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MCAT Biology > Chapter 10: Homeostasis > Flashcards

Chapter 10: Homeostasis Flashcards

1
Q

What roles does the excretory system play?

A
  1. Regulate blood pressure, blood osmolarity, acid-base balance
  2. Removes nitrogenous waste
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2
Q

What 4 parts does the excretory system consist of?

A
  1. Kidneys
  2. Ureters
  3. Bladder
  4. Urethra
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3
Q

What is the functional unit of the kidney?

A

Nephron

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4
Q

All of the nephrons eventually empty into the renal ________, which narrows to form the ________.

A

pelvis; ureter

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5
Q

Urine travels through the ureter to the ________, then goes to the ____________ to exit the body.

A

bladder; urethra

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6
Q

Each kidney is subdivided into what 2 parts?

A
  1. Cortex
  2. Medulla
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7
Q

The ________ is the kidney’s outermost layer, while the ________ sits within this.

A

cortex; medulla

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8
Q

Each kidney also has a renal ________, which is a deep slit in the center of its medial surface.

A

hilum

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9
Q

The widest part of the ureter, the renal ________, spans almost the entire width of the renal hilum.

A

pelvis

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10
Q

What 3 things enter/exit thru the renal hilum?

A
  1. renal artery
  2. renal vein
  3. ureter
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11
Q

The kidney has one of the few portal systems in the body. A portal system consists of what?

A

2 capillary beds in series through which blood must travel before returning to the heart

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12
Q

The renal artery branches out, passes through the medulla, and enters the cortex as ____________ ____________.

A

afferent arterioles

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13
Q

The highly convuled capillary tufts derived from afferent arterioles are known as ____________.

A

glomeruli

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14
Q

After blood passes through a glomerulus, the ____________ ____________ then form a second capillary bed.

A

efferent arterioles

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15
Q

These capillaries surround the loop of ________ and are known as ________ ________.

A

Henle; vasa recta

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16
Q

Around the glomerulus is a cup-like structure known as ____________ ________, which leads to a long tubule with many distinct areas.

A

Bowman’s capsule

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17
Q

What does Bowman’s capsule lead to and in what order?

A
  1. proximal convulted tubule
  2. descending and ascending limbs of loop of Henle
  3. distal convoluted tubule
  4. collecting duct
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18
Q

The bladder has a muscular lining known as the ____________ muscle.

A

detrusor

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19
Q

____________ activity causes the detrusor muscle to contract.

A

parasympathetic

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20
Q

Urine must pass through 2 sphincters, what are they?

A

Internal and external urethral sphincter

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21
Q

The ____________ urethral sphincter consists of smooth muscle and is contracted in its normal state.

A

internal

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22
Q

The internal sphincter is under ____________ control.

A

involuntary

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23
Q

The ____________ urethral sphincter consists of skeletal muscle and is under voluntary control.

A

xternal

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24
Q

When the bladder is full, ________ receptors convey to the nervous system that the bladder needs emptying. Parasympathetic neurons fire, and the detrusor muscle contracts. This causes what to relax?

A

stretch; internal sphincter relaxes

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25
Q

The relaxation of the internal urethral sphincter is known as the ____________ reflex.

A

micturition

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26
Q

If the person relaxes the ____________ sphincter or maintains its tone, urination may or may not occur.

A

external

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27
Q

The nephron’s first function is ____________.

A

filtration

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28
Q

20% of the blood that passes through the glomerulus is filtered as fluid into Bowman’s space. The collected fluid is known as ____________.

A

filtrate

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29
Q

THe movement of fluid into Bowman’s space is governed by ____________ forces, which account for pressure differentials in both hydrostatic and oncotic pressures between blood and Bowman’s space.

A

Starling

See p388

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30
Q

In addition to filtering blood, nephrons secrete what 4 things into the tubule?

A
  1. salts
  2. acids
  3. bases
  4. urea
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31
Q

Ammonia a byproduct of the metabolism of nitrogen-containing compounds and, as a base, can disturb the pH of blood and cells. The liver converts ammonia to ________, a neutral compound, which travels to the kidney and is secreted into the ________ for excretion in the urine.

A

urea; nephron

32
Q

Some compounds that are filtered or secreted may be taken back up for use via ____________

A

reabsorption

33
Q

Filtrate first enters the ____________ ____________ ________, where amino acids, glucose, water-soluble vitamins, and the majority of salts are reabosrbed along with water.

A

proximal convoluted tubule

34
Q

Solutes that enter the ____________ - the connective tissue surrounding the nephron - are picked by the ________ ________ to be returned to the bloodstream for reuse within the body.

A

insterstitium; vasa recta

35
Q

The PCT is also the site of secretion for a number of waste products. What are they?

A
  1. H+ ions
  2. urea
  3. NH3
  4. K+

Dump the HUNK

36
Q

From the PCT, filtrate enters the ____________ limb of the ________ of ________, which dives deep into the medulla before turning around to become the ____________ limb of the ________ of ________.

A

descending; loop of Henle; ascending; loop of Henle

37
Q

The vasa recta and nephron create a ____________ ________ system, which means that the flow of filtrate through the loop of Henle is the opposite direction from the flow of blood through the vasa recta.

A

countercurrent multiplier

38
Q

At the transition from the inner to outer medulla, the loop of Henle becomes thicker in what is termed the ____________ ________.

A

diluting segment

39
Q

After the loop of Henle, filtrate enters the ________ ________________ ____________.

A

distal convulted tubule

40
Q

The distal convoluted tubule responds to ____________, which promotes sodium reabsorption.

A

aldosterone

41
Q

____________ is a steroid hormone that is secreted by the adrenal cortex in response to decreased blood pressure.

A

Aldosterone

42
Q

Decreased blood pressure stimulates the release of ________ from ________________ cells in the kidney.

A

renin; juxtoglomerular

43
Q

Renin then cleaves ________________, a liver protein, to form ____________ ____.

A

angiotensinogen; angiotensin I

44
Q

Angiotensin I is metabolized by ____________-____________ enyzme in the lungs to form ________________.

A

angiotensin-converting; angiotensin II

45
Q

Angiotensin II promotes the release of ____________ from the adrenal cortex.

A

aldosterone

46
Q

Aldosterone works by altering the ability of the ________ ____________ ________ and ____________ ________ to reabsorb sodium.

A

distal convulted tubule; collecting duct

47
Q

____________ hormone, also known as vasopressin, is a peptide hormone synthesized by the hypothalamus and released by the posterior pituitary in response to high blood osmolarity.

A

antidiuretic

48
Q

____________ pressure is the “sucking” pressure that draws water into the vasculature caused by all dissolved particles

A

osmotic

49
Q

____________ pressure is the osmotic pressure that is attributable to dissolve proteins specifically.

A

oncotic

50
Q

Deepest to surface

What are the 3 layers of the skin?

A
  1. Hypodermis (subcutaneous)
  2. Dermis
  3. Epidermis
51
Q

Where does skin derive from?

A

ectoderm

52
Q

The epidermis is subdivided into layers called ________.

A

strata

53
Q

What are the strata of the epidermis going outward from the deepest layer?

A
  1. Stratum basale
  2. Stratum spinosum
  3. Stratum granulosum
  4. Stratum lucidum
  5. Stratum corneum
54
Q

The stratum basale contains stem cells and is responsible for the proliferation of ____________, the predominant cells of the skin.

A

keratinocytes

55
Q

Keratinocytes produce ____________.

A

keratin

56
Q

In the stratum spinosum, keratinocytes become connected to each other. This layer is also the site of ____________ cells.

A

Langerhans

57
Q

In the stratum granulosum, what happens to keratinocytes?

A

they die and lose their nuclei

58
Q

The stratum ____________ is only present in thick, hairless skin, such as the skin on the sole of the foot or the palms, and is nearly transparent.

A

lucidum

59
Q

The stratum corneum contains up to several dozen layers of flattened keratinocytes, what does this do?

A

Forms a barrier that prevents pathogenic invasion and prevents fluid/salt loss

60
Q

Keratin is resistant to damage and provides protection against injury, water, and pathogens. ____________ form from excessive keratin deposition in areas of repeated strain due to friction.

A

calluses

61
Q

____________ are a cell type derived from neural crest cells and found in the stratum basale. What pigment do they produce? What does it do?

A

Melanocytes; melanin - protects skin from DNA damage caused by UV

62
Q

After melanocytes make melanin, it goes to ________________.

A

keratinocytes

63
Q

Skin color is caused by what?

A

Varying levels of activity of melanocytes

64
Q

More active melanocytes result in ________ skin tones.

A

darker

65
Q

____________ cells are actually special macrophages that reside within the stratum spinosum.

A

Langerhans

66
Q

What are the 2 layers of the dermis? Upper to lower.

A
  1. papillary layer
  2. reticular layer
67
Q

The papillay layer has what?

A

loose connective tissue

68
Q

What 3 things originate in the dermis?

A
  1. sweat glands
  2. blood vessels
  3. hair follicles
  4. sensory receptors
69
Q

________ cells are sensory receptors present at the epidermal-dermal junction.

A

Merkel

70
Q

What do Merkel cells do?

A

Connected sensory neurons; responsible for deep pressure and texture sensation within the skin

71
Q

____________ ____________ respond to light touch.

A

Meissner’s corpuscles

72
Q

____________ endings respond to stretch.

A

Ruffini

73
Q

____________ ____________ respond to deep pressure and vibration.

A

Pacinian corpuscles

74
Q

____________ is a cooling mechanism controlled by the autonomic nervous system.

A

Sweating

75
Q

In cold conditions, ____________ ________ muscles contract, causing the hairs of the skin to stand up on end. This is called ________________.

A

arrector pili; piloerection

MCAT Biology (12 decks)

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