Physiology Flashcards
Where does the external ear start and end?
Starts at the pinna and ends at the tympanic membrane
Where does the middle ear start and end?
What does it contain?
Starts at the tympanic membrane and ends at the round and oval windows
Contains the mallus, incus, and stapes (MIS)
What is the membranous labyrinth and what does it contain?
It is contained within the bony labyrinth made of saclike, membranous ducts and sacs.
Cochlear duct within the cochlea, the utricle and saccule in the vestibule, and the semicircular ducts within the semicircular canals
What fluid is contained within the bony labyrinth?
Perilymph
What fluid is contained within the membranous labyrinth?
Endolymph that is similar to ICF and has a high potassium concentration
In sound transmission, what does wave amplitude signify?
Loudness
In sound transmission, what does wave frequency signify?
Pitch
How are sound vibrations transferred to the inner ear?
The stapes will be vibrating on the oval window. This wound transfer allows the amplification of sound pressure needed to move the liquid within the cochlea
When the stapes hits the oval window, where does the oval window bow into?
Bows into the scala vestibuli rhythmically
What is audible sound?
When there is movement from scala vestibuli to scala tympani through the basilar membrane
Where are the hairs required for hearing found?
In the organ of corti
What is released onto the sensory neurons in hearing?
Glutamate
Name the steps of hearing
First, bending of hairs open mechanically gated ion channels that allows potassium ions to enter from the ENDOLYMPH.
That allows it to depolarize and open the voltage-gated calcium ion channels.
Influx of calcium leads to bursts of releases of glutamate onto sensory neurons
Glutamate increases the AP production in sensory neurons into the cochlear branch of the vestibular cochlear nerve
Where and how are pitches determined?
High pitches resonate at higher frequencies at the oval window. Lower pitches resonate at lower frequencies near the apex
Neural pathways to the brain for hearing
- Fibers of sensory neurons synapse with interneurons in the brainstem.
- Sensory input from both ears converges on the same interneuron.
- Information goes to the colliculus of the midbrain.
- Signal is sent to the medial geniculate nucleus of the thalamus.
- They then all synapse with interneurons that carry information to the auditory cortex of the temporal lobe in the cerebrum
What is the plasma membrane of muscle cells?
Sarcolemma and attaches to tendons
What is the cytoplasm of the muscle cells?
Sarcoplasm
Composition of muscle fibers from large to small
Muscle – Fasciciuli – muscle fibers — myofibrils – Sarcomere – Myofilaments – Actin Filaments
What are the tails and heads of a myosin protein?
Tails are heavy chains (2). Heads are light chains (4)
Binding of troponins
TIC TAC: Troponin T = Tropomyosin;
Troponin I = Actin;
Troponin C = Calcium
Role of tropomyosin
Binds to actin and covers up active sites that would bind to myosin heads
Role of F-Actin
Binds to myosin heads and allow for contractions
What interdigitates with myosin
Actin
What are A bands composed of?
Myosin (Thick filaments)
What are I bands composed of?
Actin (Thin filaments)
What is the role of titin?
Maintains the alignment between actin and myosin filaments: It is the spring between z disc and myosin
What is the transmitter in the neuromuscular junction?
Ach
Where is Ach embedded in the neuron for skeletal muscles?
In the plasma membrane of the postsynaptic cell
What allows the release of Ach into the synaptic cleft?
Calcium allows the neuron to package and release Ach (5000) via exocytosis
Where do vesicles from the neuron bind to?
After traveling through the synaptic cleft, they bind to the sarcolemma
What prevents the Ach vesicles from reaching the sarcolemma?
Acetylcholinesterase
What is the curare poison?
Prevents calcium from entering the PREsynapic cleft. Neuron does not get calcium in order to package and release Ach
What allows the muscle cell to go through a graded potential?
Binding of two Ach will open up a cation gate. Mainly sodium is what rushes in
What is EPSP?
Excitatory Post-synaptic Potential or End Plate potential (EPP). The potential that happens after the synaptic cleft
What are T-Tubules?
When ATP Invaginations of the sarcolemma that is filled with ECF.
This allows the AP to run inward
When is a myosin head uncocked/sprung?
When ATP is bound (Not interacting with the actin filament) OR When phosphate leaves the ADP-Pi complex on the myosin head (Interacting with the actin filament. The release of the Pi is what slides the actin filament)
When is myosin cocked?
When ADP and phosphate are attached. (ATP was hydrolyzed. ADP and Pi are still attached to head. Myosin is not associated with actin filament)
How is a cocked myosin allowed to interact with the active site of the actin filament?
If troponin is attached to calcium, it pulls tropomyosin away from the active site and allows the myosin head to attach. This creates the cross bridge
What is one muscle fiber innervated by?
Only ONE motor neuron
What does one motor neuron innervate?
Multiple muscle fibers
What is a motor unit composed of?
One motor neuron and all the muscle fibers that are associated with it
T/F Muscle fiber contraction can be summed?
True: Muscle summation increases the muscle tension by increasing the number of motor units contracting that the same time
What is load?
The force exerted on a muscle by the weight of an object
What happens when Tension > Load?
Fibers shorten
What happens when tension < Load?
Fibers remain the same length
What is tension?
The force exerted on an object by a muscle
Isotonic Contractions
Muscles contract, but load stays the same
Isometric contractions
Muscle creates tension, but does not contract
Twitch
Contraction of a single muscle fiber in response to a single AP
Frequency summation
Increased muscle tension that occurs when successive AP occur (Rapidly enough that the previous twitch has not yet relaxed)
Treppe
Period of summation in which the strength of contraction increases as stimulation rises
Unfused tetanus
Maintained contraction at high stimulation in which the muscle tension oscillates due to slight relaxations (Myoplasmic calcium fluctuates)
Fused Tetanus
Tetanus maintained contraction at even higher stimulus with no oscillations of relaxations (Myoplasmic calcium stays high)
What happens when the muscles are stretched too far?
There is no overlap of myosin or actin. No cross bridges can occur. Therefore, no sliding
What creates maximum tension
When all myosin heads are attached to actin binding sites
What happens when actin filaments overlap each other?
This prevents myosin heads binding: Less optimal tension
What happens if the muscle fibers are shortened too much?
Z-lines collide and almost fall apart: Little to no tension
What are smooth muscles innervated by?
ANS
What are skeletal muscles innervated by?
CNS
What cells are mononucleated and spindle shaped
Smooth Muscle
What anchors the thin filaments to the cell membranes?
Dense bodies
What allows a single unit to work in synchrony
Gap Junctions
What activates single unit smooth muscles?
Nerves, Hormones, and Local factors
Where can single unit smooth muscle be found?
Stomach, intestine, bile ducts, ureters, uterus, and blood vessels
T/F Single unit muscle fibers can be induced into contraction by stretching
True: Multi unit smooth muscles do NOT, but single unit does
In a multiple unit smooth muscle, what does contractility depend on?
How many fibers contract and how many signals it gets
Where can multiple unit fibers be found
eyes, large airways, large arteries, and hairs of the skin
Which smooth muscle units are richly innervated by the ANS?
Multiple units?
Steps of muscle contractions in a smooth muscle
- calcium in the cell increases 2. calcium binds to calmodulin 3. calcium - calmodulin complex activates MLCK 4. MLCK uses ATP to phosphorylate both light chain heads on myosin 5. Myosin heads can now bind to actin
How are smooth muscles relaxed?
Calcium pumps that remove it from the cytoplasm and phosphatases
What are the regulators of smooth muscle contraction
Controlling calcium concentrations, transmitters from ANS, Hormones, local factors, stretch, and spontaneous electrical activity
What can induce a slow wave of smooth muscles?
Stretch, ACh, and Parasympathetics
What can induce hyperpolarization of smooth muscles
Norepinephrine and sympathetics
Varicosities
Swollen regions of an axon that are full of Ach in the ANS neuron
What hormones are produced by the kidney?
Renin, Erythropoietin, and 1,25-dihydroxyvitamin D
What contains the glomerulus, bowman’s capsule, and bowman’s space?
Renal Corpuscle of the nephron
What is the order of the tubule that branches from Bowman’s space?
Proximal tubule, Loop of Henley, Convoluted tubule, Collecting Ducts
What is filtered through bowman’s capsule?
Water, glucose, urea, and ions
Podocytes
foot processes On bowman’s capsule cells. Between the feet are slits
What causes fluid to move from the glomerular pores and into Bowman’s space?
Fluid pressure (blood pressure)
What are the opposing forces of filtration?
Fluid pressure from bowman’s space and the osmotic pressure created by the proteins in the capillary space
Of the 900 L of plasma passing through the capillaries, how much is actually filtered?
180L/day
What does constriction of the afferent capillary do?
It decreases the pressure for filtration
What does constriction of the efferent capillary do?
It increases the pressure for filtration
What would happen if we lost our ability to reabsorb?
Because globular filtration is huge, we would deplete our body of necessary molecules quickly
T/F Glucose reabsorption is under physiological control
False. Glucose is always entirely reabsorbed
How do substances move from the interstitial fluid to the peritubular capillaries?
Bulk flow: NOT active transport
How is glucose reabsorbed?
Through carrier-mediated active transport. Creates a sodium gradient, sodium must be accompanied by glucose to be let back in via SGLT protein
How is urea reabsorbed?
Reabsorption of water creates a concentration gradient that allows urea to come back into the body accidentally
How are potassium, hydrogen, drugs, and organic compounds (creatinine) secreted?
Diffusion or carrier-mediated (Paired with sodium in counter transport)
What happens when there is no secretion or reabsorption?
GFR=Clearance
A blood test with high creatinine will indicate?
Kidney failure
T/F Sodium and water are secreted
False. They are only filtered and reabsorbed
Where is sodium and water reabsorption regulated?
In the distal tubules. The proximal tubules do not have any physiological control
How is sodium reabsorption done?
Via active transport. Na/K pump creates a gradient it can move along;
Cotransport with glucose and amino acids;
countertransport with hydrogen
As sodium transport occurs, what is happening to osmolarity?
Osmolarity of the tubules are decreased. Osmolarity of the interstial fluid is increased
What does water cross in water reabsorption?
Proximal tubule is always permeable: through the tight junctions and cell membranes;
distal tubules are under physiological control with their amount of aquaporins
Where is ADH/Vasopressin released from?
Posterior pituitary
What are the effects of ADH on the distal tubules?
Causes insertions of aquaporins. Thus, increases reabsorption of water in the DISTAL tubules
Diabetes Mellitus
When the blood glucose concentrations is so high that it prevents glucose from being reabsorbed and excreted through urine
Diabetes Insipidus
When ADH is failing to be produced or is ignored. This leads to unwanted water excretion
T/F if Sodium stays in the tubules, water is excreted at a higher volume
True: Water goes where sodium goes (it is what creates the gradient)
