exam one psb3002

Conclusions of Santiago Ramon y Cajal's work

Nerve cells remain separate instead of merging

Parts of an animal cell

Membrane, nucleus, mitochondria, ribosomes, and endoplasmic reticulum

Cell membrane function

Controls the movement of substances into and out of the cell

Nucleus function

The command center of the cell that contains the chromosomes

Mitochondrion function

Performs metabolic activities and provides energy for the cell

Ribosome function

Site of protein synthesis

Endoplasmic reticulum function

Thin tubes that transports newly synthesized proteins to other parts of the cell

Parts of a neuron

Dendrites, dendritic spines, body/soma, axon, and presynaptic terminal

Dendrite function

Branchlike parts of a neuron that are specialized to receive information

Dendritic spine function

Outgrowths that increase surface area

Cell body/soma function

Contains the nucleus, ribosomes, and mitochondria. Most of a neuron's metabolic work occurs here.

Axon function

A thin fiber of a constant diameter that conveys impulses towards neurons, organs, or muscles

Presynaptic terminal function

Bulb where the axon releases chemicals that cross through the junction from one neuron to another

Characteristics of glia cells

Means glue, smaller but more numerous than neurons, no action potential

Astrocytes

Glia cell, wrap around the presynaptic terminal and shieds its from chemicals. Removes waste, controls blood flow.

Microglia

Acts as a part of the immune system, removes waste, viruses and fungi from the brain. Proliferate after brain damage and in most brain diseases

Oligodendrocytes

In the brain and spinal cord, build myelin sheaths that surround certain vertebrate axons, supply axons with nutrients

Schwann cells

In the periphery of the body, build myelin sheaths that surround certain vertebrate axons, supply axons with nutrients

Radial glia

Guides the migration of axons and dendrites during embryo development

Advantages and disadvantages of the blood-brain barrier

It keeps out both useful (fuels, amino acids) and harmless chemicals

Main source of nutrition for vertebrate neurons

Glucose

What is the membrane of a neuron made of?

Phospholipids and proteins

What is a polarized membrane?

When the membrane maintains an electrical gradient, a difference in electrical charge between the inside and outside of a cell

What is resting potential?

When the neuron inside the membrane has a slight negative potential (due to negatively charged proteins inside the cell) with respect to the outside

What happens with sodium and potassium channels when a neuron's membrane is at rest?

The channels are closed, no sodium gets through, a small flow of potassium gets through

When the neuron's membrane is at rest, does the concentration gradient drive sodium into or out of the cell?

Draws sodium in

Does the concentration gradient drive potassium into or out of the cell?

Drives potassium out

Does the electrical gradient drive sodium into or out of the cell?

Drives sodium out

Does the electrical gradient drive potassium into or out of the cell?

Draws potassium in

Action potential

Messages sent by axons

Hyperpolarization

Increased polarization, makes cell more negative, inhibits action potential, potassium out

Depolarization

Decreased polarization, sodium in

What happens when depolarization reaches the threshold of excitation?

All-or-none response

Chemical events (stages) behind the action potential

Stimulus, depolarization, action potential, hyperpolarization, refractory period

Myelin sheath function

Insulates the axon from chemical and physical stimuli that might interfere with the transmission of nerve impulses

Difference between temporal and spatial summation

Temporal: one neuron, many stimuli in close sequence. Spatial: multiple neurons, many stimuli occurring at same time

EPSP

Excitatory postsynaptic potential; graded depolarization

IPSP

Inhibitory postsynaptic potential; temporary hyperpolarization

When do EPSPs occur?

When sodium channels open and sodium rushes into the neuron

When do IPSPs occur?

When input opens gates for potassium (carrying positive charge) to leave or chloride (carrying a negative charge)

Difference between EPSP and an action potential

Action potentials are generated by the cell body and EPSPs are generated by the presynaptic neuron

Relationship among EPSP, IPSP, and action potential

EPSPs increase the chances of a postsynaptic action potential and IPSPs decrease the chances

When is an action potential more likely to occur?

If the threshold is not reached

What determines whether a neuron will fire?

Ratio of EPSPs to IPSPs

Increased permeability to which type of ion would most likely result in an IPSP?

Chloride

Increased permeability to which type of ion would most likely result in an EPSP?

Sodium

Types of neurotransmitters

amino acids, monoamines, acetylcholine, neuropeptides, purines, gases

Characteristics of nitric oxide

Colorless, nonflammable, toxic gas that supports combustion

Synthesis of acetylcholine

Acetyl coenzyme A (from metabolism) + Choline (from metabolism or diet) -> Acetylcholine

Synthesis of dopamine

Phenylalanine (from diet) -> Tyrosine -> Dopa -> Dopamine

Synthesis of norepinephrine

Dopamine -> Norepinephrine

Synthesis of epinephrine

Norepinephrine -> Epinephrine

Where are neurotransmitters stored?

Vesicles

Where are vesicles located?

In the cytoplasm

What chemical events take place when the action potential reaches the end of the axon?

Depolarization opens voltage-dependent calcium gates in the presynaptic terminal. 1-2 ms after calcium enters, it enters exocytosis

What happens when a neurotransmitter is released by the presynaptic cell?

It diffuses across the synaptic cleft to the postsynaptic membrane where it attaches to a receptor

What is exocytosis?

Bursts of release of neurotransmitter from the presynaptic neuron

Difference between ionotropic and metabotropic effects

Ionotropic are faster and metabotropic are slower

How is acetylcholine inactivated?

It is broken down by acetylcholinesterase into acetate and choline

What role do transporter proteins play in the reuptake process?

Any transmitters not taken up by transporters are broken down into an enzyme called COMT

Role of autoreceptors

Receptors that provide negative feedback

Central nervous system subdivisions

Brain and spinal cord

Peripheral nervous system subdivisions

Somatic and autonomic

Characteristics of autonomic nerves

Controls the heart, intestinesm and other organs

Characteristics of somatic nerves

Consists of the axons that convey messages from sense organs to the CNS and from the CNS to the muscles

Coronal

Brain as seen from the front

Horizontal

Brain as seen from above

Sagittal

Brain as seen from the side

Where are the bodies of sensory and motor neurons located?

Dorsal root ganglia

Differences between the sympathetic and parasympathetic nervous system

Sympathetic prepares the body for physical activity (like fight or flight) and para is for resting

Which neurotransmitter is primarily used by the parasympathetic nervous system?

Acetylcholine

Which neurotransmitter is primarily used by the sympathetic nervous system?

Norepinephrine (and some use acetylcholine)

Forebrain structure and characteristics

Two hemispheres, each is organized to receive info and control muscles from the opposite side of the body

Midbrain structure and characteristics

Middle of the brain, superior and inferior colliculus. Both are important for sensory processing

Hindbrain structure and characteristics

Medulla, pons, and cerebellum. Make up the brainstem

What parts of the brain constitute the limbic system?

Olfactory bulb, hypothalamus, hippocampus, amygdala, and cingulate

What is the function of the limbic system?

Motivation and emotion

Superior colliculus function

Receives visual sensory input

Inferior colliculus thalamus function

Receives auditory input

Basal ganglia function

Movement and motor control

Hypothalamus function

Conveys messages to the pituitary gland

Hippocampus function

Memory (specifically for individual events)

What are the ventricles of the brain?

Four cavities filled with cerebrospinal fluid

Where are the ventricles located?

One in each hemisphere, towards their posterior they connect to the third ventricle which connects to the fourth in the center of the medulla

What structures of the brain are filled with cerebrospinal fluid (CSF)?

Ventricles

Cerebrospinal fluid (CSF) function

Clear fluid similar to blood plasma that fills ventricles. It cushions the brain, provides buoyancy, has a reservoir of hormones and nutrition for the brain and spinal cord

What structures connect the two hemispheres?

Corpus callosum

Cerebral cortex lobes

Frontal, parietal, occipital, temporal

Frontal lobe characteristics and functions

Contains primary motor cortex and prefrontal cortex. Controls fine movements

Temporal lobe characteristics and functions

Primary target for auditory info, contributes to complex vision including perception of movement and recognition of faces. Important for emotional and motivational behavior

Occipital lobe characteristics and functions

Visuals, eyes provide the stimulus and the visual cortex provides the experience

Parietal lobe characteristics and functions

Information about touch and body location, helps interpret visual and auditory info. Spatial and numerical info

Which lobe is most important for the sense of touch?

Parietal

Which lobe is most important for vision?

Occipital

Damage in what lobe can result in cortical blindness?

Occipital

Which lobe is most important for auditory sensations?

Parietal

Which lobe is involved in comprehension of spoken language?

Temporal

What part of the brain receives information regarding muscle stretch and joint receptors?

Parietal

Damage to which part of the brain results in impaired ability to identify objects by feeling them?

Parietal

Which lobe contributes to the perception of movement and recognition of faces?

Occipital