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Biology > Chapter 14 - Transport in humans > Flashcards

Chapter 14 - Transport in humans Flashcards

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1
Q

Describe the need for a transport system in humans

A
  • Humans have large bodies, with cells deep inside the body
  • All these regions need materials
  • Diffusion will be too slow to supply all these regions with materials
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2
Q

State where the heart is situated

A

Behind the sternum, between the lungs in the thoracic cavity

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3
Q

Name the major part of the heart which is made up of cardiac muscle

A

Myocardium

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4
Q

Name the inner lining of the heart

A

Endothelium

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5
Q

Name the membrane by which the heart is covered

A

Pericardium

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6
Q

Name the part of the heart by which the two atria are seperated

A

Interatrial septum

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7
Q

State the function of the pulmonary vein

A

Brings oxygenated blood from the lungs to the left atrium

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8
Q

Name the two veins which brings blood to the right atrium

A
  • Vena cava inferior

- Vena cava superior

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9
Q

Name the artery which takes oxygenated blood from the heart

A

Aorta

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10
Q

Name the part of the heart by which the two ventricles are seperated

A

Interventricular septum

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11
Q

Name the valve between the right atrium and right ventricle

A

Tricuspid valve

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12
Q

Name the valve between the left atrium and left ventricle

A

Bicuspid valve

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13
Q

Name the blood vessels which supply the heart with oxygen and nutrients

A

Coronary arteries/veins

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14
Q

How to describe the functions of the different parts of the heart

A

Now that you know the main structure of the heart, you will be able to infer their functions. Always remember to refer to the parts, type of blood and the valves where necessary.

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15
Q

Name the three stages of the cardiac cycle

A
  • Atrial systole
  • Ventricular systole
  • Diastole
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16
Q

Describe what happens during atrial systole

A
  • Muscles in the walls of both atria contract (0.15 seconds)
  • Volume in the atria decrease and the pressure in the blood increases
  • Valves in veins stop blood from returning to the vena cavae and the pulmonary vein
  • Atrio-ventricular valves (bi- and tricuspid valves) open
  • Blood passes into the ventricles
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17
Q

Describe what happens during ventricular systole

A
  • Muscles in the walls of the ventricles contract
  • Volume inside the ventricles decreases and the pressure in the blood increases
  • Atrio-ventricular valves close and prevent backflow of blood
  • Semi-lunar valves (aortic and pulmonic) open
  • Blood enters the pulmonary artery and aorta
18
Q

Describe what happens during diastole

A
  • Muscles in the walls of the atria and ventricles relax (0.4 seconds)
  • Volume inside the atria and ventricles increases, and the pressure decreases
  • Blood flows into both atria
  • Semi-lunar valves close and prevent backflow of blood into arteries
  • Pressure in atria and ventricles force all valves to close
19
Q

Explain the difference in thickness of muscle walls in the heart

A
  • The atria ony have to pump blood to the ventricles over a short distance with little pressure. Thin walls (2mm) with less cardiac muscle is required.
  • The left ventricle has to pump blood to the entire body over a longer distance with greater pressure, and requires very thick walls (16mm) of cardiac muscle.
  • The right ventricle has to pump blood to the lungs over a shorter distance with less pressure, and therefore requires only thick walls (9mm) of cardiac muscle
20
Q

Describe what is meant by the term “myogenic”, with reference to the heart

A

It means that the heart beat is initiated from inside the heart muscle itself rather than by a nervous impulse from outside the heart

21
Q

State the position and function of the sino-atrial node

A
  • Known as the pacemaker, and is the initial stimulus for the heart to beat
  • Located in the wall of the right atrium near where the vena cavae enter
  • Sends a wave of excitations which spread across both atria, causing them to contract simultaneously
  • The impulse stops between the atria and ventricles at the atrio-ventricular node
  • This node delays the impulse for 0.1 seconds in order for atrial systole to complete
22
Q

State the position and function of the atrio-ventricular node

A
  • Situated between the atria and ventricles
  • Joined by long muscle fibres known as Purkyne fibres which make up the bundle of his
  • This node receives the stimulus from the SAN, and sends a wave of excitation down the Purkyne fibres
23
Q

State the function of the Purkyne fibres

A
  • Conducts the wave of excitation down the inter-ventricular septum to the apex of the heart. The wave then spreads upwards through the walls of the heart. This causes ventricular systole from the apex upwards.
24
Q

How long does one cardiac cycle last? Also state the average heartrate of a human

A
  • 0.8 seconds

- 75 beats per minute

25
Q

Name the effects of exercise on the heart beat

A
  • Heart rate will increase
  • More oxygen pumped to respiring cells and reaches active muscles
  • Faster respiration will occur
  • Faster respiration results in more energy will be released for the muscle cells
  • More carbon dioxide will be pumped to the lungs for faster excretion thereof
26
Q

List the likely causes of heart diseases

A
  • Eating a high colestrol diet
  • Obesity
  • Stress
  • Smoking
  • Not taking regular exercise
  • Genetic predisposition
27
Q

Explain how atherosclerosis can cause a heart attack

A
  • Atherosclerosis causes the hardening of arteries
  • A build up of cholestrol (fatty diposits) occurs in the linings of coronary arteries
  • Causes the narrowing of arteries which obstructs blood flow to the heart muscles
  • Eventually a blockage in the arteries form
  • Less or no blood can flow through the artery
  • The heart muscle does not recieve sufficient glucose and oxygen
  • Anaerobic respiration will occur due to lack of oxygen\
  • No removal of lactic acid and carbon dioxide occurs
  • The cardiac muscle contracts less powerfully or stops
  • This results in a heart attack (cardiac arrest)
28
Q

Explain how heart diseases can be prevented

A
  • Follow a low cholestrol diet
  • Not being obese
  • Reduce stress levels
  • Do not smoke and reduce alcohol intake
  • Take regular exercise
29
Q

What is the blood pressure inside an artery?

A

High blood pressure (10-16 kPa)

30
Q

Describe the flow of blood inside an artery

A

Blood moves in pulses and flows rapidly

31
Q

What are small arteries called?

A

Arterioles

32
Q

Name the two arteries which do not transport oxygenated blood

A
  • Pulmonary artery

- Umbilical artery

33
Q

Name the adaptations of arteries

A
  • Thick musclular walls to withstand pressure and prevent bursting
  • Single layer of endothelium to reduce friction
  • Thick layer of elastic smooth muscles and elastic tissues to stretch outwards with the pressure of the heartbeat
  • Smaller lumen to maintain pressure
  • The beginning of arteries connected to the heart have semi-lunar valves to prevent backflow of blood into the heart
  • Arteries have no valves because blood can not blow back due to the high pressure
34
Q

State the pressure at which blood flows inside veins

A

1 kPa

35
Q

Describe how the blood flows inside veins

A

Slowly with no pulses

36
Q

Name the two veins which carry oxygenated blood

A
  • Pulmonary vein

- Umbilical vein

37
Q

Describe the adaptations of veins

A
  • Thinner walls (low pressure)
  • Smooth layer of endothelium to reduce pressure
  • Less elastic fibres as there is no need for stretching
  • Tough walls with collagen to prevent bursting
  • One way valves to prevent the backflow of blood
  • Large lumen allows blood to flow with minimum resistance
  • Thin walls allow skeletal muscles to squeeze veins and cause blood to move forward
38
Q

Name the adaptations of capillaries

A
  • Numerous to carry different matrerials to and from tissues
  • Very thin walls of one cell layer to facilitate easy exchange of different materials to and from blood
  • Gaps between cells of the wall for exchange to and from blood, for white blood cells to squeeze out and tissue fluid to leak out
  • High hydrostatic pressure inside so most components of plasma can filtrate outside the capillary. This is then known as tissue fluid
39
Q

Describe the double circulatory system

A
  • Blood flows twice through the heart during one full circulation of the body
  • Pulmonary circulation carries blood to and from the lungs
  • Systemic circulation carries blood to and from the body
40
Q

State the advantage of double circulation

A

Oxygenated and deoxygenated blood is kept seperate

Biology (40 decks)

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