Whole Body Growth Lecture

Question 1

Cumulative growth over time is shaped like

Answer 1

sigmoidal curve

Question 2

Cumulative weight is expressed as

Answer 2

total weight at any given time

Question 3

Shape of cumulative growth is really

Answer 3

stair stepped due to sporadic growth spurts

Question 4

Self accelerating phase is characterized by

Answer 4

exponential growth
rapid growth with little complexity

Question 5

In the Self-accelerating phase velocity of growth continues to increase because

Answer 5

there are more and more cells available to divide

Question 6

rate at which each cell divides soon begins to slow because it becomes

Answer 6

difficult to supply each cell with nutrients and efficiently remove harmful waste

Question 7

How does the embryo respond to the slowing of the rate at which each cell divides

Answer 7

develops increasingly complex transport mechanisms to supply nutrients and remove waste

Question 8

when acceleration force is in balance with the counteracting effects of increased complexity and limited nutrients, growth becomes

Answer 8

linear

Question 9

Point of Inflection

Answer 9

point of maximum growth velocity after which the animal will continue growing but at a decreasing rate

Question 10

Maximum growth velocity=

Answer 10

period of greatest ADG

Question 11

Point of inflection occurs during

Answer 11

puberty

Question 12

Self-decelerating phase

Answer 12

animal approaches mature weight at a decreasing rate of growth

Question 13

Reduced growth rate is controlled by

Answer 13

many signals including the secretion of somatostatin by the hypothalamus

Question 14

Asymptote

Answer 14

Point at which food intake matches maintenance requirement
Mature body weight

Question 15

Mature body weight fluctuates throughout life depending on

Answer 15

available food
reproductive cycle
season

Question 16

Failure of vital systems is usually after the

Answer 16

reproductive phase of life

Question 16

Growth may be compared as a function of

Answer 16

chronological age
physiological age

Question 16

why is the death of an animal important

Answer 16

ensures space for the next generation

Question 17

Growth over time may be described using different types of curves:

Answer 17

Cumulative
absolute
relative

Question 18

Chronological age

Answer 18

age in absolute time units
not the same for every animal

Question 19

Factors that influence growth that can alter the shape of the growth curve

Answer 19

Nutrition
disease
stress
activity level

Question 20

Physiological age is used to

Answer 20

overcome drawbacks of using chronological age as a point of comparision

Question 21

Physiological age refers to specific physical or chemical stages of maturity including

Answer 21

height
weight
composition
puberty

Question 22

sexual maturity

Answer 22

the age at which animals are successfully able to reproduce

Question 23

Cumulative growth curve

Answer 23

plot of total animal weight over time sigmoidal curve

Question 24

Cumulative curves are useful to compare growth but are

Answer 24

not easy to interpret to determine the period of maximum growth (point of inflection)

Question 25

Absolute growth rate curve

Answer 25

plots gain per unit of time against time ADG per unit of time

Question 26

Calculating overall absolute growth rate

Answer 26

ADG=(Y2-Y1)/(t2-t1)

Question 27

Is absolute growth rate curve a true growth rate of the animal

Answer 27

no- rate changes as an animal grows ADG is only accurate if the time interval is short

Question 28

Are we measuring growth relative to where the animal is on its Growth curve using ADG

Answer 28

No

Question 29

Relative growth rate curve

Answer 29

growth in relation to total weight whole body or individual tissue growth

Question 30

Relative growth is greatest

Answer 30

During initial stages of development because animal is small decreases as the animal continues to grow

Question 31

Relative growth rate curve equation

Answer 31

RGR=(LnY2-LnY1)/(t2-t1)

Question 32

whole body growth curves represent a

Answer 32

sum of growth of many different tissues that develop at dramatically different rates

Question 33

First person to fully appreciate whole body growth curve

Answer 33

John Hammond (1889-1964)

Question 34

Hammond studies animals under

Answer 34

typical conditions and under malnutrition

Question 35

Hammond's observations

Answer 35

body components that are physiologically more important develop first Extremities complete their development first

Question 36

Allometric growth

Answer 36

study of how body parts change in size as an animal develops

Question 37

Julian Huxley studies

Answer 37

allometric growth in fiddler crabs fighting claw compared to the rest of the body

Question 38

b>1

Answer 38

tissue is growing at a faster rate than the whole and has a high growth impetus and are considered late developing tissues

Question 39

b<1

Answer 39

tissue is growing at a slower rate than the whole body and has a low growth impetus and are considered early developing tissues

Question 40

b=1

Answer 40

tissue is growing at a similar rate than the whole and has an average growth impetus also called isometric growth

Question 41

Allometric growth based on proportions does not fully describe

Answer 41

growth changes

Question 42

When nutrition is limiting the tissues have

Answer 42

a different priority for nutrients, based on the sequence in which they developed and on their functional priority

Question 43

Is allometric growth useful

Answer 43

yes- some tissues do grow in proportion to the whole

Question 44

early developing muscles

Answer 44

distal aspects of thoracic and hind limbs proximal thoracic and hind limb

Question 45

late developing muscle

Answer 45

abdominal muscle neck to thoracic limb- increased weight bearing duties and potential increases from secondary sex characteristics

Question 46

Muscles developing at similar rate to the rest of the body

Answer 46

muscles surrounding the spinal column

Question 47

we can measure changes in tissue or chemical composition on an

Answer 47

absolute basis percent basis

Question 48

absolute basis

Answer 48

cumulative weight gain over time

Question 49

percent basis

Answer 49

proportion of the total body weight over time

Question 50

Maximum growth for each tissues occurs

Answer 50

Bone>Muscle>Fat

Question 51

chemicals in bone, muscle and fat

Answer 51

water protein lipid ash

Question 52

Fat becomes a ______ proportion of the body with age

Answer 52

larger

Question 53

muscle and bone make up a ______ proportion with age

Answer 53

smaller

Question 54

water and protein make up a _____ proportion with age

Answer 54

smaller

Question 55

Water is how much of muscle

Answer 55

68-85%

Question 56

Water content is greatest

Answer 56

early in life and decreases with age

Question 57

Absolute and percentage protein content

Answer 57

increases with age

Question 58

Water content of fat cells is ___ early on and _____ with age

Answer 58

high decreases

Question 59

Protein content in bone is ___ early and ____ later in life

Answer 59

greatest decreases

Question 60

Absolute mineral content

Answer 60

increases with age

Question 61

Fat content tends to ____ in bone

Answer 61

increase

Question 62

Connective tissue ____ with age

Answer 62

increases

Question 63

collagen and elastin increase significantly with muscle development but as a percentage it _____ with age

Answer 63

decreases

Question 64

as muscle atrophies with age, percentage of connective tissue

Answer 64

increases