Transcript Blood and vessels PowerPoint Presentation Unit 1 VCE Biology

Ms Flecknoe
DO NOT
eat your Mentos
YET!!!
Mentos task:
-This is a SILENT task
-As you eat your Mentos, I want you to
think about the following:
-What pathway does the Mentos take?
-Where does the Mentos end up?
-Write down the pathway in your workbook
Making the link…
-During digestion, your Mentos is broken
down into smaller components (eg
monosaccharides) which can be absorbed
by the small intestine.
-These nutrients enter the underlying
blood stream
-The CIRCULATORY SYSTEM allows
these nutrients to be delivered to the
cells which need them
Chapter 6
Distribution of
Materials:
The Circulatory System
Roles of the circulatory system:
Roles of the circulatory system:
-To deliver oxygen and nutrients to the
cells of the body
-To remove carbon dioxide and other
waste products (eg urea)
-Why is this necessary?
-Also involved in transport of hormones,
heat and mediators of immune defence.
Circulatory system components:
3 main
components:
1______
2______
3______
Circulatory system components:
3 main
components:
1_Blood__
2_Blood vessels_
3_Heart _
Components of blood:
-Plasma (mostly water)
-Red blood cells
-White blood cells
-Platelets
What colour is blood?
Plasma
-Plasma is a straw coloured solution in
which blood cells are suspended
-Plasma takes up 55% of blood volume
-90% of plasma is water (easy to dissolve
substrates in)
-Other 10% of plasma is made up of
nutrients, waste products, oxygen and
carbon dioxide, hormones, plasma
proteins, antibodies and ions
Cellular components of blood
-Red blood cells,
white blood cells
and platelets all
arise from a
common STEM
cell found in
bone marrow
Red Blood Cells (erythrocytes)
-Red blood cells (RBC) are biconcave …they look like a donut
without the middle fully punched
out! (advantage?)
-Contain haemoglobin which allows
RBCs to transport large amounts
of oxygen to the body
-RBCs lack nuclei and
mitochondria (advantage?)
-Short life span relative to other
nucleated cells (only survive for
~120 days)
Red Blood Cells – unique shape
-Shape increases surface area to allow rapid
diffusion of gases
-Shape increases flexibility – RBC can squeeze
through tiny blood vessels (capillaries)
RBCs contain Haemoglobin
Deoxy-haemoglobin
-Haemoglobin GREATLY
increases the capacity for
blood to carry oxygen
(not bound to oxygen)
Oxygen binds in
the lung
O2
O2
O2
O2
O2
O2
O2
1L of plasma
holds 3mL O2
O2
O2
O2
Oxygen
released at the
tissues
O2
O2
O2 O O2
2
O 2 O 2 O2
Oxyhaemoglobin
1L of blood holds
200mL O2
(haemoglobin bound
to oxygen)
Oxygen binds reversibly
to haemoglobin
White Blood Cells
Foreign cell
White blood cell engulfing foreign cell
-Many different types
(basophils, eosinophils,
neutrophils and
lymphocytes)
-These cells have slightly
varied functions, but main
role is to fight infection.
-Can cause inflammation,
produce antibodies and
phagocytose (eat/engulf)
foreign objects.
-Only live for a few days
Platelets
-Platelets are specialized
fragments of larger cells
-Platelets are responsible
for initiating blood clotting
in response to vessel
damage
-Platelets prevent
excessive bleeding
-Platelets live for about a
week
Blood cell lifespan
-White blood cells live a few days
-Platelets survive for approximately 1 week
-Red blood cells survive for approximately 120 days
-To replace the dying cells, the body produces
~2,500,000 cells per second!
Question??
Why do we bleed when we
cut ourselves?
Vessels transport blood
- Three main types of
vessels transport blood
around the body:
1. Arteries
2. Capillaries
3. Veins
- Arterioles are small
arteries
- Venules are small veins
Arteries
-
Arteries carry blood away from the heart
-
In general, arteries carry oxygenated blood (the exception is the
pulmonary arteries)
-
Arteries have thick muscular walls
-
Thick walls needed to withstand the high pressure of blood as it is
pumped from the heart
-
Walls are too thick to allow diffusion of nutrients and gases
-
Arteries branch into smaller and smaller vessels. The smallest
arteries are called arterioles
Artery
Arteriole
Arterioles
-
Muscular walls allow blood to be directed to tissue that
needs it most - Examples?
-
Smooth muscle acts as sphincters to regulate blood
flow (pre-capillary sphincters)
-
Contraction/relaxation is not under voluntary control –
ie we can’t deliberately increase blood flow to a certain
region – it is controlled by the body
-
Continued branching of arterioles leads to capillaries
Arteriole
Capillary
Capillaries
-
Capillaries are the site of nutrient and gas transfer
-
Capillaries have a small diameter (5-8µm) – Implications?
-
Capillaries have very thin walls which are only one cell thick (these
cells are called endothelial cells). The thin walls allow substances
to diffuse across the capillary to reach the tissue (or vice versa).
-
Alternatively, larger molecules (eg proteins and white blood cells)
can squeeze between the endothelial cells to reach the other side.
-
Concentration gradients determine the direction molecules (eg
nutrients, oxygen, carbon dioxide) will move
-
Branching of arteries and arterioles leads to very large numbers
of capillaries. This leads to large surface area and decreased
blood pressure in capillaries– Why is this important?
Veins and venules
-
Venules are small veins which take blood from the capillaries to the veins
-
Veins take blood back to the heart
-
They have thinner walls compared to arteries because they function under
low pressure (blood is further from the heart)
-
Veins generally carry deoxygenated blood (exception is the pulmonary
vein)
-
Many veins are located close to your skin –What colour are they? Why?
-
Veins lack thick muscular layer and must rely on valves and contraction of
nearby skeletal muscle to pump blood back to the heart.
-
Valves prevent backflow of blood
-
Contraction of nearby muscles (eg in the leg) squeeze the veins and push
blood back to the heart.
-
Implications for deep vein thrombosis and traveling on aeroplanes?
Bringing it all together…
Heart
Summary
Function
Take large volumes of blood from
heart. Under high pressure
Connect arteries to capillaries. Role
in directing blood flow.
Allow diffusion of nutrients and
gases to tissues.
Direct blood from capillaries to
veins.
Take large volumes of blood to
heart.