neurobiology exam 1

chapters 1-3

cranial

towards the head

posterior or dorsal

back

superior

above

anterior or ventral

front

caudal

towards the tail

inferior

below

medial

towards the middle

lateral

towards the side

proximal

nearer the body

distal

farther from the body

afferent

going into something (a before e)

efferent

leaving something

coronal or frontal plane

divides front from back

transverse plane

divides top from bottom

sagittal plane

divides right from left

midsagittal

equal division of sides

hypo

below

hyper

above

endo

within

epi

over or next to

meso

middle

hemi

half

sub

under

cereb

brain

iso/ipsi

same

contra

opposite

corpus

body

cervi

neck

thorac

chest

lumb

lower back

axil

armpit

brachi

arm

cost

rib

glosso

tongue

oculo and opti

eye

moto

movement

types of muscle tissue

skeletal

smooth

cardiac

skeletal muscle

Forms muscles like the biceps, abs, glutes. You have voluntary control over them.

smooth muscle

found in walls of organs (stomach, bladder) and blood vessels. Involuntary.

cardiac muscle

forms the walls of the heart. involuntary.

phospholipid bilayer

2 layers of hydrophilic phosphates and hydrophobic fatty acids

• selectively permeable

• includes gasses, steroid hormones and small fatty neurotransmitters

• allows simple diffusion

simple diffusion

passive transport (no ATP)

Across phospholipid bilayer; Only works for small, nonpolar stuff - gases & small fats (steroid hormones & lipid neurotransmitters)

transport proteins

help stuff cross the cell membrane that cant pass through phospholipid bilayer

• sugars, amino acids, ions (NA+, K+, Ca++, Cl-)

transport protein channels

allow facilitated diffusion (NO ATP, Passive)

transport protein pumps

allow active transport (uses ATP)

transport maximum

Transport rates will increase with increased molecule concentration until saturation is met

saturation

every channel is handling as much as it can

channels

Protein “tunnels” that small, specific substances can pass through

ungated channels

always open

gated channels

open/close under specific circumstances

ligand

signal that binds to a receptor

ex. hormones, proteins

facilitated diffusion

Requires protein channels; for small polar stuff (charged ions, sugars, amino acids)

rules of movement for diffusion

Net movement of substances from high → low substance concentration

• Molecules move randomly and equilibrium is met

• substances move down their concentration gradient

what affects rates of diffusion?

Magnitude of concentration difference

– Permeability of the membrane to the molecules

• How many open channels are there?

– Remember: some channels are always open and some can

open/ close depending on situation

– Temperature of the solution

– Surface area of the membrane

active transport is needed to

End in something other than equilibrium, requiring molecules to move against their concentration gradient (low → high) OR

– move very BIG molecules (like proteins, neurotransmitters)

4 types of active transport

1. Primary active transport: Uses pumps; moves ions

2. Secondary active transport: piggy-backs on primary

3. Exocytosis – moves BIG things out of cell

4. Endocytosis – moves BIG things into cell

primary active transport

Breakdown of ATP is directly responsible for transport protein function. The transport protein is also an ATPase enzyme.

• The pump is activated by phosphorylation using a Pi from ATP

Ca2+ pump

Located on all cell membranes and on the endoplasmic reticulum of muscle & some sensory cells

• Removes Ca2+ from the cytoplasm by pumping it into the extracellular space or moving Ca2+ from cytoplasm into ER for storage.

• Creates a strong concentration gradient for rapid movement of Ca2+ back into the cell for intracellular functions.

– Aids in release of neurotransmitter from neurons & sensory cells and in muscle contraction.

Na+/K+ pump

Found on all body cells

• Pumps 3 Na+ out of the cell and 2 K+ into the cell.

• Creates strong concentration gradients of Na+ and K+ that:

– Provide the potential energy for coupled transport of other

molecules across the membrane

– Allows for electrochemical impulses in neuron & muscle cells

secondary active transport (coupled)

Uses a pump AND a cotransporter protein

• Most common way to transport sugars & amino acids into cells

- Indirectly uses ATP, 2 step process:

1. Ions are pumped (using ATP) to one side (usually Na+ using Na+/ K+ pump)

2. Next, the ion (Na+) passively flows back across pulling along a sugar or amino acid using its potential energy

exocytosis

active transport of large molecules out

• requires vesicles that fuse to the plasma membrane

• moves proteins such as enzymes, hormones, and neurotransmitters out of the cell

cells communicate using ______ signals

chemical

2 types of short distance communication

gap junction

paracrine signaling

gap junction

Allows attached cells to pass ions and regulatory molecules through a channel between the cells

paracrine signaling

Cells within an organ secrete molecules that diffuse across the extracellular space to nearby cells

• Also called Local Signaling

2 types of long distance communication

synaptic signaling

endocrine signaling

synaptic signaling

Involves neurons secreting neurotransmitters across a synapse to target cells

endocrine signaling

Involves glands that secrete hormones into the blood stream.

These can reach multiple target cells

neurotransmitters

• Target one specific cell or portion of organ tissue

• Very fast action

• Very fast deactivation

• Secreted by neurons

• Travel across a synapse

hormones

• Can target many cells/ tissues/organs simultaneously

• Slow to act

• Can last for hours/ days

• Secreted by endocrine glands

• Travel in the blood stream

both NTs and hormones

• Regulate physiology to maintain homeostasis and respond to stimuli

• Use chemicals to communicate to specific cells

• Require membrane receptors on target cells

receptor proteins

A target cell receives a signal because it has receptor proteins specific to the signal, either on the plasma membrane or inside the cell (intracellular)

intracellular receptors

Small, non-polar signal molecules cross the plasma membrane and interact with receptors inside

gene regulation

The signal may cross into the nucleus and turn on/ off genes

example of small, non polar signal?

steroids

receptor proteins specific to the signal on the plasma membrane

Polar or large signal molecules need to bind to receptors on the cell surface

• These signals require second messengers to affect change within the cell.

second messengers

a. can be ions that enter the cell when the signal binds to the receptor.

b. can be molecules produced by another membrane protein serving as an enzyme. This requires a g-protein

g-protein

3 subunits:

α, β, γ

cAMP

most common second messenger

process of cAMP

1. A signaling molecule binds to a receptor

2. G-proteins activate the enzyme adenylate cyclase which produces cAMP from ATP

3. cAMP can then activate protein kinases

4. Protein kinases phosphorylate proteins in the target cell to alter cell mechanisms

• In neurons this opens ion channels

protein kinases may…

open ion channels

IP3 process

1. Binding of a signaling molecule → G-protein activates the enzyme Phospholipase C

2. Produces IP3

3. IP3 causes release of Ca++ from the endoplasmic reticulum

4. Ca++ can then activate Calmodulin

5. Calmodulin activates protein kinases

Abnormality in IP3 function has been implicated in __________ & ______ disease

Huntington’s; Alzheimer’s

membrane potential

• a difference in charges between the two sides of the plasma membrane (inside vs. outside)

• expressed as a number that represents the voltage inside compared to the outside

  • A negative # means the inside is more negative than the outside

• measured in millivolts (mV) by a potentiometer

resting membrane potential

is the actual membrane potential of a cell (i.e. a neuron) not producing any impulses.

resting membrane potential depends on

• the ratio of the concentrations of each ion on either side of the membrane

• the specific permeability to each ion

RMP of neurons is

-70mv

K+ equilibrium potential

150 mM k+ inside

5mM k+ outside

-90mV

sodium concentration equilibrium

12mMinside

145 mM outside

+66mV

nernst equation is used to calculate

equilibrium potentials

based on ion concentrations

Na+/ K+ Pumps keep both the resting membrane potential and the concentrations of each ion on either side of the membrane ______

stable

equilibrium potential

The hypothetical membrane potential needed to maintain certain concentrations of a single ion

3 functions of nervous system

sensory input

integration

motor output

sensory input

sensory receptors detect changes called stimuli

integration

input is processed and decisions are made

motor output

a response is generated by activating effectors (muscles, glands, or organs)

2 structural divisions of NS

central

peripheral

CNS (brain, spinal cord)

command center

• integration

PNS (cranial nerves, spinal nerves)

communication lines

• sensory input

• motor output

sensory division (afferent)

Information Flow:
Receptor → Peripheral NS → Central Nervous System