Chapter 6: Minerals (Oct 4 lec)

Question 1

3 consequences of Ca toxicity

Answer 1

• osteopetrosis: over mineralization= bones become brittle
• urethral and kidney stones
• reduced absorption of other nutrients

Question 2

Blood Ca levels are tightly controlled by ____

Answer 2

homeostasis

Question 3

What is the role of Vitamin D3 in controlling blood Ca levels?

Answer 3

increases plasma Ca (from intestine, bone)

Question 4

What is the role of Parathyroid hormone in controlling blood Ca levels?

Answer 4

increases plasma Ca from kidney, bone, intestine

Question 5

What is the role of Calcitonin in controlling blood Ca levels?

Answer 5

decreases plasma Ca

• inhibits osteoclast (bone dissolution)
• increase Ca loss from kidney

Question 6

___%-___% of phosphorus is in Ca phosphates in bone

- the remainder is in:

Answer 6

80-85%

- extracellular fluid

Question 7

functions of phosphorus (2)

Answer 7

1. structure of bones and teeth
2. component of:
   - phospholipids, DNA/RNA, etc

Question 8

What is the typical deficiency of Phosphorus?

Answer 8

Pica!

• deranged appetite caused by specific mineral deficiencies
• skeletal deformities
• reduced growth, appetites, milk production
• reproductive dysfunction

Question 9

3 results of phosphorus toxicity

Answer 9

1. nutritional secondary hyperparathyroidism= excessive bone resorption die to high levels of PTH release
   - associated with long term consumption of low Ca, high P diets (“Big head”)
2. urinary calculi
3. laxative effect

Question 10

Phosphorus is stored as ___in animals because it’s not available to animals when they eat the plant

Answer 10

phytate

Question 11

___ can use phytate, ___ cannot

Answer 11

plants

animals

Question 12

In ___, phytate binds a large proportion of P in plant ingredients. Thus:
- ___(inc/dec) P availability

Answer 12

monogastrics

decreased

Question 13

True/ False

Phytate is degraded by rumen microbes in ruminants

Answer 13

true

Question 14

Why is phosphorus sometimes considered a pollutant?

Answer 14

P generally limits biological activity in most freshwater ecosystems

Question 15

T/F

Calcium and phosphorus are not closely related in terms of nutrition and metabolism

Answer 15

false

Question 16

____ is found in many tissues, half of it is in bines, and 20-25% of it is in muscles

Answer 16

magnesium

Question 17

functions of magnesium: (4)

Answer 17

• structure of bones
• oxidative phosphorylation
• rxns involving ATP
• enzyme cofactor

Question 18

3 signs of magnesium deficiency

Answer 18

1. anorexia- can sometimes lead the animal to stop eating altogether
2. reduced weight gain
3. hypomagnesemic tetany (grass tetany, grass staggers)
   - high levels of K increase Mg excretion, decrease Mg absorption

Question 19

__,__, and __ are electrolytes

- functions are:

Answer 19

K, Na, and Cl

• osmotic pressure
• acid-base balance

Question 20

list some functions of potassium in the body

Answer 20

• osmotic equilibrium
• uptake of glucose
• enzyme activation
• nerve transmission and muscle contraction
• blood pressure regulation

Question 21

How is potassium absorbed?

Answer 21

passive diffusion (not well understood)

• recycling via saliva
• high dietary availability

Question 22

K and Na homeostasis tends to be _______

- K and Cl homeostasis is ____

Answer 22

• inversely (K and Na)

- closely related (K and Cl)

Question 23

list 2 signs of potassium toxicity

- in ruminants?

Answer 23

• muscle weakness
• abnormal heart fxn
• grass tetany (hypomagnesemia) in ruminants

Question 24

T/F

Potassium deficiency is very common and induced by stress

Answer 24

False

• not common
• however, it can be induced by stress (which increases K secretion)