B5: Transportation Transport in Humans

Describe the circulatory system  The blood, heart and blood vessels make up the circulatory system.  The heart is a muscular pump  Blood is pumped around the body in one direction  There are valves in the heart and in veins to help control the direction that blood flows

 The inside of the heart is divided into two sections so that the two types of blood (oxygen-rich and oxygen-poor) are kept apart. Rem ember that the heart is always labelled as if it is in a body facing you, so the right side of the heart is on the left of the diagram. oxygen-poor blood right side of the heart oxygen-rich blood left side of the heart Double circulation

The two sides of the heart

Blood is pumped around the body by the heart. It takes about 30 seconds for blood to go once around the body. Starting with the left side of the heart, what route does the blood follow to complete one circuit of the body?

The left side of the heart pumps oxygen-rich blood to the rest of the body. This blood supplies the body’s cells with oxygen. What gas does the blood then pick up from the body’s cells and where does the blood go next? body’s cells body’s cells

The oxygen-poor blood needs to lose the carbon dioxide and pick up more oxygen. Blood picks up carbon dioxide from the body’s cells. This oxygen-poor blood then travels back to the right side of the heart. body’s cells body’s cells How does it do this?

Where does this oxygen-rich blood then travel to? Next, the right side of the heart pumps oxygen-poor blood to the lungs. In the lungs the blood gets rid of the waste carbon dioxide and collects more oxygen. lungs body’s cells body’s cells

The oxygen-rich blood then returns to the left side of the heart. This completes the blood’s journey around the body. Why is the journey of blood through the circulatory system called a double circulation? body’s cells body’s cells lungs

During one complete circuit of the body, blood passes through the heart twice. The heart has two jobs to do and so the circulatory system involves a double circulation. What are the two jobs that the heart carries out during this double circulation? body’s cells body’s cells lungs

The heart pumps blood around the circulatory system. The heart is made of muscle and keeps pumping blood around your body, even when you are asleep! muscle tissue What do the blood vessels on the outside of the heart do? Exterior heart structure What is the heart made of?

The heart is full of blood but also needs its own blood supply so that the muscle can keep pumping. blood vessels supply blood to muscle tissue The blood vessels on the outside of the heart carry oxygen-rich blood to the heart muscle cells. Oxygen-poor blood is then carried away from these cells by outer blood vessels and back into the heart. muscle tissue

♥ The inside of the heart is divided into two sections to keep oxygen-rich and oxygen-poor blood separate. ♥ Each side of the heart is also divided into two sections. Each section of the heart is called a chamber. How many chambers are there? right side of the heart left side of the heart 4 Interior heart structure

The four chambers of the heart have special names: ♥ A lower chamber is called a ventricle. ♥ An upper chamber is called an atrium (plural atria). right ventricle right atrium left ventricle left atrium

The chambers of the heart have different functions. ♥ The atria collect blood that enters the heart. ♥ The ventricles pump blood out of the heart. blood to the body blood from the body blood to the lungs blood from the lungs

Describe double circulation  The two sides of the heart (left and right) are separated by the septum  Blood in the right side is deoxygenated (oxygen- poor)  Blood in the left side is oxygenated (oxygen-rich)  the right side of the heart is less muscular as the blood is pumped to the nearby lungs  Blood is under less pressure  The left side of the heart is more muscular as the blood is pumped to the rest of the body  Blood is under higher pressure

Arteries  Carry blood away from the heart  Except for the pulmonary artery, transport oxygenated blood  Artery walls are thick and elastic so they can stretch under the high pressure of blood  As the arteries stretch, they “pulse” Habits of the heartHabits of the heart – take your pulse thick outer wall thick inner layer of muscle and elastic fibres narrow central tube

Veins  Carry blood to the heart  Except for the pulmonary vein, carry deoxygenated blood  Wider than arteries, with thinner walls  Blood under lower pressure  Valves prevent the back-flow of blood thin outer wall thin inner layer of muscle and elastic fibres wide central tube

Valves backflow prevented vein valve closed blood to the heart vein valve open When blood flows along veins it pushes past the valves, which can only open in one direction. If blood in a vein does flow backwards, it is trapped by closed valves. When valves go bad!!

Varicose veins

Capillaries  Capillaries are the tiny blood vessels that carry a blood supply to and from the body’s cells. arteryvein  Capillaries are the only blood vessels where substances can be exchanged between the blood and body cells.

The heart beat  All the parts of the heart on either side, work together in a repeated sequence.  The two atria contract and relax; then the two ventricles contract and relax.  This is how blood moves through the heart and is pumped to the lungs and the body.  One complete sequence of contraction and relaxation is called a heartbeat.

Sequence of a heart beat

The heart beat  When the heart muscles are relaxed – diastole  Blood flows from veins into atria  When the heart muscles contract – systole  Atria contract first to pump blood into ventricles (valve between atrium and ventricle opens)  Ventricles contract to pump blood into the arteries (forces valve to shut) Normal blood pressure: 120 Systolic pressure 80 Diastolic pressure

Coronary heart disease  Use pp in your text books to read about CHD.  Write notes to:  Describe the nature of CHD  State the possible causes of CHD  Describe some methods of preventing CHD

Pulse rate  Read “the heart and exercise” p 105 of your textbook  In pairs, compete the practical on p105 to investigate the effect of exercise on pulse rate.  Stopwatches are available  Draw up a results table in your notebook to show your resting heart rate compared to your HR after completing the various activities  Explain your results (think about the purpose of blood supply to your muscles)

Blood  The liquid part of the circulatory system  Blood cells are suspended in plasma  An adult human has about 5.5L of blood in their body plasma white blood cells and platelets red blood cells The four components of blood

red blood cell white blood cell platelet  Blood plasma carries three types of blood cells.  They have different shapes and carry out different functions. Components of blood

Micrographs of blood Scanning electron micrograph of blood Red blood cell White blood cell Platelet

 The most common type of blood cell.  Made in the bone marrow  Transport oxygen from the lungs to the body’s cells, where it is used in respiration. Red blood cells oxygen

A red blood cell has several features that help it do its job: Disc-shaped, with a dent on each side, creates a large surface area for gas exchange. A large surface area compared to volume, so oxygen is always close to the surface. It has no nucleus, so there is more space for haemoglobin and so more oxygen. It contains haemoglobin, a special pigment that combines with oxygen.

 Another important feature of a red blood cell is its size.  The diameter of a red blood cell is slightly bigger than the average diameter of a capillary.  This forces the RBC to slow down as it passes through a capillary.  The surface of the RBC is exposed to the surface of the capillary so gas exchange occur.

haemoglobin  Haemoglobin is the special pigment in red blood cells.  At the lungs, oxygen diffuses into red blood cells and combines with haemoglobin to form oxyhaemoglobin  This is how red blood cells are able to bind to oxygen and carry it in the blood.  Oxyhaemoglobin makes red blood cells appear bright red. oxygen + + oxyhaemoglobin

+ + oxygen haemoglobin  Red blood cells loaded with oxyhaemoglobin carry oxygen from the lungs to the body’s cells.  Here, oxyhaemoglobin changes back to haemoglobin and oxygen is released. oxyhaemoglobin  Oxygen is then able to diffuse into the body’s cells.

(not to scale) oxygen + haemoglobin oxygen + haemoglobin

oxyhaemoglobin oxygen + haemoglobin oxygen + haemoglobin (not to scale) oxyhaemoglobin

oxygen + haemoglobin oxygen + haemoglobin oxyhaemoglobin (not to scale) haemoglobin + oxygen oxyhaemoglobin

haemoglobin + oxygen oxygen + haemoglobin oxygen + haemoglobin oxyhaemoglobin (not to scale) oxyhaemoglobin

Red blood cells in an alvelous

Red blood cells in a capillary bed

White blood cells  The largest type of blood cell.  They have a large nucleus and can change their shape.  White blood cells protect the body from disease by fighting invading microbes that can cause infection.  White blood cells can squeeze through the walls of capillaries.

 Different types of white blood cells protect the body in different ways:  Phagocytes fight against infection by surrounding invading microbes and then digesting them!  Lymphocytes produce antibodies to fight against infection.

White blood cell count Unwell: white blood cell number is high Healthy: white blood cell count is low Doctors can check the number of white blood cells in a person’s blood to find out if they are healthy or fighting off an infection.

 Platelets are cell fragments that have broken off from other larger cells.  They are much smaller than red and white blood cells and do not have a nucleus. platelet Platelets  Important for blood clotting.

Platelets help to make tiny fibres that form a net at the site of a cut. 1 1 The clot dries and forms a scab which protects the cut while new skin grows. 3 3 Red blood cells are trapped in this net forming a blood clot. 2 2 Why is it important not to pick a scab?

Plasma  Liquid part of blood that makes up 55% of blood volume  Water with lots of things dissolved in it:  Nutrients : glucose, amino acids, lipids, vitamins and mineral ions  Wastes : carbon dioxide and urea  Antibodies  Hormones : insulin, adrenaline, glucagon

Which type of blood cell?

Multiple-choice quiz