FROM CRADLE TO GRAVE: DEVELOPMENT,
AGEING, AND DISEASE
BBS2002 – Summary
2023 -2024
Maastricht University
Faculty of Health Medicine and Life
Joséphine Misonne
1
,2
, 1. BRAIN DEVELOPMENT
a. PRE-NATAL DEVELOPMENT
During embryogenesis, the embryo begins as a flat disc of 3 layers:
- Endoderm
- Mesoderm
- Ectoderm (nervous system)
Neurulation = process by which the nervous system is formed from the ectoderm.
The notochord directs and induces the thickening of the
ectodermal cells to form the neural plate.
The central cells of the neural plate move outward, forming the
neural groove and the neural folds.
The continued movement of the central portion of the neural
plate brings the two neural folds together, forming the neural
tube (forms the brain and the spinal cord – CNS)
+ neural crest (give rise to PNS)
Three-vesicle stage
The first stage of the formation of brain structure is called three-
vesicle stage: at early stages of development the first three major
brain vesicles are visible and start to develop:
- Prosencephalon (forebrain)
- Mesencephalon (midbrain)
- Rhombencephalon (hindbrain)
Five-vesicle stage
The three vesicles further develop and give rise to five vesicles.
- Prosencephalon → telencephalon and diencephalon
- Mesencephalon
- Rhombencephalon → metencephalon and myelencephalon
Out of those five vesicles, the brain cells start to develop.
3
, b. BRAIN CELLS
There are two kinds of cells in the nervous system:
- Neurons: propagate the signals of the nervous system
- Glial cells (neuroglia): supporting cells.
NEURONS
Anatomy
- Soma = biggest part of the neuron. It’s the cell body. It
contains the nucleus, the mitochondria, and the
endoplasmic reticulum. It’s the receptive service for
interaction with other neurons.
- Dendrites = branched processes from soma. It’s the
receptive area for incoming signal. Multiple axons can
connect to one single dendrite.
- Axon = the output site. The action potential travels all
the neurons from the soma, through the axon, to the
other side. The axon is most of the time myelinated by
oligodendrocytes (CNS) and Schwann cells (PNS)
- Nissl bodies = the rough endoplasmic reticulum (RER)
combine with a complex of RNA and protein.
➔ Made up of grey matter.
Action potential
The axons that connect to one dendrite give it neurotransmitter. That leads to a graded action potential
(not full depolarization) on the dendrite. If there is sufficient stimuli coming in, the change will be big
enough to generate an action potential at the axon hillock/trigger zone.
The potential can be:
- Excitatory postsynaptic potential (EPSP) → hyperpolarization
- Inhibitory postsynaptic potential (IPSP) → hypopolarization
4
AGEING, AND DISEASE
BBS2002 – Summary
2023 -2024
Maastricht University
Faculty of Health Medicine and Life
Joséphine Misonne
1
,2
, 1. BRAIN DEVELOPMENT
a. PRE-NATAL DEVELOPMENT
During embryogenesis, the embryo begins as a flat disc of 3 layers:
- Endoderm
- Mesoderm
- Ectoderm (nervous system)
Neurulation = process by which the nervous system is formed from the ectoderm.
The notochord directs and induces the thickening of the
ectodermal cells to form the neural plate.
The central cells of the neural plate move outward, forming the
neural groove and the neural folds.
The continued movement of the central portion of the neural
plate brings the two neural folds together, forming the neural
tube (forms the brain and the spinal cord – CNS)
+ neural crest (give rise to PNS)
Three-vesicle stage
The first stage of the formation of brain structure is called three-
vesicle stage: at early stages of development the first three major
brain vesicles are visible and start to develop:
- Prosencephalon (forebrain)
- Mesencephalon (midbrain)
- Rhombencephalon (hindbrain)
Five-vesicle stage
The three vesicles further develop and give rise to five vesicles.
- Prosencephalon → telencephalon and diencephalon
- Mesencephalon
- Rhombencephalon → metencephalon and myelencephalon
Out of those five vesicles, the brain cells start to develop.
3
, b. BRAIN CELLS
There are two kinds of cells in the nervous system:
- Neurons: propagate the signals of the nervous system
- Glial cells (neuroglia): supporting cells.
NEURONS
Anatomy
- Soma = biggest part of the neuron. It’s the cell body. It
contains the nucleus, the mitochondria, and the
endoplasmic reticulum. It’s the receptive service for
interaction with other neurons.
- Dendrites = branched processes from soma. It’s the
receptive area for incoming signal. Multiple axons can
connect to one single dendrite.
- Axon = the output site. The action potential travels all
the neurons from the soma, through the axon, to the
other side. The axon is most of the time myelinated by
oligodendrocytes (CNS) and Schwann cells (PNS)
- Nissl bodies = the rough endoplasmic reticulum (RER)
combine with a complex of RNA and protein.
➔ Made up of grey matter.
Action potential
The axons that connect to one dendrite give it neurotransmitter. That leads to a graded action potential
(not full depolarization) on the dendrite. If there is sufficient stimuli coming in, the change will be big
enough to generate an action potential at the axon hillock/trigger zone.
The potential can be:
- Excitatory postsynaptic potential (EPSP) → hyperpolarization
- Inhibitory postsynaptic potential (IPSP) → hypopolarization
4
