Physiology Flashcards
What is the definition of physiology?
the study of functions of living things. Focuses on underlying mechanisms of body processes (structure and function are inseperable)
What are the levels of organization in the body?
Chemical level and cellular level
What is the cellular level of organization in the body?
- various atoms and molecules make up body
- Atoms: mostly O2, C, H, N (96%)
- Molecules in life: proteins, carbs, nucleic acids, fats
What is the chemical level of the body?
- Cell is basic unit of life with basic and specialized functions
- Organisms can be single-celled or multicellular
What are the 4 types of tissue in the human body?
muscle tissue, nervous tissue, epithelial tissue, and connective tissue
What are examples of muscle tissue?
skeletal, cardiac, and smooth
What does does nervous tissue do?
initiate and transmit electrical impulses
What does epithelial tissue do?
exchange materials between the cell and environment
What does connective tissue do?
connects, supports, and anchors various body parts
What is an example at the organ level, of an organ that has all 4 types of tissue?
stomach
What does muscle tissue do?
has the ability to shorten or contract in order to produce movement of the body parts
What are sensory neurons?
sensory neurons get information about what’s going on inside and outside of the body and bring that information into the CNS so it can be processed.
What are interneurons?
Interneurons, which are found only in the CNS, connect one neuron to another. They receive information from other neurons (either sensory neurons or interneurons) and transmit information to other neurons (either motor neurons or interneurons).
What are motor neurons?
Motor neurons get information from other neurons and convey commands to your muscles, organs and glands.
4 steps of an action potential
Threshold, Depolarization, Repolarization, Refractory
What happens in PNS when sensory receptor (like hair cell) receives signal?
afferent neuron moves down peripheral axon/afferent fiber to cell bodu on central axon
What happens in CNS after PNS receives a signal?
afferent neuron goes through axon terminals -> to dendrites -> to interneuron -> to another set of axon terminals -> the efferent neuron moves down the axon (efferent fiber) -> to axon terminals -> effector organ (muscle or gland) which is triggering response of skeletal muscle or gland
What part of neuron receives signal?
Soma (contains nucleus)
What carries information from other neurons to the soma?
dendrites
What sends messages in a neuron?
axon
What receives messages in a neuron?
dendrites
What ions are on the outside of a neuron?
High concentration of Na+, Ca2+, and Cl-
What ions drive positive charge in extracellular fluid?
Na+, Ca2+, Cl-
What ions are on the inside of a neuron?
K+ and organic ions
What is the resting membrane potential of a neuron?
-70 mV
What does a resting potential of -70 mV mean?
It means that the inside of the neuron is 70 mV more negative than the outside
At rest are there more Na+ ions inside or outside of the neuron?
more Na+ outside
At rest are there more K+ ions inside or outside of the neuron?
more K+ inside
What generates the resting membrane potential?
the K+ that leaks from inside the cell to outside the cell generates a negative charge inside the membrane vs outside
Why is the membrane impermeable to Na+ at rest?
all of the Na+ channels are closed
What is depolarization in an action potential?
the stimulation of voltage gated Na+ to open
What is repolarization in an action potential?
response to K+ ions being really leaky and letting K+ out
What is refractory in an action potential?
where hyperpolarization occurs where overshoot of K+ ions leads to a refractory period where the nerve can’t fire another action potential
What happens to K+ in refractory period?
K+ leaves cell for longer period of time
How is a resting membrane potential maintained?
The Na+-K+ pump moves Na+ ions out of the cell and K+ ion into the cell. This happens after K+ channels got leaky and results in a negative resting potential - trying to get back to -70mV
Where are neurotransmitters stored?
in synaptic vesicles in axon terminal in neuron
When neurotransmitters are released what does Ca2+ bind to?
Cadmodulin
What happens when Ca2+ binds to Cadmodulin?
when they bind, this activates it and starts signal transduction pathway
What does Cadmodulin activate?
Protein Kinase 2
What does Protein Kinase 2 phosphorylate?
synapsin
What happens when PK2 phosphorylates synapsin?
actin proteins release their vesicles
How are vesicles arranged next to each other?
vesicles are “docked” adjacent to the membrane where snare proteins await their release
What are in the membrane that the vesicles are “docked” adjacent to?
snare proteins that want to be released
What happens once vesicles are liberated?
They are snared, fused, and recycled to store neurotransmitters again
What is an inactivation gate?
Na+ pushes inactivation gate open as it tries to enter cell
What is happening during hyperpolarization in a voltage-gated Na+ channel?
the hyperpolarizing stops Na+ from going in cell, now K+ channel are open allowing K+ out
True or False: Inactivation gate is based on voltage of cell
True
What lets you figure out change in concentration in cell?
Nerst equation
How can you determine change in concentration with nerst equation?
know the concentrations inside and outside of the cell
What causes Na+ channels to open?
voltage of cellular membrane based on different threshold
What are glial cells?
support cells of the nervous system
What are the 4 main functions of glial cells?
- to surround neurons and hold them in place
- to supply nutrients and oxygen to neurons
- to insulate one neuron from another
- to destroy and remove dead neurons
What 2 things do glial cells form?
myelin and blood-brain barrier
Are glial cells in the CNS or PNS
CNS
What is the ratio of Na+ to K+ in a resting membrane potential?
3 Na+ out for every 2 K+ coming in
What is the resting membrane potential attempting to do?
balance out ions in ICF and ECF
What is the Node of Ranvier?
open portions of the axon that aren’t covered in myelin sheath
What are the 3 excitatory synaptic inputs?
No summation, Temporal summation, Spatial summation
What happens in no summation?
no action potential is fired because multiple EPSPs are widely spaced out in time and only 1 excitatory input that’s really spread out
What happens when multiple EPSPs arrive quickly in temporal summation
sets off action potential at a signal synapse
What happens to neurotransmitter after action potential in temporal summation
after the action potential, there’s a back to back release of the neurotransmitter into the synapse and gets added together
What happens in temporal summation
- multiple EPSPs arrive quickly at signal synapse and fire an action potential
- back to back release of the neurotransmitter into the synapse and gets added together
How many inputs are in spatial summation?
multiple inputs
What do EPSPs do in spatial summation?
EPSPs at 2 or more different synapses set off an action potential
How many neurons are providing excitatory input in spatial summation?
3 different neurons
What happens in neurons fire off individually in spatial summation?
won’t reach action potential
What happens if neurons all fire off at once during spatial summation?
cell recieves info all at once and action potential is generated via axon hillock and down the axon
Where does the action potential take place in spatial summation?
in the axon hillock and down the axon
What is EPSP and IPSP cancellation?
an EPSP and IPSP may cancel each other so no action potential is set off
What does phosphorylation do in the Na+-K+ Pump Primary Active Transport?
phosphorylation causes the pump to change transformation, Na+ binding sites are exposed to ECF
What does dephosphorylation do in Na+-K+ Pump Primary Active Transport?
dephosphorylation causes change in conformation
What are the steps in Na+-K+ Pump Primary Active Transport?
- 3 high affinity sites for Na+ and 2 low affinity sites for K+
- When 3 Na+ from ICF binds to pump, splits ADP to ATP + P and P binds to pump
- Phosphorylation
- change in shape exposes binding sites for K+ to ECF
- When 2 K+ from ECF bonds to the pump, H releases the P group
- Dephosphorylation
- 2 K+ are released into ICF it releases the P group and affinity to Na+ increases
What is part of the peripheral nervous system?
cranial and spatial nerves
what is part of the central nervous system?
brain and spinal cord
What are the 2 parts of the peripheral nervous system?
Somatic (voluntary responses) and autonomic (involuntary responses)
What are somatic functions in the body?
-conscious reactions
-sensing and responding to environment
-sight, smell, sound, etc
-motor neurons that excite muscle causing contraction
What are autonomic functions of the body?
-unconscious reactions
-regulates internal body functions that maintain homeostasis (sympathetic and parasympathetic)
What are the 2 parts of the autonomic nervous system?
sympathetic and parasympathetic
What are the main functions of central nervous system?
receive, process, and respond to sensory information
What happens when sensory organ detects a stimulus?
The peripheral nerves int he organ transmit the impulse tot eh CNS for interpretation
What is the relationship between the CNS and PNS?
PNS carries sensory info to the CNS and the PNS also carries motor info from CNS
What is dual innervation?
sympathetic and parasympathetic nervous systems dually innervate most visceral organ (innervation of a single organ by both branches of autonomic NS)
When is the sympathetic nervous system dominant?
-“fight or flight” response
-accelerates heart rate, inhibits digestion, stimulates glucose release from liver, stimulates adrenal medulla, inhibits bladder, promotes ejaculation and vaginal contractions (childbirth)
What is the parasympathetic nervous system dominant?
-“rest and digest” response
-slowed heart rate, stimulated activity in the stomach, promotes erection from genitals
What are the antagonistic effects the parasympathetic and sympathetic nervous systems have on each other?
If sympathetic NS excites an organ, the parasympathetic usually inhibits it
What is the neurotransmitter in the parasympathetic nervous system?
Acetycholine
What is the neurotransmitter in the sympathetic nervous system?
Adrenaline and noradrenaline
What is Saltatory propagation?
layers of myelin sheath insulate the axon which results in action potentials that “jump” from node to node, increasing speed of conduction
What would happen if there weren’t any myelin sheaths in saltatory propagation?
The action potential would go much more slowly down the axon b/c it’s not able to jump
What charges on on the Nodes of Ranvier?
-buildup of positive charges inside
-buildup of negative charges outside axon
What are the steps to the rapid response in relax circuits?
-an outside stimulus signals a response to occur
-receptors in the muscle respond by sending a signal along the sensory nerve
-the sensory neuron synapses with a motor neuron in the spinal cord
-the motor neuron sends an excitatory signal to the same extensor muscle, which responds by contracting
-an inhibitory interneuron inhibits contaction of the opposing flexor muscle
how do action potentials move from hillock to terminal?
the depolarization of one region of axon stimulates depolarization of next region
Why doesn’t the action potential move backwards?
the Na+ channels become inactivated/inactivation gate is closed
How does closed inactivation gate prevent action potential from moving backwards toward axon hillock?
pushes it forward towards axon terminals so message can be delivered and received to neighboring cell type
what is a synapse?
the juction between neurons
What is an electrical synapse?
neurons connected directly by gap junctions
- direct transfer between cells
What is an example that has electrical synapses?
heart muscle
What kind of cells are gap junctions found in?
cell types that require fast communication with one another-direct transfer
What is a chemical synapse?
a chemical messenger transmits information one way across a space separating the two neurons
What happens when a chemical messenger is released in a chemical synapse?
chemicals released into synapse by pre-synaptic neuron –> message sent to post-synaptic neuron which decides if its enough for them to respond
What are the majority of synapses in the human body?
chemical synapses
What ion is essential for exocytosis?
Calcium
What will happen in you bring more positive charged ions into the cell (like when Voltage-gated Na+ channel lets in more Na+)?
this changes the electrical gradient inside the cel to a more positive charge –> K+ channels open causing repolarization –> action potentials go down to hyperpolarization –> process repeats
What is the sodium-potassium pump working to do?
establish concentration gradient
What does action potential open in synapses?
Voltage-gated calcium channels
Neurons make how many neurotransmitters?
neurons make only 1 neurotransmitter
What kind of receptors do dendrites have?
ligand receptors
Why are membrane bound receptors on dendrites specific?
have many different kinds of membrane bound receptors that are specific to 1 different type of chemical messenger
What is an example of an excitatory neuron?
glutamate
What is an example of an inhibitory neuron?
gava
What is the motor endplate?
where the motor axon is synapsing onto that muscle cell to either stimulate or inhibit a contraction
What neurons initiate muscle contraction?
motor neurons
What is a stimulus?
change that is detectable by the body
What is receptor adaptation?
the adaptation to certain stimuli -> when brain deems it no longer important to respond to)
What do afferent neurons do in receptor physiology
- respond to stimuli in external and internal environment
- info detected is conveyed via afferent neurons to the CNS, where it’s used for various purposes
What is sensory transduction in general?
to convert a stimulus (such as light, or sound, or the position of the body) into an electrical signal in the nervous system.
What is photoreception?
light is illuminated to the protein receptor within the cell membrane
What is mechanoreception?
pressure pushed the cell to depolarization
What kind of polarization happens to photoreceptors?
Hyperpolarization due to signal causing Na+ channels to close
What is chemoreception?
receptors for smell and taste that generate neural signals on binding with particular chemicals in their environmen
What are chemoreceptors?
receptors for smell and taste
What do chemoreceptors influence in the stomach?
the flow of digestive juices and affect appetite
What do chemoreceptors induce?
pleasurable or objectionable sensations such as seek or avoid (sweet or bitter)
What kind of receptor does the first messenger bind to in a GCPR
ligand
What does binding to ligand in GCPR induce?
phosphorylation that converts GDP –> GTP which promotes amplification of the signal
What are cilia?
chemosensitive hairs picking up these particles sending information/impulse into the olfactory sensory neuron
What do glomeruli in olfactory bulb do?
each one detects a different odor, distinguishes odors
What are mitral cells in olfaction?
carries olfactory information from olfactory bulb to rest of the brain
What are taste receptor cells located?
on the taste buds
What does oral referral cause?
it causes us to perceive what’s happening in the nose as if it’s happening in the mouth
what is the trigeminal nerve?
detects spicy, hot, carbonation, menthol/cool sensation because this is not detected at level of taste buds
How many receptor cells does one tase bud contain?
around 50 long spindle shaped taste receptor cells
How are taste buds “packaged” or arranged?
like slices of an orange
What are the 5 basic tastes/flavors?
sweet, salty, bitter, sour, umami
What is taste discrimination?
it’s cided by patterns of activity in various taste bud receptors
What tastes are G-coupled?
sweet, savory, bitter
What taste contains Na+ ion?
salty
What does the Na+ ion do in the salty taste?
Na+ depolarizes the cell opening the voltage-gates Ca+ channels
What taste contains H+ ion?
sour
What does the H+ ion do in the sour taste?
Its acidity so the H+ ion channels depolarize but also inhibit K+ channels
How are sweet, savory. and bitter interpreting with GPCR?
through the binding of the ligand to the receptor
True or False: a taste bud is a G coupled protein receptor
True
Where can chemical receptors for taste bind?
on microvilli
Why does the tongue love fat?
enhances flavor
When is the Na+-K+ inactive (refractory period)?
during depolarization
What molecule is particular to the umami taste?
glutamate
What sharpens an image?
lateral inhibition
What adjusts motion and brightness?
amacrine cells
What are examples of tactile receptors?
mechanoreceptors Merkel’s disc, Pocinian corpuscle, Ruffini endings, and Meissner’s corpuscle
What are the 4 types of tactile receptors in the skin?
touch, pressure, vibration, and tension
What is Merkel’s disc?
light, sustained touch
What is Pacinian corpuscle?
vibrations and deep pressure
What are Ruffini Endings?
deep pressure
What is Meissner’s corpuscle?
light, fluttering touch
What is hair receptor touch?
hair movement and very gentle touch
Is touch sensitivity high or low when there’s a low threshold of activation?
high
What is spatial summation?
how often and where these neurons are firing to get at acquity
What is temporal summation?
the rate at which the cell is reading the excitatory input is going to increase the probability that action potential is going to fire
What happens to the firing when the body adapts to continuous stimuli?
the firing rate is reduced over time
What does lateral inhibition do?
lateral inhibition of sensory cells enhances edge and border detection by reducing excitation of adjacent interneurons
Lighter touch means what kind of firing rate?
low firing rate
More intense touch means what kind of firing rate?
higher firing rate
What are the 4 steps of lateral inhibition?
- strength of signal
- source of signal
- filter out noise
- spatial vs temporal summation
What cortex of the brain is the touch sensory system in?
Primary somatosensory cortex/parietal lobe
What cortex of the brain does olfaction take place?
primary olfactory cortex/frontal lobe
What cortex of the brain does gustation take place?
gustatory cortex/frontal lobe
What cortex does of the brain does hearing take place?
Primary auditory cortex/temporal lobe
What cortex of the brain does sight take place?
Visual cortex/occipital lobe
What cell type is correlated with sense of touch?
sensory afferent neurons
What cell type is correlated with olfaction?
sensory neurons
What cell type is correlated with gustation?
sensory cells
What cell type is correlated with hearing?
sensory cells
what cell TYPES are correlated with sight?
sensory cells (rods and cones)
Where does gas exchange occur in the lungs?
alveoli
What membrane moves with vibrations?
tympanum
What does frequency give insight to?
pitch
What does external ear do when it hears a sound?
funnels sound waveform onto structures inside ear
What does having a large pinna mean?
you have more info about sound waveforms leading to better hearing
What are the 3 parts of the ear?
inner, middle, and outer
What is hearing?
neural perception of sound energy
What are sound waves?
traveling vibrations of air
What is pitch?
tone
What is intensity?
loudness
What is tiembre?
quality
What happens when fluid pressure lands?
will provide info about the pitch of the signal
What are the 3 anatomical correlates of hearing loss?
- missing and damages hair cells, stereovilli in base of the basilar papilla
- redued 8th nerve fibers, fiber diameter, and cell size in nucleus
What does the movement of the cilia on hair cells cause?
depolarization
What happens when you have too much endolymph or have an infection in semicircular canal?
problem with orientation, no response to change in pressure
What is the vestibular system?
vestibular nerve synapses onto these canals that provide info about your place in space and direction and speed
Where does the inner ear lead to?
pharynx
what is the oval window?
tissue covering that separates the end of the middle ear to the beginning of the inner ear
What does the ciliary muscle in the eye do?
relaxes or contracts based on the need to focus (near or far)
What are the 4 monomers in digestion?
monosaccharide, fatty acid, nucleotide, and amino acid
What are the 4 polymers in digestion?
carbs, lipids, nucleic acid, protein
What is digestion?
the breakdown of food substances
What is mechanical digestion?
physical mixing and churning that breaks down large masses of food into smaller masses of food (increasing surface area)
What is chemical digestion?
using enzymes to break bonds of large molecules (polymers) into smaller molecules (monomers)
What are interstitial cells of Cajal?
pacemaker cells in the digestive system that generate waves of smooth muscle
What are gap junctions?
connect smooth muscle cells to allow activity to spread within each organ as a syncytium
What does smell stimulate in the stomach?
parastolysis (stomach rumbles)
What can increase rate of digestive system?
presence of food and hormones
What is secretion?
the release of chemicals
What is pepsin?
breaks down proteins into amino acids
What is exocrine secretion?
the release of digestive juices into the digestive lumen
What is endocrine sectretion?
the relsease of hormones into peripheral circulation that have distant targets that control digestive processes
What enzyme breaks down carbs?
salivary amylase
What enzyme breaks down lipids?
lipase
What is mastication?
chew food into a soft pulp that is easy to swallow (mechanical digestion)
What do incisors do?
cut and tear
What do canines do?
tear
What do premolars and molars do?
chew and grind
What is salivary amylase?
an enzyme for carbohydrate digestion
What is Lysozyme?
an antibacterial enzyme
What is saliva made of?
99.5% water, electrolytes, mucus
What is the pH of the stomach?
1.5-3
What is gastrin?
secreted when food arrives in the stomach stimulating the production of more HCl and pepsinogen
What is peristalsis?
rhythmic muscular contraction and relaxation moves food downward
Where does peristalsis occur?
GI tract
What is the pyloric sphinctor?
a band of muscle at the base of the stomach that opens and closes to regulate the rate at which the stomach empties
What are the 3 types of exocrine cells that contribute to gastric juices found in the gastric pits?
mucus cells, chief cells, and parietal cells
What are mucus cells?
thin, watery mucus
What are chief cells?
pepsinogen, precursor to pepsin, an enzyme that digests proteins
What is pepsin made from?
pepsinogen
What are parietal cells?
HCl
What is stomach lining made of?
lumen
What is the duodenum?
first part of the small intestine
How does the eye focus the image on the retina?
refracts entering light
What do the ciliary muscles do when focusing on close objects?
they contract, make the lens more round and increase the bending of the light rays
What do the ciliary muscle do when focusing on close objects?
they relax, allow the lens to flatten and reducing the bending of light rays
What does the ciliary muscle do?
relax or contracts based on the need to focus (near or far)
What is in the retina
rods and cones
