LAB setting - reversible

Acclimatization

change in response to a natural environmental variation - reversible

Phenotypic plasticity

the ability of an organism to change its phenotype in response to changes in the environment.

Polyphenism

a single genotype produces several distinct morphs

Reaction norm

the pattern of phenotypic plasticity exhibited by a genotype

Epigenetic inheritance

acquired traits can be passed on to generations

Cellular Energy

needed by cells to to work; found in ATP; stored in chemical bonds; released when chemical bonds are broken
- energy comes from the environment
- surface area to volume ratio: limits the size of cells and as the cell gets bigger, volume increases and "doorway" increases in size, ensures that the exchange of resources and waste occurs quickly enough for the cell to survive

Plasma membrane

- Helps maintain composition of intra and extracellular fluids (traffic regulation)
- Forms a framework for protein components
- Detects chemical messengers at cell surface
- Links adjacent cells together

Phospholipid bilayer

a two-layered arrangement of phosphate and lipid molecules that form a cell membrane, the hydrophobic lipid ends facing inward and the hydrophilic phosphate ends facing outward.

Diffusion of hydrophobic molecules

Go through easily because small (O2, CO2, N2)

Diffusion of small, uncharged polar molecules

Easy but not as easy because hydrophobic (glycerol)

Diffusion of large, uncharged polar molecules

Don't pass easily (glucose, sucrose)

Diffusion of ions, charged polar molecules

Don't pass well (H+, Na+, NCO3-, Ca2+, Cl-, Mg2+, K+, amino acids, ATP)

Diffusion of water

Facilitated diffusion by aquaporins
- water is excluded by the hydrophobic tails of the phospholipid bilayer

Simple diffusion

Diffusion that doesn't involve a direct input of energy or assistance by carrier proteins. Down the concentration gradient (phospholipid bilayer).
Passive, small and non-polar uncharged molecules

Passive diffusion

Movement of molecules due to kinetic energy but no ATP, net flux is 0

Electrochemical gradient

The diffusion gradient of an ion, which is affected by both the concentration difference of an ion across a membrane (a chemical force) and the ion's tendency to move relative to the membrane potential (an electrical force).
Independent of membrane charge

Flux

Measure of diffusion rate, net flux is difference between the two one-way fluxes
- Direction and magnitude depend on permeability, concentration gradient, temperature, surface area, size of molecule, distance

Osmosis

diffusion of water across a selectively permeable membrane from high to low concentration that is facilitated by aquaporins

Aquaporins

Channel proteins that form pores in membranes, mainly facilitating transport of water between cells. Direction of water movement is determined by a difference only by a difference in total solute concentration and not by types of solutes

Osmolarity

Total concentration of solutes in a solution that depends on the total number of molecules, not the individual type

Isoosmotic

the movement of water is equal in both directions

Hyperosmotic

solution with a greater concentration of solute

Hypoosmotic

lower solute concentration

Osmotic pressure

pressure that must be applied to prevent osmotic movement across a selectively permeable membrane

Hydrostatic pressure

Pressure exerted by term-57a volume of fluid against a wall, membrane, or some other structure that encloses the fluid.

Hypertonic

Shrink (higher concentration outside)

Hypotonic

Burst (lower concentration on outside)

Endocytosis

A process in which a cell engulfs extracellular material through an inward folding of its plasma membrane.
- substances include nutrients to support the cell or pathogens that immune cells engulf and destroy

Exocytosis

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

Phagocytosis

the ingestion of bacteria or other material by phagocytes

Pinocytosis

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.

Membrane Junction

Intracellular connections between plasma membranes of adjacent cells

Gap junction

Allow for direct diffusion of ions and small molecules between adjacent cells - communication and directly connect cytoplasm of two cells

Tight junctions

Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
- involved in maintaining cellular polarity and in the establishment of distinct fluid compartments

Desmosomes

Anchoring junctions that prevent cells from being pulled apart
- formed from protein plaques in the cell membranes linked by filaments, maintenance of structure

Adherens junction

a cell junction whose cytoplasmic face is linked to the actin cytoskeleton - initiation and stabilization of cell to cell adhesion, intracellular signaling and transcriptional regulation

Mediated transport systems

Solutes are either too large and/or charged cannot get into the cell; needs help

Facilitated Diffusion

PASSIVE - molecules move down the electrochemical gradeint, always proteins, transmembrane proteins facilitate diffusion of some polar or charged molecules across the plasma membrane

Anthropathic

hydrophobic and hydrophilic

Channel proteins

provide corridors that allow a specific molecule or ion to cross the membrane

Hyperpolarization

an increase in the membrane potential of a cell, relative to the normal resting potential (MORE negative)
- K+ moves out of the cell and Cl- moves in

Depolarization

LESS negative, Na+ moves into cell

Repolarization

Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.

Constitutive channels

always open (ex. aquaporins)

Gated channels

open or close in response to a stimulus

Ligand-gated channel

the binding of a specific substance (ligand) to channel leads to transition in the protein causing it to open or close (neurotransmitters act at ligand gated channels at post-synaptic membrane)

Voltage-gated channels

open and close in response to changes in membrane potential
- alters conformation of the channel proteins, regulating their opening and closing

Mechanically-gated channels

open and close in response to physical deformation of receptors (pressure, mechanical vibration, etc.)

permease- carrier mediated transport

carrier protein, ATP NOT needed, transport down concentration gradient
- binds the substrate, undergoes conformational change, releases substrate to the other side

Na+/K+ pump

Active transporter that moves three Na+ out of a cell and two K+ into the cell against their respective concentration gradients.
- More Na+ OUTSIDE and K+ INSIDE

Ca2+ pump

-hydrolysis of ATP required
-molecule binds to recognition site on carrier protein
- binding stimulates phosphorylation of carrier
- carrier protein undergoes conformational change
-hinge like mechanism releases transported molecule to opposite side of membrane

Leaky channels

non gated (K+), always open, maintenance of the resting potential, facilitated diffusion

Primary active transport

Active transport in which ATP is hydrolyzed, yielding the energy required to transport an ion or molecule against its concentration gradient.

Secondary active transport

movement of material that is due to the electrochemical gradient established by primary active transport. Ex: voltage-gated sodium pump

Steep gradient

Involvement in electrochemical impulses that promotes osmotic flow and regulates metabolic rate. Provides energy for coupled transport

Bulk transport

The process by which large particles and macromolecules are transported through plasma membranes. Inc. exocytosis and endocytosis
- moves ions and molecules via carrier proteins
- uses ATP
- phagocytosis, pinocytosis, receptor-mediated endocytosis, and exocytosis are types of bulk transport

Symporter / Cotransporter

transporter that carries two different ions or small molecules, both in the same direction

Antiporter / Exchangers

transporter that carries two ions or small molecules in different directions

Cell body (Soma)

the part of a neuron that coordinates information-processing tasks and keeps the cell alive
RECEIVES message

Axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands - MOVES message

Axon hillock

Cone shaped region of an axon where it joins the cell body.
TRANSFERS signal

Dendrite

a short branched extension of a nerve cell, along which impulses RECEIVED from other cells at synapses are transmitted to the cell body.

Myelin sheath

A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.

Schwann cell

Supporting cells of the peripheral nervous system responsible for the formation of myelin.

Nodes of ranvier

Gaps in the myelin sheath to which voltage-gated sodium channels are confined.

Axon terminal

release the neurotransmitters of the presynaptic cell between the terminals and dendrites of the next neuron

Saltatory conduction

the jumping of action potentials from node to node