Anatomy II Midterm Prep

glycolipids 

lipids with bound carbohydrate 

42%

what percentage of the cell membrane is made of lipids?

55%

what percentage of the cell membrane is made of proteins?

3%

what percentage of the cell membrane is made of carbohydrates?

head

which portion of a lipid is hydrophilic

tail

which portion of a lipid is hydrophobic

phospholipids in cell membrane 

• amphipathic molecules

• structural function 

  • aid in intracellular communciation

cholesterol

• rigid structure

• stabilizes the membrane

• 10-15% of membrane

proteins

• receptors

• enzymes

• structural proteins

• transporters

lipid anchored proteins

loosely attached to either side of cell membrane with electrostatic interactions

extrinsic proteins

• associated with weak electrostatic bonds to proteins or lipids

  • associations can be dyanmic - transient and regulated

carbohydrates in the cell membrane

• extracellular surface

• negative charge

• act as receptor for hormones (ex: insulin)

• act as antigen in immune response

functions of the cell membrane

physical isolation, regulation of materials from environment, communication, structural support

simple diffusion

• type of passive transport

• not carried mediated

• down electrochemical gradient 

• does not require energy

• measured with Fick’s law 

factors impacting movement in simple diffusion

• lipid solubility

• size of molecule

• concentration gradient

• surface area of membrane composition of lipid layer

rate of diffusion

(surface area X concentration gradient X membrane permeability) / membrane thickness

membrane permeability 

lipid solubility / molecular size 

osmosis

flow of h2o across membrane due to difference in solute concentrations

osmotic pressure 

force facilitating movement of water 

osmolality

concentration of osmotically active particles (osmoles / kg of h2o)

tonicity 

solutes effect on cell volume 

facilitated diffusion

• down concentration gradient

• no energy required

• rapid

• carrier mediated

filtration

water and solutes are forced through body membranes by hydrostatic pressure of blood

primary active transport

• against electrochemical gradient 

• requires direct input of energy (atp)

• carrier mediated - shows stereospecifity, saturation, competition

• examples: 

  • sodium potassium pump (Na, K, ATPase) 

  • proton pump (H, ATPase)

  • calcium pump (ATPasem Ca)

secondary active transport

• moving two molecules across transport membrane

• one ion moves down electrochemical gradient, allowing other ion to move against concentration gradient 

• examples: 

  • symport - moves in same direction 

  • antiport - moves in different directions 

phagocytosis

engulfment of materials (large/solid) from cell 

pinocytosis

cells take up extracellular fluids/solutes by fusing vesicles to membrane

exocytosis 

cells release proteins, hormones

depolarization

making membrane potential less negative

hyperpolarization 

making membrane potential more negative 

membrane potential

voltage difference across neural membrane

refractory period 

period right after action potential, second action potential is difficult or impossible to send 

inactivation

the time and voltage dependent decline of Na conductance, follows shortly after its activation

threshold 

membrane potential to reach in order to send action potential 

voltage gated ion channels

transmembrane proteins that open in response to changes in membrane potential, allowing particular ionic species to cross the membrane

equilibrium potenital 

measured using Nerst equation 

resting potential

determined by ion distribution, types of transport, electrochemical gradient, permeability OR sum of equilibrium potential of ions 

action potential 

occurs when stimulus is intense enough to reach threshold, when this happens Na channels open

electrical potential

diffusion of a chemical gradient and the diffusion of the charges 

ions in resting potential 

• inside of cell becomes negative 

• more K leaves than Na enters

-90 mv

resting membrane potential of neuron

-90 mv

resting membrane potential of skeletal muscle

-85 mv

resting membrane potential of cardiac muscle

-55 mv

resting membrane potential of sinus node

-55 mv to -60 mv

resting membrane potential of smooth muscle

diffusion potential

result from concentration differences of permeant ions 

excitability

capacity to generate a stimulus 

homeostasis

when the body reaches and intrnal equilibrium as processes within work to regulate environment, specifically of fluids 

• intracellular fluid (within body cells) - 67%

• extracellular fluid (outside body cells) 

  • interstitial (between cells in tissues) - 25%

  • plasma (within blood vessels)

intracellular fluid

• reducing

• high concentration of K+

• low concentration of Na+ and Ca2+ 

• more phosphates and proteins 

extracellular fluid

• oxidizing 

• low concentration of K+

• high concentration of Na+ and free Ca2+

function of extracellular/intracellular fluid

• maintains osmosis 

• carries electrical currents 

• maintains acid-base balance 

• serves as cofactors 

stimulus in homeostasis

distrubance or chage that sets the pathway in motion

sensor in homeostasis 

detects deviation from set point 

integration in homeostasis

control center, decides response

output in homeostasis

effectors produce response, efferent signal to the target

negative feedback

corrects a change in the system to return to the set point

ex: blood pressure, body temperature, blood glucose

positive feedback

effector organ creates a change in the system to push variable further from set point

ex: formation of blood clots, release of oxytocin in childbirth

all or none response 

either completely fires or not at all 

first phase of action potential

depolarization

• voltage gated Na+ channels open

• membrane potential becomes more positive

second phase of action potential 

repolarization 

• Na+ channels are inactivated 

• influx of K+ inside the cell 

third phase of action potential

refractory period

• absolute refractory period - no action potential can be sent 

• relative refractory period - action potential can be sent if impulse is strong enough

graded potential unique characteristics

• gradual 

• summation 

• no refractory period 

• variable duration 

• depolarize or hyperpolarize 

• ligand gated channels 

• somal dendrites

action potential unique characteristics

• all or none 

• no summation 

• threshold 

• refractory period 

• constant duration 

• depolarize 

• voltage gated channels on the axon hillock 

propagation of action potential

spread local currents so they depolarize

increasing conduction velocity

• fiber size - increasing diameter makes current move faster

• myelin insulatives axon for faster transfer

unmyelinated conduction

continuous carry or point to point

myelinated conduction

saltatory 

synapse

area where neurons communicate with other neurons, muscle cells, or glands

electrical synapse

• synaptic cleft (3-5 mm) 

• cytoplasmic continuity 

• gap junctions 

• ionic current to transmit 

• no synaptic delay 

• bidirectional 

• no synaptic fatigue 

• rapidity

chemical synapse

• synaptic cleft (20-50 mm)

• molecule used to transmit 

• synaptic delay 

• unidirectional 

• synaptic fatigue 

• integration 

  • of either excitatory postsynaptic potential (depolarizing)

  • or inhibitory postsynaptic potential (hyperpolarizaqtion)

    • inhibition happens when Cl- channels are open, they diffuse inside while K+ exit

adrenaline

fight or flight response

noradrenaline 

concentration

dopamine

pleasure

serotonin 

mood

gaba

calming

acetylcholine 

learning 

glutamate

memory

endorphins 

euphoria 

functions of the blood

transport and distribution, protection, homeostasis

transport / distribution (blood) 

• O2, CO2, nutrients 

• removal of waste 

• nutrients absorbed from GI and adipose tissue 

• hormones transported from endocrine glands to target tissues 

protection (role of blood)

• body defense 

• clotting with white blood cells 

homeostasis (function of blood)

• pH (buffer) 

• body temperature 

• fluid volume and water balance 

plasma

• 55% of blood

• proteins ~ 7%, water ~91%, 2% other solutes

formed elements in blood

• 45%

• platelets (less than 1%)

• leukocytes (less than 1%)

• erythrocytes (over 99%)

hematocrit

• proportion of blood that consists of red blood cells

• measures % of RBCs in given volume of whole blood 

• ( RBC height / total blood height ) x 100

function of albumin 

maintain osmotic pressure (60%)

globulins

transport molecules (amino acids, hormones, fatty acids, bilirubin, drugs)

• alpha globulins - enzymes 

• beta globulins - transfer 

• Y globulins or immunoglobulins 

serum

refers to blood plasma in which clotting factors have been removed

hematopoiesis 

formation of blood cellular components 

• produced in bone marrow 

• life span of blood cells 

  • erythrocytes - 120 days 

  • granulocytes - 6-8 h

  • lymphocytes - years 

  • platelets - 7-10 days 

• phases 

  • stem cells 

  • progenitor cells for each cell line: myeloid and lymphoid 

  • precursor cells 

erythrocytes

no nucleus and no cytoplasmic organelles

(99% of blood cells)

erythrocyte membrane 

lipids - 40%

• phospholipids

• no cholesterol 

membrane proteins - 52%

• integral membrane proteins 

• peripheral proteins 

  • outside: blood group antigens 

  • inside: spectrin 

spectrin

makes RBCs highly deformable  

anemia 

due to a low number of erythrocytes, more plasma

polycythemia

due to a high number of erythrocytes

functions of erythrocytes 

• transport of co2 and o2 (no energy needed) 

• transport of iron 

• hemoglobin acts as blood buffer

• contains carbonic anhydrase - enzyme that catalyzes reaction to generate bicarbonate which transport CO2

hemoglobin

• tetrametric protein

• 96% is globin, 4% is heme 

  • heme is binding site for o2 and globin 

  • 4 pyrole rings with bonded iron 

  • joining of o2 gives oxyhemoglobin 

• each molecule has 4 subunits, can carry 4 oxygen 

• 4 globin chains and 4 heme 

• each hemoglobin molecule carries up to 4 o2

iron 

• to bind hemoglobin, iron must be in the form ferrous (2+)

• the be moved by transferrin, must be in form ferric (3+)

prothrombin and fibringoen

molecules involved in the clotting process, located in plasma

globulins 

transporters of different hormones, found in plasma 

absorption of iron

• intake of 10-30 mg/day

• 5-10% absorbed from

• absorption increases with anemia and hypoxia