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MCAT Biology Review > Homeostasis > Flashcards

Homeostasis Flashcards

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1
Q

Excretory system

A

Regulates blood pressure, blood osmolarity, acid-base balance, and removal of nitrogenous wastes

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2
Q

Nephron

A

Functional unit of the kidney, all of which empty into the renal pelvis which narrows to form the ureter, in which urine travels to the bladder to the urethra to exit the body

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3
Q

Cortex and medulla

A

The kidney’s outermost and innermost layer, respectively

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4
Q

Renal hilum

A

Deep slit in the center of the kidney’s medial surface, connects to the renal pelvis, entrance and exit sites for the renal artery, renal vein, and ureter

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5
Q

Glomeruli

A

Highly convoluted capillary tufts derived from afferent arterioles that enter the cortex as branches of the renal artery

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6
Q

Vasa recta

A

Efferent arterioles that surround the loop of Henle in a capillary bed after blood passes through a glomerulus

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7
Q

Bowman’s capsule

A

Cuplike structure around the glomerulus that leads to a long tubule consisting of the proximal convoluted tube, descending and ascending limbs of the loop of Henle, distal convoluted tubule, and collecting duct

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8
Q

Detrusor muscle

A

Muscular lining of the bladder that contracts from parasympathetic activity

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9
Q

Internal urethral sphincter

A

Consists of smooth muscle and is contracted in its normal state (under involuntary control)

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10
Q

External urethral sphincter

A

Consists of skeletal muscle and is under voluntary control

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11
Q

Micturition reflex

A

The detrusor muscle contracts as a result of detection of full bladder, causing the internal sphincter to relax

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12
Q

Filtrate

A

Collected fluid into the Bowman’s space from the blood (20 percent of it)

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13
Q

Urea

A

Product of ammonia metabolism in liver as a result of metabolism of nitrogen-containing compounds (significant amount in meat)

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14
Q

Reabsorption

A

Some compounds that are filtered or secreted may be taken back up for use, such as glucose, amino acids, and vitamins (and even water as directed by antidiuretic hormone)

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15
Q

Horizontal segments in nephron

A

Bowman’s capsule, proximal convoluted tubule, and distal convoluted tubule are concerned with the identity of the particles in urine (keep what body needs and lose what it does not)

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16
Q

Vertical segments in nephron

A

Loop of Henle and collecting duct, focused on the volume and concentration of the urine (concentrate the urine to conserve water)

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17
Q

Proximal convoluted tubule (PCT)

A

Filtrate enters here from the Bowman’s capsule
Amino acids, water-soluble vitamins, and majority of salts (sodium and chloride) are reabsorbed along with water, also site of secretion of waste products (hydrogen ions, potassium ions, ammonia and urea)
Dump the HUNK

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18
Q

Intestitium

A

Connective tissue surrounding the nephron, solutes that enter this rea are picked up by the vasa recta to be returned to the bloodstream for reuse within the body

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19
Q

Descending limb of the loop of Henle

A

Filtrate from proximal convoluted tubule enters here, diving deep into the medulla, permeable only to water (deeper parts of medulla have greater osmolarity, favoriting outflow of water from descending limb as you go deeper)

20
Q

Ascending limb of the loop of Henle

A

Only permeable to salts and is impermeable to water, maximizing salt reabsorption as medullary osmolarity is decreased

21
Q

Countercurrent multiplier system

A

The flow of filtrate through loop of Henle is in the opposite direction from the flow of blood through the vasa recta, constantly exposing filtrate to hypertonic blood to allow for maximal reabsorption of water

22
Q

Diluting segment

A

The thicker segment of the loop of Henle as it transitions from inner to outer medulla, in which the cells lining the tube are larger and contain larger amounts of mitochondria that allow for reabsorption of sodium and chloride by active transport (only part of nephron that can produce urine more dilute than the blood)

23
Q

Distal convoluted tubule (DCT)

A

Responds to aldosterone, which promotes sodium reabsorption (water will follow sodium exiting nephron, concentrating the urine and decreasing its volume), also waste product secretion site

24
Q

Collecting duct

A

Responsive to both aldosterone and antidiuretic hormone

Permeable to water and promotes water reabsorption (more in conservation mode and less when body is well hydrated)

25
Q

ADH and aldosterone effects on blood osmolarity

A

ADH only affects water reabsorption (lower blood osmolarity) while aldosterone affects both salt and water reabsorption (no change in blood osmolarity)

26
Q

Osmotic pressure

A

Sucking pressure that draws water into the vasculature caused by all dissolved particles

27
Q

Oncotic pressure

A

Osmotic pressure attributable to dissolved proteins specifically

28
Q

Three layers of skin (surface to deepest)

A

Epidermis, dermis, hypodermis (subcutaneous layer)

29
Q

Strata

A

Subdivisions of the epidermis
From deepest layer to most outward: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
Big Shits Get Loud, (C)See?

30
Q

Stratum basale

A

Contains stem cells and is responsible for proliferation of keratinocytes that produce keratin

31
Q

Stratum spinosum

A

Keratinocytes become connected to each other and is also the site of Langerhans cells

32
Q

Stratum granulosum

A

Keratinocytes die and lose their nuclei

33
Q

Stratum lucidum

A

Only present in thick, hairless skin (on sole of foot or palms), nearly transparent

34
Q

Stratum corneum

A

Contains layers of flattened keratinocytes, forming a barrier that prevents invasion by pathogens and prevents fluid and salt loss

35
Q

Calluses

A

Form from excessive keratin deposition in areas of repeated strain due to friction

36
Q

Melanocytes

A

Derived from neural crest cells and found in the stratum basale, produce melanin (pigment that serves to protect skin from DNA damage caused by ultraviolet radiation)

37
Q

Layers of the dermis

A

Upper layer is papillary layer (loose connective tissue) and lower layer is denser reticular layer

38
Q

Merkel cells (discs)

A

Sensory receptors responsible for deep pressure and texture sensation within skin

39
Q

Free nerve endings

A

Respond to pain

40
Q

Meissner’s corpuscules

A

Respond to light touch

41
Q

Ruffini endings

A

Respond to stretch

42
Q

Pacinian corpuscules

A

Respond to deep pressure and vibration

43
Q

Hypodermis

A

Layer of connective tissue that connects skin to rest of the body, containing fat and fibrous tissue

44
Q

Sweating

A

Postganglionic sympathetic neurons using acetylcholine (instead of norepinephrine) innervate sweat glands to promote secretion of water with soluble ions onto the skin, heat is then absorbed from the body as the water molecules undergo a phase change to evaporate (arteriolar vasodilation occurs to maximize heat loss as it brings larger quantity of blood to the skin and maximizes heat energy available for liquid-gas phase exchange)

45
Q

Piloerection

A

Arrector pili muscles contract in cold conditions, causing the hairs of the skin to stand up on end to trap a layer of heated air near the skin (arterioles constrict as well to limit quantity of blood reaching the skin)

46
Q

Shivering

A

Rapid contraction of skeletal muscle, requiring sizable amount of ATP that gets converted into thermal energy to retain heat

47
Q

Brown fat

A

In contrast with white fat (which is the layer of fat just below the skin that insulates the body), this layer of fat has a less efficient transport chain, meaning that more heat energy is released as fuel is burned

MCAT Biology Review (10 decks)

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