Exam #1 Flashcards
Define homeostasis
maintenance of relatively stable internal conditions despite continuous changes in environment
*dynamic state of equilibrium
Ex of how body systems maintain homeostasis
ex. respiratory system: gas exchange (increase/decrease blood ox levels)
Most common feedback mechanism
Response REDUCES original stimulus
Reverse initial change in the body -> change in opposite direction
ex. regulation of body temp (hot=sweat, cold=shiver)
Negative feedback
Not as common
responses ENHANCES original stimulus =amplifying effect
Further in one direction
Positive feedback
macromolecules are made of monomers that include ___
lipids, carbs, nucleic acids, and proteins
lipid functions
energy storage (calories), signaling (steroid hormones), and building cell membrane (phospholipids)
carbohydrate functions
chemical energy storage, sugar storage (glycogen), cell identification
nucleic acid functions
information storage (DNA/RNA), energy storage (ATP), catalysis (RNA)
proteins diverse functions
structure (structural proteins)
movement (motor/contractile proteins)
catalysis (enzymes)
transport (transport proteins)
cell membranes are built from primarily from phospholipids (__) and (__)
bilayer and amphipathic (different properties)
cell membrane is selectively permeable, what can and cannnot pass?
oxygen passes freely, proteins need transport proteins to cross the membrane
cell membranes are fluid…
fluid mosaic model (proteins can move and pass through)
cytoplasm and organelles are….
inside the cell
what is composed of ~70-85% water, dissolved and suspended chemicals, and ions?
cytoplasm
some important organelles:
nucleus, ribosomes, ER, Golgi, mitochondria, and cytoskeleton
Nucleus
largest organelle, contains DNA, surrounded by nuclear envelope
Ribosomes
site of protein synthesis, free in cytoplasm or attached endoplasmic reticulum
Smooth ER
catalyzes lipid reactions and synthesizes other molecules
Rough ER
covered in ribosomes, makes, folds, and packages proteins
golgi apparatus
packages and sends molecules
mitochondria
manufactures ATP, double membrane (ER), has its own mitochondrial DNA
cytoskeleton
network of protein fibers that provide shape and strength to cell, move things within cells
glucose must undergo a series of rxns to release its potential energy
cellular respiration
cellular energy
convert carbs to glucose, proteins and fats are broken down into smaller components
primarily in mitochondria, undergoes 4 steps, produces ~30 ATP/glucose
cellular respiration
glucose + O2 —> ATP + CO2
aerobic respiration
Potential energy
Energy stored in position or configuration
(includes energy in chemical bonds)
Kinetic energy
energy of motion (sound, thermal energy, electricity)
ATP
stores potential energy
phosphate groups are negatively charged
covalent bond
ATP can be synthesized again by re-adding…
the phosphate group
Diffusion (all molecules have kinetic energy)
molecules vibrate and move/collide,
Diffusion =
the passive movement of molecules
(move from high to low concentration)
movement down concentration gradient
high to low
passive transport (diffusion)
high –> low, does not require cell energy
active transport
low –> high, requires cell energy (ATP)
simple diffusion
movement through intermolecular spaces or membrane openings
facilitated diffusion
interaction with carrier proteins
simple diffusion (protein channels)
tubular proteins, selective with size and electrical chargers, and they may be gated
voltage-gated
open/close in response to changes in electrical potential (ex. Na+ and K+)
chemical (ligand)-gated
open/close in response to binding of a chemical
the rate of diffusion is affected by:
temp
molecule size
concentration gradient
membrane electrical potential
pressure differential
Osmosis
net movement of water caused by a concentration difference of water
solvent
a fluid substance dissolve in (ex. water)
solute
a substance dissolved in a solvent (ex. salt)
isotonic
solution and cell have the same solute concentration, no net movement
hypotonic
solution has a lower solute concentration than inside of cell
water moves into the cell
leads to swelling and bursting (lysis)
hypertonic
the solution has greater solute concentration than inside of cell
water moves out of the cell
cell shrivels and becomes crenate
osmotic pressure
pressure from osmosis
the more solutes inside, the higher its osmotic pressure
water moves down towards the hypertonic solution
hydrostatic pressure
pressure exerted by water against the plasma membrane
primary active transport
carrier protein uses ATP directly to move molecules against their concentration gradient (ex. Na-K+ pump)
sodium-potassium pump
1 ATP powers pump to transport:
3 Na+ ions out of cell
2 K+ ions into cell
both against gradient
secondary active transport
uses the “driver” moving down the gradient to power the movement of another molecule
ATP used directly
symporter
transport substance in the same direction as “driver”
antiporter
transport substance in the opposite direction as “driver”
Vesicular transport
move across membrane (endo/exocytosis)
endocytosis
transport into cell (phagocytosis and pinocytosis)
phagocytosis
cell eating/ingest cells
pinocytosis
cell drinking/ or fluid-phase endocytosis
exocytosis
material is ejected from cell; substance ejected is enclosed in secretory vesicle
membrane potential
voltage across the plasma membrane
*voltage difference in electrical charge btwn 2 points
*down gradient
inside of cell has more ___ than outside
K+
outside of the cell has more ___ than outside
Na+
neuron is composed of:
telodendria
synaptic terminals
axon
axon hillock
golgi
dendrite
dendrite branches
mitochondria
ER
nucleus
cell body
graded potential
short-lived, localized changes in membrane potential
*triggered by a change that opens gated ions
causes channels to open:
chemical signals binding to receptors
changes in charge across the membrane
depolarization
potential difference becomes smaller (-70 mV to -65mV)
*open Na+ channels allow Na+ to rush into cell
hyperpolarization
potential difference becomes greater (-70mV to -75mV)
*K+ channels remain open longer than needed to restore resting membrane potential
action potential
rapid changes in membrane potential
stages of an action potential:
- resting
- depolarization
- repolarization
- hyperpolarization
repolarization
Na+ channels have inactivation gates that quickly stop the flow of Na+
*slower K+ channels open
*neg membrane potential
propagation (spreading)
-AP transmitted from origin down axon
-one direction
-Na+ influx through voltage gates in one membrane
-no AP is generated
refractory period
time in which neuron cannot trigger another AP
absolute refractory period
-opening of Na+ channels until resetting of channels
-ensures that AP is an all or none event
-one way transmission of nerve impulses
relative refractory period
-Na+ channels in resting state, some K+ channels still open
-repolarization occurs
-AP generation is elevated
myelinated
depends on the presence or absence of myelin
-Schwann cells wrap around axon in a paper towel roll fashion
continuous conduction
-in nonmyelinated axons
-slow
saltatory conduction
-in myelinated axons
-30x faster than continuous
intensity
all action potentials are alike in magnitude, regardless of stimulus intensity
frequency
CNA tells the difference btwn weak and strong stimuli by frequency of impulses
-# of APs received per second
-higher freq. = stringer stimulus
5 components of a reflex arc
- arrival of stimulus
- activation of sensory neuron
- integration-connection
- activation of motor neuron
- response by effector
Muscle fiber
a single muscle cell
types of muscle tissue:
skeletal, smooth, cardiac
myofibril
-built from sarcomeres
muscle-> fascicle-> muscle fiber-> myofibril
sarcomere
-highly ordered and repeating units
-attach end to end to form a myofibril
-basic contractile element of skeletal muscle
sarcomere regions:
I bands
A bands
H zone
M line
myofilaments
-keeps sarcomere together
-made of actin, myosin, + elastic filaments
-creates muscle contractions
thin filament
-actin
-light under a microscope
actin (composed of 3 proteins)
actin, tropomyosin, and troponin
-anchored at Z-disk
thick filament
in myosin
myosin
-2 intertwined filaments with globular heads
elastic filament
-runs through the core of thick filament (Z-disk)
-stabilize and position thick filament
Globular heads
-protrude 360* from thick filament axis
sliding filament theory
-actin-myosin interaction
-relaxed state ( no interactions; myofilaments overlap)
-contracted state (myosin heads pull actin, filaments slide past each other)
Sarcolemma conducts ___ ___
action potential
transverse tubules carry __ ___ deep into muscle fiber
action potential
sarcoplasmic reticulum (SR) forms network around each _____
myofibril
*Ca +2 storage
contraction (phase 2)
axon terminals form a ______ junction with a ____ ___ (do not touch)
neuromuscular; muscle
Neuromuscular junction (NMJ)
forms from axon terminals (filled with ACh)
Acetylcholine (ACh)
neurotransmitter
Cross-bridge movement steps:
- formation
- power stroke
- cross-bridge detachment
- cocking of myosin head
creatine phosphate
provide more initial ATP
static contraction
muscle produces force but does not change length
dynamic contraction
-concentric (muscle shortens while producing force)
-eccentric (muscle lengthens while producing force)
slow oxidative (SO) fibers
large number of mitochondria and extensive blood supply
fast oxidative (FO) fibers
-more tension than SO
-primarily for movements that require moderate energy (walking)
fast glycolytic (FG) fibers
-high tension
-high glycogen amounts
-not much myoglobin/mitochondria
-quick, powerful contractions
myoglobin
transports and stores oxygen
hypertrophy
enlargement of muscles
-more myofibrils
-thick muscle fibers
atrophy
loss of muscle mass
