Learn: EXSS 256 Exam 1

membrane permeability.

plasma membranes are selectively permeable. the lipid bilayer is always permeable to small, nonpolar, uncharged molecules. The membrane is impermeable to ions or charged molecules. transmembrane proteins act as channels or transporters to increase membrane permeability. macromolecules are only able to pass through by vesicular transport.

concentration gradient

the difference in the concentration of a chemical between one side of the membrane and the other.

O2 and Na ions have a greater concentration outside the cell.

CO2 and K ions have a greater concentration inside the cell.

electrical gradient

difference in concentration of ions between one side of the plasma membrane and the other. sets up membrane potential.

electrochemical gradients

electrical and concentration gradients together.

passive transport

simple diffusion, facilitated diffusion, and osmosis

active transport

primary active transport, secondary active transport, and vesicular transport.

simple diffusion

random mixing of particles in a solution as a result of the kinetic energy of those particles. both the solvent and solute can diffuse. movement from high to low concentrations.

what increases the rate of diffusion?

steeper gradient, higher temperature, smaller particle, greater surface area, and smaller diffusion distance.

diffusion through the lipid bilayer

nonpolar, hydrophobic molecules. important for gas exchange, nutrient absorption, and waste excretion.

leakage channel

gates alternate from open to closed (Na and K)

voltage-gated channels

open in response to a change in membrane potential (Na and K)

ligand-gated channels

open and close in response to a chemical stimuli like hormones, neurotransmitters, or other ions.

facilitated diffusion

solute binds to a specific transporter protein and the transporter undergoes conformational change. the solute then moves across the membrane and is released on the other side only down its concentration gradient.

glucose, urea, fructose, galactose, and vitamins.

osmosis

the net movement of a solvent through a selectively permeable membrane from an area of high concentration to an area of low concentration.

hydrostatic pressure

pressure that the water column exerts

osmotic pressure

pressure a solution exerts when its particles are not permeable to the membrane; proportional to the concentration of solute particles that cannot cross the membrane.

tonicity

how the osmolarity of a solution affects the cell volume

hypertonic

tonicity of the solution is higher than the tonicity of the cell

hypotonic

tonicity of the solution is lower than the tonicity of the cell

isotonic

tonicity of the solution is the same as the tonicity of the cell.

primary active transport

energy derived from ATP changes the shape of a transporter protein which pumps a substance across a plasma membrane against its concentration gradient. most prevalent is Na/K pump. requires 40% cellular ATP, operates continually, low Na and high K in cytosol.

secondary active transport

energy stored in Na or H ion concentration gradient used to drive other substances against their own concentration gradients. creates ion gradients. symporters move substrates in the same direction and antiporters move substrates in opposite directions.

vesicle

small membranous sac formed by budding off from an existing membrane.

endocytosis

bringing something into the cell. phagocytosis is a cell eating and pinocytosis is a cell drinking.

exocytosis

release something from the cell.

metabolism

the sum of all chemical reactions in the body.

catabolism

breakdown; exergonic

anabolism

building; endergonic

oxidation

removal of electrons from an atom or molecule

reduction

addition of electrons to a molecule

glycolysis

breakdown of glucose to produce ATP; catabolic. involves 10 reactions where a 6C glucose is split into 2 3C molecules of pyruvic acid.

rapid rate and low yield of ATP production. oxygen dependent or independent. regulated by PFK

gluconeogensis

formation of glucose from lipid or protein; anabolic

glycogenolysis

breakdown of glycogen into glucose; catabolic

glycogenesis

synthesis of glycogen from glucose; anabolic

carbohydrates

monosaccharides and disaccharides are simple sugars.

glycogen

main polysaccharide in the body. storage form of glucose

carbohydrate metabolism

oxidation of glucose to produce ATP is called cellular respiration. glycolysis, formation of acetly coenzyme A, krebs cycle, and ETC reactions

hexokinase

conversion of glucose to G-6-P in glycolysis

phosphopfructokinase

PFK; plays a major role in regulating the rate of glycolysis

lactate dehydrogenase

LDH; converts pyruvate to lactate

pyruvate dehydrogenase

PDH; convers pyruvate to acetyl-CoA

electron transport chain

each carrier in the chain is reduced as it picks up electrons and oxidized as it gives up electrons. exergonic reactions release energy used to form ATP.

lipids

triglycerides, phospholipids, steroids, fatty acids, fat soluble vitamins (a, d, e, k), and lipoproteins

chylomicrons

transport dietary lipids to adipose tissue

very low-density lipoproteins

VLDLs; transport triglycerides from hepatocytes to adipocytes

low-density lipoproteins

LDLs; carry about 75% of the total cholesterol in blood and deliver it to cells.

high-density lipoproteins

HDLs; remove excess cholesterol from body cells and the blood and transport it to the liver for elimination.

lipid metabolism

lipids may be oxidized to produce ATP only when oxygen is present. if lipids are not needed they are stored in adipose tissue.

lipolysis

lipid catabolism; the process of splitting triglycerides into fatty acids and glycerol. triglyceride hydrolysis and beta oxidation.

lipogenesis

lipid anabolism; the process of synthesizing lipids from glucose or amino acids.

ketone bodies

the result of lipid catabolism. two acetyl CoA molecules combine to form acetoacetic acid which is converted to beta-hydroxybutyric acid and acetone. heart and kidney cortex prefer to use acetoacetic acid for ATP

protein conformation

proteins are made of amino acids with three main groups: amino group, acidic carboxyl group, and side chain

protein metabolism

digested proteins are broken down into amino acids which are not stored, but are either oxidized to produce ATP or used to synthesize new proteins.

protein catabolism

yields amino acids which are converted to other amino acids, fatty acids, ketone bodies, or glucose. cells oxidize amino acids to generate ATP via Krebs cycle and is

protein anabolism

creates new proteins by bonding together amino acids on ribosomes.

exocrine gland

secrete products into ducts and ducts carry secretions to target site.

sweat, oil, mucous, and digestive glands

endocrine glands

secrete hormones into interstitial fluid of secretory cells, then diffuse into capillaries.

circulating hormones

travel in the blood and act on distant target cells

paracrine hormones

travel in extracellular space and act on neighboring cells

autocrine hormones

travel in extracellular space and act on same cell that secreted it.

hormone action

1. hormone binds to receptor on cell surface or receptor inside target cell. these receptors are continually synthesized and broken down.

2. cells may then synthesize new molecules, change permeability of membrane, or alter rates of reactions.

3. each target cell responds to hormone differently.

lipid-soluble hormone

bind to transport proteins to be carried in the blood

water-soluble hormone

circulate freely in plasma

direct gene activation

activated receptors alter gene expression and form new proteins. the proteins alter cells activity and responses of those hormones.

second messenger system

hormones can't diffuse through plasma membranes. first messenger is where the hormone binds to the cell membrane receptor. second messenger is released inside the cell where the hormone-stimulated response takes place.

humoral stimuli

hormone release in response to changes in extracellular fluids.

neural stimuli

non-voluntary process in which the nervous system stimulates hormone release.

hormonal stimuli

release of a hormone in response to another hormone

hypothalamus

the major integrating link between the nervous and endocrine systems.

receives input from cortex, thalamus, limbic system, and internal organs. controls pituitary gland with 9 different releasing and inhibiting hormones.

anterior lobe

ACTH, TSH, PRL, FSH, LH, MSH, hGH

releasing hormones

control release of hormones from anterior pituitary. made in the hypothalamus and are released into the hypophyseal portal system and travel to the anterior pituitary.

hGH

most plentiful anterior pituitary hormone. promotes synthesis and secretion of small proteins hormones (IGFs)

regulation of T3 and T4

hyopthalamus --> TRH --> anterior pituitary --> TSH --> thyroid gland --> T3 and T4

hyperthyroidism

weight loss, feeling hot, fatigue, irritability, jittery.

treatment of radioactive iodine or ablation

hypothyroidism

weight gain, feeling cold, fatigue, slowed thinking, lethargy.

treatment of TSH

what stimulates T3 and T4 release

low blood levels of T3 and T4, low metabolic rate, and increase in ATP demand.

T3 hormone

calcitonin; regulates calcium homeostasis with PTH, lower blood levels of calcium, and builds bone.

parathyroid hormone

increase blood calcium level and decrease blood phosphate level.

adrenal glands

outer cortex: produces 3 types of hormones from 3 zones

inner medulla: medulla produces catecholamines

mineralocorticoids

mineral homeostasis; aldosterone

glucocorticoids

glucose homeostasis; cortisol

androgens

steroid hormones with masculine effects; testosterone

aldosterone

reabsorption of Na and H2O. excretion of K and H in the urine. goal is to regulate Na and K levels in the body. regulated by renin-angiotensin pathway

ADH/vasopressin

made in hypothalamus, but stored and released in the posterior pituitary. decreases urine volume by causing kidneys to reabsorb water, constricts blood vessels which increases BP. increased blood osmolarity, decreased blood volume from dehydration, sweating, hemorrhage, vomiting, and diarrhea.

metabolism and stress response

muscle fibers: protein breakdown

liver: gluconeogenesis

adipocytes: lipolysis

blood arterioles: vasoconstriction

WBC: inhibition of WBC and anti-inflammatory effects

epinephrine

metabolic effects; increase substrate use and mobilization, glycogen breakdown, and lipolysis

norepinephrine

cardiovascular effects; increased heart rate, blood pressure, blood flow to heart/liver/muscle/adipose, and dilation of airways.

stimuli for release of catecholamines

increases in SNS activity, decrease in blood glucose levels, and increase in emotional stress

general adaptation syndrome

1. fight or flight (immediate)

2. resistance (longer-term)

3. exhaustion (depletion)

insulin

pancreatic beta cells; promotes glucose uptake from blood to decrease blood glucose. high blood glucose stimulates secretion of insulin.

amino acid uptake from blood to promote protein synthesis, lipogenesis, glycogenesis, and slows GNG.

glucagon

pancreatic alpha cells; promotes release of glucose into blood and increases blood glucose. low blood glucose stimulates release of glucagon

type 1 diabetes

insulin dependent DM; absolute deficiency of insulin and an autoimmune disease where the body destroys beta cells.

type 2 diabetes

non-insulin dependent DM; insulin produced, tissues insensitive, down-regulation of insulin receptors

hypothalamic-pituitary-adrenal axis

in males: regulates the production of sperm; controlled by hypothalamus

in females: regulates ovulation, ovarian cycle, and uterine cycle

menstrual cycle

involves changes in the endometrium, preparation of uterus to receive fertilized ovum, and if implantation doesn't occur the lining is shed.

estrogens

promote development and maintenance of female reproductive structures, feminine secondary sex characteristics, and breasts. increase protein anabolism, lower blood cholesterol, and moderate levels inhibit release of GnRH, FSH, and LH

progesterone

works with estrogens to prepare endometrium for implantation, prepares mammary glands to secrete milk, and inhibits release of GnRH and LH

relaxin

inhibits contractions of uterine smooth muscle and during labor increases flexibility of pubic symphysis and dilates uterine cervix.

inhibin

inhibits release of FSH and to a lesser extent LH

female reproductive cycle