Phys Exam 1

is transmission across a synaptic cleft a chemical or electrical event?

is transmission across a synaptic cleft a chemical or electrical event?

chemical

describe phospholipid bilayer

polar (hydrophilic) head includes phosphate group, nonpolar (hydrophobic) tails are fatty acids

anatomy

study of the structure of the body

physiology

the study of the functions of living things; focuses on the underlying mechanisms of body processes

levels of structural organization

atoms, molecules, organelle, cell, tissue, organ, organ system, organismal

important atoms at chemical level of physiology

O, C, H, N

molecules of life

proteins, carbohydrates, fats, nucleic acids

What are the basic units of life?

cells

basic cell functions

obtaining food and oxygen, performing energy-generating chemical reactions, eliminating waste, synthesizing proteins and cell components, moving materials through the cell, responding to the environment, reproducing

specialized cell functions

secrete digestive enzymes, retain/eliminate substances, produce intracellular movement, generate/transmit electrical impulses (ex. nerves)

4 types of tissue

nervous, muscle, epithelial, connective

necessary life functions

maintaining boundaries, movement, responsiveness, digestion, metabolism, excretion, reproduction, growth

survival needs

nutrients, oxygen, water, normal body temperature, appropriate atmospheric pressure

homeostasis

body’s ability to maintain relatively stable internal conditions despite changes in the outside environment

5 elements of homeostatic control system

stimulus, receptor, input, output, response

effector

carries out control center’s response to the stimulus

negative feedback mechanism

output shuts off original effect of stimulus or reduces its intensity (in opposite direction of initial change)

positive feedback mechanism

initial response enhances original stimulus so that further responses are even greater (change goes in same direction as initial change)

positive feedback mechanisms control ________ events

infrequent

extracellular fluid in the blood is also known as:

plasma

extracellular fluid outside of blood is also known as:

interstitial fluid

what factors are regulated by homeostasis?

nutrient concentration, O2 and CO2 concentration, concentration of waste products, changes in pH, concentrations of water, salt, and other electrolytes, volume and pressure, and temperature

to maintain homeostasis, the control system must be able to:

detect deviations from normal, integrate this info with other info, make adjustments to restore the factor to normal

intrinsic control

local control, built into an organ

extrinsic control

systemic control, regulatory mechanisms initiated outside organ to alter its activity

homeostatic imbalance

disturbance of homeostasis; increases risk of disease, contributes to changes associated with aging (less efficient control systems)

baroreceptor

measures pressure within organ

are controlling body temperature and regulating blood glucose levels examples of positive or negative feedback?

negative

which part of the brain is important for body temperature regulation?

hypothalamus

what is the byproduct of muscle constriction?

heat

what 2 things regulate blood glucose levels?

insulin (for high blood glucose levels) and glucagon (for low blood glucose levels)

are labor, blood clotting, and forming of a platelet plug examples of positive or negative feedback?

positive

if ________ feedback mechanisms become overwhelmed, destructive __________ feedback mechanisms may take over (ex. heart failure)

negative/positive

3 parts of the cell theory

1. the cell is the smallest unit of life

2. all organisms are made up of 1+ cells

3. cells only arise from other cells

functions of plasma membrane

physical barrier, selective permeability, communication, cell recognition

glycolipids

lipids attached to sugars

aquaporins

water-specific channels

osmolarity

total concentration of solute particles in a solution

tonicity

the ability of a solution to change the shape (or plasma membrane tension) of cells by altering the cells’ internal water volume

relationship between ketones and glucose

inverse

what molecules cannot pass through the lipid bilayer?

highly polarized (H2O), charged particles (Na+, K+), large molecules (proteins)

what molecules can pass through the lipid bilayer?

small, nonpolar (O2, CO2)

function of cholesterol

stiffen membrane, decreasing water solubility of membrane, keeps fatty acid chains from packing together and crystalizing

effect of too much cholesterol in lipid bilayer

overcrowding leads to hardening and rigidity, which reduces elasticity in arteries

glycocalyx

viscous, carbohydrate rich layer on periphery of cell

peripheral proteins

do not penetrate membrane

transmembrane/integral proteins

span entire thickness of bilayer

glycoproteins

proteins bonded to short chains of sugars which make up glycocalyx; identification tags, biological markers, allow immune system to recognize self

glycocalyx of some cancer cells

changes so rapidly that immune system cannot recognize cell as being damaged, so mutated cell is not destroyed and is allowed to replicate

function of membrane proteins

maintain cell shape, fix location of some membrane proteins, cell movement

tight junctions

impermeable, form continuous seals around cell, prevent molecules from passing between cells

desmososmes

anchoring junctions, bind adjacent cells together, allow “give” between cells (reducing possibility of tearing)

gap junctions

communicating junctions, linked by connecting tunnels (connexons) that allow ions, small molecules, and electrical signals to pass from cell to cell

types of passive membrane transport

simple diffusion, facilitated diffusion (carrier/channel), osmosis

3 factors influence speed of diffusion:

1. concentration

2. molecular size

3. temperature

where would tight junctions be found in the body?

stomach (contain acid)

where would desmosomes be found in the body?

skin (flexible), heart

how to steroid hormones and fatty acids move through the lipid bilayer?

simple diffusion

effect of damage to plasma membrane

substances can diffuse freely in/out of cell, compromising concentration gradients

when are carriers saturated?

all are bound to molecules and are busy transporting

hydrostatic pressure (HP)

outward pressure exerted on cell side of membrane caused by increases in volume of cell due to osmosis

osmotic pressure (OP)

inward pressure due to tendency of water to be pulled into a cell with higher osmolarities

what happens when hydrostatic pressure = osmotic pressure?

no movement of water occurs

hypertonic solution

cell loses water by osmosis (shrink)

hypotonic solution

cell takes on water by osmosis (bloat→ burst)

when would an isotonic solution be used clinically?

when blood volume needs to be increased quickly

why would a hypertonic solution be used clinically?

to pull water back into blood of swollen patients

when are hypotonic solutions used clinically?

never-- can result in dangerous lysing of red and white blood cells

3 types of active membrane transport

1. primary active transport

2. secondary active transport

3. vesicular transport (endocytosis, exocytosis)

antiporter

transports one substance into cell while transporting a different substance out of cell

symporters

transport two different substances in the same direction

primary active transport

required energy comes directly from ATP hydrolysis

secondary active transport

required energy is obtained indirectly from ionic gradients created by primary active transport

what type of transport is the Na/K pump?

primary active transport

vesicular transport

involves transport of large particles, macromolecules, and fluids across membrane in vesicles, requires cellular energy (usually ATP)

2 types of vesicular transport

endocytosis, exocytosis

3 types of endocytosis

phagocytosis, pinocytosis, receptor-mediated endocytosis

what in the body uses phagocytosis?

macrophages, other white blood cells (to destroy bacteria)

pinocytosis

cell “gulps” a drop of ECF containing solutes into tiny vesicles; no receptors used, nonspecific

by what process are nutrients absorbed in the small intestine?

pinocytosis

receptor-mediated endocytosis

extracellular substances bind to specific receptor proteins, enabling cell to ingest & concentrate specific substances in protein-coated vesicles

what substances are released via exocytosis?

hormones, neurotransmitters, cellular waste, mucus

where does voltage occur in a cell?

membrane surface

cell adhesion molecules

anchor cells to extracellular matrix or other cells, assist in movement of cells, attract white blood cells to injured/infected areas, stimulate synthesis/degradation of adhesive membrane junctions, transmit intracellular signals to direct cell migration, proliferation, and specialization

3 overlapping functions of nervous system

sensory input, integration, and motor output

graded potential

short-lived, localized changes in membrane potential

where do action potentials occur?

muscle cells and axons of neurons

what happens to graded potentials over long distances?

they decay (unlike action potential)

repolarization resets ________ conditions, not ________ conditions.

electrical/ionic

what restores ionic potentials during repolarization?

Na/K pumps

how does the CNS distinguish stimulus strength?

frequency (# of action potentials received per second)

why does large axon diameter increase conduction velocity?

large axons have less resistance to local current flow

where does continuous conduction occur?

nonmyelinated axons (slow, as opposed to saltatory conduction)

resting membrane potential of neuron

-70 mV

absolute refractory period

period when a recently activated patch of membrane is unresponsive (during action potential/when Na channels are inactive)

relative refractory period

follows absolute refractory period; second action potential can be produced but requires stronger stimulus (after action potential, during hyperpolarization)

where are voltage-gated Na+ channels located?

in nodes of Ranvier

multiple sclerosis (MS)

myelin sheaths in CNS are destroyed when immune system attacks myelin; turns myelin into hardened lesions called scleroses; impulse conduction slows and eventually ceases; demyelinated axons increase Na+ channels, causing cycles of relapse and remission

how do local anesthetics work?

block voltage-gated Na+ channels (can’t generate action potential)

what is the total change in voltage of an action potential?

about 100 mV