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Biology 20 AP > Ch. 9 - Excretion > Flashcards

Ch. 9 - Excretion Flashcards

1
Q

What is excretion?

A

The process by which the body seperates metabolic wastes from body fluids and eliminates them from the body.

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2
Q

The excretory system have four main “components/functions”. What are they?

A
  1. Lungs eliminate CO2 and H2O
  2. Skin excretes water, salts, and urea in perspiration
  3. Large intestine excretes water, salts, lipids, pigments, and other chemicals
  4. Kidney excrestes metabolic wastes that are dissolving or suspended in the blood
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3
Q

What are metabolic wastes? Examples and where does this come from?

A

Any substance produced by the body and present in excess of the body’s needs.
e.g. CO2, H2O, Na+, Cl-, H+ as well as nitrogenous (nitrogen containing) wastes like ammonia, urea, uric acid.
- Nitrogenous wastes result from protein metabolism
- The liver quickly converts highly toxic ammonia to urea (which is x1000 less toxic)
- Urea makes up majority of nitrogenous wastes in the body

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4
Q

The kidney performs 3 main functions. What are they?

A
  • Removal of wastes: mainly nitrogenous wastes produced by deamination (urea). Remove amine group (NH2) from proteins.
  • Balancing the pH of the blood.
  • Maintain water balance -> osmotic pressure
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5
Q

(Parts of the urinary system) What is the function of the adrenal gland?

A

Sits on top of kidney, produces hormones. (aldosterone which affects kidney, helps control balance of water and salts)

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6
Q

(Parts of the urinary system) What are the kidneys?

A

Two fist sized kidneys located in lower back, with the top half protected by the ribs.
Made of three regions, containing nephorns, which are the actual functional units of the kidney.

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7
Q

(Parts of the urinary system) What are the functions of the renal artery and the renal vein?

A
  • Blood vessels that carry blood from aorta to kidneys, and from kidneys back to inferior vena cava.
  • Capillaries found between the two are found in the glomerulus and in the nephron.
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8
Q

(Parts of the urinary system) What is the function of the ureters?

A

Each kidney releases urine into a 28cm ureter through which peristalsis moves urine into the urinary bladder.

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9
Q

(Parts of the urinary system) What is the function of the urinary bladder?

A

The muscular sack urinary bladder for storing urine until it is eliminated.

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10
Q

What is the function of the urethra?

A

Where urine is released from the bladder.

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11
Q

Urine release is controlled by two what? Explain.

A
  • An inner sphincter, which relaxes involuntarily when the brain sends a message that the bladder is full (@~200mL)
  • An outer sphincter, which is under voluntary and is relaxed during urination.

Normal: outer constricted, inner constricted
Filling: outer constricted, inner relaxed
Max: outer relaxed, inner relaxed

When we reach 400mL, we sense an incresased urgency, and at around 600mL we lose control.

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12
Q

Urine is released from the bladder through the __. How does this vary by gender?

A

Urethra.
In males, urethra is about 20cm long and merges with the vas deferens of the reproductive tract.
In females, about 4cm long and is located in front of and seperate from the reproductive tract.

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13
Q

What are the four main kidney structures?

A
  • Renal capsule
  • Renal cortex
  • Renal medulla
  • Renal pelvis
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14
Q

What does renal mean?

A

Relating to the kidneys.

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15
Q

What is the function of the renal capsule?

A

Provides a thin layer of protection for the outer layers of the kidney.

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16
Q

What is the function of the renal cortex?

A

Outer region of the kidney, that contains filtering mechanisms.

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17
Q

What is the function of the renal medulla?

A

Middle region which contains the long loops of the nephron and the collecting tubules where urine/water is gathered.

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18
Q

What is the function of the renal pelvis?

A

Funnel-like structure into which urine from the collecting ducts enters.

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19
Q

What are the functions of nephrons?

A

The actual filtering mechanisms in the kidney. Often coloured yellow.

They are embedded within the renal cortex and the medulla are have 1million microscopic nephrons which filter the blood, forming urine.

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20
Q

What is the renal artery’s job in relation to the nephron?

A

Supply nephrons with blood, which enters the kidney.

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21
Q

What is the renal vein’s job in relation to the nephron?

A

Blood vessels form a capillary network around the nephron.

Blood leaves the kidney via the renal vein.

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22
Q

What is the order (of structures) in which substances passing through the nephron go through?

A

The tubule begins with:
- Renal artery
- Afferent arteriole
- Glomerulus (capillary net)
- Bowman’s capsule
- Efferent arteriole
- Proximal convoluted tubule (capillary network begins)
- Descending limb of the loop of the Henle
(the bend)
- Ascending limb of the loop of the Henle (capillary network ends)
- Distal convoluted tubule
- Collecting duct OR renal vein

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23
Q

Urine is formed:

A

As a portion of the plasma. 1/5th is filtered from the blood vessels into the tubule.

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24
Q

Some substances are returned:

A

To the blood through the network of blood vessels, while the remainder stays in the tubule and leaves the body as urine.

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25
Q

What are the four basic processes involved with nephron function?

A
  1. Glomerular filtration (@Glomerulus)
  2. Tubular reabsorption (@Proximal Tubule)
  3. Tubular secretion (@Distal Tubule)
  4. Water reabsorption (@Loop of Henle & Collecting Duct)
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26
Q

What is glomerular filtration?

A
  • Blood pressure forces small molecules from the glomerulus into Bowman’s capsule.
  • Materials moved are water, glucose, amino acids, salts, and urea.
  • Larger cells, like proteins, WBCs, RBCs can’t fit through the glomerulus pores
  • Fluid that passes through is called FILTRATE (similar composition, at this point, to blood)
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27
Q

What is tubular reabsorption?

A
  • Diffusion and active transport return molecules to the blood at the proximal tubule.
  • Water moves by osmosis (diffusion of water from [high] to [low]
  • Glucose, amino acids, minerals, move by diffusion and active transport

HCO3, NaCl, H2O, Nutrients (like glucose, calcium), K out.
H, Ammonia in.

HCO3, H, vary by blood pH.

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28
Q

What is tubular secretion?

A
  • Active transport moves wastes from the blood to the distal tubule ([low] to [high] + ATP, nephron already has [high])
  • Hydrogen ions (H+) may be secreted to adjust blood pH
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29
Q

What is water reabsorption?

A
  • Water returns by osmosis following active reabsorption of salt.
  • Occurs along the length of the nephron, but notably at the loop of Henle and collecting duct
  • This prevents dehydration.
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30
Q

Secretion gets __. From __ to __.
Reabsorption gets __. From __ to__.

A

Secretion gets rid. From blood to nephron.
Reabsorption gets back. From nephron to blood.

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31
Q

What nutrients are transported between the capillaries and the proximal tubule? Using active transport or passive transport?

A

Into the nephron:
H+ (A) [if basic], Ammonia (P), Urea
Out of nephron:
HCO3- (P) [if acidic], H2O (P), K+ (P)
NaCl (A), Nutrients (like glucose, calcium, amino acids) (A)

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32
Q

What nutrients are transported between the capillaries and the descending loop of Henle? Using active transport or passive transport?

A

Out of nephron:
H2O (P)

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33
Q

What nutrients are transported between the capillaries and the ascending loop of Henle? Using active transport or passive transport?

A

Out of nephron:
Na (A)
Cl (P)
K (P)

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34
Q

What nutrients are transported between the capillaries and the distal tubule? Using active transport or passive transport?

A

Out of nephron:
NaCl (P/A), HCO3- (P) [if acidic]
H2O (P)

Into nephron:
K+ (A), H+ (A) [if normal/acidic], Drugs, Urea, Uric Acid, Ammonia

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35
Q

What nutrients are transported between the capillaries and the collecting duct? Using active transport or passive transport?

A

Out of nephron:
NaCl (A), Urea (P) (because of high concentration), H2O (P)

(In:
K+)

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36
Q

What is the salt concentration like as we go deeper into the kidney (such as the medulla)?

A

Increasing saltiness

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37
Q

How is urine reabsorbed and formed?

A

Urine from several tubules flows into collecting ducts. Urine is concentrated while water is reabsorbed due to the high NaCl concentration in the extracellular fluid.

99% of water is returned to the blood, and the urine drains from the collecting ducts into the renal pelvis (like a funnel). Leads into ureters, which carry urine into the urinary bladder.

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38
Q

In the context of glomerular filtration, what is the filtration structure at the top of each nephron? What is within each capsule?

A

A cap-like Bowman’s capsule.

Within each capsule is a renal artery that enters and splits into a fine network of capillaries called a glomerulus.

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39
Q

In the context of glomerular filtration, what do the walls of the glomerulus act as? What is a characteristic that allows of them that allows them to let in some things over others?

A

They act as a semi-permeable filtration device.

They are impermeable (don’t allow) to proteins, other large molecules, and red blood cells, so these remain in the blood.

40
Q

In the context of glomerular filtration, what happens to water, small molecules (like glucose), ions (Na+, Cl-, K+), and urea?

A

As the main waste products of metabolism, they pass through the walls and proceed further into the nephron.

41
Q

In the context of glomerular filtration, what is filtrate?

A

Filtrate is the filtered fluid that proceeds from the glomerulus into the Bowman’s capsule of the nephron.

42
Q

In the context of glomerular filtration, what factors contribute to filtration?

A
  1. Glomerular capillaries have many pores large enough to allow water and most dissolved substances in the blood to easily pass through by diffusion and osmosis. All while holding back blood cells, platelets, and proteins.
  2. High blood pressure as blood rushes into the glomerulus (4x higher than any other capillaries). It is right next to the aorta.
    - The filtered fluid in the Bowman’s capsule is called filtrate and contains glucose, Na+, Cl-, urea, ammonia, uric acid, water, and amino acids.
    - Glomerular filtrate is similar to blood plasma, in composition, except that it lacks proteins or blood cells.
    - Just forces a lot of the substances through.
43
Q

In the context of tubular absorption and secretion, how is the Bowman’s capsule connected?

A

The Bowman’s capsule is connected to a small long, narrow, tubule that’s twisted back on itself to form a loop. This long, hairpin loop is a reabsorption device.

44
Q

In the context of tubular absorption and secretion, what are the three sections of the tubule that the Bowman’s capsule is connected to?

A
  • Proximal tubule
  • Loop of Henle
  • Distal tubule
45
Q

In the context of tubular absorption and secretion, like the small intestine, the tubule that is connected to the Bowman’s capsule does what?

A

Absorbs (or reabsorbs) substances that are useful to the body (such as glucose and a variety of ions) from the filtrate passing through it.

Filtrate -> Nephron -> Tissues -> Blood

46
Q

In the context of tubular absorption and secretion, unlike the small intestine, the tubule that is connected to the Bowman’s capsule does what?

A

Also secretes substances into the tissues surrounding it.

Filtrate -> Nephron -> Tissues (Na+, Cl-)
Blood -> Nephron -> Filtrate (H+)

47
Q

In the context of tubular absorption and secretion, what are the three processes in the recovery of substances in the proximal tubule? Explain each and provide examples.

A
  1. Active Transport:
    Proximal tubule cells have many mitochondria which supply ATP to actively transport Sodium (Na+) ions, glucose, amino acids, and other solutes back into the blood.
  2. Passive Transport:
    Cl- ions passively follow the Na+ by charge attractions (opposites attract).
  3. Osmosis:
    Water follows the ions (NaCl, salt) and is reabsorbed into the blood. Trying to dilute the solute concentration of NaCl (make more isotonic).
48
Q

In the context of tubular absorption and secretion, what is the function of Henle?

A

Reabsorbs water and ions from the filtrate.

49
Q

In the context of tubular absorption and secretion, what are the three components of the Loop of Henle? Explain each.

A
  • Descending limb:
    As the limb goes deeper into the medulla region, it encounters an increasingly salty environment because of more active transport of NaCl here.
    As a result, water diffuses out of the limb and into the blood by osmosis.
  • The bend:
    Not permeable (move) to water. Na+ concentration in the filtrate is at its max and diffuses from the nephron into the blood.
  • Ascending limb: (impermeable to water, too)
    Na+ is actively transported from the nephron to the blood. This maintains a salty environment in the medulla for continued water reabsorption in other parts of the nephron. Other ions, like K+, too.

At this point, 2/3 of the Na+ and H2O from the filtrate is reabsorbed.
Animals in dry environments have long loops of Henle.

50
Q

In the context of tubular absorption and secretion, what is the role of the distal tubule?

A

Last opportunity. Active transport of Na+ into the renal cortex continues, and Cl- and water follow. Water substances are secreted from the blood to the distal tubule for elimination.

Tubular secretion.

51
Q

In the context of tubular absorption and secretion, within the distal tubule, what substances are secreted and not secreted?

A

a) H+ ions are secreted from the blood if it is acidic to maintain pH
b) Any urea, uric acid, and ammonia still in the blood
c) K+ ions are actively secreted
d) Penicillin and other drugs

52
Q

Where does the distal tubule empty?

A

Into a larger pipe-like channel called a collecting duct.

53
Q

In the context of the collecting duct, what does the collecting duct function as?

A

A water-conservation device reclaims water from the filtrate passing through it so that very little precious water is lost from the body.

Also collects urine from nephrons.

54
Q

In the context of the collecting duct, as the collecting duct extends into the medulla and into an increasingly salty (hypertonic) environment, what does this facilitate?

A

Hypertonic = [hiigher solute] to other

Water reabsorption by osmosis from filtrate back into the body.

55
Q

In the context of the collecting duct, what is the filtrate’s composition that remains in the collecting duct after filtering is done?

A

A suspension of water and various solutes and particles. It is now called urine. Its composition is distinctly different from the fluid that entered the Bowman’s capsule.

56
Q

In the context of the collecting duct, what are some examples of substances that diffuse out?

A

By active transport, is Na+
By passive transport, is Cl-.
By osmosis, is water.

(In is potassium ions)
(I guess urea if concentration is too high)

57
Q

In the context of the collecting duct, what happens when one is dehydrated?

A

Permeability to water increases through hormone control (ADH), and even more water is kept by the body, meaning even more concentrated urine.

58
Q

In the context of the collecting duct, how are the solutes and water reclaimed during reabsorption (as in what carries it back)?

A

They are returned to the body via the renal veins.

59
Q

What are the three homeostatic functions of the kidneys?

A
  • Water reabsorption (balance)
  • Salt reabsorption (blood pressure)
  • Maintaining blood pH
60
Q

What is a diuretic?

A

Something that causes an increased excretion of urine = more urine

61
Q

What is an antidiuretic?

A

Something that causes a decreased excretion of urine = less urine

62
Q

What does ADH (antidiuretic hormone) do? Where does it act on?

A

It helps to regulate high osmotic pressure in the blood (dehydration) by increasing permeability in the distal tubule and collecting duct, increasing water absorption in the kidneys. Fluid retention.

63
Q

Where is ADH produced?

A

In the hypothalamus of the brain and is stored in the pituitary gland just below it.

64
Q

What does the hypothalamus do?

A

Contains osmoreceptors (cells which are sensitive to osmotic pressure). Produces ADH.

65
Q

What will a diuretic cause? (3)

A
  1. Decreased ADH release
  2. Decreased water reabsorption
  3. Increase volume of urine
66
Q

What are examples of common diuretics?

A

Ethanol (alcohol) and caffeine (in coffee, tea, and many other carbonated drinks). These will actually intensify thirst and lead to dehydration.

67
Q

What does your body do when you are dehydrated (e.g. sweating during exercise)?

A

Blood plasma becomes too concentrated, osmotic pressure increases, and as a result:
1. Hypothalamus shrinks as water moves into the blood (we have a sensation of thirst).
2. Osmoreceptors in the hypothalamus then send an impulse to the pituitary gland.
3. ADH is released from the pituitary gland and travels to the kidney (through the blood).
4. ADH causes increased permeability of the distal tubule and collecting duct in the nephron
5. Result: more water is reabsorbed into the blood
6. Blood is more dilute and osmotic pressure decreases. A negative feedback: as blood’s more dilute, osmotic pressure decreases, fluid goes back into the hypothalamus, and ADH release decreases.

68
Q

What is osmotic pressure?

A

Osmotic pressure is the pressure created via the passage of water through a membrane.

What does high osmotic pressure mean? Dehydrated.

69
Q

How do the kidneys regulate salt balance in the blood?

A

Salt balance in the blood by controlling the absorption of Na+ and secretion K+, using aldosterone.

70
Q

What does aldosterone do?

A

Aldosterone stimulates the kidneys to reabsorb sodium ions.

71
Q

Where is aldosterone produced?

A

In the adrenal gland above the kidney.

72
Q

What happens when low blood pressure is detected?

A

Detected by sensors in the glomerulus. Aldosterone is then released.

73
Q

What is the process that happens after aldosterone is released?

A
  1. Distal tubules and collecting duct are stimulated to reabsorb Na+.
  2. Cl- follows (by charge attraction), and water (by osmosis) follows.
  3. Increased blood pressure.
  4. Decreased urine output.

(Aldosterone also causes K+ to be secreted into the nephron if the K+ concentration in the blood is too high).

74
Q

What does blood pH remain around?

A

Constant of around 7.4

75
Q

What does cellular respiration produce, especially as the respiration rate increases?

A

Produces CO2 and H2O which forms acbonic acid (H2CO3). This lowers blood pH.

As the respiration rate increases, so does carbonic acid production.

76
Q

What do the kidneys excrete as the respiration rate increases?

A

Excess H+ (hydrogen ions) and reabsorb HCO3- (bicarbonate ions) as needed to help maintain blood pH.

77
Q

What do the kidneys do when the blood is too acidic?

A

H+ is excreted, HCO3- is reabsorbed.

78
Q

What do the kidneys do when the blood is too basic?

A

H+ is not excreted, HCO3- is not reabsorbed.

79
Q

What is diabetes insipidius?

A

Either the body is not producing enough ADH or the nephrons and kidneys do not respond properly to the ADH produced.

Symptoms: Excessive urination, extreme thirst

80
Q

What is a UTI? The two types?

A

May be bacterial or viral. Symptoms include pain/burn during urination, frequent urination, brown/red urine, chills, fever, nausea, lower back pain.

Treatments: Antibiotics (for bacterial), immune system (for viral)

Cystitis: infection of bladder
Urethritis: infection of urethra

81
Q

What are kidney stones?

A

Typically form due to excess Ca in the urine.

Causes: insufficient water consumption, recurrent UTIs, low activity levels.
Treatment: pass them, ultrasound, surgery

82
Q

What is renal insufficiency?

A

General term meaning that kidneys cannot maintain homeostasis due to damage to the nephron.

Causes: - kidney infection - diabetes mellitus - poisoning - blocked tubules - high blood pressure - trauma/injury - atherosclerosis

Treatment: Nephrons can regenerate and recover from injury. A person can survive with as little as 1/3 of one kidney. If urine output is inadequate, a kidney transplant is required.

83
Q

What is diabetes mellitus?

A

Either the pancreas is not producing enough insulin or the cells of the body is not responding properly to insulin produced. No reabsorption of glucose.

Symptoms: excessive urination, extreme thirst, or increased glucose levels in the urine.

Treatment: Insulin
- Type 1: “Insul9n-dependent”, “Early onset”
- Type 2: “Delayed onset”, treated by diet

84
Q

What is proteinuria?

A

Presence of proteins in urine.
- Proteins can be forced through the glomerulus due to a variety of reasons
- Can be a sign of overproduction of proteins, pregnancy, side effect of medication, kidney inflammation (nephritis), high blood pressure, malaria.

85
Q

What is hemodialysis dialysis?

A

Blood is pumped from an artery to a dialysis machine and returned to the body by way of a vein. Artery and veins are surgically joined, forming what is called a fistula, to enable easier long-term access to the person’s blood. Each hemodialysis treatment takes 3 to 5 hours and is formed 3-4 times a week. A person must remain seated or lying down during the procedure.

In the dialyzer, waste products are filtered from the blood through an artificial membrane into the dialysate. A high concentration of substance in the machine means that the other stays in the blood.

86
Q

What is peritoneal dialysis?

A

A catheter (flexible tube) is surgically inserted into the abdominal cavity and dialysate may be delivered, removed, and replaced. Because dialysate is always present, the blood is continuously filtered. The full name for this type of dialysis is continual peritoneal dialysis or CPD.

Abultoary can be done at home, and 3-5 exchanges are needed per day.

Automated is done with a machine, done at night for up to 12 hours.

87
Q

What is another alternative to kidney failure other than dialysis?

A

Organ transplant.

88
Q

Where is salt and water transported?

A

Everywhere (water only at the descending Henle loop), but most notably at the Loop of Henle and the Collecting Duct due to the very salty enviornment.

89
Q

What’s the rule to determine whether substances are passively or actively transported?

A

Na+ and most positively charged ions are almost always active.

Negatively charged are always passive.

(Exception is K+, only passively reabsorbed in the proximal tubule; probably cause everywhere else it’s active)

90
Q

What is the best indicator of reabsorption?

A

Glucose; almost all is reabsorbed.

91
Q

What is the best indicator of secretion?

A

Urea, in distal and collecting duct.

92
Q

What hormones control blood pH?

A

Because it affects blood pressure and concentration,

Rennin (increase BP), aldosterone, ADH

93
Q

Define homeostasis.

A

A state of balance among all the body systems needed for the body to survive and function correctly.

94
Q

In relation to blood pressure, what do ADH and aldosterone do?

A

Increase BP.

95
Q

Use the words “filtration” and “reabsorption” and identify whether each uses passive or active transport? Why is this important using the misconception: kidney filters stuff?

(Take with a grain of salt, was on Glowinski’s slides)

A

Filtration = passive
Reabsorption = active

Everything is filtered out, but energy is mostly spent on reabsorption, and only wastes remain.

Biology 20 AP (12 decks)

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