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MCAT Biology > Chapter 10: Homeostasis > Flashcards

Chapter 10: Homeostasis Flashcards

(75 cards)

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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
The relaxation of the internal urethral sphincter is known as the ____________ reflex.
micturition
26
If the person relaxes the ____________ sphincter or maintains its tone, urination may or may not occur.
external
27
The nephron's first function is ____________.
filtration
28
20% of the blood that passes through the glomerulus is filtered as fluid into Bowman's space. The collected fluid is known as ____________.
filtrate
29
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.
Starling | See p388
30
In addition to filtering blood, nephrons secrete what 4 things into the tubule?
1. salts 2. acids 3. bases 4. urea
31
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.
urea; nephron
32
Some compounds that are filtered or secreted may be taken back up for use via ____________
reabsorption
33
Filtrate first enters the ____________ ____________ ________, where amino acids, glucose, water-soluble vitamins, and the majority of salts are reabosrbed along with water.
proximal convoluted tubule
34
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.
insterstitium; vasa recta
35
The PCT is also the site of secretion for a number of waste products. What are they?
1. H+ ions 2. urea 3. NH3 4. K+ | Dump the HUNK
36
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 ________.
descending; loop of Henle; ascending; loop of Henle
37
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.
countercurrent multiplier
38
At the transition from the inner to outer medulla, the loop of Henle becomes thicker in what is termed the ____________ ________.
diluting segment
39
After the loop of Henle, filtrate enters the ________ ________________ ____________.
distal convulted tubule
40
The distal convoluted tubule responds to ____________, which promotes sodium reabsorption.
aldosterone
41
____________ is a steroid hormone that is secreted by the adrenal cortex in response to decreased blood pressure.
Aldosterone
42
Decreased blood pressure stimulates the release of ________ from ________________ cells in the kidney.
renin; juxtoglomerular
43
Renin then cleaves ________________, a liver protein, to form ____________ ____.
angiotensinogen; angiotensin I
44
Angiotensin I is metabolized by ____________-____________ enyzme in the lungs to form ________________.
angiotensin-converting; angiotensin II
45
Angiotensin II promotes the release of ____________ from the adrenal cortex.
aldosterone
46
Aldosterone works by altering the ability of the ________ ____________ ________ and ____________ ________ to reabsorb sodium.
distal convulted tubule; collecting duct
47
____________ 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.
antidiuretic
48
____________ pressure is the "sucking" pressure that draws water into the vasculature caused by all dissolved particles
osmotic
49
____________ pressure is the osmotic pressure that is attributable to dissolve proteins specifically.
oncotic
50
# Deepest to surface What are the 3 layers of the skin?
1. Hypodermis (subcutaneous) 2. Dermis 3. Epidermis
51
Where does skin derive from?
ectoderm
52
The epidermis is subdivided into layers called ________.
strata
53
What are the strata of the epidermis going outward from the deepest layer?
1. Stratum basale 2. Stratum spinosum 3. Stratum granulosum 4. Stratum lucidum 5. Stratum corneum
54
The stratum basale contains stem cells and is responsible for the proliferation of ____________, the predominant cells of the skin.
keratinocytes
55
Keratinocytes produce ____________.
keratin
56
In the stratum spinosum, keratinocytes become connected to each other. This layer is also the site of ____________ cells.
Langerhans
57
In the stratum granulosum, what happens to keratinocytes?
they die and lose their nuclei
58
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.
lucidum
59
The stratum corneum contains up to several dozen layers of flattened keratinocytes, what does this do?
Forms a barrier that prevents pathogenic invasion and prevents fluid/salt loss
60
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.
calluses
61
____________ are a cell type derived from neural crest cells and found in the stratum basale. What pigment do they produce? What does it do?
Melanocytes; melanin - protects skin from DNA damage caused by UV
62
After melanocytes make melanin, it goes to ________________.
keratinocytes
63
Skin color is caused by what?
Varying levels of activity of melanocytes
64
More active melanocytes result in ________ skin tones.
darker
65
____________ cells are actually special macrophages that reside within the stratum spinosum.
Langerhans
66
What are the 2 layers of the dermis? Upper to lower.
1. papillary layer 2. reticular layer
67
The papillay layer has what?
loose connective tissue
68
What 3 things originate in the dermis?
1. sweat glands 2. blood vessels 3. hair follicles 4. sensory receptors
69
________ cells are sensory receptors present at the epidermal-dermal junction.
Merkel
70
What do Merkel cells do?
Connected sensory neurons; responsible for deep pressure and texture sensation within the skin
71
____________ ____________ respond to light touch.
Meissner's corpuscles
72
____________ endings respond to stretch.
Ruffini
73
____________ ____________ respond to deep pressure and vibration.
Pacinian corpuscles
74
____________ is a cooling mechanism controlled by the autonomic nervous system.
Sweating
75
In cold conditions, ____________ ________ muscles contract, causing the hairs of the skin to stand up on end. This is called ________________.
arrector pili; piloerection

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