Lab Exam 3 Flashcards
The urinary system is composed of the
kidneys, ureters, urinary bladder, and the urethra.
The urinary system is constantly working to maintain the
purity and health of the body’s fluids by removing unwanted substances and recycling others.
The kidneys contribute to homeostasis by
regulating plasma composition through the elimination of metabolic wastes, toxins, excess ions, and water.
Three main metabolic waste products
(nitrogenous compounds), urea, uric acid, creatinine
urea
is formed by the breakdown of amino acids
Uric acid
is formed by the byproduct of breakdown of nucleic acids
Creatinine
is formed from the breakdown of a molecule known as creatine phosphate
Kidney function 1
Regulation of the volume, composition, and pH of the body fluids
Kidney function 2
Regulation of acid-base homeostasis (via the production of ammonia)
Kidney function 3
Regulation of energy metabolism via gluconeogenesis during fasting conditions
Kidney function 4
Regulation of plasma osmolarity through the control of aquaporin receptors within the collecting duct
Kidney function 5
Detoxification of metabolic wastes through excretory mechanisms
Kidney function 6
Conversion of vitamin D3 into its active form
Kidney function 7
Synthesis and conversion of important hormones such as erythropoietin and renin.
Kidneys are located in the
retroperitoneal space just behind the peritoneum of the abdominal cavity
Right and left kidney will be located on the
upper abdominal quadrant of the retroperitoneal space
Right kidney is located
a little slightly lower compared to our left kidney
Kidney maintains its shape and structure through its
fibrous capsule that’s located along the outside of the organ itself
Renal cortex is below
fibrous capsule. Lighter pink outer region and is where urine production can occur.
renal medulla or renal pyramid
Small, triangular-shaped, darker pink shapes found inside the kidney
Renal cortex and renal medulla will make up the
renal lobe
Renal papillae
Apex of the pyramid or point of the pyramid, at the very bottom of the pyramid
Renal columns
Between each renal medulla and renal pyramid, lighter pink regions. Maintain the integrity and shape or structure of the kidneys
Minor calyx
is where urine formation that found in the medulla will travel down into this minor calyx.
Major calyx
where urine travels to after the minor calyx, three major calyxes, will form together to form the regional pelvis
Hilus
indentation found on an organ that can contain blood supply and contain neural innervation. Will include the renal pelvis, renal artery, renal vein, and the renal plexus for innervation
Urine will travel through the
renal pelvis, down into the ureter, into the urinary bladder and then finally through the urethra
in renal blood flow, the
First five arteries will be our last five veins, but they’ll be inverted with each other
Renal blood flow
Renal artery -> Segmental artery -> Interlobar artery -> Arcuate artery -> Interlobular artery -> Afferent arteriole -> Glomerulus -> Efferent arteriole -> Peritubular capillaries -> Vasa recta -> Interlobular vein -> Arcuate vein -> Interlobar vein ->Segmental vein -> renal vein
Renal artery
branch off of the abdominal aorta and it’s going to be providing deoxygenated blood to the kidneys. Will travel through the hilum
Interlobar arteries travel through the
lobes of the medulla
Arcuate artery
form arches along the outside of the cortex
Interlobular arteries
form these small tree-branch like structures off of the arcuate arteries
Afferent arteriole
provides blood supply to the glomerulus
Efferent arteriole
exiting the glomerulus
Peritubular capillaries
surrounding the tubules, specifically the portions of the proximal convoluted tubule and the distal convoluted tubule
Vasa recta
will provide a blood capillary system that surrounds the loop of Henle
Interlobar veins
between lobes and medulla
Renal vein
enter into the inferior vena cava
The Nephron
The main functional unit of the kidney responsible for urine formation, Smallest functioning unit of the kidneys
Cortical nephron
found in the cortex, Shorter loops of Henle, About 80-85% of nephrons in humans
Shorter loops of Henle
produce more diluted urine
Juxtamedullary nephron
located adjacent to the medulla or next to the medulla, Longer loops of Henle that extend down the renal medulla, Only 15-20% of nephrons in humans
Longer loops of Henle that extend down the renal medulla
allow for more water reabsorption, will be able to produce much more concentrated urine
The nephron is composed of
Renal corpuscle = Bowman’s capsule + glomerulus. Renal tubule
Renal tubule with three distinct parts
Proximal Convoluted Tubule, Loop of Henle, Distal Convoluted Tubule
The nephron produces urine through three/four main interaction mechanisms:
Filtration, Reabsorption, Secretion, Excretion
Filtration
A filtrate of the blood leaves the kidney capillaries and enters the renal tubule. Will only occur at the glomerulus to produce an ultrafiltrate product
Filtration definition
the movement of water and plasma solutes through the glomerular capillary walls into the urinary space of the Bowman’s capsule.
Reabsorption
Most of the nutrients, water, and essential ions are recovered from the filtrate and returned to the blood. Most reabsorption will occur at the proximal convoluted tubule
Reabsorption definition
when a substance is transported from the filtrate, through the tubular cell membrane walls, and eventually into systemic circulation
Secretion
Certain substances are secreted from the blood into the filtrate product to be eliminated. Can occur in the proximal convoluted tubule.
Secretion definition
a substance is transported from peritubular blood vessels into the filtrate product, which will ultimately form urine
Excretion
Process of eliminating or expelling waste matter through the final excretory product, urine
Glomerular filtration is where we see
podocytes, forming our internal wall of the glomerulus and this is what helps make it a more structured area to not allow certain products to move out and for only smaller substances to move out the area or out of the bloodstream
When podocytes are formed, there are extensions called
pedicles. Pedicles will form filtration slits in the area which will allow filtrate to leave the capillaries and actually enter into Bowman’s capsule
The endothelium of these capillaries are
very porous
The endothelium of these capillaries allow
fluid, waste products, ions, glucose, and amino acids to pass from the blood into the capsule.
Glomerular Filtration blocks out
bigger molecules like blood cells and proteins so they stay in the blood and exit through the vasa recta.
hematuria
red blood cells being present in the urine
albuminuria
albumin being present in the urine
Glomerular Filtration Rate (GFR)
volume of filtrate produced by both kidneys per minute. Physiological indicator of renal function
Glomerular filtration is determined by
Starling’s pressures
Proximal Convoluted Tubule (PCT) cell walls are made up of
cuboidal epithelial cells containing mitochondria to power pumps that pull sodium ions from the filtrate using active transport
the microvilli in Proximal Convoluted Tubule (PCT)
increase surface area to help reabsorb as much of the “good stuff” as possible
The vast majority of renal reabsorption occurs in the
proximal convoluted tubule
renal reabsorption is approximately
67% of sodium and 67% of water
The coupled sodium and water reabsorption is
proportional to each other (isosmotic). This mechanism is essential for the maintenance of the chemical integrity of the extracellular fluid composition and general homeostasis
In a healthy individual there will be
~100% reabsorption of glucose
When plasma glucose is below 200 mg/dL
most if not all filtered glucose is reabsorbed
Renal threshold for glucose
200 mg/dL
In diabetes mellitus, if its left untreated,
individuals can present with ketonuria or ketones being present in the urine due to the breakdown of fatty acids for energy
If the blood glucose concentration is higher than 200 mg/dL but lower than 350 mg/dL, what can be said regarding reabsorption and excretion?
There is some reabsorption occurring and there’s also some excretion of glucose so they will present with glycosuria
If the blood glucose concentration is higher than 400 mg/dL what can be said regarding reabsorption and excretion?
The reabsorption process has reached its maximum rate. That suggests that all glucose transporters are full with glucose. They’re no longer able to reabsorb glucose back into the bloodstream. We should see mainly excretion. No more reabsorption can occur, and excretion will be the predominant source
Loop of Henle
Starts in the cortex, dips down in the medulla, comes back into the cortex
Loop of henle contains
thin descending, thin ascending, thick ascending
Thin descending
is only permeable to water and is through passive transport that water will be reabsorbed back into our blood capillary system. Higher concentration of urine as more water leaves
Thin ascending
is impermeable to water and we have active transport of sodium outward so into the interstitial fluid of the medulla and chloride ions will follow passively. This will create a very hypertonic area in that interstitial fluid.
a very hypertonic area in that interstitial fluid will help
drive in the descending limb that passive movement of water out of the descending limb of the loop of Henle and into the capillaries
Interstitial fluid is hypertonic to the
filtrate
Loop of Henle drives the
reabsorb of water by creating a salt concentration gradient in the tissue of the medulla
The ascending portion actively
pumps out salt and is impermeable to water
The high concentration of salt in the interstitial fluid of the medulla causes
water to passively flow in the descending portion via osmosis
Distal Convoluted Tubule is responsible for
the reabsorption of sodium, bicarbonate, and the secretion of ammonium
PTH acts on the
DCT to stimulate calcium reabsorption
Distal Convoluted Tubule is
Impermeable to water. In certain cases, when we have aquaporins being inserted through what’s known as our antidiuretic hormone, it can become permeable to water
Distal Convoluted Tubule empties into
the collecting duct
Collecting Duct
Contains aquaporins which aid in the reabsorption of water into the blood. Involved in sodium reabsorption and potassium excretion
Describe the physiological mechanisms of the renin-angiotensin-aldosterone system (RAAS).
Low blood volume activates the juxtaglomerular apparatus in a variety of ways to make it secrete renin.
Angiotensin-aldosterone system (RAAS) process
Renin > angiotensin I > angiotensin converting enzyme (ACE) > angiotensin II.
Angiotensin II has a variety of effects but it also causes
the release of aldosterone from the adrenal cortex
Aldosterone role in the urinary system
Promotes sodium reabsorption in the DCT and collecting duct, Promotes the retention of water and sodium, Stimulates thirst, Increase blood volume and thus increase in blood pressure
In the presence of high ADH
the renal mechanisms produce hyperosmotic (concentrated) urine.
In the absence of ADH
the renal excretion mechanisms produce hyposmotic (diluted) urine.
ADH increases the
permeability of water of the distal convoluted tubule and collecting duct, which are normally impermeable to water. This effect causes increased water reabsorption and retention and decreases the volume of urine produced.
Urinary bladder is made of
special epithelial cells that will help allow for the stretching of the bladder for increase in volume of urine (transitional epithelial cells)
Micturition
medical term for urination
There are two sphincters, or muscular valves, that
separate the bladder from the urethra
The sphincters must open before
the urine can flow into the urethra
External sphincter is a
voluntary sphincter and its under voluntary control. Innervated by our somatic pudendal nerve.
The internal sphincter is
under involuntary control and is regulated by the alpha adrenergic receptors. Can’t be controlled at all
Bladder typically “feels full” around
150 - 200 mL
Perceiving a sense of urgency around
300 – 400 mL
involuntary urination
> 600 mL
Urinary Tract Infection
Most often occurs in sexually active women. Intercourse drives bacteria from the vagina and the anus through the nearby opening of the short urethra
The use of spermicides (found on condoms) magnifies o Urinary Tract Infection because
they also kill the natural, “healthy” bacteria and allow pathogenic bacteria to colonize.
UTI symptoms
burning sensation during micturition, increased urgency and frequency of micturition, fever, and sometimes cloudy or blood-tinged urine.
The elderly are also susceptible to UTIs due to
weakness of the bladder, incontinence, poor bladder emptying, and retention of urine. Symptoms of a UTI in the elderly include mental changes and confusion.
Renal Calculi
kidney stones
Renal Calculi types
4 different types – Calcium oxalate is the most common
Renal calculi Risk factors
family history, chronic dehydration, obesity, certain diets (such as those with high in protein and/or salt)
Stones less than 5mm in diameter
will likely pass without intervention
Stones >5 mm
may become lodged in the ureter blocking the flow of urine and increasing intrarenal pressure
Lithotripsy
uses shock waves to break up stones
Primary endocrine organs
produce and secrete hormones as their primary physiological role
Secondary endocrine organs and tissues
produce and secrete hormones in addition to their main function
Hormones
chemical messengers secreted by cells into the extracellular fluids. These messengers travel through the blood and regulate the metabolic function of other cells
The chemical structure of hormones
determines a critical property of a hormone: its solubility in water.
Water solubility affects how hormones are
transported in the blood, how long it lasts before it is degraded, and what receptors it can act upon
Type of hormones
amino acid based, steriods
Amino acid based
Derived from amino acids this includes amines (such as epinephrine and thyroxine) and peptides (such as growth hormone and vasopressin). Usually, water soluble and cannot cross the plasma membrane
Steroids
Synthesized from cholesterol. Only gonadal and adrenocortical hormones are steroids. Lipid soluble and can cross the plasma membrane
Anterior Pituitary Hormones
Adrenocorticotropic hormone (ACTH), Thyroid-stimulating hormone (TSH), Luteinizing hormone (LH), Follicle-stimulating hormone (FSH), Growth hormone (GH), Prolactin (PRL)
Adrenocorticotropic hormone (ACTH) target tissue and effect
Target tissue - Adrenal glands, specifically the adrenal cortex
Effect - Secretion of glucocorticoids, mineralocorticoids, and androgens
Thyroid-stimulating hormone (TSH) target tissue and effect
Target tissue - Thyroid
Effect - Secretion of thyroxine (T4) & triiodothyronine (T3)
Luteinizing hormone (LH) target tissue and effect
Target tissue - Ovaries and testes
Effect - In females, triggers ovulation. In males, promotes testosterone production
Follicle-stimulating hormone (FSH) target tissue and effect
Target Tissue - Ovaries and testes
Effect - In females, stimulates ovarian follicle maturation and production of estrogens. In males, stimulates sperm production
Growth hormone (GH) target tissue and effect
Target tissue - Liver, muscle, bone, cartilage, & other tissues
Effect - Regulates metabolism and body growth
Prolactin (PRL) target tissue and effect
Target tissue – mammary glands
Effect – Promotes lactation
Posterior Pituitary Hormones
Anti-diuretic hormone (ADH), Oxytocin
Anti-diuretic hormone (ADH) target tissue and effect
Target tissue – kidneys
Effect - Stimulate kidney tubule cells to reabsorb water; inhibition of diuresis
Oxytocin target tissue and effect
Target tissue - Uterine smooth muscle and mammary glands
Effect - Stimulate contractions during labor; initiates labor. Initiates milk ejection while breastfeeding
The hypothalamus controls release of
hormones from the pituitary gland in two different ways: Anterior pituitary (adenohypophysis) and Posterior pituitary (neurohypophysis)
Anterior pituitary (Adenohypophysis)
Hypothalamic hormones released into special blood vessels (the hypophyseal portal system) control the production and secretion of anterior pituitary hormones
Anterior pituitary (Adenohypophysis) step 1
Hypothalamic neurons secrete releasing and inhibiting hormones into capillary plexus.
Anterior pituitary (Adenohypophysis) step 2
Hypothalamic hormones travel though hypophyseal portal veins to the anterior pituitary; where they stimulate or inhibit release of hormones made in the anterior pituitary.
Anterior pituitary (Adenohypophysis) step 3
Anterior pituitary hormones are secreted into the secondary capillaries and in turn empties into the general circulation.
Posterior pituitary (Neurohypophysis)
Action potentials travel down the axons of hypothalamic neurons causing hormones to be released from the axon terminals
Posterior pituitary (Neurohypophysis) step 1
Hypothalamic neurons synthesize oxytocin and ADH
Posterior pituitary (Neurohypophysis) step 2
These hormones are then transported down the axons of the hypothalamic-hypophyseal tract to the posterior pituitary where they are stored in axon terminals
Posterior pituitary (Neurohypophysis) step 3
When associated hypothalamic neurons fire, action potentials arriving at the axon terminals cause the hormones to be released into the blood
pineal gland
(Epiphysis). Regulates the circadian rhythm through the production and secretion of melatonin
Melatonin production and release can be stimulated by
darkness or inhibited by light impulses
Pineal gland Important precursors:
tryptophan and serotonin
Adrenal Cortex
Release hormones called corticosteroids. Zona glomerulosa, Zona fasciculata, Zona reticularis
Zona glomerulosa
secretes mineralocorticoids such as aldosterone to regulate sodium and potassium balance
Zona fasciculata
secretes glucocorticoids such as cortisol which stimulates glucose formation and inhibits utilization of glucose
Zona reticularis
secrete sex steroids
Adrenal medulla
Regulated by neural innervation, Secretes epinephrine and norepinephrine, Fight or flight response
thyroid hormones
(T3 and T4) and calcitonin
The thyroid hormones (T3 and T4) affect
virtually every cell in the body
Thyroid hormones enters
the target cell, bind to receptors within the cell’s nucleus, and initiate transcription of mRNA for protein synthesis.
Thyroid hormones increase
basal metabolic rate and body heat production, and also regulate tissue growth and development.
Calcitonin released from
parafollicular cells (C-cells) of the thyroid gland in response to a rise in blood calcium levels
calcitonin inhibits
osteoclast activity, inhibiting bone resorption and the release of calcium from the bony matrix
calcitonin counteracts
the regulatory effects of the parathyroid glands by promoting osteoblast activity
parathyroid gland produce and secrete
parathyroid hormone (PTH)
parathyroid gland controls
calcium concentrations in the blood
Low levels of calcium trigger
the release of PTH
PTH increases calcium levels in the blood by
stimulating three target organs: skeleton, kidneys, intestine
Skeleton
stimulates osteoclasts to digest some of the calcium rich bony matrix and release the calcium and phosphates into the blood
kidneys
enhances the reabsorption of calcium
Intestine
promotes activation of vitamin D thereby increasing absorption of calcium by intestinal mucosal cell
The pancreas is both an
endocrine and an exocrine organ
Endocrine cells are located in
islets of Langerhans
Αlpha cells
Secrete glucagon. Hypoglycemia is the main activator of release
Beta cells
Secrete insulin. Hyperglycemia is the main activator of release
Diabetes Mellitus (DM)
Characterized by persistent hyperglycemia. Correlated with a variety of negative health implications such as development of Alzheimer’s disease, nerve degeneration, cognitive dysfunction, etc.
Type I DM
Insulin dependent, “adolescent-onset diabetes”, autoimmune disorder caused by destruction of the beta cells, lack of insulin secretion leads to hyperglycemia and increased lipolysis activity, little correlation with body weight, smaller % of diabetic population
Type II DM
Non-insulin-dependent, “maturity-onset diabetes”, caused by insulin resistance where the target cells no longer respond normally to insulin, Normal or elevated insulin initially; relative insulin deficiency, strong correlation with body weight; majority of patients are overweight or obese, larger % of diabetic population
Receptors for water soluble hormones must be located
on the surface of the cell so within the plasma membrane since these hormones cannot enter the cell
The receptors for lipid soluble hormones (steroid and thyroid) are going to be located
on the inside of the cell because these hormones can enter the cell
Pituitary gland is very
small
Infundibulum is important because
it connects the pituitary gland to the hypothalamus
Hypothalamus interacts with the anterior pituitary gland primarily through
the hypophyseal portal system
Hypophyseal portal system is a
capillary system so tiny blood vessels that flow between the hypothalamus and the anterior pituitary
Hypothalamus will secret hormones into
the Hypophyseal portal system and they will signal for the pituitary gland to produce and secrete its own hormones
Releasing and inhibiting hormones from the hypothalamus control
the production and secretion from the anterior pituitary
Hormones of the anterior pituitary are made in the
anterior pituitary so the anterior pituitary synthesizes its own hormones
The hypothalamus is going to make or synthesize the hormones and just deliver them to
posterior pituitary to be stored and released when needed
Tryptophan can undergo
decarboxylation to form serotonin
Within the pineal gland, serotonin is
acetylated and then methylated to yield melatonin
Blue light blocks
melatonin production and secretion
Thyroid gland is a
butterfly shaped gland located on the anterior aspect of the trachea just inferior to the larynx
Thyroid gland is composed of
hollow spherical follicles and the walls of each follicle are formed by follicular cells and then the central lumen is filled with a jelly like substance called colloid
Thyroid hormone (T3 and T4) is the body’s major
metabolic hormone
Thyroid hormone is released from the
follicular cells
Increased thyroid people and decreased thyroid people
are warm and thin, decreased thyroid people are cold, tired and put on weight
Calcitonin is released from the
parafollicular cells
Calcitonin’s job is to lower
blood calcium levels
Calcitonin lowers calcium levels by inhibiting
osteoclasts (bonce crushing) and by encouraging osteoblasts (bone building cells)
Parathyroid gland are very small glands located on
the posterior aspect of the thyroid
Adrenal glands are
pyramid shaped that sit on top of the kidneys; sometimes referred to as the suprarenal glands
All adrenal hormones help us cope with
stressful circumstances in some way
Adrenal medulla is the
innermost region and it functions as part of the sympathetic nervous system
Adrenal cortex is the
outer portion and have the release of over two dozen steroid hormones collectively called corticosteroids
Glucagon (Alpha) is a hypoglycemic hormone works to
raise our blood glucose levels it does this mainly by targeting the liver to break down glycogen to glucose and it also tells the liver to synthesize glucose from lactic acid and from other non-carbohydrate molecules
Insulin (beta) is a hypoglycemic hormone so its job is to
lower the blood glucose. It also promotes the sorts of fat. To lower the blood glucose, insulin will enhance the membrane transport of glucose. So well have the glucose being put into our cells especially our muscle cells and our fat cells so they can use this glucose as energy
The energy needs is met first and then if we have extra left over, then we will make
glycogen and then if we have even more left over after that, the glucose will be converted to fat
Without insulin, your cells cannot
accept glucose
Type 1 diabetes is treated with
injections of insulin, a type of hormone replacement therapy to make up from that lack of production
type 2 diabetes treatment
Metformin is used as treatment
