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BIO 102 > quiz 8 > Flashcards

quiz 8 Flashcards

1
Q

significance of maintaining bodily pH

A
  • tons of bodily reactions driven by enzymes with specific optimal pH ranges
  • pH varies in different areas of the body (even in different cell organelles) but all enzymes have narrow optimal pH
  • overall body pH is 7.4, drop to even 6.8 would be huge
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2
Q

how does pH play a role in perms?

A

strong pH denatures proteins in hair

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3
Q

what receptors signal a change in breathing rate in the body?

A
  • peripheral chemoreceptors (carotid bodies)
  • central chemoreceptors (medulla in brain)
  • stretch receptors in lungs
  • emotions
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4
Q

differences between peripheral and central chemoreceptors

A
  • peripheral chemoreceptors are carotid bodies, they sense O2 levels
  • central chemoreceptors are located in medulla, they sense CO2 and pH levels
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5
Q

how does the heart contribute to human metabolism?

A
  • heart is a pump; provides propulsion of blood through capillaries for nutrient/waste exchange
  • metabolism increase can be sustained by increase in pump function (higher HR or stroke volume)

*higher oxygen demand for organisms requires greater separation of oxygenated/deoxygenated blood and higher blood pressure

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6
Q

two parts of the heart

A

we consider the heart to have 2 functional pumps for 2 circuits:

  • low pressure pulmonary/lung circuit
  • high pressure arterial/body circuit
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7
Q

open vs closed circulatory design

A

open systems: hemolymph (in insects) or other blood not enclosed in vessels, heart is a mixing chamber

closed system: everything enclosed in vessels/tubing, heart is a pump

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8
Q

how do open circulatory systems work in insects?

A
  • dorsal heart tube along back contracts to move/mix blood
  • hemolymph let in via small holes called otria
  • contracts in both directions, blood squirts out excurrent openings on both ends
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9
Q

neuorogenic vs myogenic hearts

A

neurogenic hearts

  • crustaceans, insects, annelids
  • contraction under nervous control; no nerve = no heartbeat

myogenic hearts

  • vertebrates, mollusks
  • contraction initiated by heart cells
  • nervous system can modify rate but isn’t required for beating
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10
Q

what triggers heart contractions in neurogenic hearts?

A
  • regulated by peptide release from nerves

- on imaging, white areas around heart tubes are where peptides are released

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11
Q

different types of heart design

A

1-chamber (non-vertebrate): insects
2-chamber: fish; low pressure because blood travels far
3-chamber: amphibians; 2 atriums and 1 ventricle
3-chamber septated: reptiles; allows for less mixing within ventricle
4-chamber: birds and mammals; full septum

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12
Q

flow of blood in and out of the heart

A

pulmonary circuit:
vena cava - right atria - tricuspid valve - right ventricle - semilunar values - pulmonary artery - lungs

arterial circuit:
pulmonary veins - left atria - bicuspid/mitral valve - left ventricle - aorta

*values are key to one-way flow!

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13
Q

how is blood supplied to keep the heart functioning?

A
  • coronary vessels penetrate heart from the surface

- blood supply to heart occurs between contractions

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14
Q

how is coronary blood flow blocked, and how is it fixed?

A

buildup of plaque in coronary arteries can threaten blood flow to heart

  • bypass: blood vessels harvested to transport blood flow around problem area
  • cardiac stents: mesh expanded via balloon; mesh pushes out against narrowing vessel
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15
Q

how do gap junctions work?

A
  • each cardiac muscle cell has one connexon (hemichannel) which come together to form a gap junction
  • each connexon has 6 subunits
  • gap junctions allow passage of ATP, ions, signaling molecules, and electrical signaling for heart beat
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16
Q

how does cardiac contraction work? (electric signaling)

A

conduction pathway: contraction signal is spread by electrical vectors; cardiac myocytes connected through gap junctions

  • myogenic cells in the sinoatrial (SA) node initiate heartbeat–atria contract
  • AV node slows signal to allow for ventricular filling (takes time)
  • signal goes through bundle of His
  • signal goes through right and left bundle fibers
  • signal reaches Purkinje fibers–ventricles contract
17
Q

timing/sequence of cardiac contraction

A

systole: cardiac contraction (artia, then ventricle)
diastole: cardiac relaxation

p-wave: atrial contraction
qrs complex: ventrical contraction
t-wave: ventricular recovery

18
Q

solutions for problems with cardiac signaling

A

if SA node is not functioning well to initiate heartbeat, electrodes can be placed in various places to stimulate heart muscle (fix abnormal heart rhythm)

19
Q

normal heart rate, stroke volume, and cardiac output at rest

A

heart rate: 60-80 bpm
stroke volume: 50-100 ml

cardiac output: 5 L per minute

20
Q

how can cardiac output be increased?

A
  • increasing heart rate

- increasing stroke volume (blood pumped for each beat)

21
Q

how does neural regulation play a role in heart rate?

A

regulated by the autonomic nervous system in medulla
*will never stop heart or cause HR too high, as there isn’t enough time for filling

  • vagus nerve: decreases heart rate/extent of contraction (SV)
  • sympathetic cardiac nerves: increase heart rate/extent of contraction (SV)
22
Q

what factors influence blood pressure?

A
  • flow (cardiac output; HR x SV)

- peripheral resistance (radius/diameter of vessel)

23
Q

what does blood pressure reflect?

A

perfusion of tissue by blood

24
Q

blood pressure equation

A

P = Q x R

P: pressure
Q: flow
R: resistance

25
Q

how is blood pressure monitored?

A
  • carotid and aortic baroreceptors monitor blood pressure

- they project to medulla areas associated with autonomic cardiac function (vagus and sympathetic nerves)

26
Q

what do blood pressure numbers indicate? what are hypertension values?

A
  • first # systolic; 2nd # diastolic

- prehypertension starts above 120/80

27
Q

complications associated with uncontrolled hypertension

A
  • can contribute to stroke, cardiovascular disease, Atherosclerosis, dementia
28
Q

difference in blood vessel anatomy between arteries and veins

A

arteries

  • more smooth muscle layer in tunica media
  • thicker collagen fibers in tunica externa
  • pressure ~100 mmHg
  • flow driven by heart contraction

veins

  • little smooth muscle in tunica media
  • thinner tunica externa; thin vessel
  • pressures ~10 mmHg
  • valves prevent pooling of blood and keep flow going
29
Q

how do aneurysms form and why are they dangerous?

A
  • fibers of tunica externa break, causing vessels to thin and web out
  • because vessel is thin, it’s at risk of rupturing–hard to plug
  • generally leaks before rupturing
30
Q

how do we utilize our blood for all our bodies’ needs?

A
  • capillaries everywhere but only ~5L blood in our bodies–not enough to maintain maximal flow to organs/tissues
  • blood generally redirected from inactive to active tissue via autonomic nervous system
31
Q

how is blood flow through capillaries regulated?

A
  • metarteriole runs between arteriole and venule
  • precapillary sphincters regulate how much flow goes into capillary beds
  • local control–high pH/low oxygen in capillary beds in tissues can relax (open) sphincters to allow blood flow into capillaries
32
Q

types of capillaries

A

3 types–tightest to leakiest

continuous, fenestrated, discontinuous

33
Q

2 factors impacting movement in across capillary membrane

A
  • hydrostatic pressure: biggest factor impacting flow, high pressure in vessel causes blood to seep out
  • osmotic pressure: solute can move water through a selectively permeable membrane, mainly caused by high levels of albumin in blood vessels (it can’t escape) so water comes in
  • materials flow through water in between vessels/interstitial space
34
Q

starling forces across capillary wall

A

blood out:

  • capillary hydrostatic pressure
  • osmotic force due to interstitial fluid protein conc.

blood in:

  • interstitial fluid hydrostatic pressure
  • osmotic force due to plasma protein conc.
35
Q

overall changes in pressures through the capillaries

A
  • osmotic pressure stays constant through capillaries
  • hydrostatic pressure starts high, then lowers as fluid exits
  • vessel hydrostatic pressure dominates at the arterial side (blood flow out)
  • vessel osmotic pressure dominates at the venous side (blood flow in)

BIO 102 (14 decks)

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