Bios 286 Exam 1

What is the purpose of ion pumps?

They create non-random ion distributions

What is the purpose of dendrites?

They transmit electrical signals toward the cell body. They also function as receptive sites from other neurons.

What nerves are in the somatic nervous system?

sensory (afferent) nerves: touch, pain, temperature Motor(efferent)

Give the three types of neurons and differentiate between them

Motor(efferent): go from cns to body sensory(afferent): ascend spinal cord and go to brain Interneurons: carry info within regions

What is the most common demyelination disease (1/500)?

Multiple sclerosis

What gives white matter its color?

Myelin sheaths

What lobe is involved in senses?

Parietal lobe

What are microglia?

Phagocytes that are mobilized after infection, injury, or disease

What is the function of the temporal lobe?

Processing audio and encoding of memory

What are the 4 ways that the brain is protected?

Skull, Cerebrospinal Fluids, Meninges, & Blood Brain Barrier (formed by astrocytes)

Of the 3 ion channels, which is the only one that also has leak channels?

K+ channels

What are the approximate concentrations of K+, Na+, Ca2+, and Cl- in mammalian cells?

K+: Inside: 100mM (only one more abundant inside) Outside: 5mM (only one scarce on outside) Na+, Ca2+, Cl-: Inside less than outside

What regulates temperature, along with controlling food and water intake?

Hypothalamus

What happens to BBB as we age?

It becomes more permeable

What is the electrical charge across the membrane called?

Membrane potential

What is resting potential?

Membrane potential of a cell that is not firing

Are neurons polarized or unpolarized?

Neurons are very polarized

What causes multiple sclerosis?

"Activated" T cells cross the BBB and launch an attack on myelin & nerve fibers

What is the excitatory and inhibitory transmitter?

- AMPA is excitatory(depolarizes) - GABA is inhibitory(hyperpolarizes)

What are the three types of macroglia?

- Astrocytes (CNS, most abundant type of glia) - Oligodendrocytes (myelin producing cells in CNS) - Schwann cells (myelin producing cells in PNS)

What occurs when electrochemical equilibrium is established?

- Concentration gradient for the ion is exactly balanced by the electrical gradient - No net flux of the ion - No requirement for energy-driven pump to maintain concentration of gradient - Equilibrium potential of K+ ion is the neuronal resting membrane potential

What are the smallest protrusions in dendrites?

- Dendritic Spines (This is where most of excitatory connections in brain are made) - It is also the locus for synaptic plasticity associated with learning and memory

What are the 4 characteristics of inhibitory neurons?

- Interneurons - GABA synapse - Hyperpolarizing - Suppress firing

What are two functions of the brain stem?

- It connects the brain to the spinal cord - Regulates many life support functions

What are the Ion channels and their charges?

- K+ - Na+ - Ca2+

Which ion channels are leak and which are voltage gated?

- K+: leak and voltage-gated - Na+: voltage-gated - Ca2+: voltage-gated

What makes up the cell bodies and axons in the PNS?

Cell bodies: ganglia Axons: nerves

Which lobe is involved in vision and motion?

Occipital lobe

What is the purpose of an axon hillock?

It serves as an initiation zone for APs in neurons

How much will a newborn baby's brain grow in the span of one year?

It will double in size (2x)

What makes up the cell bodies and axons in the CNS?

Cell bodies: Grey matter (Cortex, Nucleus) Axons: White matter (fiber tract)

What are the two divisions of the nervous system?

Central and peripheral

What is responsible for balance and motor coordination?

Cerebellum

What are the 3 parts of the brain?

Cerebrum, cerebellum, & brain stem

What is the bottleneck in brain drug development?

Crossing the BBB

Aside from protecting the brain, what are two other roles that the CF plays?

Delivers nutrients and removes waste

What are the functions of the cerebrum?

- Movement - Sensory Processing - Language, Learning, and Memory

Give the types of neurons by structure

- Multipolar - Bipolar - Unipolar

What keeps the brain growing after birth?

- Other brain cells (glia) - New neuron connections (approx. 1000 trillion connections by age 3) - Myelination

What are the 4 characteristics of excitatory neurons?

- Principal cells - Glutamate synapse (AMPA) - Depolarizing - Promote firing

What are the 3 characteristics of ion pumps?

- Require energy to fight force of diffusion - 75% of your daily energy intake - Called ATPases that hydrolyze ATP to free energy

Give the types of neurons by function

- Sensory neurons - Interneurons - Motor neurons

What are the characteristics of astrocytes?

- Star shaped - Fill space between neurons - Regulate ion concentration in extracellular space - Neurotransmitter uptake and release - Provide neurons with nutrients (ex. glucose)

What purpose do glial cells serve?

- They provide physical support and nutrients to neurons - Cover neurons with myelin - Act as K and neurotransmitter buffers

What are the characteristics of an Action Potential?

- Triggered by depolarization - Threshold - All or none event

What are the keys to resting membrane potential?

- Unequal distribution of ion (ion pumps) - Selective permeability to K+ (leak K+ channels) - Nernst and Goldman equation

What is the resting potential of a neuron?

-65mV (The inside of the neuron is 65 mV less than the outside)

How many neurons and glial cells are in the brain?

100 billion neurons, 10x more glial cells

What are the 3 membranes that wrap around the brain?

Dura Mater: very tough leather-like outer layer Arachnoid Matter: middle layer Pia Mater: inner layer directly attached to the brain

At what stage of life will the brain have most of the neurons that it will ever have?

At birth, there will be approx. 100 billion neurons

What are the divisions within the PNS?

Autonomic nervous system (involuntary): - Sympathetic(fight or flight) - parasympathetic (rest and digest) Somatic nervous system

What transmits the electrical signal away from the body?

Axons

T/F The electric current in our body is carried by the same charge carriers as the electric current in houses

False, Household current is carried by electrons whereas bioelectricity is carried by ions

T/F Action Potential is triggered by repolarization

False, action potential is triggered by DEpolarization

T/F Bioelectricity can occur if ions are randomly distributed with the same concentration everywhere.

False, there must be unequal concentrations of ions in order for bioelectricity to occur

What is responsible for decision making and memory forming?

Frontal lobe

Which cells undergo mitosis?

Glial cells

What do leakage (passive) ion channels do?

They are always open and ions pass through them continuously

What do voltage-gated (active) ion channels do?

They open and close in response to changes in transmembrane voltage

T/F A disease where there is damage to the myelin sheath of neurons is known as a demyelinating disease

True

T/F APs jump from node to node

True

T/F Myelin sheath increases the speed of neural signals down the axon

True

T/F Na+ and K+ pumps are known as ATPase

True