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Bad Girl's MCAT Club > Biology 10: Homeostasis > Flashcards

Biology 10: Homeostasis Flashcards

1
Q

renal hilum

A

a deep slit in the center of the kidney’s medial surface

where the renal artery, renal vein, and ureter pass

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2
Q

portal system

A

system which consists of two capillary beds in series through which blood must travel before returning to the heart

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3
Q

renal portal system pathway

A

renal artery –> afferent arterioles –> glomerulus –> efferent arteriole –> vasa recta

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4
Q

detrusor muscle

A

muscular lining around the bladder

innervated by parasympathetic system to contract

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5
Q

what are the two sphincters that urine must pass through to leave the body?

A

internal urethral sphincter - smooth muscle - normally contracted - involuntary

external urethral sphincter - skeletal muscle - voluntary

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6
Q

micturition reflex

A

when the bladder is full…

  1. stretch receptors send message to nervous system
  2. parasympathetic signaling causes detrusor muscle to contract
  3. internal urethral sphincter relaxes

individual chooses to relax the external urethral sphincter

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7
Q

filtrate

A

fluid collected from the passage of blood through the glomerulus into Bowman’s space

does not contain cells or proteins due to size of glomerular pores

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8
Q

what happens to blood that is not filtered at the Bowman’s capsule?

A

blood remaining in the glomerulus travels into afferent arterioles, which empty into vasa recta

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9
Q

filtration

A

movement of solutes from blood to filtrate at Bowman’s capsule

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10
Q

secretion

A

movement of solutes from blood to filtrate anywhere besides Bowman’s capsule

allow kidneys to eliminate ions or other substances when present in excess amounts in the blood

allows kidneys to excrete wastes that are too large to pass through glomerular pores

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11
Q

reabsorption

A

movement of solutes from filtrate to blood

compounds filtered/secreted can be taken back up for use

glucose, amino acids, vitamins are always reabsorbed

water reabsorbed depending on ADH or aldosterone

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12
Q

proximal convoluted tubule

A

filtrate’s first stop after the Bowman’s capsule

amino acids, glucose, water-soluble vitamins, salts, water are reabsorbed

solutes enter the interstitium and are picked up by the vasa recta to be returned to the bloodstream

secretion of H+, K+, NH3+, urea

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13
Q

interstitium

A

the connective tissue surrounding the nephron

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14
Q

descending loop of Henle

A

receives filtrate from the proximal convoluted tubule

dives deep into the medulla with an increasing osmolarity

permeable only to water

as it gets deeper, the interstitial concentration favors the outflow of water which is reabsorbed in the vasa recta

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15
Q

countercurrent multiplier system

A

created by the vasa recta and nephron

the flow of filtrate through the loop of Henle is in the opposite direction from the flow of blood through the vasa recta

filtrate is constantly exposed to hypertonic blood, allows for maximal reabsorption of water

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16
Q

ascending limb of Henle

A

portion of the loop of Henle that is only permeable to salts, impermeable to water

at deeper parts of the medulla, salt concentrations are high but decrease as the ascending limb rises

increasing amounts of salts are removed from the filtrate as it travels up the loop of Henle

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17
Q

diluting segment

A

portion of the loop of Henle at the transition of the loop of Henle from the inner to outer medulla

thicker because the cells lining the tube are larger

cells have lots of mitochondria, reabsorption of Na and Cl by active transport

only portion of the nephron that can produce urine that is more dilute than the blood

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18
Q

how does filtrate change as it moves through the loop of henle?

A

at the beginning of the loop of henle, filtrate is isotonic to interstitium

at the end, there is a slight degree of dilution

volume of filtrate is significantly reduced - lots of water reabsorbed

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19
Q

distal convoluted tubule

A

portion of the nephron after the ascending limb of the loop of henle

responds to aldosterone, which promotes sodium reabsorption - water follows

the urine is concentrated and its volume is decreased

also the site of waste product secretion

20
Q

collecting duct

A

final section of the nephron

responsive to both aldosterone and ADH to change permeability of water

as permeability of the collecting duct increases, water is reabsorbed, further concentrating the urine

if well hydrated, collecting duct is fairly impermeable to salt and water

21
Q

how does aldosterone work to decrease blood pressure?

A
  1. decreased blood pressure stimulates release of renin from juxtaglomerular cells in kidney
  2. renin cleaves angiotensin (liver protein) –> angiotensin I
  3. angiotensin-converting enzyme (ACE) in lungs cleaves A1 –> angiotensin II

angiotensin II promotes the release of aldosterone from the adrenal cortex

aldosterone causes distal convoluted tubule and collecting duct to reabsorb calcium, causing water reabsorption, increasing blood volume and pressure

22
Q

how does ADH work to decrease blood pressure?

A

released by posterior pituitary in response to high blood osmolarity

cause more water to be reabsorbed by making the cell junctions of the collecting duct leaky

high conc of interstitium causes water to follow

23
Q

osmotic pressure

A

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

24
Q

oncotic pressure

A

osmotic pressure attributable to dissolved proteins specifically

25
Q

what are the three layers of the skin from the deepest to outermost layer?

A

hypodermis (subcutaneous layer)

dermis

epidermis

26
Q

from deepest layer outward, what are the strata of the epidermis?

A

stratum basale

stratum spinosum

stratum granulosum

stratum lucidum

stratum corneum

Come Lets Get Sun Burned

27
Q

stratum basale

A

deepest layer of the epidermis

contains stem cells

responsible for the proliferation of keratinocytes (produce keratin)

28
Q

stratum spinosum

A

second-most deepest epidermal layer

cells are connected to each other

site of Langerhans cells

29
Q

stratum granulosa

A

third-most deepest layer in epidermis

keratinocytes die and lose their nuclei

30
Q

stratum lucidum

A

fourth-deepest layer of the epidermis

only present in thick, hairless skin (sole of feet, palm of hands)

nearly transparent

31
Q

stratum corneum

A

outermost layer of epidermis

several layers of flattened keratinocytes

forming a barrier that prevents invasion by pathogens

helps to prevent loss of fluids and salt

32
Q

calluses

A

regions of the epidermis that form from excessive keratin deposition in areas of repeated strain due to friction

33
Q

melanocytes

A

cell type derived from neural crest cells, found in stratum basale

produce melanin that is passed onto keratinocytes

34
Q

langerhans cells

A

special macrophages that reside within the stratum spinosum

capable of presenting antigens to T-cells in order to activate the immune system

35
Q

what are the layers of the dermis?

A

papillary layer (upper) of loose connective tissue

denser reticular layer (lower)

36
Q

epidermis

A

top layer of skin

main cells are keratinocytes

divided into five strata

37
Q

dermis

A

second layer of the skin

sweat glands, blood vessels, hair follicles originate here

38
Q

merkel cells (discs)

A

sensory receptors present at epidermal-dermal junction

responsible for deep pressure and texture sensation within the skin

39
Q

free nerve endings

A

sensory receptors in the skin that respond to pain

40
Q

meissner’s corpuscles

A

sensory receptors in the skin that respond to light touch

41
Q

ruffini endings

A

sensory receptors in the skin that respond to stretch

42
Q

Pacinian corpuscles

A

sensory receptors that respond to deep pressure and vibration

43
Q

hypodermis

A

innermost layer of skin

layer of connective tissue that connects the skin to the rest of the body

contains fat and fibrous tissue

44
Q

sweating

A

cooling mechanism that is contrlled by the autonomic nervous system

body temp rises above set point, hypthalamus starts thermoregulation

postganglionic sympathetic neurons that use acetylcholine innervate sweat glands

evaporation of water from skin absorbs body heat

45
Q

how does the body react to cold conditions?

A
  1. arrector pili muscles contract - causing piloerection (hairs of skin to stand up)
    • traps layer of heated air near skin
  2. arterioles that feed capillaries of skin constrict, keeping blood from reaching skin
  3. skeletal muscles contract rapidly - shivering
46
Q

white fat

A

a layer of fat just below the skin that helps to insulate the body

47
Q

brown fat

A

fat present in infants

less efficient ETC - more heat energy released as fuel burned

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