APK2105 - Applied Human Physiology | Exam 2

how does water typically travel through the plasma membrane?

diffusion through channels (is polar, so needs integral proteins)

which of the following molecules would be able to diffuse through the plasma membrane without an integral protein: glucose, calcium ions, sodium ions?

none of the above, because the only things that can get through without an integral protein are small, nonpolar, and uncharged molecules.

which molecule is important for initiating the breakdown of glycogen?

epinephrine (accumulating in the bloodstream) or calcium (accumulating in the muscle fiber)

if oxygen was not present, how would this affect the ETC?

the 4th complex would accumulate electrons as O2 would not be there to remove them

what would cause pyruvate to accumulate in the mitochondria?

too little NAD+ in the mitochondria

if there is a nonpolar molecule that is a higher concentration outside the cell compared to inside? what type of transport is going to be used?

simple diffusion (nonpolar can move w/o integral protein)

what is an example of simple diffusion?

atmospheric oxygen passing through the plasma membrane

what is the function of the axon hillock in a neuron?

point of initiation of action potentials

describe the ion concentrations associated with the intracellular and extracellular fluid of a neuron.

higher [K+] inside, higher [Na+] outside

"salty banana"

with regard to depolarization, which of the following occurs when any given region of the axon hits -55mV?

activation gates on the voltage gated sodium channels open.

1. starting position of the sodium gated voltage channels is when activation gates are closed and inactivation gate is open (resting membrane potential -70 mV)

2. -70 mV -> -55 mV activation gate on voltage gated sodium channels will open since the inactivation gate is already open, allowing sodium to enter the axon

which molecule is most likely to travel across a plasma membrane via facilitated diffusion: sodium, potassium, CO2, calcium, or glucose?

glucose, it is polar and large so it cannot simply diffuse.

T-cells release protein-filled vesicles called cytokines in the extracellular fluid. what is this process called?

exocytosis

what refers to the period of time in which another action potential cannot be generated under any circumstance?

absolute refractory period

relative refractory period

a period after firing when a neuron is returning to its normal polarized state and will fire again only if the incoming message is much stronger than usual

place the following events in order:

I. the NT inside the synaptic vesicles is released via exocytosis

II. the ligand-gated channels on the postsynaptic neuron open

III. the voltage-gated calcium channels on the axon terminal button open

IV. the NT binds to the ligand-gated channels on the postsynaptic neuron

III. the voltage-gated calcium channels on the axon terminal button open

I. the NT inside the synaptic vesicles is released via exocytosis

IV. the NT binds to the ligand-gated channels on the postsynaptic neuron

II. the ligand-gated channels on the postsynaptic neuron open

what is true regarding the first half of hyperpolarization?

the cell is more permeable to K+ in comparison to the resting membrane potential.

hyperpolarization

the cell gets more negative. this can be achieved by negative cells entering the cell or positive cells leaving the cell

which of the following statements regarding osmosis are correct?

I. water moves from an area of low osmolarity to high osmolarity

II. water moves from an area of low solute concentration to an area of high solute concentration

III. a cell swells when submerged in a hyperosmotic solution

IV. a red blood cell will shrink when submerged in a hypoosmotic solution

I. water moves from an area of low osmolarity to high osmolarity

II. water moves from an area of low solute concentration to an area of high solute concentration

which of the following correctly pairs a tropic hormone with its respective regulated hormone?

tropic hormones stimulate another gland to release an additional hormone

FSH -> estrogen

TSH -> thyroid hormone

ACTH -> aldosterone and cortisol

which transport involves diffusion of Na+ ions past an integral protein so another molecule can move from low to high?

secondary active transport (low -> high = active; sodium ions through an integral protein so another molecule can move = secondary)

if someone is taking anabolic steroids, there will be a significant increase in testosterone. what would happen next?

the hypothalamus will not release GnRH (negative feedback loop and the anterior pituitary will not release FSH and LH

T/F: passive transport is against the gradient and requires ATP to function

false

how does an action potential allow for exocytosis of neurotransmitters from the bouton?

it allows for voltage gated Ca+ channels to open in the bouton, which in turn opens voltage gated channels, allowing NT to leave the neuron

in nerve and skeletal muscle cells, a stimulus that causes sufficient depolarization

causes voltage-gated Na + channels to open, allowing a small amount of Na+ to enter the cell down its electrochemical gradient

what is a synapse and what function does it serve?

the meeting of a neuron with another cell and allows for the sharing of info

T/F: if a neuron's axon hillock at rest depolarizes by 10mV, then an action potential will occur.

false. a neuron will be resting at -70 mV, and if it depolarizes by 10, it is at -60, but it needs to be at -55 for an action potential to occur.

why does the charge of an action potential never go above +30 mV and begin repolarizing from there?

the inactivation gates of the sodium channels close at +30 mV and the rate of K+ leaving the cell begins to be greater than Na+ entering.

during depolarization, Na+ enters the cell, making it more positive. upon reaching +30 mV, inactivation gates of the sodium channels will close, preventing sodium from entering, and the potassium channels will open, allowing potassium to leave.

what is true regarding absolute refractory periods?

absolute refractory period requires sodium channels to be reset between -60 and -70 mV before another AP can be generated.

during a relative refractory period, an AP can occur, but it requires a greater stimulus. during an absolute, no AP can occur until the resting potential gets back to -70 mV.

electron transport chain (ETC)

series of electron carrier proteins that shuttle high-energy electrons during ATP-generating reactions. functions to produce ATP.

where does the ETC take place?

inner membrane of mitochondria

what is the role of oxygen in the electron transport chain?

it acts as the final electron acceptor, which allows the chain to continue functioning. specifically, it oxidizes the fourth complex.

what would happen to the ETC if there was a lack of oxygen?

electrons would not be able to be removed efficiently, leading to a back up in the ETC and a lack of ATP production.

what system is used when ATP demand is moderate?

oxidative phosphorylation

what happens during exercise and increased ATP demand?

cardiac output is increased and blood flow is enhanced. this results in more oxygen being inhaled and transported to muscle fibers, where it is used in the mitochondria to produce ATP.

what happens when a muscle fiber contracts more frequently (ATP demand increases?)

ATP consumption rises, so the body enhances glycolysis and oxidative phosphorylation.

aerobic glycolysis

a metabolic pathway that requires oxygen to facilitate the use of glycogen for energy (ATP). the body prefers this pathway to meet ATP demands when possible, as it is more efficient and sustainable than anaerobic pathways.

what stimulates glycogen breakdown to provide glucose for ATP production?

increased levels of epinephrine in the blood and calcium in muscle fibers

consequences of insufficient oxygen

1. electron traffic jam

2. NADH backup

3. pyruvate accumulation

electron traffic jam

insufficient oxygen creates a bottleneck in the ETC, leading to a buildup of electrons and a reduced rate of ATP production.

NADH backup

without adequate oxygen, NADH can't be converted back to NAD+, leading to a shortage of NAD+ that is needed for glycolysis and the Krebs cycle.

pyruvate accumulation

a lack of NAD+ causes excess pyruvate, since it cannot enter the krebs cycle. this leads to its accumulation in the cytosol, leading to increased lactate production and anaerobic metabolism.

ATP production is limited by

amount of oxygen available

cells need about ____ ATP per second but typically make around ____ ATP per second.

700; 400

how is NAD+ regenerated?

conversion of pyruvate to lactate by lactate dehydrogenase

muscle fiber fatigue

occurs when ATP demand exceeds supply.

during intense exercise, glycolysis speeds up, producing large amounts of pyruvate and NADH. excessive pyruvate is then reduced to lactate, allowing ATP to be produced quickly, but cannot be sustained.

how do cancer cells metabolize?

they exploit fast, anaerobic glycolysis to proliferate without needing oxygen

passive transport

movement of molecules across the plasma without energy. requires a concentration gradient.

simple diffusion

molecules move from high to low concentration without a protein channel

what types of molecules can move via simple diffusion across the membrane?

small, nonpolar molecules like fatty acids and oxygen

facilitated diffusion

movement of molecules across cell membranes through protein channels or carriers

what types of molecules move via facilitated diffusion across the membrane?

polar or charged molecules

sodium typically moves ____ the cell, while potassium moves ____, both passively.

into; out

osmosis

water moves from an area of low solute concentration (high water concentration) to high solute concentration (low water concentration). water follows where the solutes go.

osmolarity

total solute concentration in a solution, measured in miliosmols (mOsm)

osmotic pressure

tendency of a solution to draw water towards itself; pressure exerted by the movement of water molecules across a membrane

hypotonic

having a lower concentration of solute than another solution

hypertonic

having a higher concentration of solute than another solution.

how does glucose move into the cell?

GLUT proteins, which change shape to move glucose into the cell.

primary active transport

direct use of ATP to transport substances.

ex. sodium-potassium pump

sodium-potassium pump

a carrier protein that uses ATP to actively transport 3 sodium ions out of a cell and 2 potassium ions into the cell

secondary active transport

utilizes the electrochemical gradient created by primary active transport.

ex. glucose moves against its gradient using energy from sodium moving with its gradient

humoral stimuli

changes in blood levels of ions and nutrients

neural stimuli

nerve fibers stimulate hormone release

hormonal stimuli

hormones stimulate other endocrine glands to release their hormones

luteinizing hormone (LH)

stimulates ovulation and the release of estrogen in females and testosterone production in males

follicle-stimulating hormone (FSH)

stimulates the growth of ovarian follicles in females and sperm production in males.

growth (somatotropic) hormone

directly stimulates growth in various tissues and indirectly by prompting the liver to secrete insulin-like growth factor

insulin-like growth factor (IGF-1)

promotes bone and tissue growth

growth (somatotropic) hormone deficiency

can lead to stunted growth/dwarfism

prolactin (PRL)

stimulates milk production in mammary glands. in males, elevated levels can result from steroid abuse

posterior pituitary

aka neurohypophysis; composed of nervous tissue and is an extension of the brain. releases hormones produced by neurons in the hypothalamus

oxytocin

stimulates uterine contractions during labor and milk ejection during breastfeeding

antidiuretic hormone (ADH, vasopressin)

promotes water reabsorption in the kidneys, reducing urine output and concentrating urine. humoral stimulus.

vasopressin and dehydration

the release of AHD/vasopressin is a response to high blood osmolarity, indicating dehydration

how does the hypothalamus control the anterior pituitary?

it releases hormones into the hypothalamic-pituitary portal system

gonadotropic-releasing hormone (GnRH)

stimulates the release of LH and FSH from the anterior pituitary, which in turn stimulates the production of sex hormones (testosterone and estrogen)

negative feedback loop in endocrine system (sex hormones example)

increased levels of testosterone and estrogen inhibit the release of GnRH from the hypothalamus, reducing LH and FSH secretion, which in turn decreases sex hormone levels.

steroid hormones

derived from cholesterol, such as cortisol and aldosterone

cortisol

helps reduce inflammation and suppresses the immune system

aldosterone

regulates sodium and potassium balance in the kidneys

what can occur from steroid abuse?

it can cause unnaturally high levels of testosterone. excess testosterone inhibits GnRH release, which reduces LH and FSH levels and in turn leads to decreased natural testosterone production

role of oxygen in the ETC

oxidizes the fourth complex, removing electrons from the chain

when ATP demand is moderate, oxygen and ATP demands can be met by

oxidative phosphorylation

epinephrine and calcium

during muscle contraction, these stimulate glycogen breakdown to provide more glucose for ATP production

glycolysis and its consequences

when oxygen is maxed out glycolysis runs rapidly, leading to an accumulation of NADH and pyruvate in the mitochondria.

what does excess NADH in the cytosol result in?

a shortage of NAD+

anaerobic glycolysis

without sufficient oxygen, glycolysis becomes anaerobic glycolysis, where pyruvate is converted to lactate. the conversion of pyruvate regenerates NAD+, allowing glycolysis to continue.

what converts pyruvate to lactate?

lactate dehydrogenase

endocrine system

consists of glands that secrete hormones into the bloodstream to target other cells or tissues that help control bodily functioning

hormones

chemical messengers involved in regulating various physiological processes

pituitary gland

releases hormones that fan out around the body, stimulating actions in the other endocrine glands

tropic hormones

stimulate other glands to release their hormones

ACTH

stimulates the adrenal cortex to release its hormones

FSH and LH

stimulate the release of estrogens and are involved in reproductive processes

anterior pituitary gland

AKA the adenohypophysis, the anterior pituitary is made of glandular tissue. It makes and secretes six different hormones: FSH, LH, ACTH, TSH, prolactin, and growth hormone. The anterior pituitary is controlled by releasing and inhibiting factors from the hypothalamus

the anterior pituitary gland is connected to the hypothalamus via

the infundibulum

thyroid-stimulating hormone (TSH)

stimulates the thyroid gland to release thyroid hormones (T3 and T4), which regulate metabolism

adrenocorticotropic hormone (ACTH)

stimulates the adrenal cortex to release cortisol and aldosterone, which help regulate metabolism and immune response

gonadotropins

anterior pituitary tropic hormones, follicles stimulating hormone (FSH) and luteinizing hormone (LH) which stimulate the gonads (ovaries and testes) to produce gametes and to secrete sex steroids

hyperthyroidism

excess thyroid hormones, leading to increased metabolism and weight loss