HU Neuropsychology exam 4 (PSYC023)

Types and functions of Glia

1) Astrocyte (astroglia)- star-shaped cells providing physical and nutritional support for neurons (clean brain debris, transports nutrients, holds neurons in place, digests dead neurons, regulate context of extracellular space) 2) Microglia- like astrocytes, microglia digest parts of dead neurons. 3) Oligodendroglia- provide insulation (myelin) to neurons in the CNS 4) Satellite cells- provide physical support to neurons in the PNS 5) Schwan cells- provide insulation (myelin) to neurons in the PNS

How neurons are classified:

1) By number of extensions extending from the neurons cell body (soma) - bipolar neurons-2 processes extending from the cell body - pseudounipolar cells-2 axons, 1 extending toward the spinal cord and 1 extending toward the skin or muscle - multipolar neurons-many processes extending from the cell body. Each neuron has 1 axon 2) By the direction that they send information - sensory (afferent) neurons-send information from sensory receptors towards the CNS - motor (efferent) neurons-send information away from CNS to muscles or glands - interneurons-send information between sensory and motor neurons

Ways that neurons are different than other cells in the body:

1) Have specialized cell parts (dendrites and axons) dendrites bring electrical signals to the cell body, and axons take information away from the cell body 2) Communicate with each other through an electrochemical process 3) Contain some specialized structures and chemicals

Ways that Glia cells differ from neurons

1) Neurons have 2 processes (dendrites and axons), while Glial cells have 1 process 2) Neurons can generate action potentials, while Glial cells cannot. Glial cells do not have resting potential 3) Neurons have synapses that use neurotransmitters, while Glial cells do not have chemical synapses

Ways that neurons are Similar to other cells in the body:

1) Surrounded by a cell membrane 2) Have a nucleus containing genes 3) Contain cytoplasm, mitochondria, and other organelles 4) Carry out basic cellular processes like protein synthesis and energy production

Cerebrospinal fluid functions:

1.Protection (cushions the brain from damage) 2.Buoyancy (Pressure at the base is reduced from 1400g to 50g) 3.Excretion of waste products (takes harmful substances away from the brain) 4.Endocrine medium for the brain (transports hormones to other areas of the brain)

The brain receives what percent of the body's blood supply?

15-20%

The brain is what percent of the total body weight in humans?

2%

What is hydrocephalus and what does it result from?

A condition in which the cerebrospinal fluid builds up within the ventricles. It results from: 1. overproduction of cerebrospinal fluid 2. An obstruction within the ventricular system 3. Problems with cerebrospinal absorption

What can restore the balance in a neuron at rest?

A pump

When cerebrospinal fluid pressure is less than venous pressure what occurs?

Arachnoid villi will not let blood pass into the ventricular system.

Differences between axon and dendrites:

Axons: - take information from the cell body - smooth surface - 1 axon/cell - no ribosomes - myelin - branch further from cell body Dendrites: - bring information to the cell body - rough surface - many dendrites/cell - have ribosomes - no myelin insulation - branch near the cell body

Why does the brain receive so much of the body's blood supply?

Because brain cells will die If the supply of blood which carries oxygen is stopped.

Materials coming out of the brain:

Carbon dioxide, ammonia, lactate, and hormones.

When cerebrospinal fluid pressure is greater than venous pressure what occurs?

Cerebrospinal fluid flows into the bloodstream.

Nucleus

Contains genetic material, chromosomes

Neurons send messages how?

Electrochemically. Ions are electrically charged chemicals in the body. Neurons have a semi-permeable membrane because it allows the passage of some ions and blocks the passage of other ions.

Most knowledge we have about how neurons work comes from where?

Experiments on the giant axon of the squid

_ and _ are carried to the brain by many _ _ found on the surface of the brain and deep within the brain that enter through holes in the skull called _

Food;Oxygen;Blood vessels;Foramina

graded potential vs action potential

Graded potential occur at dendrite sites (chemical). Action potential occur at axons.

slatatory

Hopping, jumping

Arachnoid villi

How the cerebrospinal fluid exits the ventricular system (absorption of the cerebrospinal fluid into the blood stream takes place in the superior sagittal sinus)

Choroid plexus

Main structure producing cerebrospinal fluid in the lateral (2), third, and fourth ventricles.

Organelles in neurons:

Nucleus, Nucleolus, Nissl bodies, Endoplasmic Reticulum (ER), Golgi apparatus, Microfilaments/neurotubles, Mitochondria

Action potential of a neuron

Occurs when a neuron sends information down an axon, away from the cell body.

Resting potential of a neuron

Occurs when forces balance out and the difference in the voltage between the inside and outside of the neuron is measured.

Meninges of the brain:

PAD-Pia mater, arachnoid, dura mater.

Mitochondria

Produces energy to fuel cellular activities

Nucleolus

Produces ribosomes for translation of genetic information

Ventricles

System of fluid-filled cavities containing the cerebral spinal fluid.

What happens to the brain when hydrocephalus occurs?

The brain becomes compressed and moves out towards the skull.

Blood is supplied to the brain by 2 arteries called what?

The internal Carotid Arteries and Vertebral Arteries lying at the base of the brain.

Why do the right and left vertebral arteries come together and what do they form?

The right and left vertebral arteries come together to form a single basilar artery which joins the blood supply of the internal carotid arteries In a ring at the base of the brain (circle of willis).

Microfilaments/neurotubles

Transport for materials used for structural support

Threshold

When the depolarization reaches about -55mV and the neuron fires an action potential

A neuron is at rest when

a neuron is not sending a signal. When at rest, the inside of the neuron is negative relative to the outside. the concentration of ions cannot balance out because of the semi-permeable membrane.

Blood vessels in the brain:

anterior cerebral artery, anterior communicating artery, internal carotid artery, middle cerebral artery, posterior communicating artery, basilar artery, vertebral artery, anterior spinal artery.

cerebrospinal fluid (CSF)

clear, colorless fluid bathing the entire surface of the Central Nervous System.

interventricular foramen (foramen of monro)

connects lateral ventricles to third ventricle allowing the cerebrospinal fluid to flow this way.

cerebral aqueduct (Aqueduct of Sylvius)

connects the third and fourth ventricles allowing the cerebrospinal fluid to flow into the subarachnoid space.

Depolarizing current

creates the action potential; an explosion of electrical activity (a stimulus causes the resting potential to move towards 0mV)

Meningitis

inflammation of the meninges (symptoms-discomfort of the neck (tightness).

Neurons

nerve cells; cells of the nervous system that make up the human body. Different shapes and sizes.

Materials coming into the brain:

oxygen, carbohydrates, amino acids, fats, hormones, and vitamins.