Ms FlecknoeMs Flecknoe

DODO NOT NOT

eat your Mentoseat your Mentos

YET!!!YET!!!

Mentos task:Mentos task:

-This is a SILENT taskThis is a SILENT task

-As you eat your Mentos, I want you to As you eat your Mentos, I want you to think about the following:think about the following:

-What pathway does the Mentos take?What pathway does the Mentos take?-Where does the Mentos end up?Where does the Mentos end up?

-Write down the pathway in your work-Write down the pathway in your work-bookbook

Making the link…Making the link…

-During digestion, your Mentos is During digestion, your Mentos is broken down into smaller components broken down into smaller components (eg monosaccharides) which can be (eg monosaccharides) which can be

absorbed by the small intestine.absorbed by the small intestine.-These nutrients enter the underlying These nutrients enter the underlying

blood streamblood stream-The The CIRCULATORY SYSTEMCIRCULATORY SYSTEM allows allows

these nutrients to be delivered to the these nutrients to be delivered to the cells which need themcells which need them

Chapter 6Chapter 6

Distribution of Distribution of Materials:Materials:

The Circulatory SystemThe Circulatory System

Roles of the circulatory Roles of the circulatory system:system:

Roles of the circulatory Roles of the circulatory system:system:

-To deliver oxygen and nutrients to the To deliver oxygen and nutrients to the cells of the bodycells of the body

-To remove carbon dioxide and other To remove carbon dioxide and other waste products (eg urea)waste products (eg urea)

-Why is this necessary?Why is this necessary?

-Also involved in transport of Also involved in transport of hormones, heat and mediators of hormones, heat and mediators of

immune defence.immune defence.

Circulatory system Circulatory system components:components:

3 main 3 main componentcomponent

s:s:

1______1______

2______2______

3______3______

Circulatory system Circulatory system components:components:

3 main 3 main componentcomponent

s:s:

1_Blood__1_Blood__22_Blood vessels__Blood vessels_

3_Heart _3_Heart _

Components of blood:Components of blood:

-Plasma (mostly water)Plasma (mostly water)-Red blood cellsRed blood cells

-White blood cellsWhite blood cells-PlateletsPlatelets

What colour is blood?

PlasmaPlasma

-Plasma is a straw coloured solution in Plasma is a straw coloured solution in which blood cells are suspendedwhich blood cells are suspended

-Plasma takes up 55% of blood volumePlasma takes up 55% of blood volume

-90% of plasma is 90% of plasma is water water (easy to (easy to dissolve substrates in)dissolve substrates in)

-Other 10% of plasma is made up of Other 10% of plasma is made up of nutrients, waste products, oxygen and nutrients, waste products, oxygen and

carbon dioxide, hormones, plasma carbon dioxide, hormones, plasma proteins, antibodies and ions proteins, antibodies and ions

Cellular components of Cellular components of bloodblood

-RedRed blood blood cells, cells, whitewhite blood cells and blood cells and plateletsplatelets all all arise from a arise from a common common STEMSTEM cell found in cell found in bone marrowbone marrow

Red Blood Cells Red Blood Cells (erythrocytes)(erythrocytes)

-Red blood cells (RBC) are bi-Red blood cells (RBC) are bi-concave …they look like a concave …they look like a donut without the middle fully donut without the middle fully punched out! punched out! (advantage?)(advantage?)

-Contain haemoglobin which Contain haemoglobin which allows RBCs to transport large allows RBCs to transport large amounts of oxygen to the bodyamounts of oxygen to the body

-RBCs lack nuclei and RBCs lack nuclei and mitochondria mitochondria (advantage?)(advantage?)

-Short life span relative to Short life span relative to other nucleated cells (only other nucleated cells (only survive for ~120 days)survive for ~120 days)

Red Blood Cells – unique Red Blood Cells – unique shapeshape

-Shape increases surface area to allow rapid Shape increases surface area to allow rapid diffusion of gasesdiffusion of gases

-Shape increases flexibility – RBC can squeeze Shape increases flexibility – RBC can squeeze through tiny blood vessels (capillaries)through tiny blood vessels (capillaries)

RBCs contain HaemoglobinRBCs contain Haemoglobin

-Haemoglobin GREATLY Haemoglobin GREATLY increases the capacity increases the capacity for blood to carry oxygenfor blood to carry oxygen

1L of plasma holds 3mL O2

1L of blood holds 200mL O2

O2

O2

O2O2

O2

O2

O2

O2

O2

O2

O2O2 O2

O2O2O2

O2

O2

Oxyhaemoglobin (haemoglobin bound

to oxygen)

Deoxy-haemoglobin (not bound to oxygen)

Oxygen binds in the lung

Oxygen released at the

tissues

Oxygen binds Oxygen binds reversibly to reversibly to haemoglobinhaemoglobin

White Blood CellsWhite Blood Cells

-Many different types Many different types (basophils, eosinophils, (basophils, eosinophils, neutrophils and neutrophils and lymphocytes)lymphocytes)

-These cells have These cells have slightly varied functions, slightly varied functions, but main role is to fight but main role is to fight infection.infection.

-Can cause Can cause inflammation, produce inflammation, produce antibodies and antibodies and phagocytose phagocytose (eat/engulf) foreign (eat/engulf) foreign objects.objects.

-Only live for a few daysOnly live for a few days

Foreign cellForeign cell

White blood cell engulfing foreign cell

PlateletsPlatelets

-Platelets are specialized Platelets are specialized fragments of larger cellsfragments of larger cells

-Platelets are responsible Platelets are responsible for initiating blood for initiating blood clotting in response to clotting in response to vessel damagevessel damage

-Platelets prevent Platelets prevent excessive bleedingexcessive bleeding

-Platelets live for about a Platelets live for about a week week

Blood cell lifespanBlood cell lifespan-White blood cells live a few daysWhite blood cells live a few days

-Platelets survive for approximately 1 weekPlatelets survive for approximately 1 week

-Red blood cells survive for approximately 120 Red blood cells survive for approximately 120 daysdays

-To replace the dying cells, the body produces To replace the dying cells, the body produces ~2,500,000 cells per second!~2,500,000 cells per second!

Question??Question??

Why do we bleed when Why do we bleed when we cut ourselves?we cut ourselves?

Vessels transport bloodVessels transport blood

- Three main types of Three main types of vessels transport blood vessels transport blood around the body:around the body:

1.1. ArteriesArteries

2.2. CapillariesCapillaries

3.3. VeinsVeins

- Arterioles are small Arterioles are small arteriesarteries

- Venules are small Venules are small veinsveins

ArteriesArteries- Arteries carry blood away from the heartArteries carry blood away from the heart

- In general, arteries carry oxygenated blood (the exception is In general, arteries carry oxygenated blood (the exception is the pulmonary arteries)the pulmonary arteries)

- Arteries have thick muscular wallsArteries have thick muscular walls

- Thick walls needed to withstand the high pressure of blood as Thick walls needed to withstand the high pressure of blood as it is pumped from the heartit is pumped from the heart

- Walls are too thick to allow diffusion of nutrients and gasesWalls are too thick to allow diffusion of nutrients and gases

- Arteries branch into smaller and smaller vessels. The Arteries branch into smaller and smaller vessels. The smallest arteries are called smallest arteries are called arteriolesarterioles

ArteryArtery ArterioleArteriole

ArteriolesArterioles- Muscular walls allow blood to be directed to tissue Muscular walls allow blood to be directed to tissue

that needs it most - that needs it most - Examples?Examples?

- Smooth muscle acts as sphincters to regulate blood Smooth muscle acts as sphincters to regulate blood flow (pre-capillary sphincters)flow (pre-capillary sphincters)

- Contraction/relaxation is not under voluntary Contraction/relaxation is not under voluntary control – ie we can’t deliberately increase blood control – ie we can’t deliberately increase blood flow to a certain region – it is controlled by the flow to a certain region – it is controlled by the bodybody

- Continued branching of arterioles leads to Continued branching of arterioles leads to capillariescapillaries

ArterioleArteriole CapillaryCapillary

CapillariesCapillaries- Capillaries are the site of nutrient and gas transferCapillaries are the site of nutrient and gas transfer

- Capillaries have a small diameter (5-8µm) – Capillaries have a small diameter (5-8µm) – Implications?Implications?

- Capillaries have very thin walls which are only one cell thick Capillaries have very thin walls which are only one cell thick (these cells are called endothelial cells). The thin walls allow (these cells are called endothelial cells). The thin walls allow substances to substances to diffusediffuse across the capillary to reach the tissue across the capillary to reach the tissue (or vice versa). (or vice versa).

- Alternatively, larger molecules (eg proteins and white blood Alternatively, larger molecules (eg proteins and white blood cells) can squeeze between the endothelial cells to reach the cells) can squeeze between the endothelial cells to reach the other side.other side.

- Concentration gradients determine the direction molecules Concentration gradients determine the direction molecules (eg nutrients, oxygen, carbon dioxide) will move(eg nutrients, oxygen, carbon dioxide) will move

- Branching of arteries and arterioles leads to very large Branching of arteries and arterioles leads to very large numbers of capillaries. This leads to large surface area and numbers of capillaries. This leads to large surface area and decreased blood pressure in capillaries– decreased blood pressure in capillaries– Why Why is this is this important?important?

Veins and venulesVeins and venules- Venules are small veins which take blood from the capillaries to the Venules are small veins which take blood from the capillaries to the

veinsveins

- Veins take blood back to the heartVeins take blood back to the heart

- They have thinner walls compared to arteries because they function They have thinner walls compared to arteries because they function under low pressure (blood is further from the heart)under low pressure (blood is further from the heart)

- Veins generally carry deoxygenated blood (exception is the Veins generally carry deoxygenated blood (exception is the pulmonary vein)pulmonary vein)

- Many veins are located close to your skin –Many veins are located close to your skin –What colour are they? What colour are they? Why?Why?

- Veins lack thick muscular layer and must rely on valves and Veins lack thick muscular layer and must rely on valves and contraction of nearby skeletal muscle to pump blood back to the contraction of nearby skeletal muscle to pump blood back to the heart.heart.

- Valves prevent backflow of bloodValves prevent backflow of blood

- Contraction of nearby muscles (eg in the leg) squeeze the veins and Contraction of nearby muscles (eg in the leg) squeeze the veins and push blood back to the heart. push blood back to the heart.

- ImplicationsImplications for deep vein thrombosis and traveling on aeroplanes? for deep vein thrombosis and traveling on aeroplanes?

Bringing it all together…Bringing it all together…HeartHeart

SummarySummary

FunctionFunction

Take large volumes of blood Take large volumes of blood from heart. Under high pressurefrom heart. Under high pressure

Connect arteries to capillaries. Connect arteries to capillaries. Role in directing blood flow.Role in directing blood flow.

Direct blood from capillaries to Direct blood from capillaries to veins.veins.

Take large volumes of blood to Take large volumes of blood to heart. heart.

Allow diffusion of nutrients and Allow diffusion of nutrients and gases to tissues.gases to tissues.