Ion and Water Balance

Question 1

Three homeostatic processes

Answer 1

Osmotic regulation, ionic regulation, and nitrogen excretion

Question 2

Osmotic regulation

Answer 2

Osmotic pressure of body fluids

Question 3

Ionic regulation

Answer 3

Concentrations of specific ions

Question 4

Nitrogen excretion

Answer 4

Excretion of end-products of protein metabolism

Question 5

Ionic/osmotic challenges of marine environments

Answer 5

Animals tend to gain salts and lose water

Question 6

Ionic/osmotic challenges of freshwater environments

Answer 6

Animals tend to lose salts and gain water

Question 7

Ionic/osmotic challenges of terrestrial environments

Answer 7

Animals tend to lose water

Question 8

Osmoconformer

Answer 8

Internal and external osmolarity are similar (ex. marine invertebrates)

Question 9

Osmoregulator

Answer 9

Osmolarity constant regardless of external environment (ex. most vertebrates)

Question 10

Ionoconformer

Answer 10

Exert little control over ion profile within extracellular space. Exclusively found in marine animals, ex. many invertebrates

Question 11

Ionoregulator

Answer 11

Control ion profile of extracellular space (ex. most vertebrates)

Question 12

Regulatory volume increase

Answer 12

Importing ions –> influx of water

Question 13

Regulatory volume decrease

Answer 13

Exporting ions –> efflux of water

Question 14

Aquaporin

Answer 14

Channels that move water through cell membrane

Question 15

Epithelial tissues purpose

Answer 15

To form a boundary either between animal and environment. External boundary like skin, or internal boundary like lumen of digestive tract, excretory system, kidneys.

Question 16

Mechanisms to reduce water flux

Answer 16

Cover external surface with hydrophobic molecules (mucous, cornified stratum corneum with keratin, hydrophobic matrix of keratin and lipids, or cuticle with chitin)

Question 17

Four features of transport epothelia

Answer 17

1 - asymmetrical distribution of membrane transporters (solutes selectively transported across membrane)
2 - cells interconnected to form impermeable sheet of tissue (little leakage between cells)
3 - High cell diversity within tissue
4 - abundant mitochondria (large ATP supply)

Question 18

Transcellular transport

Answer 18

Movement through cells across membranes

Question 19

Paracellular transport

Answer 19

Movement between cells; tight vs leaky epithelia

Question 20

Types of transporters

Answer 20

Na+/K+ATPase, other ATPases, Ion channels, electroneurtal cotransporters, electroneutral exchangers

Question 21

Fish gill surface composed of…

Answer 21

Chloride cells (large mitrochondria-rich cells) --> PNA+
Pavement cells --> PNA-

Question 22

Six roles of vertebrate kidneys in homeostasis

Answer 22

1 - ion balance
2 - osmotic balance
3 - blood pressure
4 - pH balance
5 - Excretion of metabolic wastes and toxins
6 - hormone production

Question 23

Composition of nephron

Answer 23

Vasculature (glomerulus, capillary beds surrounding renal tubule) and renal tubule

Question 24

Four renal processes

Answer 24

Filtration, reabsorption, secretion, and excretion

Question 25

Site of filtration

Answer 25

Glomerulus

Question 26

Filtration structure of glomerulus

Answer 26

Podocytes with foot processes

Question 27

Mesangial cells of glomerulus

Answer 27

Control blood pressure and filtration

Question 28

Primary urine

Answer 28

Initial filtrate filtered in Bowman's capsule that is isosmotic to blood

Question 29

Renal thershold

Answer 29

Concentration of a specific solute that will saturate reabsorptive capacity

Question 30

Function of proximal tubule

Answer 30

Most solute and water reabsorption

Question 31

Function of Loop of Henle descending limb

Answer 31

Water reabsorption

Question 32

Function of Loop of Henle ascending limb

Answer 32

Ion reabsorption

Question 33

Function of distal tubule

Answer 33

Reabsorption completed for most solutes and water

Question 34

Function of collecting fuct

Answer 34

Regulation of final urine composition Drains multiple nephrons Carries urine to renal pelvis

Question 35

Solutes reabsorbed by proximal tubule via Na+ cotransport

Answer 35

Glucose, lactate, a.a., water-soluble vitamins, phosphates

Question 36

Effect of aldosterone on kidney function

Answer 36

Slow response

Question 37

Effect of vasopressin on kidney function

Answer 37

Rapid response

Question 38

Glomerular Filtrate Rate (GFR) is determined by...

Answer 38

Pressure across glomerular wall as created by: - glomerular capillary hydrostatic pressure - bowman's capsule hydrostatic pressure - oncotic pressure

Question 39

Oncotic pressure

Answer 39

Osmotic pressure due to protein concentration in blood

Question 40

Three intrinsic regulation pathways of glomerular filtrate rate

Answer 40

1. Myogenic regulation 2. Tubuloglomerular feedback 3. Mesangial control

Question 41

Myogenic regulation of GFR

Answer 41

Constriction/dilation of afferent arteriole

Question 42

Tubuloglomerular feedback of GFR

Answer 42

Juxtaglomerular apparatus contains macula densa cells in distal tubule and juxtaglomerular cells in afferent arteriole Macula densa cells of distal tubule control diameter of afferent arteriole

Question 43

Mesangial control of GFR

Answer 43

Alters permeability of glomerulus

Question 44

What causes differences in transport and permeability in tubule regions?

Answer 44

Differences in epithelium along the tubule

Question 45

Alternate name for vasopressin

Answer 45

Antidiuretic hormone (ADH)

Question 46

Where is ADH produced/released

Answer 46

Produced in hypothalamus and released by posterior pituitary

Question 47

Function of ADH

Answer 47

Increases water reabsorption from collecting ducts and distal tubules by increases number of aquaporins

Question 48

How is ADH release stimulated/inhibited?

Answer 48

Release is stimulated by increasing plasma osmolarity detected by osmoreceptors in hypothalamus Release is inhibited by increasing blood pressure detected by stretch receptors in atria and baroreceptors in carotid and aortic bodies

Question 49

Where is aldosterone produced?

Answer 49

Adrenal cortex, in tetrapods

Question 50

What stimulates aldosterone production?

Answer 50

Angiotension II, high K+, ACTH, decreased blood pressure sensed by stretch receptors in atria

Question 51

Function of aldosterone

Answer 51

Targets principal cells in distal tubule and collecting duct, and stimulates Na+ reabsorption from urine, enhances K+ secretion, produces N+/K+ATPase to target basolateral membrae, and produces K+ and Na+ channels to target apical membrane

Question 52

Apical surface

Answer 52

Faces lumen/external environment

Question 53

Basal surface

Answer 53

Faces internal environment

Question 54

When is renin secreted?

Answer 54

When blood pressure of GFR is lower than normal

Question 55

Which cells secrete renin?

Answer 55

Juxtaglomerular cells

Question 56

Low BP causes basoreceptors in juxtaglomerular cells to release....

Answer 56

Renin

Question 57

Low BP causes sympathetic neurons in medulla oblongata to trigger secretion of...

Answer 57

Renin

Question 58

Low flow causes macula densa cells in distal tubule to release paracrine signal that induces .... to release ...

Answer 58

Juxtaglomerular cells to release renin

Question 59

Renin converts angiotensionogen to..

Answer 59

Angiotensin I

Question 60

Angiotension converting enzyme (ACE) on epithelia of blood vessels converts angiotension I to...

Answer 60

Angiotension II

Question 61

Angiotension II causes synthesis and release of ..... from ....

Answer 61

Aldosterone from adrenal cortex

Question 62

Angiotension II causes release of

Answer 62

vasopressin