Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Block 11 > Physiology Of Growth > Flashcards

Physiology Of Growth Flashcards

1
Q

Intrauterine growth phase is dependent on three factors….

A

Genetics

Nutrition

Placenta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What drives the infancy phase of growth

A

Nutritional factors in the first 2-3 years of postnatal life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Early childhood phase of growth is dependent on…

A

Growth hormones s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What regulates the pubertal growth spurt

A

Combination of GH and sex hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Growth is characterised by an increase in …..

A

Hypertrophy

Hyperplasia

Volume of intracellular material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Examples of when apoptosis occurs during foetal development

A

Webs between fingers are removed

Hollow organs such as the heart begin off as solid structures

Apoptosis normal event in fully developed tissues with sites of high cell turnover

Replacement and regeneration of cells in the skin, respiratory and GI tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What cellular changes are observed with a cell undergoing apoptosis

A

Condensation of the chromatin

Formation of membrane blebs that go on to form apoptotic bodies (cellular fragmentation)

Phagocytosis of bodies and fragments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What triggers the intrinsic and extrinsic pathways of apoptosis

A

Extrinsic = mainly by adjacent cells and immune cells via superfamily of caspases

Intrinsic = stimuli which is lethal such as DNA damage or ER stress, hypoxia and metabolic stress

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When is foetal growth at its peak

A

16- 20 weeks

By cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When does foetal weight gain peak

A

34 weeks

Due to deposition of fat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Senescent changes occur when

A

Sex hormones decline eg menopause

Reduces capability to initiate homeostatic mechanisms in response to internal or external environmental stresses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What change occurs to the cardiovascular system in senescence

A

Reduced blood flow

Arteriosclerosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Respiratory system senescence change:

A

Reduced elasticity of lungs

Decreased lung function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Urinary system changes in ageing

A

Decreased muscle tone and decreased GFR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Changes to the skin in senescence

A

Loss of elasticity —> sagging and wrinkling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Immune system senescent changes

A

Reduced sensitivity and responsiveness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens to brain in senescence

A

Impaired coordination, memory and intellectual function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Senescent changes to the GI system

A

Decreased GI muscle tone and less peristalsis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Senescent changes to endocrine function

A

Decreased in hormone production and sensitivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What happens to bones as a person ages

A

Decline in rate of Bone deposition
Decrease in mobility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens to muscular system as a person ages

A

Reduction in muscle mass, strength and ability

22
Q

Why does growth not occur after puberty

A

Epiphysis and diaphysis of bones fuse so no further increase in length is possible

23
Q

4 zones of bone growth at the epiphyseal plate

A

Proliferation zone = chondroblasts divide quickly and push the epiphysis away from the diaphysis lengthening the bone

Hypertrophic zone = chondrocytes enlarge and signal surrounding matrix to calcify

Calcification zone (not bone yet) matrix calcifies and chondrocytes die

Ossification zone

24
Q

Which types of hormones required in combination to result in growth

A

Growth hormones
Thyroid hormones
Sex hormones

25
Q

Effects of growth hormones

A

Produced by anterior pituitary

Direct = fat metabolism

Indirect = stimulates liver to produce IGFs which indirectly affect bones

26
Q

Which 5 tissues make IGF-1 and IGF-II

A

Liver
Kidney
Bone
Muscle
Cartilage

27
Q

Which IGF is stimulated by growth factor after birth and which plays a role in foetal development

A

IGF-I stimulated by GF after birth and is independent previous to birth. Rises during childhood and peaks at puberty and declines to low levels at old age

IGF-II = largely independent of GF and role in foetal development

28
Q

Overexpression of IGF-II in foetuses leads to

A

Disproportionate growth of tongue, other muscles, kidneys, heart and liver

29
Q

Role of thyroid hormones in growth

A

T3 - triiodothyronine
T4 - thyroxine

Secretion commences at 15-20 wks of gestation

Essential for protein synthesis in brain of foetus and young children
Normal differnetaotn and maturation of skeletal and nervous tissue
Promotes linear growth of bone until puberty and ossification of bones and maturation of epiphyseal growth regions

30
Q

Deficiencies in thyroid hormones lead to

A

Mental retardation
Insufficient bone and height growth

31
Q

What is cretinism

A

Inadequate levels of thyroid hormones during foetal period lead to severe mental retardation

Due to:
- decrease in size and number of cerebral cortical neurons
- reduction in degree of branching of dendrites
- deficiencies in myelination of nerve fibres
- reduced blood supply to the brain

32
Q

Hypothyroidism detected at birth if left untreated leads to what

A

Permanent neurological and intellectual damage (cretinism)

33
Q

In relation thyroid function what does the Guthrie blood spot detect

A

High TSH levels in case of hypothyroidism

34
Q

How do corticosteroids affect growth

A

Cortisol if in excess has inhibitory actions on growth

Interfere with cartilage and bone synthesis at growth plates = increased rate of skeletal maturation so potential for further growth is reduced

35
Q

How do sex steroids influence growth

A

Androgens have anabolic effects

Oestradiol and testosterone (leydig cells) positive effect on secretion of GH

Results in increase in long bone growth and height

36
Q

Somatotropin/ growth hormone is what kind of hormone

A

Peptide hormone

37
Q

What is the diurnal variation in secretion of GH

A

Most secretions occur with slow wave deep sleep
(Pursatile bursts)

38
Q

How does GH secretion change over lifetime

A

Continues to increase from birth until puberty where it peaks. Slight decline in adulthood which remains constant until senescent age (significant reduction but still constant in this period)

39
Q

How does IGF-1 inhibit secretion of GH to regulate levels of growth

A

1) direct inhibition by suppressing somatotrophs

2) indirectly reducing gnRH release from arcuate nucleus in hypothalamus

3) indirectly via increasing secretion of somatostatin from periventricular region

40
Q

What is achondroplasia

A
  • dwarfism
  • autosomal dominant inheritance pattern
  • mutation in gene on C. Four that code for fibroblast growth factor receptor 3 FGFR3

Avg male height 125cm
Avg female height 120cm

41
Q

Mutation of gene that produces FGFR3 results in what

A

Increased function of gene which:

Decreased endochondral ossification

Inhibited proliferation of chondrocytes in growth plate cartilages

Decreased cellular hypertrophy and decreased cartilage matrix production

Earlier closure of epiphyseal plates

42
Q

Presentation of achondroplasia

A

Large forehead

Proportionate trunk but limbs are v small compared to rest of body

43
Q

What causes acromegaly

A

Hypersecretion of GH

Adenoma of pituitary somatotroph cells

Affects all organs and tissues. Leads to gigantism

44
Q

Those with acromegaly at higher risk of

A

T2 DM

CVD

Hypertension

Arthritis

45
Q

How is GH secretion pattern diurnally different in those with acromegaly

A

Constant elevated levels throughout day and night

46
Q

A way to test for acromegaly

A

Administer glucose

Glucose normally suppresses GH secretion but in those with acromegaly there is no change

47
Q

What is pituitary dwarfism

A

GH deficiency may be accompanied by under secretion of other pituitary hormones. As a result skeleton fails to grow and 120cm height achieved with normal proportions

48
Q

Causes of pituitary dwarfism

A

Pituitary or hypothalamic tumours

Infections such as meningitis or syphilis

Pituitary infarction and vascular malformations

Head trauma

49
Q

What is panhypopituitarism

A

Absence of all pituitary hormones

50
Q

What is Laron dwarfism

A

Mimics GH deficiency but GH levels are high

Levels of IGF-I and IGFbinding protein3 are low

Caused by mutation in GH receptor - becomes unresponsive —> growth retardation

Treated with recombinant IGF-1

51
Q

What is the most common cause of growth failure worldwide

A

Malnutrition

Mainly due to lack of protein and other basic nutrients

Shows sign of weakness, frailty and muscle wasting

Block 11 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions