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AQA a-level biology 🧬🔬 > Exchange and transport - HEART STRUCTURE/CARDIAC CYCLE > Flashcards

Exchange and transport - HEART STRUCTURE/CARDIAC CYCLE Flashcards

1
Q

Describe the route of deoxygenated blood flow through the heart

A
  • Vena cava
  • Into the right atrium
  • Tricuspid valve
  • Right ventricle
  • Pulmonary artery to lungs - becomes oxygenated.
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2
Q

Describe the route of oxygenated blood flow through the heart

A
  • Pulmonary veins to heart
  • Left atrium
  • Bicuspid valve
  • Left ventricle
  • Aorta
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3
Q

Why is the left ventricular wall thicker?

A

To maintain a higher pressure as blood leaves the heart via the aorta to the whole body

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4
Q

What is the function of the coronary arteries and veins?

A

To supply the cardiac muscle cells with oxygen for respiration (ATP for muscle contraction) and remove waste products

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5
Q

What is the function of the papillary muscles and tendinous cords (tendons)?

A

(Tendons attach to the valves, papillary muscles attach to the tendons)
- Prevent the inversion and prolapse of the valves
- Keep the valves open correctly, to keep blood flowing in one direction

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6
Q

What is the function of the pericardium?

A
  • Tissue that protects the heart from infection and other sources of disease
  • Holds the heart in the chest wall
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7
Q

Suggest why it is important to prevent mixing of the blood in the two sides of the heart

A
  • Prevent the mixing of oxygenated and deoxygenated blood
  • Reduces concentration gradient - inhibits gas exchange at tissues
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8
Q

Why are valves important?

A

They prevent the unwanted backflow of blood

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9
Q

What are valves made of?

A
  • Many flaps
  • Made of tough but flexible, fibrous tissue
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10
Q

What causes valves to open?

A
  • When the pressure is greater on the convex side
  • Valves move apart to let blood through
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11
Q

What causes valves to close?

A
  • When pressure is greater on the concave side
  • Blood collects in the cusp
  • Valves push together to prevent blood flow
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12
Q

In which direction does blood move? (Hint: pressure)

A

From high blood pressure to low blood pressure

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13
Q

What causes the ‘lub’ sound?

A
  • Atrioventricular valves shutting
  • Tricuspid/bicuspid valves
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14
Q

What causes the ‘dub’ sound?

A
  • Semilunar valves shutting
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15
Q

What is atrial systole?

A

Atrial contraction

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16
Q

What is ventricular systole?

A

Ventricular contraction

17
Q

What is diastole?

A

Filling of the atria with blood

18
Q

Why is cardiac muscle described as being myogenic?

A

Can contract and relax without nervous external stimulation

19
Q

What is the P wave?

A
  • Impulses spreading across the atria
  • Atrial systole
20
Q

What is the QRS complex?

A
  • Impulses spreading up through ventricles
  • Ventricular systole
21
Q

What is the T wave?

A

Recovery of ventricles during diastole

22
Q

What is the function of the sinoatrial node?

A
  • Pacemaker of the heart
  • Generates electrical activity starting a heartbeat
23
Q

What is the function of the atrioventricular node?

A

Delays spreading of electrical signal to allow the atria to fully contract and ventricles to fully fill

24
Q

What is the function of the Bundle of His?

A

Electrical signal passes through to the bottom of the septum

25
Q

What is the function of the Purkinje fibres?

A

Electrical impulse makes ventricles contract from the base up

26
Q

What is the purpose of the autonomic nervous system?

A

Regulates involuntary physiologic processes such as:
- Heart rate
- Blood pressure
- Respiration

27
Q

Where are chemoreceptors found?

A

In the carotid arteries

28
Q

Describe the process of increasing heart rate if increased CO2 is detected in blood (5 marks)

A
  • Blood pH lowered
  • Chemoreceptors increase frequency of impulses to medulla oblongata
  • Higher frequency of impulses to SA node via sympathetic nervous system
  • SAN increases heart rate//increased blood flow
29
Q

Describe the process occurring in the heart when blood pressure is higher than normal

A
  • Pressure receptors transmit more nerve impulses to medulla oblongata
  • Sends impulses via parasympathetic nervous system to SAN
  • Decrease in heart rate
30
Q

Describe the process occurring in the heart when blood pressure is lower than normal

A
  • Pressure receptors transmit more impulses to medulla oblongata
  • Sends impulses via sympathetic nervous system to SAN
  • Increase in heart rate

AQA a-level biology 🧬🔬 (32 decks)

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