Lecture midterm #1 Flashcards
1
Q
Explain Diffusion in relation to a concentration gradient?
A
The Net movement of particles or molecules down a concentration gradient (area of high concentration to low concentration).
The greater the gradient the faster the diffusion takes place
2
Q
What are the 4 main types of Passive transport (diffusion)?
A
Simple diffusion, channel-mediated diffusion, facilitated diffusion and osmosis.
In all 4 cases NO energy is required and movement occurs DOWN the concentration gradient.
3
Q
What are the 5 special senses and the 1 general sense?
A
special senses (specialized cells limited to the brain): Sight, smell, hearing, taste, equilibrium
general senses: Touch
4
Q
What are the 5 types of receptors?
A
1) Chemorecptors: (respond to chemicals in a solution)
2) Nociceptors (respond to painful stimuli)
3) Phororeceptors (respond to light energy)
4) Thermoreceptors (sensitive to temperature change)
5) Mechanoreceptors ( sensitive to mechanical force, touch/pressure/stretching. but also involves the mechanically gated ion channels)
5
Q
What is homeostasis?
A
Maintaining a relatively constant internal environment.
Cells are surrounded by extracellular fluid (ECF) which can be effected due to certain things (temp/ chemical ect) so in order for your cells to function optimally the window for change in these variable is narrow
6
Q
Homeostasis: Difference between “Autoregulation & Extrinsic Regulation” ?
A
Autoregulation: A local response within one cell, tissue or organ.
Extrinsic regulation: Involves multiple organs (endocrine/ nervous).
7
Q
What are the 3 main components of maintaining homeostasis and what do each do?
A
1) Receptor: Monitors the changing level of variables (temp, blood pressure, blood CO2 levels)
2) Control center: (Usually in the brain/ brains stem or hypothalamus). Recieves the info taken from the receptors on the changing variable levels.
3) Effector: Control center sends info to the effector and the effector can change the levels and bring them back to normal range.
8
Q
Homeostasis: What is negative feedback?
A
If there is deviation from the “Set point” negative feedback reduces the level of deviation and brings it back down closer to the set point. Bringing it back to normal range (optimal range)
(eg) Sweating. when youre too hot your body sweats to lower your internal body temp.
(eg) blood sugar regulation
9
Q
What is the main differences between the CNS and PNS?
A
CNS is the Brain and spinal cord and acts as the command centre for the body.
PNS is outside the CNS, consists of cranial and spinal nerves and carry information to and from the CNS
10
Q
Homeostasis: What is positive feedback?
A
It increases the deviation from the set point. “spiraling out of control”. If childbirth is happening you need to get to the end of it quickly and positive feedback helps with that.
(eg) childbirth. Blood clotting
11
Q
What is biology?
A
Study of life and living things
12
Q
What is anatomy?
A
Study of structure
13
Q
What is physiology?
A
Study of function
14
Q
What is a covalent bond?
A
When molecules SHARE electrons to fill up their valence shells.
15
Q
What are the 4 kinds of Neuroglia in the CNS and what is there function?
A
- Astrocytes: Transfer mitochondria to neurons, recycles neurotransmitters and maintains the blood brain barrier.
- Ependymal cells: Assist in producing, circulating and monitoring the cerebrospinal fluids
- Oligodendrocytes: Myelinate axons in the CNS and provide a structural framework.
- Microglia: Removes cell debris, wastes and pathogens by phagocytosis.
Ashley
Eats
Olivers
Muff
16
Q
What 2 kinds of Neuroglia can be found in the PNS? what are their functions?
A
- Satellite cells: surround neuron cells bodies in ganglia which regulates nutrients, neurotransmitter levels and gases (CO2,O2) around the neuron.
- Schwann cells: Surround all axons in the PNS. Responsible for myelination of peripheral axons and participates in the repair process after injury.
17
Q
What is polar and nonpolar?
A
Polar: unequal sharing of electrons (water) causing a partial charge.
Nonpolar: equal sharing of electrons (no charge)
18
Q
How does hydrogen bonding work?
A
The slight + charge the hydrogen have are attracted to the slight - charge of the oxygen end on another water molecule.
Results in “Cohesion” (water sticks to water) (surface tension)
19
Q
Explain the differences between Structural and Functional Neurons?
A
Functional classification is based on which direction the information is traveling (either towards the CNS, within the CNS or away from it.)
Structural classification is based on the number of processes (axons and dendrites) that are attached to the cell body. (Multipolar neurons, bipolar and unipolar.)
20
Q
Difference between hydrophobic and hydrophilic?
A
Hydrophobic: Not gay for water (wont mix with water) (nonpolar molecules with no charge are hydrophobic) (eg) oil
Hydrophilic: Gay for water (will mix with water) (polar molecules with charges are hydrophilic) (eg) sugar/ salt
21
Q
What does microvilli do?
A
Increases surface area
22
Q
What does the Golgi apparatus do?
A
It alters and packages cellular products. stores and exports.
it looks like a stack of pancakes
23
Q
What does the nucleus do?
A
Contains genetic information
24
Q
What does the smooth ER do?
A
Synthesizes lipids.
Builds and breaks carbohydrates.
Detoxifying poisons,
Stores calcium ions.
Some
Bitches
Don’t
Snitch
25
What does the rough ER do?
Synthesizes proteins
Modification and secretion of glycoproteins.
Distributes transport vesicles containing proteins.
Studded with ribosomes.
26
What does the rough ER do?
Synthesizes proteins
Modification and secretion of glycoproteins.
Distributes transport vesicles containing proteins.
Studded with ribosomes.
Some
Mens
Dick
Pics
Suck
27
What do the ribosomes do?
Protein synthesis
28
What does the mitochondria do?
ATP synthesis
29
What does the cytoskeleton do?
Structure and nutrient transport
30
What do ALL CELLS NEED?
DNA
RIBOSOMES
CYTOPLASM
PLASMA MEMBRANE
31
Describe the various concentrations of K+, Na+, Cl- and negatively charged proteins in the ICF.
High K+
Low Na+
Lower Cl-
High Negatively charged proteins.
32
Describe the various concentrations of Na+, K+, Cl- and negatively charged proteins in the ECF.
Low K+
High Na+
high Cl-
low negatively charged proteins.
33
What is the "Fluid mosaic model"?
Its the phospholipid bilayer (fluid) with embedded proteins (mosaic).
Phosphorus heads (outside) (polar) (hydrophilic)
Lipid tails (inside) (hydrophobic) (nonpolar)
Regulates what can enter or exit the cell
34
Fluidity of the membrane allows for some things to cross the membrane easily. What are those things?
Small, uncharged and/or hydrophobic
35
Some things need the assistance of a transport protein to help them across the membrane. what are those things?
Larger molecules, hydrophilic
Water is the exception because it is hydrophilic but also very small and can travel across the membrane easily
36
Tell me some shit about simple diffusion?
*passive transport* no energy required
Small, lipid soluble particles that pass through the gaps of the bilayer.
37
Tell me some stuff about channel mediated diffusion?
*passive transport* no energy required
Small, water soluble particles may diffuse through channel proteins (always open leak channels or gated channels)
38
What is facilitated diffusion?
*passive transport* no energy required
Large, water soluble MOLECULES that can not fit though the channel proteins. They use CARRIER PROTEINS to help get through (they look alot like channel proteins but the protein takes in the molecule and kinda drops it off on the other side.
39
What is osmosis?
*passive transport* no energy required
-Diffusion of WATER down its concentration gradient.
-Dissolved substances in a solution will LOWER the water concentration in that solution.
-Low solute conc=high water conc
-High solute conc=low water conc
40
What are the terms used in reference to SOLUTE concentration?
Isotonic = equal solute content
Hypertonic = larger solute content (a cell in a hyper solution will shrivel)
hypotonic = smaller solute content. (a cell in a hypo solution will gain water and eventually explode)
41
What is Active transport?
-Mediated transport. *REQUIRES ENERGY* in the form of ATP
-Goes AGAINST concentration gradient.
42
Simple answer. What is the sodium (Na+) and potassium (K+) pump do?
Na+ goes out (lowers its concentration gradient)
K+ goes in (increases its concentration gradient)
43
Is simple terms, describe "membrane potential"?
Overall the ECF and ICF have similar charges respectively but due to the membrane separation they are different. This difference in charge is the "membrane potential" (potential difference).
44
What is secondary active transport?
*simple answer*
*requires ATP*
-Symport & Antiport
-Symport=both ions and solutes go into the cell (via channel protein) at the same time.
-Antiport=ions go in and solutes go out at the same time.
45
What is "Resting Membrane Potential"?
Resting Membrane Potential= Potential difference across the cell membrane in an "unstimulated cell" (typically -70mv).
46
Cotransport (symport) vs Countertransport (antiport)
add later
47
What is receptor mediated endocytosis?
Requires ATP
Cells taking in substances from outside of the cell by engulfing them in a vesicle derived from the plasma membrane.
(usually for larger particles)
*like the opposite of exocytosis
48
What is phagocytosis?
a type of endocytosis.
Brings in solid material into the cell. instead of forming a vesicle around the material it forms a phagosome..(pretty much the same thing)
49
Describe the movements of K+ across an unstimulated membrane.
Through K+ leak channels (always open) the molecules tend to diffuse OUT of the cell down its concentration gradient.
50
What is pinocytosis?
*part of endocytosis*
Takes in liquid particles into the cell by wrapping around them with a vesicle made from the plasma membrane
51
What is exocytosis?
Expelling contents of a vesicle to the outside of the cell.
I vesicle migrates over to and fuses with the cell membrane, releasing its contents to the outside of the cell.
52
yo mama
so fat
53
Describe the movements of Na+ across an unstimulated membrane.
Through NA+ leak channels (always open) the molecules tend to diffuse INTO the cell down its concentration gradient.
54
The axon membrane is more permeable to which molecule K+ or Na+?
more permeable to K+, meaning more K+ moves out than Na+ moves in.
55
Aside from leak channels what is another way for molecules and ions to diffuse into the ECF/ICF respectively?
Via Gated channels.
*THIS IS IMPORTANT BECAUSE THIS HAS AN EFFECT ON BOTH SIDES OF THE MEMBRANE*
56
Name the two most common gated ion channels and a brief description of them.
Chemically-gated channel (ligand-gated): Molecule binds to the receptor changing the structure of the membrane protein opening the channel.
Voltage-gated channel: Change in charge across the membrane causes the channel to open or close.
57
Example of a Chemically gated channel?
Neurotransmitters (Acetylcholine), hormones
58
Example of a Voltage gated channel?
Those which are selectively permeable to Na+. K+, Cl-, Ca2+
59
In relation to membrane potential, define "Depolarization" aka "Hypo-polarization".
A decrease in charge difference across the membrane (Becomes less negative/more positive)
BECOMES MORE POSITIVELY CHARGED (more Na+ floods in
60
In relation to membrane potential, define "Repolarization".
Returning to resting potential.
61
In relation to membrane potential, define "hyper polarization".
Membrane potential becomes more negative. (bigger difference in charge inside and outside the membrane).
62
How do sensory receptors get stimulated?
-Energy from a stimulus (mechanical/ heat/ light) produces a change in the receptor protein (membrane protein).
-When change in receptor protein also means change in the membrane. makes a "receptor potential"
-change might involve opening/ closing ion channel/ altering membrane potential/ or making an action potential more or less likely.
63
What is sensory transduction?
Converting stimulus energy into receptor potential. (could lead to AP).
64
What are transducers
They convert one form of energy into another.
Sensory receptors = transducers
-They convert energy from sensory stimulus (mechanical/ light/ heat) and turn it into to nerve impulses (electrical signals)
65
What happens to your sensory receptors when they get stimulated?
A signal from outside of the cell is TRANSDUCED so that it can be transmitted throughout the body as an ELECTRICAL SIGNAL.
66
Do all receptor cells have to be neurons?
NO BITCH. some sensory receptors cant generate that sweet action potential themselves BUT they can stimulate a nearby neuron to undergo AP for them.
67
Receptor cells: Direct effect on membrane potential.
-Stimulus directly causes an opening/closing of an ion channel.
-changing the membrane potential.
-AP more likely to occur or the release of a neurotransmitter
68
Receptor cell: Indirect effect on membrane potential.
-Stimulus binds to receptor protein.
-Activates a second messenger (inside receptor cell).
-Triggers cascade of events in receptor cell causing membrane potential to change.
-AP more likely to occur or the release of a neurotransmitter.
69
Receptor cells: Example of Indirect effect on membrane potential?
Olfaction. "odorants" (smell molecules) bind to receptor proteins
70
Receptor cells: Example of Direct effect on membrane potential?
Come back to this
71
What does Adaptation mean in regards to receptor cells?
-Adaptation= Decreased sensitivity to continuous stimulus.
-Can be central (in the CNS) or peripheral (at the sensory receptor itself)
-for peripheral it can be TONIC or PHASIC
72
What are Tonic receptors?
-Slow adapting
-Always send info about the stimulus to the CNS
73
What are Phasic receptoris?
-Fast adapting
-Only send info about changes to the stimulus to the CNS
74
What are the 5 special senses? (add the fancy names too)
1) Smell (olfaction)
2) Taste (gustation)
3) Vision
4) Hearing
5) Equilibrium
75
Give me a lil rundown of the anatomy of the nose (olfaction)
- Nasal cavitiy lined with pseudostratified ciliated columnar epithelium with olfactory receptor cells.
- Odorants (smelly molecules) stimulate olfactory receptors.
- Superior/ middle/inferior nasal conchae
- Cribriform plate
76
Dont think we need to know this but ill throw it in anyways. What is the olfactory pathway to the cerebrum?
1) olfactory epithelium
2) olfactory nerve fibers
3) olfactory bulb
4) olfactory tract
5) CNS
Even
Nerds
Buy
Trojan
Condoms
77
What type of receptors are for olfaction?
Chemoreceptors
78
What does mucus do for olfaction?
Acts as a solvent to dissolve airborne odorants
79
What happens with odorants bind to a specific receptor?
-Triggers a series of ecents inside of the receptor cell that lead to the opening of Na+ channels.
-Indirect effect on membrane potential
-Receptor cell is a neuron
80
Gustation anatomy review
-Sensory receptor organs = taste buds
-Taste buds found on papillae (receptors in the papillae epithelium).
-Each papillae has 50-250 taste buds (each bud contains several receptor cells)
-"Tastants" (taste molecules) get dissolved by enzymes in saliva.
-enter taste pore. stimulate cells.
81
What are the 3 layers of the eye?
1) Fibrous tunic
2) Vascular tunic
3) Neural tunic (inner layer) (where photoreceptors are)
82
What receptors do you find in your eye and what do they see?
Photoreceptors
Only see "Visible light" 380-750nm
83
Tell me what happens when light hits our eyes?
The light gets bent (refracted) by the cornea and the lens to focus the image on the retina.
If light gets bent too much or too little the vision will be blurred and thats why people need glasses
84
What are the 2 types of photorecetors in the eyes and what do they do?
1) Rods: Allow for vision in low light (more peripheral) (found in the retina)
2) Cones: For colour vision and fine details, but must be in bright light. (found in the retina in the center part called the macula or fovea..no rods there)
*both rods and cones contain outer segments that are packed with disks. Disks have visual pigments that respond to specific types of light energy
85
What is "Dark Current"? (detailed)
- Plasma membrane on the outer portion of the photoreceptos contains chemically gates sodium ion channels.
- In darkness these channels are kept open causing the resting MP to be at -40 mV instead of the typical -70 mV.
- This causes the photoreceptors to continuously release neurotransmitters across the synapses at the inner segment.
- Inner segment is continuously pumping sodium ions out into the cytoplasm.
86
What is "Dark Current" ? (simple)
The movement of sodium ions into the outer segment, onto the inner segment, then out of the cell.
87
What happens to the lens for close vision and why?
The ciliary muscles attached to the lens are contracted, making the lens rounded.
88
What happens to the lens for distant vision and why?
The ciliary muscles attached to the lens are in a relaxed state, making the lens flattened.
89
Why do most people need reading glasses when the get older?
Probably because their ciliary muscle isnt working as well as it does when your young so your lens is getting the contracted the same.
90
What is Myopia?
- Nearsightedness
- If the eyeball is too deep or the curvature of the lens is too strong then distant vision is projected INFRONT of the retina and not on it so the distant vision is blurred
*close up vision will be fine though
91
How is myopia corrected?
A diverging concave lens
92
What is hyperopia?
- Farsightedness
- If the eyeball is too shallow or the lens is too flat the close vision is projected BEHIND the retina and vision is blurred.
- Also makes them have to contract the lens for distant vision.
*older people get this because their lenses lose elasticity.
93
How do you correct hyperopia?
A converging convex lens
94
Ear anatomy. What are the parts of the external ear?
Auricle
Elastic cartilages
External acoustic meatus
95
Ear anatomy. What are the parts of the middle ear?
Tympanic membrane
Tympanic cavity
Malleus, Incus, Stapes
96
Ear anatomy. What are the parts of the Internal ear?
Oval window
Round window
Vestibule
Semicircular canals
Auditory tube
Cochlea
Facial nerve VII
Vestibulocochlear nerve VIII
97
What is the function of the external ear?
To funnel sound waves towards the tympanic membrane
98
What is the function of the middle ear?
Once vibrations hit the tympanic membrane it triggers vibrations of the ossicles (ear bones)
99
What is the pathway vibration take once they reach the internal ear?
1) Stapes vibrates and transmits vibration to the vestibular duct.
2) Vestibular membrane vibrates
3) Endolymph in the cochlear duct vibrates
4) Basilar membrane vibrates
5) Movement is dected by the hair cells on the Corti.
6) Vibrations are transmitted out via the scala tympani and round window.
100
What are hearing cells and where are they?
- Mechanoreceptors. Hair cells. Found in the organ "Corti" (in the cochlear duct of the cochlea)
101
What is the structure of a hair cell?
- Hair cells are covered by "stereocilia" that are attached to one another by "tip links".
- Stereocilia are embebedded on a gelatinous cap "Tectorial membrane" on the Corti.
- When the sterocilia move they pull open gated K+ channels on the membrane and depolarize the cell.
102
How do hair cells work when their stimulated? 5 steps
1) Tip links stretch and mechanically open the K+ channels. (stereocilia bend towards the tallest)
2) K+ enters cell depolarizing it
3) Depolarization opens voltage gated Ca2+ channels.
4) Ca2+ enters and causes a greater release of neurotransmitters.
5) More neurotransmitters leads to a higher rate of AP.
103
What happens to a hair cell when it is not stimulated? (5 steps)
1) Stereocilia relax and close K+ channels (bend towards the shortest one).
2) No K+ enters. Cell Hyperpolarizes.
3) Ca2+ channels close.
4) No neurotransmitters are released.
5) No AP occurs
104
How do we perceive different pitches?
Different frequencies of sound waves.
Different frequencies vibrate different cells on the basilar membrane.
105
How do we perceive different volumes?
Louder sound means larger wavelengths.
larger waves=greater amplitude=louder sound
Larger waves with more energy (more movement of the basilar membrane)
**excessive loudness can cause permanents damage to hair cells.
106
Where does equilibrium take place in the ear?
Angular and Linear acceleration
Semicircular cannels and vestibular apparatus
Semicircular cannels are responsible for "Angular acceleration" (movement of the head in different dirrections)
The Maculae which is close to the Saccule which is in the Uricle is for "Linear accelation" (forward/backward/up/down and position of head in relation to gravity)
107
How does equilibrium work in the maculae?
Otoliths/ statoconia (little crystals) on a gelatinous material that sit atop hair cells. when the crystals move it displaces the stereocilia of the hair cells stimulating them
108
What is pain and what receptors are stimulated by it?
An indication of potential or actual tissue damage.
Nociceptors. get stimulated by chemicals release from damaged cells.
This sensory input can get confused and results in referred pain.
109
Nociceptors. When the sensory input comes into the spinal chord where does it enter from? And what different pathways can it take
Enters via the Dorsal root and synapses with a new neuron there. This second neuron carries info up to the brain.
1) Info relayed to the thalamus and out the cerebral cortex (where we become consciously aware of the sensation).
2) Info relayed to the reticular formation (makes us more alert)
3) Info relayed to the lymbic system (for emotional reactions)
110
Are nociceptors tonic or phasic?
Tonic. They always send info
111
What is the path of blood flow through the heart?
1) Deoxygenated blood enters the right atrium from the superior/inferior vena cava.
2) Blood leaves the right atrium through the Right AV valve (tricuspid) into the right ventrical.
3) blood leaves the right ventricle through the Right semi lunar valve into the pulmonary arteries.
4) blood travels up the pulmonary arteries into the lungs where it gets oxygenated.
5) Now oxygenated blood travels back to the heart via the pulmonary veins.
6) enters the Left atrium.
7) leaves the left atrium via the Left av valve (bicuspid) into the left ventricle.
8) leaves left ventricle via the left semi lunar valve into the aorta (oxygenating the body)
112
What makes the heart electric?
Cardiac conducting cells and contractile cells (make that heart contract)
113
AP in cardiac muscles cells (contractile cells in ventricular muscle cell)
1) Resting potential
2) Depolarization
3) Early Repolarization and Plateau
4) Final Repolarization
5) Refractory period
6) Return to resting potential
114
AP in cardiac muscle cells. Depolarization (detailed)
- Voltage gated Na+ ion channels open (Na+ moves in)
- Voltage gated Ca2+ ion channels start to open
**(Voltage gated K+ channels are closed)
115
AP in cardiac muscle cells. Early repolarization and Plateau (detailed)
- Voltage gated Na+ ion channels close (no more Na+ influx)
- Voltage gated Ca2+ ions open (Ca2+ moves in) some K+ channels are open (K+ moves out)
116
Briefly explain a graded potential (local potential).
-Slight change in membrane potential at one place on the membrane, causes depolarization to occur within the membrane (not enough to reach threshold).
-Weak signals to be sent over small distances.
117
AP in cardiac muscle cells. Final repolarization (detailed)
- Voltage gated Ca2+ ion channels close (no more Ca2+ influx)
- Lots of voltage gated K+ channels open (K+ exits)
-
118
What is "Automaticity/ Autorhythmicity"?
The heart generates its own rhythm.
Cardiac muscle is involuntary
"It initiates and distributes the stimulus to contract"
***consists of the SA/ AV node, conducting cells, AV bundle, bundle branches, purkinje fibers****
119
Explain an action potential in its fundamental terms.
If depolarization is such that it reaches threshold than an "all or none" response happens (action potential)
rapid depolarization, repolarization and hyper polarization all occur within milliseconds.
moves one way down the axon and can travel long distances.
120
Explain the flow of Ions during an Action potential step by step.
At resting potential, K+ and Na+ voltage gated channels are closed.
once threshold is reached at a specific spot on the membrane, Na+ voltage gated channels are opened and sodium ions rush into the membrane down its electrical/concentration gradient. (membrane depolarizes)
Once the peak of depolarization is reached, Na+ gated channels close and voltage gated K+ channels open rushing potassium out of the membrane down its electrical/concentration gradients. (repolarization)
Hyperpolarization occurs then resting potential is restored, Only now there is more K+ outside the membrane and more Na+ inside the membrane.
Diffusion (passive transport) and K+,Na+ pumps (active transport) return the membrane to its "normal" state of resting potential (more K+ inside, more Na+ outside.)
121
What are Nodal cells?
Conducting cells in the heart nodes (i think. doesnt say in slides or textbook)
- Cannot hold a stable resting potential
- They gradually "drift" towards threshold (depolarization)
122
Where is the SA node and tell me some shit about it?
- In the wall of the right atrium
- "pacemaker of the heart"
- 80-100 AP/ minute (with no other input)
123
Where is the AV node and tel me some shit about it?
- Between the right and left ventricle
- 40-60 AP/ minute (with no other input)
124
What does ECG stand for?
Electrocardiogram
125
Briefly explain what the ECG does?
- It measured the activity of a specific node, conducting and contractile cells in the heart.
Measures
- P waves
- QRS waves
- T waves
126
What do P waves measure on an ECG?
The depolarization of the Atria
127
What do QRS waves measure on an ECG
The depolarization of the ventricles
**(and repolarization of the Atria)
128
What is an absolute refractory period?
The membrane can not respond to any further stimulus (no more action potentials can take place during this time).
129
what is a relative refractory period?
The membrane can only respond to a a larger than normal amount of stimulus to trigger another Action Potential.
130
What is a "propagation of action potential"?
When the electrical signals (action potential) from one spot on the cell membrane move down the length of the neuron.
131
Ight. Step by step (5 steps) tell me how ECG relates the the contractions of the heart?
***DONT NEED TO KNOW THE SPECIFICS FOR LECTURE EXAM BUT WILL BE ON THE LAB EXAM
1) SA node and Atrial activity begin (ECG TRACING) 60-100 AP
2) Stimulus spreads across atria to AV node (P waves, atrial depolarization)
3) 100 msec delay at AV node (Atrial contractions start) (P-R interval, conduction through AV node and AV bundle)
4) Impulse travels up the interventricular septum/Av bundle/bundle branches/ purkinje fibers to the papillary muscle of the right ventricle. (Q wave, beginning of ventricular depolarixation)
5) Purkinje fibers distribute impluses and relay them though the ventricular myocardium. (Attrial contractions end and ventricular contractions begin) (QRS complex, completion of ventricular depolarization)
132
Name two ways in which an AP can be propagated faster.
Along a myelinated axon, a fatty sheath (myelin sheath) made up of Schwann cells and oligodendricytes. The AP needs only occur at the nodes of Ranvier instead of the length of the axon. This = saltatory conduction. the thicker the sheath the faster the AP propagation.
A larger diameter axon will transmit the AP faster (larger surface area decreases resistance).
133
What is systole?
The contraction of the chambers (ventricles) to pump/ eject blood out into the arteries
134
What is Continuous propagation of an AP?
The AP travels like a wave along the length of the axon (dominoes falling). Triggering action potentials for each section along the axon.
135
What is diastole?
Heart relaxing after contraction allowing chambers to fill with blood.
ewww yuck
136
What is atrial systole?
- Atrias are contracting
- This creates higher pressure in the atria to push (a little more) blood into the ventricles
**Atrial systole ends and Atrial diastole begins
137
What is Saltatory Propagation of an AP?
The AP "skips" over the myelinated sections of the axon to the Nodes of Ranvier (the space between myelin sheaths). This allows for the propagation of the AP to occur faster down the length of the axon.
138
What is ventricular systole?
- Ventricles are contracting
- Pressure in ventricles stars to rise, (closes AV valves. * no blood flow out yet because the semilunar valves are still closed
**(called ISOVOLUMETRIC CONTRACTION)
- Pressure in the ventricles eventually exceeds that of the aorta/arteries, and the semilunar valves open and blood rushes out into the arteries.
**(ventricles have reached the peak of their contractions and begin to relax. End of systole and beginning of Diastole)
139
Compare and Contrast Saltatory vs Continuous propagation. Which one is faster?
Compare: Both forms of propagation move the AP down the length of the axon by following the local flow of electrical current.
Contrast: Whereas Continuous propagation causes a response along each section of the axon, Saltatory propagation skips over myelinated sections of the axon and triggers a response in the nodes of Ranvier. This makes Saltatory propagation faster than continuous.
140
What is Ventricular Diastole?
- Pressure in the ventricles drops and they enter a period of "ISOVOLUMETRIC RELAXATION" (no blood flow in or out)
- Ventricles relax even more and the pressure has now decreased enough to allow the AV valve to open (blood from the atria can now pass ito the ventricles (passively)
141
Explain what a synapse is, and what are they made up of?
Synapse is "a junction between two cells", made up of the Presynaptic cell (the neuron transmitting the signal), the synaptic cleft (space in between both neurons) and the post-synaptic cell ( the neuron receiving the signal).
142
Two main types of synapse?
Electrical and Chemical
143
Describe what happens during an electrical synapse.
Using Gap junctions, neighbouring cells are connected via "connexons" that allow the electrical current to flow. Rare in the nervous system but important in the cardiac system.
144
What happens during a chemical synapse?
An action potential in the presynaptic cell causes chemicals to be released by the presynaptic cell. The chemicals cross the synaptic cleft and bind to receptors in the post synaptic cell, this can cause chemical gated channels to open making an AP more or less likely to happen.
145
What is isolvolumetric contraction?
Ventricles are contracting
Pressure in ventricles start to rise closing the AV valves, but no blood flow out because the semilunar valve is still closed.
146
What is a Cholinergic synapse?
A chemical synapse where the neurotransmitter involved is Acetylcholine.
147
What is isovolumetric relaxation?
AV valves and semilunar valves close (causes the second "heart sound", no blood can flow in or out
148
What is auscultation?
The action of listening to the heart sounds
149
What are the 4 heart sounds?
S1= lupp, AV valves closing (start of ventricular systole)
S2=dupp, semilunar valves closing (start of ventricular diastole)
S3=blood flowing into ventricles
S4=atrial contraction
150
What is happening in the presynaptic neuron when acetylcholine is released?
An arriving AP depolarizes the presynaptic neuron, this opens voltage gated Ca2+ channels. The Ca2+ enter the cytosol in the axon terminal and ACh is released via exocytosis from synaptic vesicles.
151
What is happening for the S1 and S2 heart sounds?
S1 (Lupp) Recoil of blood due to the AV valves closing (start of ventricular systole)
S2 (Dupp) Recoil of blood due to the semilunar valves closing (start of ventricular diastole)
152
What is happening for the S3 and S4 heart sounds?
*very faint, seldom audible
S3- blood flowing into the ventricles
S4- Atrial contraction
153
What happens to the postsynaptic neuron when ACh is released?
ACh diffuses across the synaptic cleft and binds to receptors. These in turn open Na+ chemically gated channels which cause graded depolarization or an action potential if threshold is achieved.
154
What are the 2 forces that effect blood flow (and air flow)?
Pressure and Resistance
155
Increased pressure = _____?
Increased flow
156
Increased resistance = _____?
Decreased flow
157
How and why is Acetylcholine removed from the synapse?
Acetylcholinerase (an enzyme) breaks down ACh in acetate and choline in the synaptic cleft. The presynaptic neuron reabsorbs the choline to help resynthesize ACh in the future. This removal is important otherwise there could be a constant stimulus to the postsynaptic neuron when their shouldn't be.
158
What does SV, EDV and ESV stand for?
SV - Stroke volume
EDV - End-diastolic volume
ESV - End-systolic volume
SV = EDV - ESV
159
Why is it necessary to remove the neurotransmitter from the postsynaptic neuron?
So that Choline can be recycled for future use, and so the depolarization and hyper polarization can occur in the postsynaptic neuron (end the signal/transmission).
160
Normal SV at rest is?
70-80 mL
*the volume ejected by each ventricle per "beat"
161
What is an EPSP (excitatory postsynaptic potential)?
When the post synaptic membrane depolarizes, the response is excitatory and causes a graded potential which can trigger an AP.
162
What is an IPSP (Inhibitory postsynaptic potential)?
When the postsynaptic cell Hyper-polarizes, the response is inhibitory. Less likely to trigger an AP as the membrane potential moves further from the threshold.
163
Tell me about EDV?
- The amount of blood in the ventricles just before contraction
- This volume can be affected by "filling time" and "venous return" (flow of blood back to the heart)
164
Tell me about ESV?
-Amount of blood in ventricles after systole.
- Influenced by "preload" "contractility" and "after load"
165
What is preload?
"degree of stretching in ventricular muscle cells during diastole"
- More full = More stretch = More preload = More efficient, forceful contraction
*More in More out
166
What is contractility?
"amount of force produced during contraction (at any given preload)"
- Can be increased or decreased by autonomic nervous system and hormones (often related to Ca+ levels available in muscle cells)
167
What is afterload?
"the amount of tension needed to force open the semilunar valves and eject blood out of the ventricles"
-Blockages in the arteries or hormones or anything that causes high blood pressure can effect afterload
168
What does CO stand for?
Cardiac Output = amount of blood pumped by each ventricle in 1 minute
CO = HR x SV
(eg) HR=75 beats/min and SV=80ml/beat
CO = 75 x 80
= 6000 ml/min or 6 L/min
169
What is "summation" in relation to the Post synaptic cell?
Summation is the adding up of EPSP's and IPSP's on the postsynaptic cell
2 kinds: Temporal and Spatial
170
Describe the features of Temporal Summation.
One synapse is active repeatedly over time. A membrane receives two depolarizing stimuli from the same source in rapid succession, these effects are added up to help trigger or cancel an AP.
171
What homrones affect the SA node?
Epinephrine, Norepinephrine, thyroid hormone
172
describe the features of Spatial Summation.
Many synapses are active simultaneously across space. When the sources of stimulation arrive at the same time from different locations. The areas of overlap experience the depolarizing effects of both sources.
173
What is a regulatory neuron?
Axons making synapses with other axon terminals to either help or hinder the activity of a given AP (Presynaptic facilitation and inhibition).
174
Describe Presynaptic facilitation.
Make it more likely for the presynaptic neuron (axon terminal) to release its neurotransmitter.
Example: Action potential arrives to the facilitatory Neuron, it releases serotonin into the presynaptic cell which opens Ca2+ gated channels, more Ca2+ enters the cell, more neurotransmitters are released increasing the effect on the postsynaptic neuron.
175
Describe Presynaptic Inhibition.
Make it less likely for a presynaptic neuron (axon terminal) to release its neurotransmitter.
Example: AP arrives to the Inhibitory neuron
