Lec 2/3 Flashcards
Neuroaxis for animals?
same plane as the ground
Neuroaxis for humans?
tilted by 90 degrees
Why are directional terms given in biology?
In biology, directional terms are given with respect to the organism’s body axis.
These terms are important for navigating creatures with unusual body planes or lifestyles.
What is a coronal section?
a coronal section is cut in a vertical, from the crown of the head down, yielding a frontline’s view of the brain’s internal structures
What is a horizontal section?
the view or the cut falls along the horizon, is usually viewed looking down on the brain from above, a dorsal view
What is a sagittal section?
cut lengthways from front to back and viewed from the side, a medial view. Imagine the brain oriented as an arrow - in Latin, Sagitta
The nervous system is organized into ________________
the central and peripheral divisions
What does the central nervous system consist of?
Brain
Spinal cord
What does the peripheral nervous system consist of?
Somatic nervous system
Autonomic nervous system
What is the brain and spinal cord encased by?
The brain is encased by the skull, the spinal cord is encased by the vertebrae
What type of connections are in the peripheral nervous system?
- sensory connections to receptors in the skin
- motor connections to body muscles
- sensory and motor connection to internal organs
What are the two divisions and subdivisions of the peripheral nervous system?
Somatic (meaning “body”) nervous system:
- Efferent (outgoing) nerves: Motor nerves that connect the CNS to the skeletal muscles.
- Afferent (incoming) nerves: Sensory nerves that carry information from the sense organs to the CNS.
Autonomic (independent, out of our control) nervous system: Regulates homeostasis.
- Sympathetic nervous system (SNS): Arousing. “Fight or flight.”
- Parasympathetic nervous system (PNS): Calming. “Rest and digest.” (Also for returning to homeostasis)
What are some of the things the parasympathetic nervous system does?
- contracts pupils
- constricts bronchi
- slows heart beat
- stimulates activity in stomach/intestines
- dilates vessels
What are some of the things the sympathetic nervous system does?
- dilates pupils (enhanced vision)
- relaxes bronchi (increased air to lungs)
- accelerates/strengthens heartbeat
- inhibits activity in the stomach/intestines (blood sent to muscles)
- contracts vessels (increased blood pressure)
What are ventricles?
The brain is cushioned and supported by a series of inter-connected hollow spaces
The ventricles are clearly visible in coronal and horizontal sections of the brain.
What happens to ventricles during stress?
They are enlarged when there is cell loss
This is because stress causes us to lose brain cells and this results in a loss of brain volume in the skull. The ventricles enlarge to account for the extra space in the skull (because of volume loss)
What are the brain and spinal cord protected by?
protected by special membranes called meninges.
What happens when the meninges is infected?
When these membranes are infected, meningitis results
What is the meninges made up of?
Dura matter
Arachnoid
Pia matter
What view does a coronal section yield?
a frontal view
What view does a horizontal section yield?
a dorsal view
What view does a sagittal section yield?
a medial view
What does dura mean?
hard
What does arachnoid mean?
means spidery (looks like a spider web) where the CSF circulates
What does Pia mean?
means pious because it’s very thin - stuck into the surfaces of the skull
What is the CSF?
fills the ventricles and circulates around the brain and spinal cord.
Provides cushioning for the brain as it is encased in the skull (however not very good at protecting)
What allows the brain to float comfortably in the skull?
CSF possesses a similar density to the brain
What is the CSF made of?
Like plasma, CSF contains glucose, various salts, and minerals, but unlike plasma it contains very little protein - this is why it looks black when you image the brain
a few ________ of ___________________ are all that separate the brain from the dangers of the outside world
millimetres; skin, bone, and muscle
What is the blood-brain barrier?
The tight gaps between endothelial cells (cells that line the blood vessels) that prevent large molecules from passing into the brain
what separates brain tissue from the bloodstream.
One of the protective mechanisms of the nervous system; prevents potentially lethal substances from entering the brain
Why is the blood-brain barrier not perfect?
Lipophilic and gases can pass this barrier so it’s not perfect.
specialized proteins can use active transport to pass through
___________ cannot enter the brain
hydrophilic proteins
What is the Area Postrema?
(back part of bran) responsible for vomiting – if youinjesteda toxin that passed the blood brain barrier the first area it will hit is the area postrema and this will make you vomit to get the toxin out
Who is Santiago Ramon y Cajal?
Santiago – first person to take images of brain cells – traced images of what he saw through the microscope
Saw dendritic spines
What do dendritic spines do?
Dendritic spines- allow increased surface area – more contact
What are neurons?
The basic information processing units of the brain.
Are specialized cells that are specialized for transferring information from one place to another.
What are glial cells?
- Support and modulate neurons’ activities.
- Creates the myelin sheath - increases the conductivity of neurons
- Makes contact with the blood vessels and provides the active transport of nutrients from the circulatory system to the neurons
- Glial cells actually have much of an active role in the nervous system (they can actually communicate between each other)
How many neurons are in the brain?
Approximately 80 billion in the human brain.
How many glial cells are in the brain?
Approximately 100 billion in the human brain.
What can you use to see the neurons?
Apply Golgi stains that only penetrate certain proteins –only stick to neurons, or cell membranes. Slices of cells and apply stains to them.
Why are neurons organized and what happens when it isn’t?
All these neurons are orientated in the same direction – very organized to enhance cell communication – in schizophrenia and certain psychiatric disorders thisorganizalstructure does notoccur
What are the specialized structures that make up neurons?
-Dendrites (“tree”)
Gather information from other neurons.
-Cell body (also known as the soma)
Core region; contains the nucleus and DNA.
-Axon hillock
Junction of the cell body and axon, summing all the electrical changes that occur across the cell membrane. Where the action potential is generated
-Axon
Carries information to be passed onto other cells.
-Terminal button
Knob at the tip of an axon that conveys information to other neurons.
Connects with dendrites of other neurons.
__________ tells us a little bit about their function
form of a cell
What are axons covered in?
Myelin sheath