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BIOMOLECULES AND CELLS > Vertebrate heart structure and function > Flashcards

Vertebrate heart structure and function Flashcards

1
Q

Why do animals need a circulatory system?

A
  • O2, nutrients must be transported around the body to tissues and organs
  • waste products removed
  • communication via hormones
  • temperature regulation & reproduction
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2
Q

Open circulatory system

A
  • Blood flows freely with body cavities making direct contact with all tissues and organs
  • vessels are open ended - blood flows out and bathes tissue
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3
Q

Closed circulatory system

A
  • circulating blood contained in a continuous series of vessels
  • specific components of the fluid filter out of blood vessel and penetrate tissues
  • blood kept separate to interstitial fluid
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4
Q

What are the advantages of a closed circulatory system?

A
  1. faster, more efficient delivery of fluid to tissues
  2. ability to control distribution
  3. assists in the delivery of larger molecules to specific tissue
  4. enabled the evolution of circulatory system that keeps oxygenated and deoxygenated blood separate
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5
Q

Fish heart structure

A
  • one atrium and one ventricle, one circulation
  • specialisation of vessels (Arteries and veins)
  • Blood pumped over gills to become oxygenated but leaves under very low pressures
  • very low pressure in capillary bed - limits efficiency of delivery of nutrients and O2 to tissues
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6
Q

Air-breathing fish hearts

A
  • 2 circulations (pulmonary and systemic)
  • partially divided atrium and ventricle
  • oxygenated (right) and deoxygenated (left) blood is kept separate
  • Gill specialisation:
    • low-resistance by-pass to lung
    • direct link to aorta
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7
Q

Amphibians (i.e. frog) hearts

A
  • 3 chambered heart
  • Left atrium - oxygenated blood, right atrium - deoxygenated blood
  • single ventricle - potential for some mixing of blood but septum directs blood movements and maintain separation
  • partial separation of pulmonary and systemic circuits allow for different pressures
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8
Q

What are the similarities of a closed and open circulatory system?

A

• hearts pump the fluid to different regions of the body via blood vessels
• fluid drains back to the heart
- via veins for closed
- via ostia (openings) for open system (Act as valves)
• Valves ensure one-way flow of fluid

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9
Q

What is the bulbus arteriosus in fish hearts?

A

• In teleosts
• elastic
• works to reduce extreme pulsing of blood leaving the ventricle, giving a more constant, even flow
(like water passing through a balloon)

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10
Q

What is the Sinus venosus in fish hearts?

A

Preliminary collecting chamber

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11
Q

What does the septum do in amphibian hearts?

A

Directs blood movement & maintains separation of oxygenated and deoxygenated blood

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12
Q

Reptiles heart structure

A

• 3/4 chambered hearts
• 2 aortae
Left: oxygenated blood from left ventricle to body
Right: mixed - receives blood from both ventricles
• reptiles dont always breathe - blood by-passes lungs and flows directly to the systemic circuit via the right aorta
• direction of blood is controlled by resistance in the pulmonary circuit

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13
Q

Birds and Mammal heart structure

A
  • 4 chambered heart

* separate pulmonary and systemic circuits

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14
Q

What are the advantaged of having separate pulmonary and systemic circuits?

A
  • pulmonary and systemic circuits can operate at different pressures
  • systemic circuit always receives blood with higher O2 content
  • gas exchange is maximised
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15
Q

What change occur in the heart immediately after birth?

A

• fetal heart: foramen ovale and ductus arteriosus is open

In the newborn heart, both these structures are closed

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16
Q

What is Atrial Septal Defect (ASD)

A
  • Hole in the septum
  • congenital
  • deoxygenated and oxygenated blood mix and the heart does not work efficiently
  • shortness of breath, fainting, irregular heart rhythm and fatigue after regular activity
  • no treatment - surgery needed
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17
Q

What is the septum?

A

Muscle wall between atria

18
Q

Define congenital

A

Present at birth

19
Q

Difference between arteries and veins

A
  • Arteries: carry blood away from the heart

* veins: return blood to the heart

20
Q

What are the 4 main valves in the human heart and where are they found?

A
  1. Tricuspid valve - right
  2. bicuspid valve - left
  3. Aortic semilunar valve - aorta
  4. pulmonary semilunar valve - pulmonary artery
21
Q

Briefly describe the blood flow through a mammalian heart

A

DEOXYGENATED
• from the body, enters via the vena cava to the right atrium, to right ventricle
• passes pulmonary valve and through pulmonary artery to the lungs
GETS OXYGENATED
• through pulmonary vein to left atrium
• through atrioventricular valves to left ventricle
• passes aortic valve and through aorta to the body

22
Q

Summarise the blood flow of the mammalian heart

A

DEOXYGENATED (from body)
• vena cava, into right atrium
• pulmonary artery to lung

OXYGENATED
• lung to pulmonary vein, to left atrium
• from left ventricle through aorta (to body)

23
Q

Function of valves

A

Prevent backflow of blood

24
Q

Difference between the pulmonary and systemic circuits?

A
  • PULMONARY: blood takes up oxygen in the lungs

* SYSTEMIC: oxygenated body is distributed to body tissues

25
Q

What are the atrioventricular valves and their function?

A
  • mitral (bicuspid) - left
  • tricuspid - right

Prevent the backflow of blood into the atria when the ventricles contract

26
Q

What is the function of the pulmonary and aortic semilunar valves?

A

Prevent the backflow of blood into ventricles when ventricles relax

27
Q

What are cardiomyocytes?

A

Cardiac muscle cells

28
Q

Describe the features of the cardiac muscle

A
  • Cardiomyocytes branched with cross striations - formed by myosin and actin
  • intercalated discs - provide mechanical adhesion
  • gap junctions - allow rapid transmission of electrical signal
  • thickness of myocardium - affects pressure generated
29
Q

Describe the steps in a heart cycle

A

RELAX - Diastole
1. atria contract
2. ventricles contract and atrioventricular valves close “lub”
CONTRACT - systole
3. pressure in the ventricles build and aortic/pulmonary valves open
4. blood is pumped out of the heart
5. ventricles relax and pressure drops at the end of systole
RELAX - diastole
6. pressure in arteries is higher, aortic and pulmonary arteries shut “dub”
7. heart fills with blood again

30
Q

Summarise the the stages of the heart cycle with sounds

A 
1. Relax - Diastole
"Lub"
2. Contract - Systole
"Dub"
3. Relax - Diastole
31
Q

Describe the pressure changes during a human cardiac cycle

A

Diastole - relax
• volume in left ventricle high = low pressure
• pressure in aorta high

Systole - contract
• left ventricle decreased volume - high pressure
• aorta pressure also high

Diastole - relax
• left ventricle volume very low but starts to increase - pressure decreasing
• pressure of slowly decreases

32
Q

Mitral regurgitation

A

Narrowing or leaking of valves

33
Q

What are heart murmurs?

A
  • Mital regurgitation
  • congenital, age related changes, infections
  • increased heart work and decreases efficiency - may decrease O2 levels in the blood
  • shortness of breath, pain, fainting
  • treatment: valve repair surgery if serious
34
Q

What is Cardiomyopathy?

A

• Chronic disease of the heart muscle

35
Q

Dilated cardiomyopathy

A
  • Heart is weak and enlarged - cannot pump blood effectively

* most common type and is caused by various medical problems

36
Q

Causes of Hypertrophic cardiomyopathy (HCM)

A
  • Genetic
  • Infections - damage cardiac muscle
  • Excess, long-term alcohol consumption
  • nutritional deficiencies
  • extreme physical activity
37
Q

Restrictive cardiomyopathy

A
  • Ventricles don’t properly fill because heart muscle is still
  • rare
38
Q

Describe the structural changes in Hypertrophic cardiomyopathy (HCM)

A
  • enlarged left ventricle wall - reduced space for blood which reduces output
  • increased stiffness - reduces pumping force
  • thicker ventricle septum
  • disorganised cardiac muscle cells
39
Q

Symptoms of hypertrophic cardiomyopathy (HCM)

A

Shortness of breath, fatigue, dizziness

- can result in sudden cardiac death

40
Q

Explain the sounds that are heart when measuring blood pressure.

A
  1. First sound of flow “tapping” - systolic pressure

2. continuous “whoosh” sound - diastolic pressure

41
Q

What are the different types of blood flow?

A
  • Laminar blood flow - silent (pulse present)
  • occluded blood flow - silent (no pulse)
  • Turbulent blood flow is noisy

BIOMOLECULES AND CELLS (32 decks)

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