Chapter 1: Homeostasis Flashcards
Physiology
Study of how organisms function
Cells
The smallest structural unit that can perform all the functions needed for life
Cell Differentiation
The process to becoming specialized for a task
4 Categories of Cells
Muscle, Neuron, Epithelial, Connective
What cell type are blood vessels considered?
Connective Cells
Tissue
Group of similarity differentiated cells
Organ
Collection of tissues that work together for the same function
Organ System
Collection of organs that work together for a common function
Muscle Cell Function
Transmit force
Muscle Cell Types
Skeletal, Cardiac, and Smooth
Neuron Cell Function
To initiate, integrate, and conduct electrical signals
Basement Membrane
Thin layer of ECM that the epithelial cells sit on
Basolateral Side
Faces the basement membrane
Apical Side
Faces the lumen
Tight Junctions
Fill the space between epithelial cells and have selectively permeable membranes
Loose connective tissue
loose tissue below the epithelial layer
Dense connective tissue
Tendon, Ligament, Bone, Adipose
Fluid connective tissue
Blood
ECM [ two functions ]
Provides a stable scaffold, transmits chemical messengers cell to cell
Ropelike ___ fibers, and rubber band like ____ fibers.
Collagen, and elastin
Functional Unit
Smallest unit with a common function
Intracellular Fluid
Inside cells, 67% of body fluid
Extracellular Fluid
Fluid surrounding cells and in blood 20%
Interstitial Fluid
surrounds cells, but not counting the blood plasma
Comparing concentrations between blood plasma and interstitial fluid
about the same
5 common physiological variables
blood pressure, body temp, oxygen, glucose, sodium ions
Homeostasis
Relatively stable internal conditions
Dynamic constancy
Variable may fluctuate in short term, but be averagely stable or predictable in the long term
Pathophysiology
A condition giving loss to homeostasis
Steady state vs. equilibrium
Both have a constant variable, but equilibrium does not require additional energy to maintain this
Negative Feedback System
A system result will reduce the conditions that made it start in the first place
How is the production of ATP an example of negative feedback?
As energy is stored in ATP bonds, it slows the enzymes that break down glucose, therefore preventing additional creation of ATP.
Example of positive feedback:
Giving birth. Uterine contractions cause release of oxytocin, which further causes more uterine contractions.
Set point
The value at steady state for a particular biological variable
Clashing demands
Sometimes it is only possible to maintain a set point at the expense of less important set points
Why is it a benefit that multiple systems can control a single parameter?
The redundancy allows for the parameter to continue to be regulated in case a disease knocks out one of the systems.
Feedforward example
When sensors can sense the body external temperature to proactively start the body warming before it actually starts to cool internally.
Reflex
Involuntary built in response to a specific stimulus
Reflex Arc Components
Stimulus–>Receptor–>Integrating Center–>Effector–>Response
Afferent and Efferent Pathways
Afferent: Sensing the stimulus up to the integrating center
Efferent: From the integrating center to the effector
Hormone
Chemical messenger sent normally through blood to another site
Local Homeostatic Responses
Response in a local area to a stimulus
Neurotransmitters
Transmitted between neurons or to their effectors
Paracrine
Transmission within a local neighboring area
Autocrine
Signaling of a cell to itself
Juxtacrine
Signaling of a cell to another when touching through the membrane
Diffusion
Random thermal motion of a molecule
Flux Gradient (In General)
Solute particles move from high to low concentration
Define “Net flux”
While flux may occur in both directions, net flux is the summation of both directions.
Lipid Bilayer is made of:
Phospholipids… with a polar phosphate head group, and a non polar fatty acid chain.
What sort of substances can get through the bilayer?
Small non polar molecules, such as O2, CO2, ethanol, fatty acids, steroid hormones
What sort of substances cannot get through the bilayer without help?
Large polar molecules such as glucose, or charged ions [Na+,K+,Cl-,Ca2+]
What elements of ion channels make them selective?
Size of the pores, and the charge of the channel.
What are three ways that channels can be gated?
Chemical, Electrical, Mechanical
Define a ligand:
A chemical messenger
In what way is a plasma membrane generally charged?
Positive on the inside, and negative on the outside
What are the three general types of Mediated Transport?
1) Facilitated Diffusion
2) Primary Active Transport
3) Secondary Active Transport
Describe 4 properties of facilitated diffusion:
1) Net flux is down the gradient
2) No energy required
3) Selectivity because of binding sites
4) Transporter can be at saturation due to limited amount of binding sites.
What is a primary example of Facilitated Diffusion?
Glucose transport into the body of the cell
What is the primary example of the Primary Active Transport?
Na+K+ATPase Pump
Before Primary Active Transport, what is the general concentration of K+ and Na+
Intracellular: Low Na+, High K+
Extracellular: High Na+, Low K+
PAT step 1:
3 Na+ ions, and ATP attach to the binding sites
PAT step 2:
ATP –> ADP, and the channel is opened, and the Na+ goes out of the cell
PAT step 3:
2K+ attach to binding sites from outside of the cell, and phosphate is removed, switching the conformation of the channel back to open into the cell, releasing the 2K+
Describe 4 properties of Active Transport
1) Flux is against the concentration gradient
2) Energy required
3) Certain selectivity due to binding sites
4) Channel can be saturated due to limited binding sites
Intracellular Ion Concentrations
Na+ 15mM, K+ 150mM
Extracellular Ion Concentrations
Na+ 145mM, K+ 5mM
Describe 4 properties of Secondary Active Transport
1) Against a concentration gradient
2) Energy provided by an ion’s gradient
3) Certain Selectivity
4) Transporter saturation
What is the usual ion in Secondary Active Transport?
Na+
What does it mean for a mediated transport system to saturate?
Since there is a limited amount of channels and binding sites, there is a maximum amount of solute particles that can cross the membrane at a time.
Channels in the membrane for water:
aquaporins
Can water pass through the lipid bilayer?
Yes because the molecules are small, but they are also polar, and therefore quite slow for any efficient physiological process.
Osmolarity
The total solute concentration of a solution
Osmole
one mol of solute particles
What is the osmolarity of 1 mol of NaCl in 1 liter of water?
2 osmoles/liter
What is the general osmolarity of the ECF?
300mOsm
What is tonicity?
The concentration of non - penetrating solute
What happens to a cell in a hypotonic solution?
The water concentration outside of the cell is greater than inside the cell, therefore water will enter the cell, causing it to expand.
What happens to a cell in an isotonic solution?
Nothing. It will retain its volume.
What happens to a cell in a hypertonic solution?
The water concentration inside the cell is greater than outside the cell, therefore water will leave the cell, causing it to shrink.
Endo and Exo cytosis
When a lipid bilayer is formed around particles that fuse to the membrane either allowing for entrance [endo] or exiting [exo] of solute particles.
Functional unit in the Nervous System
nerve cell or neuron
Nerve
collection of nerves bound together by connective tissue
CNS: Central Nervous System
Brain and spinal cord
PNS: Afferent division defintion
sensory cells that send signals AT or TOWARDS the CNS
PNS: Efferent division definition
cells that send signals AWAY from the CNS to the periphery
Somatic sensory
touch
Visceral sensory
organs
Special sensory
hear, taste, smell, see
Somatic motor
skeletal muscle
Autonomic motor: enteric
gi tract
Autonomic motor: sympathetic
fight or flight
Autonomic motor: parasympathetic
rest and digest
Dendrites
incoming receiving branches of neuron
Cell body of nerve is also called:
soma
Initial segment of nerve cell is also called [2]:
axon hillock, trigger zone; is where the e- starts
Axon
Sends signal from soma to axon terminals
axon terminals
sends the signal to another nerve cell by neurotransmitters from vesicles
What do axon terminals target?
other neurons, muscles, or glands
Interneurons
exist in the CNS to integrate information
ratio of afferent to inter to efferent neurons
1A=200000 Inter = 10E
Presynaptic and post synaptic
self explanatory
Glial Cells - 2 types, and where they are found
Nourish and protect neurons:
Oligodendrocytes: CNS
Schwann Cells: PNS
How many patches of protection do an oligodendrocyte and schwann cell provide for neurons?
Oligodendrocytes: many
Schwann Cells: one
When measuring membrane potential, readings are usual taken with the reference electrode in the ___ and the recording electrode in the ____.
ECF,ICF
The typical resting membrane potential is at:
-70mV
Sodium is typically at a higher concentration in the [ECF/ICF]
ECF
Potassium is typically at a higher concentration in the [ECF/ICF]
ICF
Chloride is typically at a higher concentration in the [ECF/ICF]
ECF
Anions are typically at a higher concentration in the [ECF/ICF]
ICF
Are there more K+ or Na+ leak channels open at rest?
K+
Nernst Equation
E[ion] = 61/Z * log (Co/Ci)
Which ion dominates in determining resting membrane potential?
Potassium [K+ is king]
At RMP, are there more K+ or Na+ leak channels?
K+ channels
At RMP which directions are the K+ and Na+ chemical and electrical gradients?
Potassium chemical gradient is out, electrical is in. Sodium both are into the cell.
Even though we have more K+ leak channels, why doesn’t the leak out as much?
The resting potential of the cell is already close to the desired potential of K+ [-70 is close to -90].
For Type I cells, describe the chloride concentrations
The resting potential for chloride is very similar to -70mV. Also, the membrane is not very permeable to Cl-, therefore the concentration of chloride is relatively equal in the ECF and ICF.
For Type II cells, describe the chloride concentrations
There exists minor pumping exchange of Cl- for HCO3-. This creates a slightly less concentration of Cl- inside the cell, therefore via Nernst, the RMP is -76mV for chloride.
Depolarization
Going from negative to 0.
Overshoot
Going from 0 to positive
Repolarizing
Returning from positive to -70mV
Hyperpolarizing
Going from -70mV to more negative
Ligand gated channel
chemically activated
Depolarization [excitatory/inhibitory]
Excitatory
Hyper polarization
[excitatory/inhibitory]
Inhibitory
Graded stimulus
Depolarization or hyper polarization proportional to the size of the stimulus
During an action potential, which is positive feedback, and which is negative feedback between Na+ and K+?
Sodium is positive feedback, because the more depolarized the cell becomes, the more the sodium channels open, further depolarizing the cell.
What is one reason that afterhyperpolarization occurs?
The voltage K+ channels are slow.
Absolute refractory period
The cell CANNOT undergo another action potential at this time.
Relative refractory period
The cell CAN undergo another action potential, but it takes a stronger stimulus than before.
Why does it take a stronger stimulus in the relative refractory period?
Not all the Na+ channels have yet closed, and some of the K+ channels are still open.
What is one thing that a refractory period ensures?
One way propagation of signal.
What part of the neuron has the highest density of voltage gated Na+ channels?
The axon hillock.
What does the myelin sheath do for neurons?
it allows saltatory conduction
What is saltatory conduction?
When there is no potential on certain stretches of the axon, therefore charge can jump from one node of Ranvier to another quicker.
What property of the axon determines velocity?
The diameter.
What are gap junctions?
Places where cells merge like a bridge. conducts electrical signals very quickly and directly,.
Where are gap junctions found?
in the heart, smooth muscle, and some brain cells
What is the role of Ca2+ in neurotransmitter release?
When the AP reaches the axon terminal, it opens voltage gated Ca2+ channels which enter the neuron and induce exocytosis of the synaptic vesicles. Neurotransmitters are then diffused across the synaptic cleft.
What are V snares and T snares?
Little protein chains, [vesicle, and terminal] which bind together on contact with Ca2+ and cause the synaptic vesicles to merge with the post synaptic cell.
What is an EPSP?
Excitatory Post Synaptic Potential
What are 4 reasons that Postsynaptic potentials are more brief in their depolarization than APs?
1) NT’s rapidly bind and unbind from the receptors on the post synaptic cell
2) NT’s are taken back during reuptake into the presynaptic terminal
3) NT’s can diffuse away from the cells while in the synaptic cleft.
4) NT’s can be destroyed by enzymes.
What is the typical threshold value?
-55mV
Convergence and Divergence of neurons
self explanatory
Chloride Type I and how this can be an inhibitory signal
Chloride, while wanting a -70mV RMP will not show a change in RMP, influx of Chloride does keep the cell at 70mV instead of allowing it to move up into an AP.
If B is going to C, but A is going to B, what is this called?
Axoaxonal synapse
What are three terms that dictate synaptic strength?
Facilitation, Inhibition, and Autoregulation
How do drugs modify synaptic strength?
They can affect multiple spots of regulation of neurotransmitters from creation to reception etc.
Long Term Potentiation: Function with Glutamate
Some of the glutamate neurotransmitters activate the non-selective AMPA receptors, while some causes Ca2+ influx at NMDA receptors that cause a second messenger system for more glutamate receptors, and the release of Mg2+ that can return to the presynaptic cell and increase the synthesis of glutamate.
Neuromodulators are usually made of
small peptides
Neuromodulators are usually released…
with NTs
Neuromodulators usually activate ___
2nd messenger cascades
Frontal Lobe
Thought
Parietal Lobe
Speech
Occipital Lobe
Sight
Temporal Lobe
Sound
Cerebrum
contains 4 lobes [frontal,parietal,occipital, temporal]
Diencephalon
contains thalamus and hypothalamus
Forebrain
contains diencephalon and cerebrum
Thalamus
synaptic relay station
Hypothalamus
neural and endocrine command center
Cerebellum
balance, posture, but not skeletal muscle control
White Matter
Contains mostly mylenated axons on the inside of CNS, and outside of spinal cord
Gray Matter
Mostly cell bodies and dendrites on the outside of CNS, and the inside of the spinal cord
Basal Nuclei
Deep clusters of cell bodies that affect inputs and outputs from the cortex involved in posture and movement
Thalamus
Sensory relay station
Hypothalamus
Integrator of homeostasis, Master Control. Hormones, autonomic nervous system, feeding and drinking behavior etc.
Pituitary gland:
Master gland of the endocrine system. Releases epinephrine and norepinephrine.
Spinal Cord: Ventral Horn
Contains cell bodies of efferent neurons
Spinal Cord: Dorsal Root Ganglion/ Horn
Contains cell bodies of afferent neurons
Spinal Cord: Dorsal Root
Afferent axons
Spinal Cord: Ventral Root
Efferent axons
Cranial Nerves: Optic
Carries input from receptors in eye
Cranial Nerves: Glossopharyngeal
From tongue, auditory tube skin, and carotid baroreceptors –> skeletal muscles involved in swallowing and parotid salivary gland
Cranial Nerves: Vagus
From thorax and abdomen to skeletal muscles of pharynx and larynx and smooth muscle and glands of thorax and abdomen. [breathing?]
Cranial Nerve: Accessory
Innervates sternocleidomastoid and trapezius muscles in neck.
The Spinal Nerves: Neck,arms,hands,shoulders
Cervical [8]
The Spinal Nerves: Chest, Upper abdomen
Thoracic [12]
The Spinal Nerves: Lower abdomen, hips, legs
Lumbar [5]
The Spinal Nerves: Lower GI, genitals
Sacral [5]
The Spinal Nerves: Tailbone
Coccygeal [1]
Give the other name, and relative sizes of the pre and post ganglionic nerves: Parasympathetic
Craniosacral, pre is large, post is small.
Varicosities
Bulges in the axon near the tissue to be signaled. “Crop dusts” the tissue with neurotransmitters.
Dual innervation
Organs are connected to both sympathetic and parasympathetic nervous system. Effects are usually opposite, and both are tonically active.
Somatic NS: NT and Receptor
Acetylcholine and Nicotinic
Autonomic-Para: NT and Receptor
Acetylcholine, Nicotinic and then Muscarinic
Autonomic-Sympathetic-NonHormonal: NT and Receptor
Acetylcholine,Nicotinic,Norepinephrine,Adrenergic receptors
Autonomic-Sympathetic-Hormonal: NT and Receptor
Acetylcholine,Nicotinic,Epinephrine,Adrenergic receptors
Receptor Potential
A graded potential at the peripheral ending of an afferent neuron or on a specialized sensory cell adjacent to an afferent neuron.
Where is the first place you can get an AP in the neuron?
The First Node of Ranvier
Rapidly Adapting receptor
On and Off, [i.e. clothes pressing on skin]
Slowly Adapting Receptor
Continue to fire the whole duration of the stimulus, [i.e. maintaining posture]
Describe Sensory Coding
Converting a stimulus energy into a pattern of action potentials to the CNS.
Sensory Unit
A single afferent neuron with all of its receptor endings
Receptive Field:
are of the body that leads to activity in a particular sensory neuron
What does “Adequate Stimulus” mean when referring to sensory coding?
It means “right type”, but not necessarily enough strength.
What are two ways that intensity is differentiated in primary sensory encoding?
Frequency of action potentials, and by recruitment, where neighboring afferent neurons also are signaled.
What is “acuity” when referring to signals?
Precision in localizing a stimulus
Labeled Lines
Predetermined pathways that encode for a specific sensation in the CNS. Example, is activating phantom limb.
Two point discrimination is better with a [large/small] number of individual sensory neurons, and [larger/smaller] receptive fields
larger number of individual sensory neurons, smaller receptive fields.
What can be said about the gradient of receptor fields?
The neuron responds more vigorously when a stimulus is applied in the center of the receptive field because the density is greatest there.
Receptive Field Overlap
When different neurons have overlapping receptive fields, the stimulus site can be more accurately determined by the CNS.
Lateral Inhibition
When a neuron is excited, it causes an inhibitory response in local neurons so that the stimulus is localized.
Ascending Neural Pathways normally consist of how many neurons in the chain?
- Sensory neuron, labeled line to thalamus or brainstem, then to cerebral cortex
One sense does not always go through the thalamus.
Olfactory sense.
Association Areas
Final perceptive destination
Most nociceptors are [slow/rapid] adapting
slow adapting
What neurotransmitter is released usually for nociceptors?
Substance P or Glutamate
How do anti-inflammatory drugs work, such as aspirin?
blocks prostaglandin synthesis
How do opiates work?
They block ascending synapses to the brain
What is TENS?
Transcutaneous Electrical Nerve Stimulation: When you rub a bump after an injury, the somatic receptor activation can stimulate your descending neurons that inhibit transmission of pain
What is referred pain?
When your cortex incorrectly senses the location of pain. Often this can be because your visceral and somatic afferent neurons are converging on the same neurons in the spinal cord
Where is a heart attack normally felt?
Your left arm or shoulder
What can referred pain tell you about?
Which part of your viscera might be damaged.
Eye Anatomy: Sclera
White protective eye capsule over all but cornea
Eye Anatomy: Cornea
Transparent covering for focusing image
Eye Anatomy: Choroid Layer
Dark pigment to absorb light at back of eye
Eye Anatomy: Iris
Determines pupil diameter, also gives eye distinct color
Eye Anatomy: Ciliary muscle
controls lens shape
Eye Anatomy: Zonular Fibers
connect ciliary muscle to lens
Eye Anatomy: lens
alters light diffraction by changing shape
Eye Anatomy: Macula lutea
No blood vessels here, yellow spot, good for acute vision
Eye Anatomy: Fovea Centralis
high color acuity, cones focused here
Eye Anatomy: Optic Disc
neurons exit eye to the brain, no photoreceptors, blindspot
Eye Anatomy: Aqueous Humor
Anterior fluid compartment between iris and cornea
Eye Anatomy: Vitreous Humor
Posterior space filled with jelly substance between lens and retina
Which is larger? Refraction at lens or cornea?
Cornea
What in general is the accommodation reflex for the eye?
Lens changes shape to account for distance focusing
What happens when ciliary muscle contracts?
The zonular fibers are lessened in tension, curving the lens. This is the parasympathetic response
What happen when the ciliary muscle relaxes?
The zonular fibers are tightened, flattens the lens. This is the sympathetic response.
Why is it considered parasympathetic when the lens is rounded?
It focused in on close things. Focus on your food. Rest and digest.
Rounding the lens increases or decreases refraction?
Rounding the lens increases refraction.
Myopia [definition,cause, accommodation reflex, optical correction]
Can’t see far. Eye too long, focal point before the retina. Accommodation reflex is in reverse, allowing for seeing close objects, optical correction is concave lens that diffracts the light before the cornea so that the usual over focusing occurs right at the retina.
Hyperopia [definition,cause, accommodation reflex, optical correction]
You can’t see near. The eye is too short, focal point after the retina. Accommodation reflex is normal, rounding the lens focuses earlier right at retina. Optical correction is convex lens that starts to straighten or focus close object earlier so focal point is at retina instead of behind.
Presbyopia [cause]
Lens loses flexibility, and cannot round… similar to hyperopia where close up objects cannot be focused.
Rods
Sensitive, low acuity, no color vision, located in periphery, 100:1 ratio with ganglia.
Cones
Not sensitive, high acuity, color vision, located in fovea centralism, 1:1 ratio with ganglia
In the dark: Phototransduction
cGMP high, photoreceptor depolarized, which releases inhibitory information to bipolar cell. No neurotransmitter released to ganglion, therefore no APs to brain.
In the light: Phototransduction
cGMP low, photoreceptor polarized, no inhibitory information to bipolar cell. Neurotransmitter released to ganglion, therefore APs to brain.
Guanyl Cyclase
Enzyme that creates cGMP constantly
cGMP gated channels
opens in response to cGMP allowing entrance of Na+/Ca2+depolarizing the photoreceptor in the dark
Photopigment(opsin) and Retinal Unbinding
activated by light
Transducin
G-protein turned on by photopigment
cGMP phosphodiesterase
Enzyme that breaks down cGMP , cells hyper polarize, turned on by transducin
