1.11 - Normal control of cell growth and differentiation

Question 1

what is hypertrophy

Answer 1

increase in the size of cells, leading to an overall increase in tissue or organ size.

Question 2

what is hyperplasia

Answer 2

increase in the number of cells within a tissue or organ, leading to an overall increase in size.

Question 3

What is atrophy

Answer 3

decrease in size or wasting away of tissue or organ due to a reduction in cell size and/or number of cells.

Question 4

What is hypotrophy

Answer 4

inadequate development or underdevelopment of tissue or organ, usually due to insufficient growth or nutrition.

Question 5

What is neoplasia

Answer 5

abnormal and uncontrolled growth of cells or tissues, forming a neoplasm (or tumor)

Question 6

What is apoptosis

Answer 6

programmed cell death process that occurs in a controlled and regulated manner.

e.g interdigital death zone

Question 7

What is necroptosis

Answer 7

a regulated form of necrosis (cell death) that combines features of both necrosis and apoptosis

traumatic cell death?

Question 8

5 stages of prenatal development

Answer 8

from cleavage to morula = proliferation BUT no increase in size = so cells get smaller

Question 9

what is a blastomere

Answer 9

cell produced by the early division (cleavage) of a fertilized egg (zygote) during the early stages of embryonic development.

within the first 30 hours

Question 10

draw out the 5 stages of pre-embryonic development

Answer 10

from cleavage to morula = proliferation BUT no increase in size = so cells get smaller

Question 11

structure of the blastocyst after 6 days / 8 days / 2 weeks

Answer 11

note germ layers form after 2 weeeks

Question 12

what are the primary germ layers

Answer 12

ectoderm

mesoderm

endoderm

Question 13

define trophoblast / embryoblast / epiblast / hypoblast

Answer 13

trophoblast =outer layer of cells in the blastocyst that will form the placenta

embryoblast =inner cell mass (ICM) of the blastocyst, which will develop into the embryo itself.

epiblast =upper layer of the embryoblast in the bilaminar disc

hypoblast = lower layer of the embryoblast in the bilaminar disc

Question 14

how do the primary germ layers form

Answer 14

gastrulation

Question 15

What is gastrulation, and why is it important in development?

Answer 15

process where the blastocyst reorganizes into a three-layered structure, forming the germ layers

Each germ layer gives rise to specific tissues and organs.

crucial for establishing body axes (e.g., anterior-posterior).

Question 16

how does gastulation occur

Answer 16

epiplast cells migrate over the surface and down into the primitive groove

first replacing hypoblast cells with endoderm

then filling space between epiblast and hypoblast with mesoderm

epiplast will soon become ectoderm

Question 17

What is neurulation

Answer 17

process by which the ectoderm forms the neural tube, which will develop into the brain and spinal cord.

Question 18

how does neuralation occur

Answer 18

neural plate folds into neural grove

As the neural folds approach each other, they fuse at the midline, forming the neural tube.

fusion starts in the cervical region (midway along the body axis) and proceeds both rostrally (towards the head) and caudally (towards the tail).

tube give rise to brain (rostral) + spinal cord

neural crest cells = found at edges of the neural folds

they will migrate + form PNS

neural folds close around day 24-26 = then CNS can form

Question 19

when does neurulation occur

Answer 19

week 3-4

Question 20

what is the neural plate

Answer 20

a flat, thickened region of the ectoderm.

Question 21

what are nueropores and function

Answer 21

openings at both ends of the tube

rostral neuropore closes around day 24 to form the brain region.

caudal neuropore closes around day 26 to form the spinal cord region.

Question 22

when does the body cavity form and what is it called

Answer 22

week 3-4

coelom

Question 23

what does each germ layer give rise to

Answer 23

ectoderm (formed by gastulation of the epiblast) = nervous system / skin / sense organs

mesoderm (Formed during gastrulation from the epiblast) = musculoskeletal + cardiovasuclar + reproductive

endoderm (gastrulation from the hypoblast) = digestive system / urinary system / endocrine glands

Question 24

development will be properly covered in 15

Answer 24

okay

Question 25

how is growth and division controlled

Answer 25

growth - growth factors

cell division - mitogens

Question 26

what are growth checkpoints

Answer 26

points within the cell cycle past which the cell will not progress unless specific growth factors are present

Question 27

where are growth checkpoints

Answer 27

Between G1 and S, where G1/S cyclin dependant kinases (CDKs) are required for progression

Between G2 and M, where G2 cyclin dependant kinases are required for progression

Question 28

how do growth factors work

Answer 28

binding to a complementary growth factor receptor on
their target cells, which releases a G-protein that activates intracellular signalling molecules
such as MAPK

signalling molecules then cause transcription factors to be inserted on target genes for growth in the nucleus and phosphorylated, resulting in the transcription and translation of
these genes

Macromolecule and organelle synthesis follow this and hence the cell grows, leading to its
proliferation once this reaches a certain point

Question 29

types of growth factors

Answer 29

Global growth factors with global effects

Global growth factors with specific effects

Local growth factors with local effects

Question 30

Global growth factors with global effects

Answer 30

Secreted into the blood, affect multiple tissue and cell types

Eg. IGF-1 (insulin-like growth factor from the liver)

Endocrine signallers as secreted through the blood to affect distant cells

Question 31

Global growth factors with specific effects

Answer 31

Also secreted into the blood, but only effect specific types of tissue or cell

Eg. Erythropoietin, which is produced in the kidneys and causes the growth of
erythrocyte progenitor cells in the bone marrow

Endocrine

Question 32

Local growth factors with local effects

Answer 32

Many morphogens in early development follow this, but it is also relevant in adults
as well

Eg. Nerve growth factor (NGF)

Paracrine or autocrine, so secretion into the extracellular matrix or through gap
junctions results in its action on neighbouring cells or itself only

Question 33

growth after birth

Answer 33

renewing tissue = skin / gut epithelium = continually diving stem cells

resting tissue = liver = cells only multiply to repair damage

non dividing tissue = neurones = do not multiply after birth