Anatomy and Cell Biology 3309 Lecture Notes - Lecture 1: Cerebrospinal Fluid, Dura Mater, Pia Mater
22 May 2018
School
Department
Professor
Histology 3309
Cerebrum and Cerebellum
The Brain
The Human Brain
- 2% of body mass but consumes 20% of energy of body
- top part is cerebrum (aka cortex)
- bottom small part is cerebellum
- spinal cord is sticking out from bottom
- if you cut it open,
o you see brain stem, which continues down as spinal cord
The Meninges
- tissue that wraps around the brain
- 3 layers of connective tissue:
o Dura mater
▪ Most outer layer
▪ Tough layer connected to skull
▪ Dense connective tissue
o Arachnoid
▪ Middle layer
▪ Contains blood vessels
▪ Loose connective tissue
▪ Has subarachnoid space (liquid filled space that contains the big blood vessels)
▪ Subarachnoid space is filled with cerebral spinal fluid
▪ Brain floats in cerebral spinal fluid that is contained in subarachnoid space
▪ Brain needs to be floating, suspended in a liquid that has a similar density as
brain mass itself so that the brain doesn’t compress itself
o Pia mater
▪ Most inner layer
▪ One cell layer (thin) membrane that covers surface of cerebrum and cerebellum
▪ Goes into the folds and sticks close to surface of nervous tissue
▪ Also lines along major blood vessels
- Note: meninges wrap around the brain but has NOTHING to do with the blood brain barrier
find more resources at oneclass.com
find more resources at oneclass.com
The Blood Brain Barrier
- O2,CO2 and certain lipophilic substances can pass
- Other substances have to be actively transported
- Endothelial cells connected with tight junctions, creating a capillary that is not fenestrated
- So everything that wants to diffuse out of the blood capillary and cant freely diffuse through
membranes has to be actively transported
- Endfeet of astrocytes are in close connected with endothelial cells pick up anything that is
transported through the endothelial cells and transport it to the neurons
- BBB is important in keeping things like glutamate out (this is needed as we get glutamate
through our diet and it would affect brain activity if it was able to cross BBB)
- Immune system of peripheral body cant access brain bc of BBB
- Multiple sclerosis
o If there is info going on in the brain, thhe BBB breaks down and T cells and other parts
of immune system can invade the brain
o Immune system attacks myelin sheath in CNS
- BBB is within the blood vessel
The Meninges
- DM =
o dura mater (dense connective tissue)
- Ar=
o Arachnoid
o With lots of hollow space
o See some blood vessels (small purple circles)
- PM=
o Pia mater
o Thin membrane that goes into folds of cortex
The Human Brain
- Brain is derived from the ectoderm
The Neural Tube
- when the embryo develops, at gestation date 20, the CNS starts to form
- there is a neural plate forming on the ectoderm on the outside of the embryo
- the neural plate starts to fold and form 2 ridges
find more resources at oneclass.com
find more resources at oneclass.com
- these 2 ridges come together and fuse, forming a tube
- the tube becomes totally detached from embryo
- this happens first in the middle of the embryo (before the head and tail end of the neural tube
closes)
- 21 days after gestation, the neural tube starts to close
- we start to see segmentation in embryo
- eventually, the neural tube completely close
o unless something goes wrong and it doesn’t close
o this is a condition called spina bifida
o this can be avoided by giving folic acid to pregnant women
o if there is a lack of folic acid, there is a risk that the neural tube at tail end does not
entirely close
- normally, the neural tube at the tail end does close, leaving the neural tube to deatch from the
bodies surface
- this neural tube (one tube of ectodermal tissue) gives rise to entire nervous system
Organization of the Brain
- the neural tube forms the entire nervous system (spinal cord, brain stem, fore
brain)
- at specific parts off the neural tube, the tissue grows immensely
o this happens at the hindbrain (where tissue bulges out and forms
cerebellum)
o there are some stocks growing out of interbrain, called the optic stocks –
these grow out and form the optic nerve in retina
o tissue in end brain grows immensely to create cerebrum (cortex)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The meninges tissue that wraps around the brain. Note: meninges wrap around the brain but has nothing to do with the blood brain barrier. O2,co2 and certain lipophilic substances can pass. Other substances have to be actively transported. Endothelial cells connected with tight junctions, creating a capillary that is not fenestrated. So everything that wants to diffuse out of the blood capillary and cant freely diffuse through membranes has to be actively transported. Endfeet of astrocytes are in close connected with endothelial cells pick up anything that is transported through the endothelial cells and transport it to the neurons. Bbb is important in keeping things like glutamate out (this is needed as we get glutamate through our diet and it would affect brain activity if it was able to cross bbb) Immune system of peripheral body cant access brain bc of bbb.
