interactions between cells and the extracellular environment 1 & 2

in most individuals, approx. how much of the total weight of body fluids is water within cells, in the intracellular compartment

67%

how much of the total body water comprises the extracellular compartment

33%

about what percent of this extracellular fluid is contained in vessels of cardiovascular system, where it comprises the fluid portion of the blood, or blood plasma

20%

what is extracellular matrix

the extracellular environment fluids, as interstitial, or tissue, fluid, within a matrix of glycoproteins and proteoglycans

what are intergrins

a class of glycoproteins that extend from the cytoskeleton within a cell, through its plasma membrane, and into the extracellular matrix; serve as adhesion molecule between cells and the extracellular matrix by binding to components within the matrix

what is passive transport

the net movement of molecules and ions across a membrane from higher to lower concentration

types of passive transport

simple diffusion, osmosis, facilitated diffusion

what is active transport

net movement across a membrane that occurs against a concentration gradient (low to high)

which transport involves specific carrier proteins

active transport

characteristics of simple diffusion

• only form of transport that isn’t carrier-mediated

• no metabolic energy needed; passive

• occurs down an electrochemical gradient

factors that increase permeability in simple diffusion

• high oil/water of solute inc. solubility of the lipid of the membrane

• dec. radius of solute inc diffusion speed

• dec membrane thickness dec diffusion distance

what solutes have the highest permeabilities in lipid membranes during simple diffusion

small hydrophobic solutes

characteristics of facilitated diffusion

• occurs down an electrochemical gradient; similar to simple diffusion

• no energy needed

• more rapid than simple diffusion

• carrier-mediated, meaning it exhibits stereospecificity, saturation, and competition

a deficiency in insulin can lead to what type of diabetes

type 1 diabetes

what causes a deficiency in insulin

self-destruction of pancreatic beta cells

a mutation of insulin receptor can lead to

type 2 diabetes

characteristics of primary active transport

• occurs against an electrochemical gradient (uphill)

• requires direct input of metabolic energy in the form of ATP; thus is active

• carrier mediated, meaning it exhibits stereospecificity, saturation, and competition

example of primary active transport

two different ions (sodium and potassium) require ATP. releasing CA from sarcoplasmic reticulum (SR) for muscle. hydrogen potassium pumps in stomach, parietal cells release HCl in lumen.

over secretion of hydrogen ions in lumen of stomach can lead to what

gastritis (gastric ulcers); inflammation of stomach b/c of excess acids

how can gastritis be treated

use medicine to block acid into lumen called omeprazole (proton pump inhibitor)

characteristics of secondary active transport

• transport of 2+ solutes is coupled

• one solute (usually Na+) is transported downhill and provides energy for the uphill transport of the other solute(s)

• energy not provided directly, but indirectly from Na+ gradient that is maintained across cell membranes

during secondary active transport, if the solutes move in the same direction across the cell membrane, it is called what

cotransport or symport

during secondary active transport, if the solutes move in opposite directions across the cell membranes, it is called what

countertransport, exchange, or antiport

what is osmosis

the flow of water across a semipermeable membrane from a solution with low solute concentration to a solution with high solute concentration

the solution with the higher osmolarity is considered as what

hyperosmotic

the solution with lower osmolarity is considered as

hyposmotic

when does osmotic pressure increase

when the solute concentration increases

a solution with high osmotic pressure means what

more water is able to flow into it

what is isosmotic

when two solutions have the same calculated osmolarity

what is cystic fibrosis

genetic defect; abnormal NaCl and water movement occurs across wet epithelial membranes; a mutation in cystic fibrosis transmembrane conductance regulator (CFTR) which controls the excretion of chloride into the lumen

too much mucus in the ovary can lead to what

infertility

too much mucus in babies can lead to what

death

clinical significance of cystic fibrosis

lung congestion and infection and malabsorption of nutrients by the pancreas

what is normal osmolality in plasma

280-303 mili-osmoles per kg

what happens when there is a mutation to CFTR

overexertion of chloride from cell into lumen then sodium gets into lumen to increase osmotic pressure causing WBC to enter secreting mucus and create inflammation

how does regulation of blood osmolality work

• dehydrated → blood becomes more concentrated as total volume is reduced

• inc blood osmolality and osmotic pressure stimulate osmoreceptors, which are neurons located in the hypothalamus

• as a result of inc osmoreceptor stimulation, person becomes thirsty and drinks water, if available

• dehydrated person excretes a lower volume of urine

what is edema

excessive accumulation of fluid in tissue; swelling

what happens if cystic fibrosis impacts GI tract

severe diarrhea, dehydration, and collitis

what happens if cystic fibrosis effects pancreas

pancreatitis

can CF (cystic fibrosis) be treated

there is no treatment. inflammation can be suppressed by using an anti-inflammatory such as cortisol

what can cause edema

1. pregnancy b/c of hormonal changes

2. destruction of capillaries or blood vessels

3. obstruction or congenital issues of lymphatic system; can be caused by infection or virus or bacteria

4. cardiovascular disorders

5. renal disorders

6. deficiency of proteins in blood stream such as albumin

blood glucose below 50 mg/dl is considered as what

hypoglycemia

blood glucose of above 120 mg/dl is considered

hyperglycemia

what is oral rehydration therapy

treatment given after severe dehydration, which causes a person’s blood to become concentrated

how does oral rehydration treatment work

involves small amounts of fluid w/ glucose and NaCl which acts as an oral rehydration fluid. Na in fluid acts in secondary transport in the lumen to symport Cl, glucose and H2O.

oral rehydration therapy is effective for

diarrhea

A pregnant female has slight hypertension, sleep disorder, and vomits sometimes. the blood test shows that everything is normal - sodium, potassium, RBCs, WBCs, glucose. what is the cause of symptoms in pregnant female?

hormonal imbalance

• vomiting: progesterone may inc this and prostaglandin

• hypertension: blood volume changes for circulation of placenta

• diet: eating more has carbohydrate inc

step 1 of action potential

• resting membrane potential: -70 mV

  • many negative ions and few potassium inside cells

  • cell outside are positively charged while inner is negative

step 2 of action potential

stimulus from outside the cell to reach its threshold resulting in slow opening of sodium channel

step 3 in action potential

depolarization results in fast opening channels resulting in more sodium entering cell

step 4 of action potential

Na reaches equilibrium potential +65mV & closes the Na channel(s)

step 5 of action potential

at +65mV Na channels are closed, the cell returns to -70mV through repolarization

• this is done by K leaving the cell

step 6 of action potential

K has equilibrium potential of -85 mV

• the process of K leaving cell → hyper-polarization

what is a diffusion potential

the potential difference generated across a membrane b/c of a concentration difference of an ion

when can a diffusion potential be generated

only if the membrane is permeable to the ion

the size of the diffusion potential depends on what

the size of the concentration gradient

how do you know if the diffusion potential is positive or negative

depends on if the diffusing ion is positive or negative

diffusion potentials are created by the diffusion of very few ions and therefore what

do not result in changes in concentration of the diffusing ions

what is the equilibrium potential

the diffusion potential that exactly balances the tendency for diffusion caused by a concentration differences

what is the equilibrium potential for ENa+

+65mV

equilibrium potential for ECa2+

+120mV

equilibrium potential for EK+

-85mV

equilibrium potential for ECl-

-85mV

equilibrium potential for a resting membrane

-70mV

what is Ach (Acetylcholine)

stimulatory neurotransmitter that is important for muscle contraction. it is also important in autonomic nervous system. it is secreted by the vagus nerve which stimulates peristalsis in GI tract

deficiency in Ach can lead to what

muscle contractions

excess Ach can lead to what

gastritis and increase motility

depolarization in action potential makes what

makes the membrane potential less negative (cell interior)

hyperpolarization makes the membrane potential…

more negative (cell interior)

what is repolarization

K outflow

what is the absolute refractory period

the period in which another action potential can’t be elicited, no matter how large the stimulus

what is the relative refractory period

• happens at the end of the absolute refractory period and continues until the membrane potential returns to the resting level

• action potential can be elicited during this period only if a large than usual inward current in provided

conduction velocity is increased by

1. increased fiber size

2. myelination

   a. myelinated nerves exhibit saltatory conduction b/c action potentials can be generated only at the nodes of Ranvier, where there are gaps in the myelin sheath

what is the neuromuscular junction

the synapse between axons of motoneurons and skeletal muscle

the neurotransmitter released from the presynaptic terminal of a neuromuscular junction is

Ach

the postsynaptic membrane of a neuromuscular junction contains…

a nicotinic receptor

what is myasthenia gravis

• type of auto-immune disease caused by the presence of antibodies to the AcH receptors

• characterized by skeletal muscle weakness and fatiguability resulting from a reduced number of Ach receptors on the muscle end plate

what is the treatment of myasthenia gravis

AChE inhibitors

• medication: neostigmine; prevents AchE from breaking down Ach in synaptic cleft, which allows Ach to remain in synaptic cleft longer

types of neurotransmitters

• Ach

• norepinephrine, epinephrine, and doamine

• seretonin

• histamine

• glutamate

• GABA

• glycine

what is norepinephrine

the primary transmitter released from postganglionic sympathetic neurons

where is norepinephrine synthesized

in the nerve terminal and released into the synapse to bind w/ alpha or beta receptors on the postsynaptic membrane

norepinephrine and epinephrine are involved in controlling what

blood pressure

Norepinephrine is important for which nervous system

autonomic nervous system b/c it increases heart rate, conduction velocity, and contractility of myocardium. it also relaxes smooth muscle of bronchii.

over secretion of norepinephrine and epinephrine causes what

hypertension, palpitation and arrhythmia w/ excess sweating

what are symptoms of hypertension

headache, vomiting, nose bleeding, sleep disorder, vertigo (dizziness)

what is epinephrine

synthesized from norepinephrine; secreted from the adrenal medulla

what is dopamine

• prominent in midbrain neurons

• released from the hypothalamus and inhibits prolactin secretion

what is serotonin

• present in high concentrations in brain stem

• converted to melatonin in pineal gland

• formed by tryptophan

what is histamine

• formed from histidine

• present in neurons of the hypothalamus

what is glutamate

• most prevalent excitatory neurotransmitter in the brain

• has a kainate receptor, which is an ion channel for Na+ and K+

what is GABA

• inhibitory neurotransmitter

• synthesized from glutamate by glutamate decarboxylase

what is glycine

• inhibitory neurotransmitter found mainly in the spinal cord and brain stem

• increases Cl- conductance

examples of excitatory neurotransmitter(s)

• Ach

• norepinephrine, epinephrine, and dopamine

• seretonin

• histamine

• glutamate

examples of inhibitory neurotransmitter(s)

• GABA

• glycine

deficiency in serotonin can cause what

depression and bipolar disorder

histamine secreted by mast cells in the skin causes what

vasorelaxation, which is widening of blood vessels

histamine secreted by lungs can act as a

vasoconstrictor

histamine secreted by stomach can increase what

HCl secretion

over secretion of HCl in stomach can cause what

gastritis and gastric ulcers

glutamate is for

memory and learning; activates sodium potassium channels