Lecture Exam 2 Study Guide Flashcards
(112 cards)
1
Q
Function of sodium in the body
A
- nerve function
- osmotically controls water
- maintains blood volume
2
Q
Function of potassium in the body
A
- nerve function
- cotransport of hydrogen
- pH homeostasis
3
Q
Function of chloride in the body
A
- form HCl
- break down foods in the stomach
4
Q
Function of calcium in the body
A
muscle contraction and nerve conduction
5
Q
Function of phosphorus in the body
A
building block of DNA, RNA, and ATP
6
Q
Function of magnesium in the body
A
helps enzymes to function properly (acts as a cofactor)
7
Q
Function of iron in the body
A
binds oxygen on hemoglobin/oxygen transport
8
Q
Function of zinc in the body
A
- required for DNA, protein synthesis, and mitosis
- growth of several leukocytes
9
Q
Function of vitamin A in the body
A
part of photoreceptors (retinol) - vision, maintain epithelium
10
Q
Function of vitamin C in the body
A
protein, collagen, and hemoglobin synthesis
11
Q
Function of vitamin D in the body
A
calcium absorption
12
Q
Function of vitamin E in the body
A
antioxidant
13
Q
Function of vitamin K in the body
A
blood clotting
14
Q
Function of vitamin B1 in the body
A
- carbohydrate metabolism
- acetyl coa transfer
15
Q
Function of folic acid in the body
A
- RBC production
- neural tube development
- breaks down harmful amino acids
16
Q
What is thermoregulation and what is its role in metabolism?
A
- balance between heat production and loss
- enzymes used for metabolism need a stable environment to function properly
17
Q
Mechanisms that increase body temperature
A
- cutaneous vasoconstriction: blood vessels tighten to reduce blood flow; keeps core warmer
- shivering thermogenesis: shivering
- nonshivering thermogenesis: body increases metabolism to warm up
- behavioral thermoregulation: making a conscious decision to get warmer
18
Q
Function of the kidneys
A
- fliters blood and removes waste
- regulate blood volume, pressure, and osmolarity
- controls electrolyte and acid-base balance
- secretes hormones
19
Q
Function of the ureters
A
transport urine from the renal pelvis to the urinary bladder
20
Q
Function of the urinary bladder
A
storage tank for urine
21
Q
Function of the urethra
A
channel where urine exits the body
22
Q
Function of the of the urinary system
A
- fliters blood and removes waste
- regulate blood volume, pressure, and osmolarity
- controls electrolyte and acid-base balance
- secretes hormones
- supports blood glucose levels
23
Q
Describe the blood supply to the kidney
A
- blood enters the renal artery
- renal artery divides into segmental arteries
- interlobar arteries pass through the renal columns
- arcuate arteries arch along the base of the renal pyramids
- cortical radiate arteries radiate outward into the cortex
- afferent arterioles supply blood to the glomerulus
- filtration occurs in the glomerulus
- blood exits the glomerulus via the efferent arterioles
- peritubular capillaries surround the tubules for reabsorption and secretion
24
Q
Describe the blood supply from the kidney
A
- blood from the peritubular capillaries or vasa recta flow into the cortical radiate veins
- follows through the arcuate veins
- through the interlobar veins that pass through the renal pyramids
- blood exits the kidney via the renal vein and enters the inferior vena cava
25
What are nephrons?
functional units of the kidney
26
What are the two components of nephrons?
- renal corpuscle: filters blood plasma
- renal tubule: converts filtrate into urine
27
Describe the renal corpuscle (glomerular capsule)
- glomerulus: ball of capillaries where blood is filtered
- glomerular capsule (bowmans capsule): surrounds the glomerulus and collects the filtrate
28
What are the layers of the glomerular capsule
- visceral layer: podocytes
- parietal layer: simple squamous
29
What are the 3 sections of the renal tubule?
- proximal convoluted tubule (PCT)
- nephron loop
- distal covoluted tubule (DCT)
30
Describe the 3 sections of the renal tubule
proximal convoluted tubule:
- first and longest segment
- reabsorbs 65% of the glomerular filtrate
- simple cuboidal
nephron loop:
- u-shaped structure
- maintains osmotic gradient in the medulla
- simple cuboidal in thick part for active transport; simple squamous in thin part for water diffusion
distal convoluted tubule:
- shorter, less coiled tubule
- further adjusts filtrate composition under hormonal control
- simple cuboidal
31
Describe the flow of urine from the collecting duct to release from the body
- urine flows from the **collecting ducts** into the **papillary ducts**
- these ducts empty into the **minor calyces** and then into the **major calyces**
- urine flows from the major calyces into the **renal pelvis**
- **ureter** transports urine to the **urinary bladder** and is stored until urination occurs
- during urination, urine flows from the bladder through the **urethra** to the outside of the body
32
What is the juxtaglomerular complex?
- structure in the kidney that helps regulate blood pressure and filtration rate
- consists of macula densa, mesangial cells, juxtaglomerular cells
33
What is the collecting system and what does it do?
final part of the nephron that:
- receives tubular fluid via the collecting ducts
- reabsorbs water as it passes through the medulla
- recycles urea in the medulla
- ADH regulates water permeability in the collecting duct
34
What are the two types of nephrons?
- cortical nephrons
- juxtamedullary nephrons
35
How are two nephron types different?
cotrical nephrons:
- barely dips into the medulla
- involved in filtration and reabsorption
juxtamedullary nephrons:
- extend deep into the medulla
- maintains osmotic gradient and concentrates urine
36
Define filtration
filtering of water and small solutes from the blood
37
Define reabsorption
renal tubules reabsorb water and solutes from the tubular fluid and return them to blood
38
Define secretion
renal tubules pull chemicals from the capillary blood and secretes them into the tubular fluid
39
Components that stay in the blood during glomerular filtration
- blood cells
- plasma proteins
- large anions
- protein-bound minerals and hormones
40
Components that leave the blood during glomerular filtration
- water
- urea
- electrolytes
- glucose
- amino acids
- fatty acids
- vitamins
- uric acid
- creatinine
41
Describe the layers that filtrates need to pass through during glomerular filtration
fenestrated endothelium:
- endothelial cells are honeycombed with large pores
basement membrane:
- contains a proteoglycan gel that prevent large solutes to reach the other side
filtration slits:
- contain tiny slits that only allow for extremely small solutes to pass through
42
What pressure pushes the filtrate out of the blood during glomerular filtration
blood hydrostatic pressure (BHP)
43
What is glomerular filtration rate (GFR)?
amount of filtrate formed per minute by both kidneys
typical values:
- male: ~ 125 mL/min
- female: ~ 105 mL/min
44
Describe the two autoregulatory mechanisms that kick in when GFR is too low
myogenic mechanism: constriction or dilation of the arteries or arterioles
tubuloglomerular feedback: macula densa detects increased NaCl and results in constriction of the afferent arterioles which causes GFR to decrease
45
Describe podocytes and how they impact the glomerulas
- octopus-shaped cell in the visceral layer of the glomerular capsule
- forms the filtration membrane
- prevents protein loss
- regulates filtration
46
What neural and endocrine mechanisms control GFR?
neural control:
- sympathetic nervous system: constricts afferent arterioles, reducing GFR and urine output
endocrine control:
- renin-angiotensin-aldosterone mechanism: low BP stimulates renin release, which produces angiotensin II, which constricts efferent arterioles and stimulates aldosterone secretion
- natriuretic peptide: secreted by the heart due to high BP which dilates afferent arterioles, constrict efferent arterioles, and inhibit ADH and aldosterone secretion, increasing GFR
47
Function of macular densa
- sensory cells that secretes ATP when GFR is too high
- ATP is converted into adenosine
48
Function of justaglomerulus (granular) cells
- responds to adenosine by constricting the arteriole, reducing blood flow into the glomerulus and lowering GFR
- contains renin that is secreted in response to low BP
49
Renin angiotensin aldosterone pathway
- drop in BP stimulates kidney to release **renin**
- renin converts **angiotensinogen** to **angiotensin I**
- **angiotensin-converting enzyme (ACE)** in the lungs converts **angiotensin I** to **angiotensin II**
- this signals the **hypothalamus** in the brain to increase thirst and drinking; blood vessels to constrict, and the **adrenal cortex** to secrete **aldosterone**
- aldosterone signals the kidney to reabsorb more sodium and water
- all of these increase BP
50
Where does most of the reabsorption happen?
proximal convoluted tubule
51
Which parts of the nephron allow for reabsorption and why?
- proximal convoluted tubule: reabsorbs ~65% due to its length, microvilli, and abundant mitochondria
- nephron loop: reabsorbs ~25% Na+, K+, and Cl-, and 15% of water to maintain osmotic gradient
52
Function of the distal convoluted tubules (DCT)
- reabsorption
- hormonal regulation: aldosterone, ADH, PTH, natriuretic peptides
- secretes potassium and hydrogen ions
- maintains acid-base balance
53
Function of collecting ducts
conserve water and concentrate urine
54
Role of ADH on the DCT and collecting duct
add aquaporin for increased water reabsorption
55
Role of aldosterone on the DCT and collecting duct
stimulates sodium reabsorption and potassium secretion for both
56
Role of angiotensin II on the DCT and collecting duct
stimulates aldosterone secretion, indirectly promoting sodium and water absorption for both
57
Role of parathyroid hormone on the DCT and collecting duct
increases calcium reabsorption
58
Role of natriuretic peptides on the DCT and collecting duct
DCT: dilates afferent arterioles and constrict efferent arterioles, which increases GFR
Collecting duct: inhibit sodium reabsorption leading to increased urine volume and decreased BP
59
What is the transport maximum?
maximum rate of reabsorption that can occur for a given solute
60
Describe the different ways that materials can be transported in and out of the tubules
- transcellular route: substances pass through the cytoplasm and out the base of the epithelial cells
- paracellular route: substances pass through gaps between the cells
- active transport: requires ATP to move substances against their concentration gradient
- passive transport: doesn't require energy and moves substances down their concentration gradient
- osmosis: water moves across the membrane from an area of low solute concentration to an area of high solute concentration
61
Describe important dynamics of carrier proteins
- saturation: once all carrier proteins are occupied, the system can no longer be more saturated; transport maximum
- specificity: each carrier protein is designed to bind and transport a specific substance
- competition: transport rate may be reduced if two substances are fighting for the same carrier protein
- regulation: activity can be regulated by hormones and other factors
62
What are the peritubular capillaries and vasa recta?
peritubular capillaries:
- surrounds the proximal and distal convoluted
tubules
- reabsorbs water and solutes from the tubular fluid and secretes substances into the tubular fluid
vasa recta:
- long, straight capillaries that dip down into the medulla alongside the nephron loops
- helps maintain the osmotic gradient in the medulla
63
Function of the proximal convoluted tubule (PCT)
reabsorbs 65% of the filtrate
64
What materials are transported in the PCT and where are they transported?
reabsorbs water, sodium, chloride, glucose, amino acids, and urea and transports them into the peritubular capillaries
65
Pathway of reabsorbed materials
- materials in the **tubular fluid** are reabsorbed in the **PCT, nephron loop, DCT, or collecting duct**
- passes through the apical membrane of the **tubule cells**
- enters the **interstitial fluid** surrounding the tubules
- taken up by the **peritubular capillaries** in the cortex OR the **vasa recta** in the medulla
- peritubular capillaries and vasa recta drain into the **venous system** eventually leading to the **renal vein** and **inferior vena cava**
66
What types of things are secreted back into urine? Why and how?
- hydrogen ions: regulates blood pH
- potassium ions: maintains electrolyte balance
- urea: increase its concentration in the urine
- uric acid: eliminate it from the body
- creatinine: ensure its complete excretion
67
Main function of the nephron loop
establish and maintain an osmotic gradient in the renal medulla
68
What materials are transported in the nephron loop and where are they transported?
transports water, sodium, potassium, and chloride out of the tubule into the medullary interstitial fluid
69
What process occurs in the descending limb?
water reabsorption
70
What process occurs in the ascending limb?
solute reabsorption
71
What is countercurrent multiplication and why is it important?
- mechanism that creates the osmotic gradient in the renal medulla
- essential for concentrating urine and conserving water
72
What is countercurrent exchange and why is it important?
- mechanism that preserves the osmotic gradient in the renal medulla
- allows the vasa recta to remove water from the medulla without washing away the high solute concentration
73
What causes a large volume of dilute urine to be released?
when the body needs to get rid of excess water due to high fluid intake, low ADH levels, diuretics
74
What causes a small volume of concentrated urine to be released?
when the body needs to conserve water due to dehydration, high ADH levels, low GFR
75
Describe the flow of filtrate from glomerulus to collecting duct
- filtrate enters the **glomerular capsule**
- reabsorption and secretion occurs in the **PCT**
- filtrate flows through the descending and ascending limbs of the **nephron loop**
- **DCT** fine tunes the filtrate composition
- filtrate now flows through the **collecting duct**, where water reabsorption occurs, concentrating the urine
76
What is secreted and absorbed from the nephron loop?
- reabsorbs water, sodium, chloride
- urea
77
What is secreted and absorbed from the PCT?
- absorbs Na+, water, glucose
- secretes H+ and drugs
78
What is secreted and absorbed from the DCT?
- absorbs Na+, Ca2+
- secretes K+, H+
79
What is secreted and absorbed from the collecting duct?
- absorbs water and urea
- secretes K+ and H+
80
Describe the pH of urine
typically 6.0 but can range from 4.5-8.2
81
Describe the color of urine
varies from colorless to deep amber depending on hydration
82
Describe the clarity of urine
normally clear but can turn cloudy due to bacterial growth
83
What shouldn't be found in urine in high amounts or at all? What causes them to be released?
- glucose: diabetes mellitus
- blood: kidney damage, infection, stones, or trauma
- proteins: kidney damage, glomeruluar disease, or strenuous exercise
- ketones: starvation, uncontrolled diabetes or a high-fat diet
- bile pigments: liver disease or obsutrction of the bile ducts
84
What is urinalysis and why is it useful?
- examination of the physical and chemical properties of urine
- provides information about metabolic disorders, infections, overall health, and kidney damage, infection, or disease
85
Why is creatine clearance useful?
- used to estimate GFR
- assesses kidney damage
- monitors kidney disease
86
Why is blood urea nitrogen (BUN) useful?
- assesses renal insufficiency or kidney damage
- detects dehydration
- tracks effectiveness of treatment for kidney disease
87
Describe the anatomy and physiology of the ureters
anatomy:
- retroperitoneal, muscular tubes
- 3 layers: adventitia, muscularis, mucosa
physiology:
- peristalsis occurs when urine enters the ureter
- flap of mucosa acts as a valve at the opening of each ureter preventing backflow
88
Describe the anatomy and physiology of the urinary bladder
anatomy:
- muscular sac on the pelvic cavity floor
- 4 layers: serosa, adventitia, muscularis, mucosa
- has a trigone
physiology:
- stores urine
- detrusor muscle contracts to expel urine and the internal urethral sphincter relaxes
- max capactiy of 700-800mL
89
Describe the urethra and how it is different in males and females
females:
- short
- solely for urine excretion
- external urethral sphincter for voluntary control
males:
- long
- passageway for urine and semen
- 3 regions: prostratic urethra, membranous urethra, spongy urethra
- internal urethral sphincter for involuntary control and external urethral sphincter for voluntary control
90
Describe the flow of urine from the collecting duct to release from the body
- urine flows from the collecting ducts into the **papillary ducts**
- these ducts empty into the **minor calyces** and then into the **major calyces**
- urine flows from the major calyces into the **renal pelvis**
- **ureter** transports urine to the **urinary bladder** and is stored until urination occurs
- during urination, urine flows from the bladder through the **urethra** to the outside of the body
91
What are the major differences between plasma and urine?
plasma:
- high protein content
- contains blood cells
- contains glucose and amino acids
urine:
- higher concentration of waste
92
Describe the urine voiding reflex
- bladder fills with urine and stretches
- **stretch receptors** send signals to the **sacral spinal cord** and to the **micturition center in the pons**
- **efferent signals** from the spinal cord stimulate the **detrusor muscle** to contract
- when ready to urinate, the pons sends signals to relax the **internal (in males) and/or external urethral sphincter**
- when **not** ready to urinate, the cerebrum sends signals that keep the external urethral sphincter contracted
93
Describe the urinary storage reflex
- sympathetic pathways originate in the upper lumbar spinal cord
- **postganglionic fibers** travel via the hypogastric nerve to the **detrusor muscle** causing it to relax and allow the bladder to fill
- in males, sympathetic fibers stimulate the **internal urethral sphincter** to contract to prevent leakage
- **somatic motor fibers** from the sacral spinal cord keep the **external urethral sphincter** constricted
94
Describe the urinary storage reflex
- sympathetic pathways originate in the upper lumbar spinal cord
- **postganglionic fibers** travel via the hypogastric nerve to the **detrusor muscle** causing it to relax and allow the bladder to fill
- in males, sympathetic fibers stimulate the **internal urethral sphincter** to contract to prevent leakage
- **somatic motor fibers** from the sacral spinal cord keep the **external urethral sphincter** constricted
95
Describe the urinary storage reflex
- sympathetic pathways originate in the upper lumbar spinal cord
- **postganglionic fibers** travel via the hypogastric nerve to the **detrusor muscle** causing it to relax and allow the bladder to fill
- in males, sympathetic fibers stimulate the **internal urethral sphincter** to contract to prevent leakage
- **somatic motor fibers** from the sacral spinal cord keep the **external urethral sphincter** constricted
96
What percentage of our body weight is water?
55-60%
varies with age and gender
97
What is the distribution of ECF and ICF?
ICF: 65%
ECF: 35%
98
What fluids are found in the ECF compartment?
- interstitial fluid: 25%
- blood plasma and lymph: 8%
- transcellular fluid: 2% (CSF, synovial fluid, serous fluid)
99
Explain how solutes and water flow between fluid compartments
osmotic gradient and hydrostatic pressure
100
Explain how fluid is gained in the body and the relative amounts of each
- drinking 1600mL
- food 700mL
- metabolic reaction (respiratory exclusive) 200mL
101
Explain how fluid is lost in the body and the relative amounts of each
- urine 1500 mL
- feces 200 mL
- sweat 100 mL
- insensible loss 600 mL
102
3 hormones that play a role in fluid regulation
- **ADH**: conserves water and reduces urine output
- **aldosterone**: promotes Na+ and water reabsorption
- **natriuretic peptides**: promotes Na+ and water reabsorption
103
How is fluid intake is regulated
osmoreceptors (hypothalamus) detect osmolarity which stimulates the thirst center which promotes fluid intake
104
How is fluid output regulated
- GFR
- hormones
- ANP/BNP (natriuretic peptides)
- sympathetic nervous system
105
Role of osmoreceptors in the hypothalamus
detects osmolarity levels
106
How is ADH involved
ADH is secreted when blood becomes viscous to make blood flow more smoothly
107
Describe volume depletion and give examples
- proportionate amounts of water and sodium are lost without replacement
- hemorrhage, severe burns, diarrhea
108
Describe dehydration and give examples
- loss of more water than sodium
- lack of drinking, diabetes mellitus, profuse sweating
109
Describe volume excess and give examples
- when both sodium and water are retained; excessive
- aldosterone hypersecretion, renal failure
110
Describe hypotonic hydration and give examples
111
Describe fluid fluid sequestration and give examples
112
Explain how removing water from the ECF will affect ECF osmolarity and ICF volume
