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Anatomy & Physiology > Unit 3 - Cardiovascular > Flashcards

Unit 3 - Cardiovascular Flashcards

1
Q

heart function

A

transport!
- oxyen, nutrients, hormones to cells
- CO2 + other metabolic products from cells -> lungs, liver, kidneys
- heat to extremities

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2
Q

cardiovascular made up of

A
  1. circulatory system
    - heart
    - vessels
    - blood
  2. arteries (away from heart)
  3. veins (to heart)
  4. lymphatics (tissue fluid AKA lymph to large veins)
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3
Q

heart location

A

dog: rib 3-6
- 45 degree angle with sternum

cat: ribs 3/4-6/7
- more acute angle (more sternum contact)

horse: ribs 2-5
- apex at elbow.

bovine: os cordis within heart (2 bones separating atria + ventricle)

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4
Q

heart layers

A
  1. pericardium
    - thin fibro-serous heart covering
    - fibrous part outer
    - serous part inner
    a) parietal (in contact with fibrous)
    ~pericardial space (fluid) between~
    b) visceral (in contact with heart)
  2. myocardium
    - muscle layer
  3. endocardium
    - membrane on internal surface of heart
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5
Q

heart chambers

A

each side has an:
1. atrium (receives blood from veins)
+ interatrial septum b/w R/L

~ atrio-ventricular valve in between~
~ leaflets preventing backflow

  1. ventricle (pumps blood to arteries)
    + interventricular septum b/w R/L

RIGHT
right atrium:
- thin wall
- gets blood from systemic (everything but lungs) veins
- right auricle = blind portion

~right AV valve (tricuspid) between~
~ anchored to R ventricle through chordae tendinae connecting to RV’s papillary muscles

right ventricle:
- more muscular than atria
- thinner wall than L ventricle
- doesn’t reach apex
- blood goes R atrium -> R AV -> R ventricle

~pulmonary trunk drains RV~
~ blood leaves RV
~ pulmonary semilunar (3 cusp) valve at base of trunk

LEFT
left atrium:
- thin wall
- gets blood from pulmonary veins
- left auricle: blind portion

~left AV valve (mitral) between~
~ anchored to L ventricle through chordae tendinae connecting to LV’s papillary muscles

left ventricle:
- thickest wall
- connects to apex
- blood goes L atrium -> L AV -> LV

~ aortic semilunar valve~
~ separates LV from aorta
->
~ aorta~
~ blood leaves LV

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6
Q

heart valves

A
  • anchored by CT separating atria from ventricles
  • one-way

AV valves:
- one side of leaflet attached to inner ventricle where it connects to atrium
- free edges loosely attached to V by chordae tendineae (prevent valve from flipping when Vs contract)
- leaflets pushed together from blood in V -> AV valve closes

semilunar:
- stop blood from returning into V when they relax

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7
Q

tree branch

A
  • arteries start large where they carry blood from heart -> smaller branches
    a) arterioles: smallest branch -> lead to capillaries

capillaries: one cell thick tubes for nutrient exchange
- selectively permeable
- take in water, O, nutrients
- pushes waste into the blood
- lymphs remove excess fluid from capillaries

venules:
- united capillaries that have passed through tissue
- then venules unite -> larger veins

vena cava:
- largest of veins
- empty into heart

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8
Q

veins vs artieries

A

vein difference:
- larger
- thinner wall
- more superficial
- valves where 2+ veins meet to form a larger vein (prevent backflow)
- TO heart

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9
Q

filtration

A

arterial end:
- blood forced into capillaries through hydrostatic pressure from heart
- but only water + small ions and nutrients get through

venule end:
- fluid reabsorbed, low hydrostatic pressure
- plasma proteins more concentrated, their osmotic pressure draws water in (this part of osmotic pressure = ‘oncotic pressure’)
- oncotic pressure: comes from molecules too large to escape capillaries

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10
Q

edema

A
  • excess tissue fluid
    from:
  • leaky vessels
  • high hydrostatic pressure (heart failure)
  • low oncotic pressure (low albumin from GI disease or liver failure)
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11
Q

blood flow path

A

L/R pulmonary veins -> L atrium -> L AV -> L ventricle -> aortic semilunar -> aorta ->

…. -> arteries -> arterioles-> capillaries -> tissue -> venules -> veins -> vena cava -> …..

R atrium -> R AV -> R ventricle -> pulmonary semilunar -> pulmonary trunk -> L/R pulmonary arteries

2 circulations:
1. systemic
- deoxygenated vein
2. pulmonary (lungs only)
- oxygenated vein

venous blood:
- veins -> heart
- unoxygenated

arterial blood:
- heart -> body
- oxygenated

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12
Q

pulmonary circulation

A
  • blood moving through lungs
  • vast capillary network
  • swap air in alveoli for CO2 in blood -> becomes oxygenated
  • blood changes from dark red (no oxygen) to bright red
  • ONLY place where there is unoxygenated blood in arteries + oxygenated in veins

PATH:
pulmonary trunk -> pulmonary arteries -> capillaries -> pulmonary veins -> L heart

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13
Q

systemic AKA somatic circulation

A
  • O blood to all body (- lungs) -> unO blood back to heart
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14
Q

aorta

A

carries blood from LV -> tissues

3 parts:
1) ascending (connects to arch)

2) arch
- 2 branches:
a. brachiocephalic trunk
- supplies head, R thoracic limb
I. common carotid artery: head
ii. R subclavian artery: R thoracic limb
- further branches into R jugular

b. L subclavian artery: L thoracic limb
- further branches into L jugular

(subclavian -> axillary -> brachial -> median)

3) descending
- supplies rest of body (not head and thorax)
a. celiac artery
- just below diaphragm, unpaired
3 branches:
I. hepatic: liver
ii. L gastric: stomach
iii. splenic: spleen

b. cranial mesentric artery
- just below celiac, unpaired
- supplies intestince

c. renal arteries
- paired
- supply kidneys

d. gonadal arteries
- paired
- supply testes/ovaries

e. caudal mesentric artery
- unpaired
- supply colon

f. iliac arteries
- supply pelvis + pelvic limbs
I. external: paired, down each leg to become ‘femoral arteries’ -> popliteal -> cranial tibial
ii. internal: paired just below external, supply glutes

g. median sacral artery AKA caudal
- unpaired, supplies tail

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15
Q

systemic blood flow

A

cranial/caudal vena cava return blood from cranial/caudal parts of body -> R atrium

CRANIAL
jugular + subclavian veins -> brachiocephalic veins -> cranial vena cava

CAUDAL
iliac veins -> gonadal veins -> renal veins -> portal vein (spleen, GIT, liver) -> hepatic veins -> caudal vena cava

  • azygous vein helps drain both thorax + abdomen
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16
Q

hepatic portal circulation

A
  • carries blood from capillaries of 1 organ to capillaries of another
  • blood drains from capillaries of stomach, spleen, intestines, pancreas
    -> connects in hepatic portal vein -> liver sinusoids (large capillaries)
  • in liver, nutrients can be modified and stored
  • also detoxifies liver from harmful things absorbed from GIT

leave sinusoids -> into hepatic veins (not portal) -> caudal vena cava

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17
Q

coronary circulation

A

ascending aorta -> L/R coronary arteries -> myocardium

‘coronary’ = heart muscle

  • can be blocked from fatty deposits, treated by balloon angioplasty or bypass
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18
Q

fetal circulation

A
  • blood moves through placenta -> exchanges CO2 + waste for O and nutrients from mother
  • umbilical veins = oxygenated
  • fetal lungs collapsed, resistant to flow, so blood moves from R to L side of heart through ‘foramen ovale’ and ‘ductus atereriosus’ (artery directly connecting pulmonary trunk + aorta)
  • placenta -> fetus through umbilical -> ductus venosus -> drains into caudal vena cava

birth:
- air enters lungs, blood can flow normally.
- foramen ovale and ductus ateriosis close
- ductus venosis on mother closes

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19
Q

which vessels are oxygenated/unoxygenated?

A

O:
- aorta, systemic arteries
- pulmonary veins, umbilical veins

unO:
- vena cava, systemic arteries, pulmonary arteries, umbilical arteries

20
Q

circulatory system pressure

A
  1. systemic: high
    - hyrdostatic forces blood through capillaries
    - needs to pump against gravity
  2. pulmonary: low
    - little resistance in lung vessels
    - delicate capillaries easily leak if pressure too high
21
Q

blood volume distribution

A

lungs: 15%
body: 80%
heart: 5%

22
Q

pressures

A

systole: contraction of ventricles causing heart to eject blood
- max artery pressure during ventricle contraction

diastole: relaxation of ventricles causing heart to fill
- min artery pressure during ventricular relaxation

  • pulse pressure: difference b/w systolic + diastolic
  • peripheral/systemic resistance: friction in arteries that limits flow
23
Q

pressure related terms

A

contractility: ability of heart to contract

afterload: force ventricles need to overcome to pump blood

preload (AKA end diastolic volume): amount of blood in heart before contraction

stroke volume (AKA systolic discharge): amount of blood ejected out of heart w/ventricular contraction

cardiac output: volume of blood heart can pump per minute
- stroke volume x heart rate

starlings principle: stretched muscle fibers have increased contractility
- more blood in -> stronger contraction

isometric contraction: just before V pump, valve stay closed and V starts to contract -> increasing pressure

ventricular ejection: semilunar open, valve empties

24
Q

preload

A

determined by end diastolic volume (ventricle filling - how much blood you have in your heart at rest [max volume before pumping])

affected by:
- leaky semilunars
- incomplete emptying from poor contractility

starling: if preload increases, contractility increases

25
Q

contractility

A

determined by:
- preload
- sympathetic stimulation (increases)
- blood and tissue concentrations
- drugs (eg. digoxin)

26
Q

afterload

A

resistance ventricles pump against
- arterial ‘tone’
- measured by BP

affected by:
- sympathetic (vasoconstriction)
- para (vasodilation)

  • in heart failure we reduce afterload w/vasodilators
27
Q

heart rate

A

controlled by:
- body temp (decreased -> lower)
- autonomic NS (cardio-regulatory center in medulla)
- hormones (adrenal releasing epinephrine) (thyroid T4 hormone increases HR -> low HR sign of hypothyroidism)
- ion levels (hyperkalemia = excess K, decreases HR)

medulla:
- BP drops -> sympathetic stimulated -> norepinephrine released -> HR increases
- symp also makes BP increase through vasoconstriction

  • BP rises -> parasympathetic stimulated -> vagus nerve releases acetylcholine to SA and AV nodes -> HR slows
  • atropine used to correct low HRs (block acetylcholine)
28
Q

shock

A

failure of tissue perfusion
- sometimes vessels dilate to a volume that exceeds blood volume -> BP falls

  • systolic BP <40 = dead
  • body shuts down peripheral circulation to focus on brain an heart
  • IV fluid treatment
29
Q

heart sounds

A

S1: AV close
- ‘lub’
- prevents backflow into atria

S2: semilunar close
- ‘dub’
- prevents backflow into ventricles

S3: passive filling of ventricle
- 80% of blood
- normal in horses, not dogs/cats

S4: atrial contraction
- final 20% of blood, preload established
- normal in horses, not dogs/cats

30
Q

cardiac sound cycle

A

atrial contraction (S4) -> ventricular contraction/AV close (S1) -> ventricles relax/semilunar close (S2) -> passively fill as AV open (S3)

31
Q

cardiac muscle

A
  • striated
  • involuntary
  • impulses travels through junctions in ‘intercalated disks’ (not through nervous stimulation of each cell)
  • automatic: can contract w/out external stimuli
32
Q

heart conduction system

A
  • network of specialized cardiac muscle cells generate action potential
  • excitation: APs propagated (coordinated spread)
  • AP: depolarization of resting membrane potential from change in ions (Na, K, Ca)
  • repolarization: ions back to original concentration

COMPONENTS:
- SA node (pacemaker)
- AV node
- Bundle of His
- R/L bundle branches
- Purkinje fibers (smaller branches of bundles)

33
Q

SA node

A

small mass of cells embedded in R atrial wall near vena cava
- depolarize spontaneously (100bpm in humans)
- input from autonomic NS modifies
- discharge is what determines HR

pacemaker = depolarizes fastest

34
Q

sequence of activation

A

SA node spontaneously depolarizes -> signal to R/L atriums -> contract downward -> blood squeezed into ventricles -> impulse gets through via AV node -> L/R bundle branches OR bundle of His -> apex of heart -> purkinje fibers -> upward spread through ventricle muscle -> blood squeezed up + out of pulmonary and aortic valves

35
Q

AV node

A

slow conduction, allows atria to finish filling ventricles before they contract

36
Q

refractory period

A

relaxation right after contraction
- cannot respond to another stimuli
- allows chamber refill

37
Q

ECG (electrocardiogram)

A
  • electrical impulse is predictable in a healthy heart (magnitude and direction)
  • electrodes put on skin (bc body fluid conducts impulses)
  • measures magnitude + direction of depolarization

TERMS
- p-wave: atria depolarization (contraction)
- QRS complex: ventricle depolarization (contraction) (large, so hides atria repolarization)
- t-wave: ventricular repolarization (relaxation)

38
Q

stroke volume determined by…

A

preload
afterload
contractility

39
Q

cardiac rhythm

A

sinus rhythm: heart depolarizing normally, controlled by SA node

sinus arrhythmia: consistent irregeular rhythm that increases w/breath in and decreases w/breath out
- normal in dogs

tachy/bradycardia: HR faster/slower than normal
- bradyarrythmia can be sinus arrest or AV block
- tachyarrhythmia may be supraventricular (signal for depolarization above AV) or ventricular (below AV/in ventricles)

atrial fibrillation: extremely rapid atria contraction, V contractions slower and irregular bc AV node only sporadically stimulated

ventricular fibrillation: extremely rapid contraction of V in various small portions of wall at once
- produces no pulse
- will die if not CPR/defibrillation

  • electrocardiography will diagnose
40
Q

heart pathology

A

murmur: turbulent flow of blood
- during systole…..
- leak/insufficiency in AV valve (should be closed)
- narrowing (stenosis) in semilunar (should be open)
- OR insufficient semilunar/stenosis AV in diastole
- normal in some large animals
- ultrasound to diagnose

41
Q

pulse rate

A

rate = number of V contractions/minute

pressure = difference b/w systolic + diastolic (amplitude)

pressure required to occlude vessel = systolic
- shock: pulse easy. to occlude, pressure low

FEELING
cat: femoral
dog: femoral, lingual, dorsal pedal
horse cow: facial

42
Q

comparative anatomy

A

pulmonary AKA semilunar:
- dog horse cow: 3 intercostal
- cat: 4 intercostal

aorta:
carnivores: L subclavian branches off aorta
ungulates: L subclavian off brachiocephalic

43
Q

congenital pathologies

A

atrial septal defects/patent foramen ovale:
- foramen ovale fails to close -> blood passes through L/R atrium
AKA shunting

ventricular septal defects:
- small opening - complete absence of septum
- blood passes through ventricle with force
- shunt usually L to R
- depending on size of opening, no signs or cyanosis, weakness, anorexia
- common in horses, cows, large dogs

persistent ductus arteriosus:
- doesn’t close after fetus born
- results in ‘machinery murmur’
- common in mini/toy

persistent R aortic arch:
- embryonic arch persists -> displaces esophagus + trachea
- often traps them in a ‘ring’ that compresses and results in dyspnea and regurgitation

pulmonic stenosis:
- narrowing at/just below semilunar
- makes a murmur during systole

aortic stenosis:
- narrowing where L V outflows, difficult emptying

tetralogy of fallot:
- pulmonic stenosis + septal defect + malpositioned aorita + R V hypertrophy

44
Q

heart failure

A
  • first noticed during auscultation from murmurs or arrhythmias
  • cause decrease in pumping efficiency
  • left-sided, right-sided, or generalized

left-sided AKA congestive failure:
- back pressure increases pressure at venous end of pulmonary capillaries
- fluid forced out in lung -> edema
- exercise intolerance, dyspnea, lung congestion

right-sided failure:
- fluid can’t get out of organs -> swell and decrease function
- jugular veins engorged
- fluid builds up in abdomen in dogs (ascites), chest in cats (hydrothorax), under skin in large (SQ edema)

generalized:
- L + R failure
- failure of 1 side usually results in generalized failure eventually

45
Q

acquired cardiovascular diseases

A

dilated cardiomyopathy:
- dobermans, danes, boxers, cocker spaniels
- link to grain-free diets + taurine deficiency
- coughing, weak, weight loss, murmur + arrhythmia

mitral valve degeneration

parasites:
- horses get aneurysm in cranial mesentric artery by stronglus vulgaris
- heartworm usually in dogs, rarely in cats. grow in pulmonary arteries, R A + R V -> R V dilation + hypertrophy -> right-sided failure . weakness, exercise introlerance, coughing, fainting, murmur

Anatomy & Physiology (16 decks)

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