Blood and circulation

Which blood vessels link to the lungs?

Towards: pulmonary artery

Away: pulmonary vein

Which blood vessels link to the heart?

Towards: vena cava

Away: aorta

Which blood vessels link to the liver?

Towards: hepatic artery

Away: hepatic vein

Which blood vessels link to the kidneys?

Towards: renal artery

Away: renal vein

What are the features/functions of capillaries?

* Carry blood at lower pressure within tissues.
* Carry both oxygenated and deoxygenated blood. -
* Have walls that are one cell thick – this makes for a short diffusion distance.
* narrow central tube with endothelium smoothing flow

What are the features/functions of veins? 6 points

* Carry blood at low pressure towards the heart.
* Carry deoxygenated blood (other than the pulmonary vein).
* Thin outer walls with some collagen
* Thin inner layer of muscle and few elastic fibres
* Have a wide lumen (central tube) with endothelium
* Contain valves to prevent backflow

What are the features/functions of arteries? 5 points

* Carry blood at high pressure away from the heart
* Carry oxygenated blood (other than the pulmonary artery)
* Thick outer walls with some collagen
* Thick inner walls of smooth muscle and elastic fibres
* Have a narrow lumen with endothelium

How does smoking cause coronary heart disease? 3 points

* Chemicals in smoke cause an increase in plaque build up
* increase in blood pressure as well as blood clots
* as the smoke causes the blood to thicken

How does high cholesterol cause coronary heart disease?

Speeds up the build-up of fatty plaques in the arteries, leading to blockages.

How does high blood pressure cause coronary heart disease?

This increases the force of the blood against the artery walls and consequently leads to damage of the vessels.

How does obesity cause coronary heart disease?

Carrying extra weight puts a strain on the heart. Increased weight can lead to diabetes which further damages your blood vessels.

What is coronary heart disease?

* when the coronary arteries become blocked by fatty deposit cutting off blood supply to the cardiac muscle
* this means the heart is no longer receiving enough oxygen and glucose to respire and release energy
* therefore it is unable to contract and pump blood resulting in a heart attack

How does exercise affect heart rate?

heart rate increases when doing exercise as your heart is pumping blood around your body at a faster pace because your cells are needing more oxygen and glucose to respire and release energy

How is the heart rate measured?

A heart rate is measured by counting the number of times a heart beats in a minute (bpm).

Explain the path of oxygenated blood.

* Oxygenated blood returns via the pulmonary vein to the left atrium.
* The atrium contracts and forces the blood through the bicuspid (atrioventricular) valve into the left ventricle.
* The ventricle contracts and the blood is forced through the semi-lunar valve and out through the aorta.
* Thicker muscle walls of the left ventricle produce a high enough pressure for the blood to travel around the whole body.

Explain the path of deoxygenated blood.

* Deoxygenated blood coming from the body flows through the vena cava and into the right atrium.
* The atrium contracts and the blood is forced through the tricuspid (atrioventricular) valve into the right ventricle.
* The ventricle contracts and the blood is pushed through the semi-lunar valve and into the pulmonary artery.
* The blood travels to the lungs through the pulmonary artery and moves through the capillaries past the alveoli, where gas exchange takes place.
* Low pressure blood flow on this side of the heart prevents damage to the capillaries in the lungs.

What is the purpose of valves?

Valves prevent backflow

What are platelets?

Platelets are fragments of cells that help us release chemicals to make a blood clot when we cut ourselves

What is fibrinogen

a soluble plasma protein

What is fibrin

an insoluble fibre

Explain the process of making a blood clot when we are cut

* the platelets in our blood produce a chemical which cause the fibrinogen to change into fibrin
* this forms a clot/scab which prevents excess blood loss and the entry of bacteria

What are the disadvantages of vaccines?

The vaccine does not always give immunity. There can be side effects to the vaccine, including swelling or a rash. More severe reactions include seizures.

What are the advantages of vaccines?

Diseases that were once common are now fairly rare due to widespread vaccinations. Epidemics can be prevented if a large number of the population is vaccinated against it.

How do vaccinations work?

* Vaccinations work by introducing a weakened or dead form of a virus or bacteria into the body triggering the immune system to produce antibodies


* These antibodies remain in the body and provide immunity to the disease, so in the future they can fight off this disease quicker

What are the stages of the primary immune response?

1. lymphocytes recognise pathogen
2. pathogen release toxin making you feel unwell
3. antibodies are released
4. once enough antibodies bring the pathogen under control
5. production of memory cells

What are the stages of the secondary immune response?

1. memory cells replicate and produce antibodies much quicker than the first time
2. immunity

What are the functions of lymphocytes? 3 points

* make chemicals called antibodies to fight the infection
* they work by recognising antigen markers on diseases causing microbes
* the antibodies produced make it easier for the body to destroy the virus

What are the functions of phagocytes? 2 points

* when in contact with the foreign cells carry out phagocytosis by engulfing and digesting pathogens
* have a lobed shaped nuclei

What are the adaptations of red blood cells?

* biconcave discs with no nucleus but plenty of haemoglobin (a protein that binds to oxygen)


* small and flexible to fit well in capillaries
* transport oxygen from lungs to cells in the body
* thin cell membrane wall so gases can easily diffuse

Why is heat energy in the plasma?

Created in respiration (an exothermic reaction), heat energy is transferred to cooler parts of the body or to the skin, where heat can be lost.

Why are hormones in the plasma?

Chemical messengers released into the blood from the endocrine organs (glands) and delivered to target tissues/organs of the body.

Why is urea in the plasma?

The waste substance produced in the breakdown of proteins by the liver. Urea is dissolved in the plasma and transported to the kidneys.

Why are digested food/mineral ions in the plasma?

Dissolved particles absorbed from the small intestine are delivered to cells around the body from the plasma

Why is carbon dioxide in the plasma?

It is the waste product of respiration which is dissolved into the plasma

Describe the plasma in the blood. 3 ppints

* Plasma is a straw-coloured liquid.


* It carries carbon dioxide, food, urea, hormones and heat energy.
* It helps to transport nutrients to cells, including gases, hormones and food substances.

Describe the white blood cells in the blood. 3 points

* White blood cells are large cells with a big nucleus.


* Phagocytes engulf and digest pathogens, releasing enzymes.


* Lymphocytes produce antibodies to destroy pathogens and neutralise toxins.

Describe the red blood cells in the blood.

* biconcave discs with no nucleus but plenty of haemoglobin
* small and flexible
* transport oxygen from lungs to cells in the body
* thin cell membrane wall

What does the blood contain?

Blood consists of red blood cells, white blood cells, platelets and plasma.

What percentage of the blood is plasma

55

Roughly how many white blood cells are there in a ml of blood?

5000

Roughly how many red blood cells are there in a ml of blood?

5-6 million