There is an intimate relationship between ______ and _____ in all biological systems.
This relationship is well studied in the shape of the gut microvili. Why does it have this shape?
Structure, function
Elongated folds of tissue, more surface area to absorb nutrients from food.
The electrochemical gradient and changes in ___________ of the cell membrane result in changes of membrane potential.
permeability
The release of neurotransmitter is called a __________ which occurs at the axon terminal.
Neurotransmitters are carried in ___________ until they are released into the synapse.
What triggers the exocytosis of NT into the synapse?
synaptic vesicles
Depolarization causes Ca+ channel to open, which allow Ca+ to flood into the terminal and initiate exocytosis of NTs.
Ascending tracts carry __________ signals
afferent
____________ is determined by integration of afferent signals
Perception
Processes including growth, reproduction, and movement all require _________. How is this obtained?
Energy
Chemical energy is obtained through eating.
The resting potential of a cell is
-70mV
After NTs are relased into the synaptic cleft, what are some possible fates?
1. NTs bind and cause an EPSP or IPSP
2. NTs are broken down by enzymes
3. NTs diffuse out of the synaptic cleft
4. NTs are brought back into terminal and reused
Descending tracts carry _________ signals
efferent
Somatic sense iclude
What two systems assist the human body with coordinating, integrating, and communicating within itself.
Endocrine system: Hormones are released into the blood, disperse, and act upon target cells or tissues.
Nervous system: Neurotransmitters/neurohormones are released and carry info to and from CNS.
Define hyperpolarization, repolarization, and depolarization.
Hyperpolarization: Increase in negative charge within cell
Repolarization: returning to -70mV from above or below threshold.
Depolarization: Decrease in negative charge within cell
Using Acetylcholine as a model NT and nicotinic vs muscarinic receptors, explain the differences between ionotropic and metabotropic receptors.
Ionotropic receptors are protein channels that directly bind to NTs and open. Acetylcholine activates the nicotinic receptors in the brain and directly opens.
Metabotropic receptorsare G-protein coupled receptors which ultimately open an ion channel. Acetylcholine NTs act on muscarinic receptors, which aren't channels themselves.
The spinal cord contains integration center much like the brain and can cause these quick reactions.
give an example of this
reflexes.
knee-jerk reaction
The amount of area in sensory cortex is proportional to ________
sensitivity
In addition to the nervous system and endcrine system, how else does the body communicate within itself?
Gap junction: form direct cytoplasmic connections to and from adjacent cells (sharing nutriets etc.)
Contact dependent signals: require interaction between membrane bound molecules on two cells.
Autocrine signals: Chemicals that are released and act upon the cell that released them.
Paracrine signals: Chemicals that are released and act upon neighboring cells.
The ________ is the smallest functional unit of the nervous system.
neuron
Unused acetylcholine is broken down by __________ and returned to the terminal to be recycled.
acetylcholinesterase
This structure in the brain consists of the midbrain, pons, and medulla oblongata.
This structure connects the spinal cord to the brain.
Brain stem
_____________ are sensitive to less than body temp, and up to 45 degress celcius, then ___________ take over.
Thermoreceptors
Nociceptors
Define homeostasis
the state of steady internal physical and chemical conditions maintained by living systems
the maintenance of a relatively constant internal environment around a “set point.”
Dendrites are responsible for ___________________.
The _________ integrates incoming signals.
The axon conducts _____________.
The pre-synaptic terminal is responsible for the ____________
Receiving chemical signals (input) from post-synaptic neuron.
Cell body
Electrical signals (action potential)
output of NT
The __________ consists of the brain and spinal cord.
CNS
Why does the left side of your brain control the right side of your body?
Tracts cris-cross in the pyramids of the medulla
Special senses include
Smell (olfaction)
Tastse (gustation)
hearing
sight
____________serves to reduce the original stimulus and is critically important for maintaining homeostasis.
Negative feedback
Changes in membrane potential that occur in the dendrites and cell body are called____________ which degrade overtime.
If the graded potential ___________ the cell to -55mV, an ______________ is triggered in the __________
graded potentials.
depolarizes
action potential
axon hillock
_______ are the cells in the nervous system that do not propagate electrical signals.
There are 6 types.
glial cells
The _______ processes sensory information and coordinates movement.
"Little brain"
cerebellum
Taste receptor are chemoreceptors
and are responsible for sour, salty, sweet, bitter, and umami
Define positive feedback
positive feedback refers to the body increasing the original stimulus and keeps moving the body away from a set point. NOT HOMEOSTATIC
Unlike graded potentials, ___________ do not vary in amplitude.
Intensity corresponds to __________, which correlates to the duration in which the cell maintains depolarization at -55mV.
action potentials
frequency
These two cell types are similar in that they both myelinate neurons, but do so in different ways. What are they and how are they different?
Schwann cells (PNS) myelinate a single axon
Oliigodendrocytes (CNS) myelinate multiple axons at the same time.
The diencephalon is composed of the thalamus and hypothalamus. The thalamus is responsible for __________________and the hypothalamus is important in ____________
The endocrine system, regulation of homeostasis
Hearing occurs via integration of afferent signals due to __________
Mechanoreceptors
_______________ control refers to two systems that control a parameter in opposite directions. This allows for better control over the parameter.
Antagonistic
Subthreshold potentials do not trigger action potentials, whereas ________ do.
suprathreshold potentials.
__________ provide nutrients and absorb waste and contribute to the blood brain barrier.
Astrocytes
What are some functions of the cerebrum?
"human-ess"
complex information processing, including cognition, perception, memory, motivation, mood, learning, memory, and language.
Explain hearing
Sound waves enter the ear canal, pass through the eardrum and into the middle ear where they vibrate three small bones that allow sound waves to be converted into fluid waves within the tectorial membrane within the cochlea. These waves them stimulate mechanoreceptors called hair cells. When the waves cause the hair cell to bend towards the tallest sterocillia, channels open, depolorizes cell and causes a release of NTs. When waves bend towards shortstereocillia, channels close, no action potential, no NTs released.
Sweating/Shivering
Sympathetic/Parasympathetic Neural pathways
If the sum of two graded potentials arising from two separate synaptic neurons is -55mV and action potential is triggered. This is termed ________
Spatial summation
Microglia are cells that cleanup damaged cells and foreign material from CNS and are modified _________ cells.
immune
PET scans show where the brain is working, how?
How are MRS different?
Shows the uptake of radiolabeled glucose. More glucose being used=more active
MRI's look at blood flow, more blood flow to a certain area=more active
Explain seeing
Seeing is due to photoreceptors, rods (low light vision) cones (color vision)
Fever is not an example of loss of homeostasis. Why?
The 'set point' has changed. Fever serves to reduce infection.
Temporal summation occurs when two graded potentials from one post-synaptic neuron occur close together in time and allow depolarization to occur.
Satellite cells are located only in the ______ and provide support for cell bodies in ganglia.
PNS
There are two types of sensory receptors. Both send affarent signals to the brain, how do they differ?
1st type: Stimulus acts directly on the receptor protein immediately depolarizing a neuron.
2nd: Stimulus acts on cell that released NT onto neuron and signal is tranduced.
The __________ division of the Peripheral nervous system is composed of the ________ and somatic motor
Efferent
Autonomic
Another mechanism for maintaining homeostasis is __________, which is an anticipatory mechanism meant to minimize fluctuations during regulation.
Give an example of this
feedforward control
Drooling when we smell/see food.
What are the three protein channels that are important in generating an action potential?
Na+/k+ pump: responsible for creating electrochemical gradient, always working.
Voltage gated Na+ channel: opens @-55mV, closes at peak depolarization @+30mV due to inactivation gate, allows for Na+ to enter cell then closes at peak depolarization.
Voltage gates K+ channel: slowly opens at -55mV, fully opens during repolarization, begins closing during hyperpolarization and close fully when cell returns to resting potential.
What are ependymal cells and what do they do?
Ependymal cells create the ependyma, the semipermeable epithelial membrane between cerebrospinal fluid and interstitial fluid.
What are the four types of sensory receptors that humans have?
chemoreceptor
photoreceptor
mechanoreceptor
thermoreceptor
The autonomic nervous system is governed through antagonistic control via the ____________ and ___________
sympathetic
parasympathetic
There are two fluid compartments in the body, what are they and explain their ion concentrations.
Intracellular fluid vs Extracellular fluid
Intracellular fluid is composed of high concentrations of k+ and proteins and is inside cells.
Extracellulr fluid is all the fluid outside of the cells including the interstitial fluid containing high concentrations of Na+ and Cl-, and blood plasma containing high concentrations of k+, Na+, and proteins.
The VG Na+ channel actually has two gates.
The _________ gate opens at -55mV
The _________ gate closes at +30mV
Activation
Inactivation (ball in cup)
What two glial cell types are only found in the PNS?
Schwann cells, satellite cells
Most receptors are sensitive to multiple forms of stimulus energy but are most sensitive to the ______________
adequate stimulus
What are the anatomical sifferences between sympathetic and parasympathetic pre and post ganglions?
Sympathetic have short pre-ganglionic neurons and long post ganglionic neurons
Parasympathetic have long pre-ganglionic neurons and short post ganglionic neurons
Due to these differences in ion concentration, the fluid compartments in the body are in __________________.
How is this maintained?
maintained via Na+/K+ ATP-ase which pumps ions against concentration gradient.
The neuron cannot be activated during the ___________.
refractory period
_________ is related to processing and integration and is not myelinated whereas ________ is highly myelinated and responsible for signal transduction within the CNS
grey matter
white matter
Receptors have receptive fields. The smaller the receptive field the ______ sensitive an area is.
more
Both sympathetic and parasympathetic pre-ganglionic neurons release Ach onto nicotinic receptors, but the difference lies in the post-ganglionic neurons where sympathetic release _____________ onto adrenergic receptors and parasympth release Ach onto _________ receptors
norepnephrine
cholinergic
The concentration of solutes within each fluid compartment is _______mOsm/L
The fluid compartments are said to be in _______________
~300
osmotic equilibrium
What are two physical factors that affect impulse conduction?
Diameter of axon enables faster signal movement because the larger the diameter of the axon, the less likely the incoming ions will run into something that could bounce them back. Think about water flowing through a giant tube vs a small tube.
Myelination from Schwann cells (PN) and Oligodendrocytes (CN)
The CNS is bathing in __________ which provides protection against damage.
Cerebrospinal fluid CSF
The CNS must integrate afferents and distinguish
The type of stimulus, the location of the stimulus, intensity of the stimulus, and the duration.
What happens to a cell in a hypertonic solution, isotonic solution, and hypotonic solution?
Hypertonic: Water moves out of the cell causing it to burst.
Isotonic: Cell is happy.
Hypotonic: Water moves into the cell causing it to burst.
Depolarization jumps down the axon in the ____________, which is termed _________
nodes of ranvier
saltatory conduction
These cells have long foot like projections that form a tight barrier between capillaries within the CNS and the brain.
Neurons are protected from blood infections because these cells prevent leakiness.
Astrocytes
__________ are useful for monitoring levels of a given parameter whereas and adapt slowly ________adapt quickly and are useful for determining acute changes in a parameter
tonic receptors
phasic receptors