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Anatomy and physiology > Urinary system > Flashcards

Urinary system Flashcards

1
Q

renal hilus

A

the kidneys medial surface is concave and has a cleft called the renal hilus that leads into the renal sinus

the ureters, blood vessels, and nerves are in the sinus and enter the kidney at the hilus

on top of each kidney is an adrenal gland

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2
Q

Kidneys 3 protective tissue layers

A

outer renal capsule- inner layer of protective tissue, the renal capsule is a tough fibrous outer skin of the kidney that protects from injury and infection

adipose capsule -outside the renal capsule is a fatty layer that protects the kidney from trauma

renal fascia -outer layer is a dense fibrous connective tissue that keeps the kidney in place inside the abdominal cavity

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3
Q

three distinct regions of the kidney

A

cortex, medulla and pelvis

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4
Q

outer renal cortex

A

just inside the renal capsule, is a continuous outer region with several projections called (cortical columns) and extend between the medulla pyramids

within the cortex are glomerular capsule and the distal and proximal convoluted tubule sections of the nephrons along with the associated blood vessels

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5
Q

renal medulla

A

deeper within the kidney lies the renal medulla that is divided into sections called pyramids that point toward the center of the kidney

located in the medulla are the loop of Henle and the collecting duct sections of the nephrons and associated blood vessels

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6
Q

renal pelvis

A

the centermost section of the kidney near the renal hilus is the renal pelvis, which constitutes a funnel shaped tube that connects the ureter as it leaves the hilus

the extensions on the pelvis are called calyces

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7
Q

calyces

A

collect urine which drains continuously into the renal pelvis and subsequently into the ureter. The ureter transports urine to the bladder to be stored

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8
Q

segmental arteries

A

the renal arteries branch into five segmental arteries that divide further into lobar arteries, then further into interlobar arteries, which pass between the renal pyramids. The interlobar arteries diveide further into the arcuate ateries, whicb divide into the interlobular that feed the afferent arterioles.

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9
Q

interlobar arteries

A

divide into arcuate arteries which branch into several interlobular arteries that feed into afferent arteries that supply the glomeruli

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10
Q

efferent arterioles

A

After filtration occurs, the blood moves into efferent arterioles and either the peritubular or vasa recta capillaries and then drains into the interlobular veins which converge into arcurate veins, then interlobular veins, then to the renal vein, which exits the kidney

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11
Q

renal plexus

A

the kidney and nervous system interact via the renal plexus whose fibers follow the renal arteries to reach the kidney

input from the sympathetic nervous system adjusts the diameter of the Renal arteries, thereby regulating blood flow

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12
Q

ureters

A

urine is carried from the kidneys to the badder by thin muscular tubes called ureters that begin as a continuation of the renal pelvis and descend at the base of the bladder

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13
Q

ureterovesicle valves

A

are sphincters located where the ureters enter the bladder.

the downward flow of urine in addition to the ureterovesicle valve help to prevent urine from flowing back toward the kidney

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14
Q

Three layers of the ureters

A

inner lining made up of traditional epithelium continuous with the kidney lining

middle layer is two sheets of muscles-one longitudinal and the other circular

the outer adventitia layer is fibrous connective tissue

distention on the middle muscle layer by the urine as it enters the ureter causes it to contract and push the urine through the ureter

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14
Q

bladder

A

is a hollow, muscular, elastic pouch that receives and stores urine excreted by the kidneys before the urethra

in males, the base of the bladder lies in front of the rectum and just behind the pubic symphysis.

In females, the bladder sits below the uterus and in front of the vagina, so the maximum capacity of the bladder is lower in females than in males

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14
Q

transitional epithelium

A

the cells in transitional epithelium are specialized to stretch, allowing for the organ to increase its volume as it fills, while protecting and covering the underlying tissues.

As the bladder empties they recoil back to their original shape

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15
Q

three layers of the bladder

A

the outer adventitia is a fibrous connective tissue

the middle layer is a muscular layer known as detrusor muscle with inner and outer longitudinal layers and a middle circular layer

inner mucosal layer composed of transitional epithelium

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15
Q

urethral orifices

A

both ureters open into the bladder via the urethral orifices

the urethra begins as it opens at the base of the bladder

these three openings occupy the corners of the smooth triangular center region of the bladder called trigone

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16
Q

bladder anatomy

A

the bladder is very elastic, collapsing into a pyramidial shape when empty

As its filled with urine, the bladder swells and becomes pear shaped, rising in the abdominal cavity

the muscular wall stretches and thins, allowing the bladder to store larger amounts of urine without a significant rise of internal pressure

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17
Q

Rugae

A

folds in the bladder wall that also extend to help the capacity of the bladder internally.

A moderatley full bladder holds approximately 500 ml of urine

If necessary the bladder can hold 1000 ml, which is stored in the bladder until urination (miticulation) is convenient.

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18
Q

urethra

A

is a thin walled muscular tube that carries urine from the urinary bladder out of the body.

the mucosal lining of the urethra starts off as transitional cells as it exits the bladder, which become stratified columnar cells near the external urethral orifice

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19
Q

internal urethral sphincter

A

involuntary controlled internal urethral sphincter is located near the bladder and keeps the urethra closed to prevent urine from leaving the bladder

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20
Q

external urethral sphincter

A

composed of skeletal muscle, surrounds the urethra as it passes through the pelvic floor

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21
Q

male and female differences of the urethra

A

the length of the urethra differs in length.

the female urethra is shorter and only carries urine while the male urethra is about 5 times longer and carries both semen and urine from the body

since the female urethra is so short and the external opening is close to the anus, poor hygiene after defication can easily carry fecal bacteria into the urethra. Bacteria enter the urethra and travel up to the bladder causing a UTI

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22
Q

Three regions of the male urethra

A

prostatic urethra- which runs within the prostatic gland

membranous urethra- which runs within the urogenital diaphragm

spongy (penile) urethra- which runs within the penis and opens to the external urethral opening

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23
Q

nephrons

A

the basic and structural unit of a kidney is called a nephron of which there are about million present in each kidney

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23
Q

function of nephron

A

to control the concentration of water and soluble materials for filtering the blood, reabsorbing needed materials, and excreting the rest as urine

The nephron thereby eliminates wastes from the body, regulates blood volume, pH and pressure, and controls the levels of elecctrolytes

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24
Q

what are the two parts of the nephron

A

glomerular capsule (renal capsule) and the renal tubule

these two parts are connected through the tubule to the associated connecting ducts

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25
Q

glomerular capsule and renal tubule

A

renal corpuscle -filters blood

renal tubule - reabsorbs needed materials and the collecting ducts carry the remaining material away to be excreted as urine.

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26
Q

the three parts of the renal tubule

A

the proximal convoluted tubule (PCT)

the loop of henle

distal convoluted tube (DCT)

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27
Q

glomerulus

A

the renal corpuscle is composed of glomerulus, a network of tiny blood capillaries surrounded by the glomerular capsule (Bowman’s)

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28
Q

glomerular capsule

A

a double walled simple squamous epithelial cup

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29
Q

glomerulus capillaries of the renal corpuscle

A

the capillary pores are extremely porous

the capillary endothelium has fenestrations (pores) that allow certain substances to leave the capillaries

the glomerulus capillaries are the only capillaries in the body that lie between two arterioles (the afferent arteriole and the efferent arteriole) rather than between and artery and a vein

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30
Q

afferent arteriole and efferent arteriole

A

which is fed by the interlobular artery is much larger in diameter than the efferent artery - this difference in diameter causes an extremely high blood pressure in the glomerulus capillaries forcing water and solutes out the blood, thus making filtration possible

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31
Q

filtrate

A

water and solutes leave the glomerulus, enter the glomerular capsule, and subsequently flow into the renal tubule. Once water and solute leave the blood and enter the glomerular capsule is called filtrate

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32
Q

Cortical nephrons

A

Most of the kidneys nephrons are cortical nephrons (85%)

these are in the cortex region of the kidney except for a portion of the loop on Henle which extends into the medulla

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33
Q

juxtamedullary nephrons

A

the remaining nephrons that are not cortical nephrons, pass deeply into the medulla because of their location and their longer loops of henle

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34
Q

proximal convoluted tubule

A

first section of the renal tubule

is specialized to reabsorb water and many solutes from the glomerular filtrate into low pressure peritubular capillaries that surround the renal tubule as well as secrete unwanted substances

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35
Q

loop of henle

A

the second section of the renal tubule is the hairpin loop of henle

initially the loop of henle has the descending limb followed by the ascending

the descending limb allows water loss and the ascending limb allows salt loss (NaCl)

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36
Q

distal convoluted tubule

A

the last section of the Renal tubule

which allows for hormonally controlled reabsorption of water and solutes

mainly responsible for the secretion of unwanted substances

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37
Q

urine

A

the filtrate is considered urine once it reaches the renal pelvis

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38
Q

collecting ducts

A

urine passes from several tubules and then drains it the collecting ducts

many collecting ducts converge to form papillary ducts which drain into the calyces and subsequently into the renal pelvis and out the kidneys by way of the ureter

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39
Q

three types of capillary beds

A

glomerular capillaries, peritubular capillaries, and the vasa recta

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40
Q

glomerular capillaries

A

glomerulus - are highly coiled capillary beds formed from the afferent arteriole, leaving as the efferent capillaries

because of the porosity and high pressure in the glomerular capillaries, they are specialized for filtration as it forces fluid and solutes out of the blood and into the glomerulus (Bowman’s) capsule

about 99 percent of glomerular filtrate is reabsorbed through the renal tubule and returned to the blood in the peritubular capillary beds, which arise from the efferent tubules as they leave the glomerulus.

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41
Q

the peritubular capillaries

A

closely follow the renal tubules and drain into the interlobular vein

because of their porosity and low blood pressure- these are adapted for absorption reclaiming water and solutes from filtrate

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42
Q

vasa recta

A

third set of capillaries -which follow the loop of henle in the juxtamedullary nephrons of the medulla

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43
Q

micturition

A

urination also called micturition is the act of emptying the bladder

As urine accumulates the rugae flatten and the wall of the bladder thins and stretches allowing the bladder to store larger amounts of urine without significant rise is internal pressure

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44
Q

when does the urge to urinate start?

A

usually when urine has accumulated around 200 ml, causing distention of the bladder walls, which initiates the vicseral reflex arc

this causes the detrusor muscles to contract and the internal sphincter to relax, forcing stored urine through the internal sphincter into the upper part of the urethra.

a person can consciously resist their initial urge to urinate because the external urethra is voluntarily controlled

as the bladder continues to fill the urge becomes stronger

eventually if the amount of urine reached 100% of the bladders capacity, the voluntary sphincter opens and micturition happens involuntarily

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45
Q

incontinence

A

the inability to control micturition voluntarily

this is a normal condition in babies and later life with diagnosis such as end stage dementia

can also occur from emotional trauma, pregnancy, nervous system injuries such as stoke or spinal cord injury

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46
Q

urinary retention

A

the inability to expel stored urine

this is common condition after general anesthesia since the detrusor muscle is slow to regain muscular activity

male urinary retention can occur due to an overgrowth of the prostate gland which narrows the urethra, making micturition difficult

insertion of a rubber tube (catheter) tube in the urethra is necessary to allow urine to empty from the bladder

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47
Q

how many times do kidneys filter blood plasma a day?

A

The kidneys filter the entire blood plasma volume about 60 times a day and subsequently use 25% of the resting body energy to excrete waste from the body

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48
Q

filtrate quantities

A

47 gallons of glomerular filtrate containing water, essential ions, and nutrients are removed from the blood plasma daily

by the time filtrate enters the collecting ducts it contains about 0.5 gallons of urine, with the other 99% being returned to the blood

the filtrate loses most of its water, nutrients, and essential ions and contains mostly wastes

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49
Q

what are the three processes must occur for the body to filter all the blood and retain important elements

A

filtration -takes place in the glomerulus

reabsorption and secretion take place in the renal tubules so excretion can occur

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50
Q

glomerular filtration

A

filtration in the glomerulus takes place across a very porous membrane that lies between the capillaries and glomerular capsule

filtration at the glomerulus is mechanical and does not require energy

the filtration at the glomerulus depends on the opposing pressures exerted within the glomerular capsule and glomerulus capillary

all fluid pressures discussed are in units of mmHg

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51
Q

hydrostatic pressure (HP)

A

is the amount of pressure found inside the blood in the capillaries, driving fluid out of the capillaries

the hydrostatic pressure varies from person to person, depending on the blood pressure in the heart and
vessels

If blood pressure rises so does the hydrostatic pressure

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52
Q

colloid osmotic pressure (COP)

A

also called oncotic pressure is dependent on the amount of protein in the plasma

COP opposes Hydrostatic pressure (HP) by driving fluids back into the capillary beds, drawing water out of the filtrate

COP needs to remain in a normal range between 25-32 mmHg

damage occurs to the glomerulus if the COP goes outside of the normal range

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53
Q

capsular hydrostatic pressure

A

is the mechanical pressure exerted by the recoil of elasticity inside the glomerular arterioles

this pressure also opposes blood hydrostatic pressure (HP) and drives fluid back into the glomerular capillaries

54
Q

net filtration pressure (NFP)

A

is the difference in pressures between outgoing and incoming forces at the glomerulus

the NFP is the pressure with which the filtrate enters the convoluted tubule

55
Q

how do fluids and solutes move through the membranes?

A

fluids and solids (such as water, glucose, amino acids, and nitrogenous wastes) are forced out through the membrane by high hydrostatic pressure inside the glomerular capillary

the size of the fenestrations prevents passage of red blood cells and proteins from exiting the filter

total fluid loss inside the capillaries is prevented by the colliod osmotic pressure pressure of the glomerular blood.

the presence of proteins in the capillaries help to maintain the osmotic pressure of the glomerular blood

56
Q

glomerular filtration rate (GFR)

A

is the amount of blood filtered by the glomerulus over time

the normal GFR is 120-125 ml/min or 180 L/day due to the huge surface area of the glomerular capillaries, the large degree of filtration membrane permeability, and the moderate net filtration pressure

the GRF is increased by an increase in arterial (and therefore glomerular) blood pressure in the kidneys

57
Q

what decreases GFR?

A

The GRF is decreased by an increase glomerular osmotic pressure most often caused by dehydration

58
Q

why is important to maintain a relatively constant GFR?

A

it is important for adequate reabsorption of water and other needed substances from the filtrate and filtration of waste

if flow is too rapid, needed substances can not be adequately reabsorbed.

If flow is too slow, nearly all the filtrate is reabsorbed, including most of the waste that should be excreted

59
Q

three mechanisms that regulate renal flow and therefore regulate the GFR

A

renal autoregulation, nervous system control, and hormone control

60
Q

renal autoregulation

A

Under normal circumstances the GFR is controlled by the kidney itself - this is called renal autoregulaition

the kidney determines its own rate of blood flow by controlling the diameter of the afferent and efferent arterioles

by means of the renal autoregulaiton, the kidney can maintain a constant GFR despite variations in the arterial blood pressure in the rest of the body

61
Q

when is the renal autoregulations suspended

A

in times of emergency it becomes necessary to divert blood away from the kidneys to vital organs such as the heart, skeletal muscles, brain

during these times the renal autoregulatory system is suspended by higher nervous system controls.

when the nervous system takes over regulation the afferent arteriole diameter is narrowed by sympathetic nerve fibers

62
Q

epinephrine

A

the release of epinephrine by the adrenal medulla (in the adrenal glands) causes a decrease in blood flow and decreases the GRF

constriction of the renal arteries is only to be used for a short time

if the nervous system continues to constrict blood flow to the kidney for long periods of time, kidney damage occurs because of the decreased blood supply to the cells and kidneys

63
Q

renin angiotensin aldosterone system (RAA)

A

a hormone control mechanism also controls the renal flow and GRF

the RAA system responds when blood pressure drops too low

64
Q

angiotensinogen

A

is a pre-enzyme produced by the liver and freely circulates in the blood

65
Q

renin

A

when blood pressure drops too low, renin is released by the juxtaglomerular (JG) cells of the nephron

renin causes constriction of the afferent and efferent arterioles

in addition renin converts angiotensinogen to angiotensin I

66
Q

angiotensin II

A

In the lungs angiotensin 1 is converted to angiotensin II which triggers the thirst mechanism in the hypothalamus to cause a person to feel thirsty

drinking water helps increase blood volume and therefore blood pressure

angiotensin II also acts to constrict the body’s blood vessels (vasoconstriction) to increase peripheral blood pressure

once angiotensin II reaches the adrenal cortex it causes the release of aldosterone

67
Q

aldosterone

A

aldosterone causes the renal tubules in the nephron to reabsorb more sodium ions, increasing water retention

The RAA system helps reabsorption of more water and sodium from the filtrate

68
Q

reabsorption

A

most of the contents of glomerular filtrate that enter the renal tubules get reabsorbed back into the blood by the peritubular capillaries.

the process of fluid and substances moving from the filtrate back to blood is called reabsorption

69
Q

what would happen if reabsorption does not occur?

A

the entire plasma would be drained away as urine within an hour

70
Q

tubular reabsorption process

A

the tubular reabsorption process occurs by the reabsorbed substances moving through the membrane barriers of the tubules to reach the peritubular capillary blood

reabsorption of water and ions are hormonally regulated and may be passive or active

diffusion is the passive process and active means that the pumps are ATP-driven, requiring energy expenditure

71
Q

proximal convoluted tube (PCT)

A

the greatest amount of renal tubular reabsorption occurs in the cells of the PCT.

all glucose and amino acids are actively reabsorbed in the PCT in addition to most water and other ions

65 % Na+
65% water
90% bicarbonate
50% chloride
50% of potassium K+
along with most of the calcium
most of the phosphate
most of the magnesium

are reclaimed in the filtrate

72
Q

Loop of henle reabsorption

A

the ascending and descending limb portions of the loop have different characteristics

Water can leave the descending limb but not the ascending limb

Na+ and K+ can leave the ascending limb but the not the descending limb

in the loop of henle another 25% Na +, 15% water, and 40% K+is reabsorbed by the peritubular capillaries to return the ions to the blood circulation

73
Q

hormonal control that regulate the kidney

A

they regulate the kidneys ability to form dilute and concentrated urine via controls over channels placed in various places along the nephron

74
Q

reabsorption after the PCT, and Loop of henle in the Distal convoluted tube

A

10% of Na+ and Cl-
20% of water
remain in the filtrate once it reaches the DCT

hormonally regulated reabsorption can reclaim nearly all the water and Na+ if necessary

abnormal blood pressure, low blood volume, low Na+ concentration or high K+ concentration in the extracellular fluid are all conditions that can be controlled through ion channels in placed in the DCT and the collecting ducts

75
Q

secretion

A

certain substances present in the peritubular capillaries need to be removed through tubular secretion

secretion involves substances entering the filtrate from the surrounding fluid, allowing for the elimination of undesirable substances such as urea

the body also increases the concentration of filtrate and rids itself of extra K+, and drugs such as penicillin

secretion of bicarbonate (HCO3-) and H+controls blood pH

76
Q

the composition of urine that is excreted

A

is a combined process of glomerular filtration, tubular filtration, and tubular secretion

77
Q

homeostasis

A

urine concentration and volume is altered by the kidneys to maintain homeostasis, or equilibrium state of the total solute concentration of body fluids

the blood vessels (vasa recta and peritubular capillaries and the filtrate through the loop of henle accomplish this through countercurrent flow

78
Q

countercurrent flow

A

is the movement of the fluids in the opposite directions through opposite channels

in the nephrons, filtrate flows in one direction through the renal tubules while blood in the adjacent blood vessels flow in the opposite direction

this helps the kidneys maintain an osmotic gradient from the renal cortex to medulla

79
Q

osmatic gradient

A

refers to the concentration of solutes inside a solution measured in mOsm/L

80
Q

isomotic

A

when the fluid outside and inside have the same have the same osmotic concentrations

81
Q

urea

A

is a substance converted from ammonia to be excreted in urine

urea also contributes to high osmolarity of the deep medullary area

concentration of urea is high in the DCT and cortex regions of collecting ducts because the tubules in the cortex are impermeable to it

Medullary ducts are highly permeable to urea so it diffuses out of the ducts and into the medullary interstitial fluid

in the medulla it causes high osmolarity until its concentration inside and outside the ducts are equal

82
Q

Antidiuretic Hormone (ADH)

A

a hormone produced by the hypothalamus and stored in the posterior pituitary.

It inhibits urine output

The release of ADH is tied to the degree of hydration, allowing the body to respond to dehydration

83
Q

dehydration

A

many factors lead to dehydration, excessive water loss, such as vomiting, diarrhea, sweating

84
Q

ADH and hemorrhage

A

it also responds to life threatening circumstances like hemorrhage (blood loss) - a severe hemorrhage causes large amount of blood loss and severe drop in blood pressure.

ADH responds by retaining up to 99% of water in filtrate. Kidneys excrete a small amount of concentrated urine

when ADH is released the osmolarity of the filtrate can be concentrated as much as 1200 mOsm/L

when no ADH is released dilute urine is excreted which can be as low as 65 mOsm/L

85
Q

Aldosterone

A

a hormone secreted by the adrenal cortex under control of the RAA system

It acts to place several types of ion channels inside the cells of collecting ducts

86
Q

Aldosterone and sodium-hydrogen ion pump

A

Aldosterone increases Na+ reabsorption through the excretion of H+ ions

sodium ions are pumped out of the filtrate and H+ ions are pumped inside for excretion

**because water follows salt, Na+ reabsorption also causes water reabsorption

87
Q

Aldosterone and sodium-potassium pumps

A

this is to increase potassium secretion through the sodium-potassium pump

Na+ is pumped out of the filtrate and returned to the blood while potassium (K+) is excreted in urine

88
Q

what is the overall goal of aldosterone?

A

To increase the blood volume and therefore the blood pressure when needed

aldosterone release can occur directly (without stimulation from RAA) in response to high K+ levels or low Na+ levels in the extracellular component

however normal triggers from the RAA system are from the CNS, decreased renal filtrate, decreased osmotic pressure, or decreased blood pressure

this aldersterone control system is slow acting, requiring hours to days to take effect

89
Q

diuretic

A

are substances that act on the nephrons to increase urinary output

most diuretic drugs decrease Na+ reabsorption, therefore less water is being reabsorbed from the filtrate

90
Q

types of diuretics

A

caffeine- is a diuretic that causes renal tubules to increase in diameter, increasing the amount of flow through the tubules

alcohol is another diuretic that inhibits the release of ADH

other diuretics act on different parts of the nephron to cause a greater flow of urine

when filtrate moves at a faster rate through the nephron, it allows for less time for ions to be removed from the filtrate

91
Q

cardiovascular baroreceptors

A

also exert control over the nephron to regulate blood volume

these are found in the aortic arch and carotid sinus arteries under the control of the vagus and glossopharyngeal cranial nerves.

these are mechanoreceptors that detect stretch inside the vessels

the two nerves relay info to the medulla, which monitors blood volume to maintain blood pressure

92
Q

urochrome

A

the yellow color of urine is caused by urochrom, the principle pigment in urine derived from the metabolic breakdown of hemoglobin

normal urine is pale to deep yellow and clear

93
Q

Abnormal colors of urine

A

may result from drugs, food (such as beets or rhubarb), the presence of bile or blood in the urine

94
Q

cloudiness in urine

A

due to the presence of pus and may indicate a UTI

pus is the presence of dead white blood cells indicating a recent or current infection in the urinary system

95
Q

odor of urine

A

it is slightly aromatic but develops a stinging ammonia oder upon standing because of bacterial breakdown of the urea

asparagus and some drugs cause abnormal odors as do some diseases like diabetes, which imparts a fruity smell due to acetone formed

96
Q

pH of urine

A

a normal range is 4.5-8

a diet high in citrus, vegetables, or dairy cause higher (basic pH).

a diet high in protein causes lower acidic pH

97
Q

urine density

A

urine has a higher density than water (1.00) since it contains dissolved solutes with its normal density range between 1.003- 1.035 depending on whether it is dilute or concentrated

98
Q

urine composition

A

urine contains 95% water, with about 5% solutes of varying amounts

urea is the most abundant solute at 2%

urea is a nitrogenous waste found in urine, which also include uric acid, creatine, and ammonia

other solutes include sodium, potassium, phosphate, sulfate calcium, magnesium, chloride, and bicarbonate ions

99
Q

abnormal things in urine

A

abnormal substances in urine include glucose, blood proteins, red blood cells, hemoglobin, white blood cells, bile pigments

100
Q

urine volume

A

on average 1.4 Liters for an adult a day

101
Q

intercellular fluid and extracellular fluid

A

intercellular is the fluid inside the cell

extracellular is the fluid outside the cell

water is found in two main components -intercellular and extracellular

intercellular fluid accounts for 60 percent of fluid in the body ) -in a 150 pound adult male this is around 25 L

extracellular fluid accounts for 40 percent of fluid in the body (about 15 L in a 150 pound adult male)

102
Q

two parts of extracellular fluid

A

plasma and interstitial fluid

plasma is the fluid portion of the blood that contains about 3 L (8% of total body water)

interstitial fluid is the fluid in the microscopic spaces between cells that contains about 12 L (32% of total water in the body)

103
Q

acid-base pH

A

refers to the balance of concentration of Hydrogen ions (H+ in the blood)

104
Q

pH scale

A

pH scale ranges from 1-14

a pH of 0 is the most acidic, 7 is neutral, and 14 is the most alkaline (basic)

higher concentration of H+ means more acidic - when strong acids dissolve in water they produce H+ ions making the solution more acidic and lowering pH

a lower concentration of H+ means the solution is more basic. when bases dissolve in water. OH- is produced, which combines with H+. the combo of OH- and H+ removes the H+ ions so they are no longer active becoming more alkaline (basic and raising pH)

105
Q

enzymes

A

maintaining a constant pH is particularly important for enzymes, specialized proteins that control the rate of metabolic reactions

all proteins need a narrow range of pH in the fluid which they function.

normal pH is 7.35-7.45

106
Q

alkalosis

A

if arterial blood pH rises above 7.45, the condition is called alkalosis because the pH is more alkaline than normal (basic)

107
Q

acidosis

A

if the arterial blood pH drops below 7.35 this is called acidosis because it more acidic than normal

venous blood and interstitial fluid have lower (more acid) pH because of the acidic materials produced by cellular metabolism

108
Q

cellular metabolism

A

chemical reactions inside the cell to maintain life is the principle method through which acids enter the human body.

the blood acidity (pH) is controlled by three main methods: chemical buffer systems, the brain stem respiratory center, and the renal system

109
Q

anion

A

negatively charged ion

an example is bicarbonate ion (HCO3-)

110
Q

cation

A

is a positively charged ion such as ammonium (NH4+)

111
Q

Chemical acid base buffers

A

are composed of combinations of weak acid and its anion or a weak base and its cation

these pairs act to minimize pH changes since the one substance of the pair (weak acid anion or weak basic) reacts with free H+ in the acid to bind it.

this prevents the substance from lowering the pH

the other substance ( weak acid or weak base cation) reacts with the OH- to bind it, preventing a rise in pH

112
Q

three main chemical buffers systems in the body

A

these are fast acting, generally responding in seconds

bicarbonate system acts as the main buffer for plasma fluids and interstitial fluids

phosphate system acts as one of the buffers in the urine and intercellular fluid

protein system acts as the main buffer on intercellular fluid

they act within seconds to minimize changes in pH by binding free H+ or free OH-

113
Q

bicarbonate system

A

is composed of weak carbonic acid (H2CO3) and bicarbonate (HCO3-)

114
Q

phospate system

A

is composed of the weak acid (H2PO4- ) and mono hydrogen phosphate (HPO4 2-)

115
Q

protein system

A

provides three times the buffering capacity of all the systems combined due to substantial concentration of proteins in the cells

the protein buffer includes amino acids, hemoglobin, and plasma proteins

116
Q

respiratory center

A

CO2 is removed from the blood and O2 is added to the blood under the control of the respiratory center

117
Q

chemoreceptors

A

the respiratory center has chemoreceptors in the medulla (of the brainstem that monitor the level of CO2 in the blood

118
Q

carbonic acid

A

CO2 reacts reversibly with water to form carbonic acid

carbonic acid dissociates when dissolved in water to form H+ and bicarbonate ions in a series of equilibrium reactions

bicarbonate is the form in which carbon dioxide is transported in the blood plasma

these reactions are carefully regulated by the respiratory center to maintain blood pH

119
Q

respiratory rate control

A

the brainstem controls the respiratory rate to increase or decrease depending on the levels of CO2 and therefore pH detected in the blood

the normal range of CO2 is between 35-45 mm

120
Q

hyperventilation

A

If blood pH begins to fall (becoming more acidic), the respiratory center is excited causing hyperventilation

this is an increase in respiratory rate, helping to remove additional CO2

within minutes increasing amounts of CO2 is removed, which pushes reaction 1 to the left

removing CO2 uses up H+ causes the pH to rise (become more alkaline and restores correct blood pH

121
Q

reaction 1

A

CO2 + H2O <—> H2CO3 <–>H+ +HCO3-

122
Q

hypoventilation

A

if blood pH begins to rise (become more alkaline), the respiratory center is depressed causing hypoventilation

during hypoventilation, the respiratory rate slows down, allowing more CO2 to accumulate

reaction 1 shifts to the right forming more H+ ions. The pH falls becoming more acidic and restores the correct blood pH

123
Q

respiratory center malfunctions

A

these lead to pH imbalances called respiratory acidosis (due to CO2 retention) or respiratory alkalosis (due to CO2 or removal)

124
Q

Weak acids

A

do not significantly contribute to the pH

H+ is tightly bound and cannot dissociate to become free H+

ex. carbonic acid

125
Q

renal control mechanisms

A

only the kidneys can remove (rather than just bind) acids and bases from the body

the renal control is much slower acting compared to the respiratory system (1-3 mins), and chemical buffers (less than 1 min) taking hours or days to take effect

however the renal control has a larger impact on the pH level

this is a major system used to manage acid-base imbalances caused by daily metabolic processes or abnormal disease conditions

126
Q

what is the major renal control mechanism

A

the major renal acid-base regulating process is by way of excreting or reabsorbing the bicarbonate ion

this acid-base balance by the renal mechanism depends on H+ ion secretion and the conversion of bicarbonate.

H+ secretion through the renal filtrate is in response to the pH of extracellular fluid

127
Q

what allows for secretion and reabsorption

A

the renal peritubular capillaries are tiny blood vessels that travel alongside the nephrons allow for secretion and reabsorption between blood and the nephron

128
Q

conservation of bicarbonate

A

another important pH regulating mechanism is the conservation of bicarbonate, the most important anion responsible for chemical buffering of the extracellular compartment

bicarbonate can be replenished in the plasma by reclaiming it from the renal filtrate

129
Q

How does the blood react to alkalosis with bicarbonate?

A

during alkalosis, renal collecting duct intercalated cells can secrete bicarbonate while simultaneously recovering H+ to lower the pH of blood

130
Q

respiratory or metabolic disorders

A

disorders are classified as respiratory or metabolic depending on whether they cause lower CO2 pressure (respiratory) or other cellular process in the body (metabolic)

131
Q

acidosis

A

disorders of body’s acid base balance systems cause acidosis ( pH less then 7.35)

in severe acidosis, the blood pH drops below 7.0, and the CNS is markedly depressed causing coma and imminent death

132
Q

alkalosis

A

blood pH more than 7.4

in severs alkalosis the blood pH rises above 7.8, and the CNS is markedly excited causing extreme nervousness, muscle contraction, convulsion, and death due to cessation of breathing

133
Q

respiratory acidosis

A

is characterized by lower pH because of higher pressure of CO2 (PCO2 > 45mm)

respiratory acidosis is caused by shallow breathing or limited gas exchange

diseases such as cystic fibrosis, pneumonia, emphysema limit gas exchange increasing CO2 in the blood

134
Q

respiratory alkalosis

A

is characterized by higher pH because of lower CO2 pressure (PCO2 <35mm)

this is almost always caused by hyperventilation (over breathing such as in the case of a panic attack

135
Q

renal compensation

A

respiratory acidosis or respiratory alkalosis causes the renal system to attempt to correct the disorder

136
Q

metabolic acidosis

A

is characterized by lower pH (with normal CO2 levels) because of lower HCO3- concentration (bicarbonate)

this is caused by a buildup of acidic metabolic products like acetic acid (from alcohol overdose), lactic acid (byproduct of muscular contractions when exercising), diabetic ketosis, or extreme diarrhea

137
Q

metabolic alkalosis

A

is characterized by higher pH (with normal CO2 levels) because of higher HCO3- concentration.

this is caused by vomiting (loss of acidic stomach contents, intake of excess antacids, and constipation (which is caused by abnormal absorption of HCO3-)

the respiratory system works to correct metabolic alkalosis and metabolic acidosis with renal compensation

138
Q

normal blood serum levels

A

normal pH - 7.35-7.45
normal PCO2 = 35-45 mm
normal HCO3- = 22-26 mEq/L

Anatomy and physiology (15 decks)

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