8. Animal Organogenesis And Circulation

Question 1

What is a gastrula?

Answer 1

An animal embryo with three layers of cells (endoderm, ectoderm, mesoderm) surrounding a central cavity with a small opening (blastopore) to the exterior.

Question 2

What is invagination?

Answer 2

The process of being turned inside out or folded back on itself to form a cavity or pouch.

Question 3

What is morphogenesis?

Answer 3

The origin and development of morphological characteristics.

Question 4

What is embryogenesis?

Answer 4

The process of initiation and development of an embryo from a zygote.

Question 5

What is a gastrocoel?

Answer 5

The primitive gut formed during gastrulation.

Question 6

What do the germ layers develop into?

Answer 6

Every other type of tissue in the body.

Question 7

The gastrulation of embryos only occurs in…?

Answer 7

Animals.

Question 8

Why are diploblast body plans simpler than triploblast body plans?

Answer 8

Diploblasts lack certain structures and tissues derived from the mesoderm, such as muscles and most internal organs.

Question 9

What is the classification of an animal where the blastospore forms the anus?

Answer 9

A deuterostome.

Question 10

What is the classification of an animal where the blastospore forms the mouth?

Answer 10

A protostome.

Question 11

What is a protostome?

Answer 11

An animal where the blastospore eventually forms the mouth.

Question 12

What is a deuterostome?

Answer 12

An animal where the blastospore eventually forms the anus.

Question 13

Unlike most other animals’ eggs, human eggs are…?

Answer 13

1. Small.
2. Contain very little nutrition for the developing embryo.

Question 14

What are 4 steps of human embryonic development?

Answer 14

1. The egg is released from the ovary into the oviduct, where it is fertilised.
2. The zygote travels down the oviduct to the uterus over 6 days, undergoing cleavage to form a blastocyte (mammalian blastula).
3. The outer layer of the blastocyte initiates the implementation of the embryo into the wall of the uterus on day 7.
4. Extra embryonic layers start to form after about 10 days and gastrulation begins.

Question 15

What are the 3 ways mammals give birth?

Answer 15

1. Laying eggs. monotremes
2. Birthing at an early developmental stage. marsupials
3. Birthing fully developed offspring. humans and whales

Question 16

What 2 things are considered adaptions for land animals to enable embryonic development in a fluid environment?

Answer 16

1. Shells.
2. The uterus.

Question 17

What are the 4 extraembryonic membranes?

Answer 17

1. Amnion.
2. Chorion.
3. Yolk sac. Vitellus
4. Allantois.

Question 18

What is the purpose of the amnion membrane?

Answer 18

Fiills with amniotic fluid, causing the ammion to expand and become the amniotic sac.
Provides a protective environment for the developing embryo.

Question 19

What is the purpose of the chorion membrane?

Answer 19

The outermost membrane.
Largely used for gas exchange of O2 and CO2.

Question 20

What is the purpose of the yolk sac membrane?

Answer 20

1. Provides nutrition before the formation of the placenta.
2. Produces RBCs.
3. Gas exchange between mother and embryo in a mammal.

Question 21

What is the purpose of the allantois membrane?

Answer 21

1. Associated with the formation of the placenta and umbilical chord in mammals.
2. Disposes of waste in reptiles.

Question 22

What is the placenta?

Answer 22

An organ that develops in the uterus during pregnancy.
Provides oxygen and nutrients to a growing baby, as well as removing the baby’s waste products.

Question 23

What is neurulation?

Answer 23

The process of the neural plate bending and fusing to form the hollow tube that will differentiate into the brain and spinal cord of the CNS.
A type of organogenesis.

Question 24

What is the notochord?

Answer 24

A cartilaginous skeletal rod supporting the body in all embryonic and some adult chordate animals.

Question 25

What is the neural tube?

Answer 25

The structure that forms the early brain and spinal cord.

Question 26

What are somites?

Answer 26

Precursor cells that give rise to important structures associated with the vertebrate body plan.
They eventually differentiate into skeletal muscle, cartilage, tendons, and vertebrae.

Question 27

What are neural crest cells?

Answer 27

Embryonic cells pinched off during the formation of the neural tube that migrate extensively to form sensory and autonomic neurons.
They also produce parts of the teeth and skull bones.

Question 28

What is induction?

Answer 28

The process of a group of cells or tissues influencing another group through close-range interactions.

Question 29

What are 3 steps of neurulation?

Answer 29

1. The neural plate forms the dorsal epidermis (ectoderm).
2. The neural tube develops from the folding and pinching of the neural plate.
3. The neural crest cells form between the epidermis and the neural tube.

Question 30

Which precursor cells determine the migration paths of neural crest cells?

Answer 30

Somites.

Question 31

Which structure helps embryonic cells migrate? How?

Answer 31

The cytoskeleton.
It enables cells to ‘crawl’ through the extracellular matrix by extending and retracting fibres.

Question 32

What is the cytoskeleton?

Answer 32

A structure that helps cells maintain their shape and internal organisation while providing mechanical support for functions like division and movement.
Capable of rearranging - enabling the cell to change shape.

Question 33

What mechanism is used to help with organ sculpting?

Answer 33

Cell apoptosis - programed cell death that kills off unnecessary cells.