Circulatory Systems, Heart & Blood Vessels

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Notas de aula

Circulatory System Overview

The circulatory system is an organ system that transports blood around the body.
Components include blood vessels, a pump (heart), and valves for one-way flow.
Fish have a two-chambered heart and single circulation (blood passes through heart once per circuit).
Mammals have a four-chambered heart and double circulation (blood passes through heart twice per circuit).
Double circulation: right side pumps deoxygenated blood to lungs (pulmonary circulation); left side pumps oxygenated blood to body (systemic circulation).
Advantage: blood pressure lost in lung capillaries is restored by the heart before blood travels to the body, ensuring faster delivery of oxygen and glucose.

The double circulatory system

The Mammalian Heart

The heart is a muscular pump; its own blood supply comes from the coronary arteries.
The septum separates the right and left sides, preventing mixing of oxygenated and deoxygenated blood.
Right side: receives deoxygenated blood from body via vena cava; pumps it to lungs via pulmonary artery.
Left side: receives oxygenated blood from lungs via pulmonary vein; pumps it to body via aorta.
Atria have thinner walls; ventricles have thicker walls (left ventricle thickest as it pumps to whole body).
Valves: atrioventricular valves (tricuspid on right, bicuspid on left) prevent backflow into atria; semilunar valves in pulmonary artery and aorta prevent backflow into ventricles.

Structure of the mammalian heart

Heart Function & Cardiac Cycle

Deoxygenated blood enters right atrium → passes through tricuspid valve into right ventricle → ventricle contracts → blood pushed through semilunar valve into pulmonary artery → to lungs.
Oxygenated blood returns from lungs via pulmonary vein → enters left atrium → passes through bicuspid valve into left ventricle → ventricle contracts → blood pushed through semilunar valve into aorta → to body.
Atrioventricular valves open when atria contract; close when ventricles contract to prevent backflow.
Semilunar valves open when ventricles contract; close to prevent blood flowing back into heart.

Heart valves and septum

Monitoring Heart Activity & Exercise

Heart activity monitored by ECG, pulse rate (bpm), or listening to valve sounds with a stethoscope.
During exercise, heart rate increases to deliver more oxygen and glucose to muscles and remove waste faster.
After exercise, heart rate remains elevated to remove excess waste and repay oxygen debt (break down lactic acid).
Pulse rate gradually returns to resting level over several minutes.

Coronary Heart Disease (CHD)

Coronary arteries supply oxygen and nutrients to heart muscle.
CHD occurs when these arteries become narrowed or blocked by fatty plaques (mainly cholesterol).
Partial blockage causes angina (chest pain); complete blockage leads to heart attack (muscle cells die).
Risk factors: smoking, high-fat diet, lack of exercise, obesity, high blood pressure.
Prevention: quit smoking, eat less animal fat, exercise regularly.

The coronary arteries

Blood Vessels: Arteries, Veins, Capillaries

Arteries carry blood away from heart at high pressure; thick muscular walls with elastic fibres; narrow lumen; mostly oxygenated (except pulmonary artery).
Veins carry blood towards heart at low pressure; thin walls; wide lumen; contain valves to prevent backflow; mostly deoxygenated (except pulmonary vein).
Capillaries are one cell thick with 'leaky' walls for diffusion; very narrow lumen; connect arterioles to venules.
Arteries divide into arterioles then capillaries; capillaries merge into venules then veins.

Adaptations of blood vessels

Circulation Around the Body

Key blood vessels: aorta (to body), vena cava (from body), pulmonary artery (to lungs), pulmonary vein (from lungs).
Renal artery carries blood to kidney; renal vein carries blood from kidney.
Hepatic artery brings oxygenated blood to liver; hepatic portal vein brings deoxygenated blood from gut to liver; hepatic vein carries blood away from liver to heart.

Circulation around the body

Components of Blood

Blood consists of plasma, red blood cells, white blood cells, and platelets.
Plasma transports carbon dioxide, digested nutrients, urea, hormones, and heat.
Red blood cells contain haemoglobin and transport oxygen as oxyhaemoglobin; no nucleus; biconcave disc shape.
White blood cells defend against infection: phagocytes engulf pathogens (phagocytosis); lymphocytes produce antibodies and antitoxins.
Platelets are cell fragments involved in blood clotting.

Composition of blood

Blood Clotting

When skin is broken, platelets release chemicals that convert soluble fibrinogen into insoluble fibrin.
Fibrin forms a mesh that traps red blood cells, creating a clot.
The clot dries to form a scab, preventing blood loss and entry of pathogens.

Blood clotting

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CADASTRE-SE — GRÁTIS ENTRAR

Questões de prática

Prévia grátis — 8 de 51 perguntas. Cadastre-se para ver todas.

1.Which sequence lists the heart chambers in order from thinnest wall to thickest wall?
Medium
- Aleft ventricle → right ventricle → left atrium
- Bleft atrium → left ventricle → right ventricle
- Cright ventricle → left atrium → left ventricle
- Dleft atrium → right ventricle → left ventricle
2.Which of the following statements would be incorrect for most of the veins in the human body?
Easy
- AThey carry blood at low pressure.
- BThey have valves.
- CThey have a pulse.
- DThey return blood to the heart.
3.The blood contains lymphocytes. What is their purpose?
Easy
- ATransport of hormones
- BPhagocytosis
- CAntibody production
- DBlood clotting
4.Which of the following would be found dissolved in the blood plasma of a human?
Medium
- AGlucose, urea and hormones
- BOxygen, urea and starch
- CCarbon dioxide, hormones and haemoglobin
- DCarbon dioxide, oxygen and urea
5.In which list of the following do all three blood vessels carry deoxygenated blood?
Medium
- Aaorta, pulmonary vein, renal artery
- Bvena cava, pulmonary vein, renal vein
- Cvena cava, pulmonary artery, renal vein
- Daorta, pulmonary artery, renal artery
6.What happens to the heart valves when the ventricles contract?
Medium
- Aatrioventricular valves close, semilunar valves close
- Batrioventricular valves close, semilunar valves open
- Catrioventricular valves open, semilunar valves close
- Datrioventricular valves open, semilunar valves open
7.Which part of the blood contains haemoglobin?
Easy
- Aplasma
- Bplatelets
- Cred blood cells
- Dwhite blood cells
8.The diagram shows a cross-section through a human blood vessel. Which type of blood vessel does the diagram show?
Easy
- Aan artery
- Ba capillary
- Ca vein
- Da ventricle

Mais perguntas

9.What is a function of some white blood cells?
Easy
- Ato carry glucose
- Bto carry oxygen
- Cto produce antibiotics
- Dto produce antibodies
10.In a section through the human heart, the pulmonary vein enters which chamber?
Medium
- Aright atrium
- Bleft atrium
- Cright ventricle
- Dleft ventricle
11.The diagram shows a cross-section through a human blood vessel. Which type of blood vessel is shown?
Easy
- AArtery
- BVein
- CCapillary
- DVentricle
12.A student recorded their pulse rate immediately after stopping exercise and then every minute for 6 minutes. The results are shown in the table. Time (min): 0,1,2,3,4,5,6. Pulse rate (bpm): 175,135,110,89,68,66,66. Which statement is correct?
Medium
- AThe pulse decreases at a constant rate over the six minutes.
- BThe pulse rate decreased by more than 100 bpm in the first three minutes.
- CThe pulse rate returns to a resting rate of 66 bpm after 5 minutes.
- DThe pulse rate decreases fastest between 2 and 3 minutes.
13.A student investigated the effect of exercise on heart rate. They measured pulse rate at rest, then after 1 minute of exercise, then after 2 minutes, and so on up to 5 minutes. The results are shown. Resting pulse: 72 bpm. After 1 min: 98 bpm. After 2 min: 115 bpm. After 3 min: 128 bpm. After 4 min: 136 bpm. After 5 min: 140 bpm. What is the approximate increase in heart rate per minute of exercise?
Medium
- A10 bpm per minute
- B14 bpm per minute
- C20 bpm per minute
- D28 bpm per minute
14.The diagram shows the blood vessels associated with the liver. Which vessel carries blood away from the liver, back towards the heart?
Medium
- AHepatic artery
- BHepatic portal vein
- CHepatic vein
- DBile duct
15.A person has a heart rate of 72 beats per minute and a stroke volume of 70 cm³. What is the cardiac output?
Medium
- A0.084 dm³/min
- B5.04 dm³/min
- C5040 dm³/min
- D5.04 cm³/min
16.Which of the following is a function of the plasma?
Easy
- ATransport of oxygen
- BTransport of carbon dioxide
- CBlood clotting
- DProduction of antibodies
17.The diagram shows a section through a human heart. Which chamber has the thickest muscular wall?
Easy
- ARight atrium
- BRight ventricle
- CLeft atrium
- DLeft ventricle
18.A blood sample is taken from a patient. The results show a low platelet count. Which process would be slower than normal?
Easy
- AAntibody formation
- BBlood clotting
- COxygen transport
- DPhagocytosis
19.Which row correctly describes the blood in the pulmonary artery and the pulmonary vein?
Medium
- APulmonary artery: deoxygenated, low pressure; Pulmonary vein: oxygenated, high pressure
- BPulmonary artery: deoxygenated, low pressure; Pulmonary vein: oxygenated, low pressure
- CPulmonary artery: oxygenated, high pressure; Pulmonary vein: deoxygenated, low pressure
- DPulmonary artery: oxygenated, low pressure; Pulmonary vein: deoxygenated, high pressure
20.Which of the following is a correct explanation as to why mammals have a double circulatory system?
Medium
- ATo reduce pressure of blood returning from the lungs to supply cells of the body most efficiently with the reactants for respiration.
- BTo increase the pressure of blood sent to the lungs to supply cells of the body most efficiently with the reactants for respiration.
- CTo increase the pressure of blood returning from the lungs to supply cells of the body most efficiently with the reactants for respiration.
- DTo reduce pressure of blood sent to the lungs to supply the cells most efficiently with the products for respiration.
21.A scientist measures the blood pressure in three different blood vessels: W, X, and Y. The results are: W: 120/80 mm Hg, X: 25/10 mm Hg, Y: 8/2 mm Hg. Which vessels are most likely an artery, a vein, and a capillary?
Hard
- AW: artery, X: capillary, Y: vein
- BW: artery, X: vein, Y: capillary
- CW: vein, X: artery, Y: capillary
- DW: capillary, X: vein, Y: artery
22.A student investigates the effect of exercise on heart rate. They measure pulse rate at rest, then after 1 minute of stepping onto a 20 cm block, then after 2 minutes, and so on. To ensure the results are reliable, which of the following should they do?
Medium
- ARepeat the experiment on the same person several times and calculate the mean
- BUse a different person for each exercise duration
- CMeasure pulse rate only at the end of the exercise period
- DTake the pulse rate from the carotid artery instead of the wrist
23.The diagram shows a cross-section of a blood vessel. Which type of blood vessel is shown?
Easy
- AArtery
- BVein
- CCapillary
- DArteriole
24.A student measures the pulse rate of a person at rest and then after 2 minutes of running. The results show the pulse rate increased from 72 bpm to 156 bpm. Which of the following explains why the pulse rate remains elevated for several minutes after stopping exercise?
Medium
- ATo deliver extra oxygen to muscle cells to break down lactic acid
- BTo increase the rate of carbon dioxide production
- CTo reduce the amount of glucose supplied to muscles
- DTo allow the heart muscle to rest and recover
25.Which component of blood is primarily responsible for blood clotting?
Easy
- ARed blood cells
- BWhite blood cells
- CPlatelets
- DPlasma
26.The diagram shows the heart and associated blood vessels. Which blood vessel carries deoxygenated blood from the heart to the lungs?
Easy
- AAorta
- BPulmonary vein
- CPulmonary artery
- DVena cava
27.A scientist measures the blood pressure in three different blood vessels: W, X, and Y. The results are: W: 120/80 mm Hg, X: 25/10 mm Hg, Y: 8/2 mm Hg. Which vessel is most likely the pulmonary artery?
Hard
- AW
- BX
- CY
- DNone of these
28.Which of the following is a function of plasma?
Easy
- ATransport of oxygen
- BTransport of carbon dioxide
- CBlood clotting
- DProduction of antibodies
29.The table shows the concentration of oxygen and carbon dioxide in four blood vessels. Which vessel is the pulmonary vein? | Vessel | Oxygen concentration | Carbon dioxide concentration | |--------|---------------------|------------------------------| | A | high | low | | B | low | high | | C | low | low | | D | high | high |
Medium
- AA
- BB
- CC
- DD
30.A student investigates the effect of exercise on heart rate. They record pulse rate at rest, then after 1 minute of exercise, then after 2 minutes, etc. The results are shown in the table. | Time (min) | Pulse rate (bpm) | |------------|------------------| | 0 | 72 | | 1 | 98 | | 2 | 120 | | 3 | 138 | | 4 | 150 | | 5 | 155 | | 6 | 156 | Which of the following is the most likely explanation for the increase in pulse rate during exercise?
Medium
- AThe heart pumps more blood to supply working muscles with oxygen and glucose
- BThe heart rate increases to reduce blood flow to the muscles
- CThe heart rate increases to decrease the removal of carbon dioxide
- DThe heart rate increases to lower blood pressure
31.Which blood vessel has a relatively low carbon dioxide concentration, a high oxygen concentration and a low blood pressure?
Medium
- APulmonary artery
- BPulmonary vein
- CAorta
- DVena cava
32.Which component of the circulatory system ensures one-way flow of blood?
Easy
- Aarteries
- Bveins
- Cvalves
- Dcapillaries
33.What is the main function of red blood cells?
Easy
- Ato carry oxygen
- Bto fight infection
- Cto clot blood
- Dto transport hormones
34.Which blood vessel carries deoxygenated blood away from the heart?
Easy
- Aaorta
- Bpulmonary vein
- Cpulmonary artery
- Dvena cava
35.What is the function of the septum in the heart?
Easy
- Ato prevent mixing of oxygenated and deoxygenated blood
- Bto pump blood into the arteries
- Cto allow blood to flow from atria to ventricles
- Dto supply the heart muscle with blood
36.Which blood vessel has the lowest blood pressure?
Easy
- Aaorta
- Bpulmonary artery
- Cvena cava
- Dcapillary
37.The diagram shows the heart and its major blood vessels. Which vessel carries oxygenated blood away from the left ventricle to the body?
Easy
- Apulmonary vein
- Baorta
- Cvena cava
- Dpulmonary artery
38.Arteries always carry oxygenated blood.
Easy
True or false?
39.The left ventricle has a thicker muscular wall than the right ventricle.
Easy
True or false?
40.Match each blood vessel on the left with its correct description on the right.
Medium
- pulmonary artery
- pulmonary vein
- aorta
- vena cava
- carries oxygenated blood from lungs to heart
- carries deoxygenated blood from heart to lungs
- carries oxygenated blood from heart to body
- carries deoxygenated blood from body to heart
41.Arrange the following events in the correct order as blood flows through the heart and lungs, starting with deoxygenated blood entering the heart.
Medium
- Oxygenated blood returns to the left atrium via the pulmonary vein
- Blood enters the right atrium via the vena cava
- Blood is pumped into the aorta
- Blood is pumped through the pulmonary artery to the lungs
- Blood passes through the bicuspid valve into the left ventricle
- Blood passes through the tricuspid valve into the right ventricle
42.Which of the following are functions of the circulatory system? (Select all that apply)
Medium
- ATransport of oxygen to cells
- BTransport of carbon dioxide away from cells
- CProduction of hormones
- DDistribution of heat around the body
- EDigestion of food
43.The diagram shows a cross-section of a blood vessel with a thick muscular wall, a narrow lumen, and elastic fibres. Which type of blood vessel is shown?
Easy
- AArtery
- BVein
- CCapillary
- DArteriole
44.A student measures the pulse rate of a person at rest and then after 2 minutes of running. The results show the pulse rate increased from 72 bpm to 156 bpm. Which of the following is the most likely explanation for the increase?
Medium
- AThe heart is pumping more blood per beat.
- BThe heart is beating faster to deliver more oxygen to muscles.
- CThe blood pressure has decreased.
- DThe person is breathing more slowly.
45.Complete the sentence about blood clotting.
Easy
When the skin is cut, platelets release chemicals that convert soluble ____ into insoluble ____ to form a mesh across the wound.
46.Name the three main types of blood vessel in the human circulatory system.
Easy
The three main types of blood vessel are ____, ____ and ____.
47.Calculate the cardiac output of a person with a heart rate of 72 beats per minute and a stroke volume of 70 cm³. Give your answer in cm³/min.
Medium
48.Calculate the cardiac output of a person with a heart rate of 75 beats per minute and a stroke volume of 80 cm³. Give your answer in cm³/min.
Medium
49.Explain why the heart rate remains high for a period of time after exercise has stopped.
Hard
50.Calculate the cardiac output of a person with a heart rate of 72 beats per minute and a stroke volume of 70 cm³. Give your answer in cm³/min.
Medium
- A4536 cm³/min
- B5544 cm³/min
- C6048 cm³/min
- D5040 cm³/min
51.Calculate the cardiac output of a person with a heart rate of 75 beats per minute and a stroke volume of 80 cm³. Give your answer in cm³/min.
Medium
- A6600 cm³/min
- B5400 cm³/min
- C6000 cm³/min
- D7200 cm³/min

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