Chapter Nine Review

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Chapter Nine Review

• READ
• Page 298 -321
• REVIEW
• Lab, Worksheets
• QUESTIONS
• p. 303 1-3,6
• p. 312 1,5
• p. 321 1,2,4,8a

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Unit 3 Maintaining HomeostasisTopic I
Homeostasis and Temperature Regulation

• Biology 2201

3
Chapter 9

• In chapter 9 we will look into homeostasis and
  circulation.
• Both of these processes are vital to the
  development, growth and maintenance of an
  organism.

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Homeostasis

• Organisms will strive to keep their internal
  environment regulated to a certain set of
  conditions.
• This resisting tendency is known as homeostasis.

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homeostasis

• Why do organisms spend precious time, energy and
  nutrients on maintaining homeostasis?

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homeostasis

• There are many reasons for organisms to maintain
  their bodies within a certain range.
• A major reason is that organic compounds can
  undergo serious shape changes with large changes
  in environment.

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homeostasis

• Proteins are held together loosely by weak
  chemical bonding forces. These bonds are very
  temperature and acid/base sensitive.
• Denatured proteins cannot fulfill their roles as
  structural components and/or enzymes.

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Homeostasis

• DNA is also vulnerable to heat and strong
  acids/bases.
• If the DNA of a cell is damaged severely, the
  cell will surely die.

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Homeostasis

• Other reasons that organisms need to maintain
  homeostasis
• Poisonous chemicals need to be kept out.
• Invaders and parasites need to be kept out.
• Nutrients must reach all of the organism.
• Wastes must be removed from all the organism.

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Homeostasis

• How does an organism maintain homeostasis?

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Homeostasis

• An organism maintains homeostasis by controlling
  biological systems, making them push against the
  changing environment.
• For example, if temperature is rising, it will
  react to cause cooling effects.
• If temperature is falling, it will react to
  prevent heat loss and/or produce more heat.

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homeostasis

• By pushing back and forth against change, the
  body never is quite at rest it is always
  regulating itself.
• This actively balanced state is known as dynamic
  equilibrium.

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Dynamic equilibrium

• To see how dynamic equilibrium works, lets
  consider an example of a house equipped with a
  furnace and an air conditioner.

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Dynamic equilibrium

• The house has its thermostat set at 25C .
• If the temperature goes above or below this, the
  furnace or AC will turn on.

25C
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Dynamic equilibrium

• If the sun is exceptionally strong, the house
  will begin to overheat.

27C
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Dynamic equilibrium

• Once the rising temperature is detected, the AC
  will turn on the cool the house back down.

27C
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Dynamic equilibrium

• Once everything is back to normal, the AC will
  shut off.

25C
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Dynamic equilibrium

• If a strong wind blows all day the house will
  begin to cool down.

23C
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Dynamic equilibrium

• This time, the furnace will start up to warm up
  the house.

23C
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Dynamic equilibrium

• Again, the house will return to normal.

25C
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Temperature Regulation

• Humans and many other organisms will keep their
  temperatures at a set level.
• Because they keep their temperature the same,
  they are known as homeotherms. These are
  sometimes known as warm-blooded.
• Organisms who do not regulate their temperature
  are called poikilotherms.

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Temperature regulation

• There are advantages and disadvantages to each
  method.
• Poikilotherms can save on energy by not having to
  spend energy producing or releasing heat.
• However, poikilotherms are more influenced by the
  environment, meaning they may not be able to
  survive in extreme climates or sudden changes in
  the climate.

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Temperature regulation

• There are advantages and disadvantages to each
  method.
• Homeotherms must spend time and energy to
  regulate their temperature. In times of scarcity,
  using as little energy as possible may help the
  organism survive.
• Homeotherms however can survive in many different
  environments because they can keep the
  temperature inside themselves different from the
  outside environment.

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Temperature Regulation

• When an organism needs to change its temperature,
  it can do so in two ways
• Behavioral Changes
• An organism will move around or start/stop
  certain activities in in order to change its
  current environment to raise/lower its
  temperature.
• Examples include moving into the shade, bathing
  in a river, curling up, nocturnalism and
  burrowing into the earth.

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Temperature Regulation

• When an organism needs to change its temperature,
  it can do so in two ways
• Physiological Changes
• An organism will change its biochemical or
  physical structure to raise/lower its
  temperature.
• Examples include sweating, shivering, increased
  pulse, and change in blood vessel size.
• When blood vessels enlarge (vasodilatation), the
  organism can cool off easier. Shrinking blood
  vessels (vasoconstriction) will help retain heat.

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Regulation Mechanisms

• Control of homeostasis is done by feedback loops.
• A feedback loop involves a series of senses body
  systems and biochemicals enhancing or inhibiting
  each other.

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Regulation Mechanisms

• There are three players in feedback loops
• Sensory Receptors
• The parts of the body that detect the state of
  the environment. (e.g. heat-sensing nerves)
• Effectors
• The parts of an organism that perform a role to
  change a certain situation. (e.g. sweat gland)
• Integrators
• The go-between for receptors and effectors. It
  takes in receptor data and orders effectors
  accordingly. (e.g. the brain)

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Regulation Mechanisms

• A temperature sensor on the skin (sensory
  receptor) notices extreme heat.

Skin Temperature Sensor
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Regulation Mechanisms

• A temperature sensor on the skin (sensory
  receptor) notices extreme heat.
• It sends this information to the hypothalamus
  part of the brain (integrator).

Skin Temperature Sensor
Hypothalamus
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Regulation Mechanisms

• The hypothalamus realizes that the body needs to
  cool down. It sends instructions to a sweat gland
  (effector) to begin sweating.

Skin Temperature Sensor
Hypothalamus
Sweat Gland
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Regulation Mechanisms

• As the sweat gland works, the skins temperature
  will lower.

Skin Temperature Sensor
Hypothalamus
Sweat Gland
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Regulation Mechanisms

• As the sweat gland works, the skins temperature
  will lower.
• This change will be noticed by the skins
  receptors and they will stop signaling the brain.

Skin Temperature Sensor
Hypothalamus
Sweat Gland
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Regulation Mechanisms

• Once the skin receptor stops signaling the brain,
  the brain will stop signaling the sweat gland.
• The system returns to normal.

Skin Temperature Sensor
Hypothalamus
Sweat Gland
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Regulation Mechanisms

• Because the effector (sweat gland) causes a
  change (sweating)that goes against the stimulus
  (overheating skin), this is known as negative
  feedback.

Skin Temperature Sensor
Hypothalamus
Sweat Gland
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Regulation Mechanisms

• Positive feedback is rare. This is because the
  organism seldom would want to further increase a
  problem.
• An example of positive feedback involves high
  blood pressure.

High Blood Pressure
Scarring of the Blood Vessels
Impeded Blood Flow in Vessels
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Dynamic Equilibrium
Points to Consider What are Homeostasis and
Dynamic Equilibrium and how are they
maintained? How do different types of organisms
regulate their body temperature? How can blood
vessels change to deal with temperature? What
are the components of a feedback loop? How are
positive and negative feedback loops different?

• Chapter 9, pp. 300-303

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Extremophile

• Organisms that can maintain homeostasis in
  severely harsh conditions are called
  extremophiles.
• These organisms are capable of living in very
  high or very low temperatures, high acidity, or
  even in highly radioactive environments!

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Extremophile

• Tardigrades (also known as water bears) are
  amazingly capable of survival in extreme
  conditions.

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Extremophile

• Tardigrades can survive
• Temperatures up to 151C.
• Temperatures as low as -272C.
• Up to 6000 atmospheres of pressure.
• No pressure a vacuum.
• 10 years without water
• Radiation up to 570,000 rads (1-2000 rads kills
  a human)

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Extremophile

• During extreme conditions, these animals are
  capable of reducing their metabolism to 0.01 of
  the normal level.

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Unit 3 Maintaining HomeostasisTopic II
Introduction to the Mammalian Circulatory System

• Biology 2201

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Review

• In the previous topic we discussed homeostasis
  and how dynamic equilibrium is maintained through
  feedback loops.
• Today we will begin to study the circulatory
  system and see its role in maintaining
  homeostasis.

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Introduction

• What the circulatory system?
• What is the role of the circulatory system?
• Why have animals evolved to have a circulatory
  system?

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Circulatory System

• The major role of the circulatory system is
  circulation, that is, transport.
• As animals became larger and more complex, there
  came a need for the animal to develop a system to
  transport substances throughout the body.

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Circulatory System

• What sort of items are transported by the
  circulatory system?
• Nutrients
• Oxygen
• Wastes
• Hormones
• Immune System Components

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Circulatory System

• Without a circulatory system, food would not
  reach all cells and wastes would build up and
  have no way to be excreted.
• Transport and signaling would only work by
  diffusion and would be much, much slower and
  inefficient.
• Quick responses to changing environments would be
  very difficult and failure to adapt could result
  in cell damage and even death.

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Evolution

• The most basic of animals, such as poriferans,
  have no circulatory system at all. Each cell is
  on its own and much receive food and remove
  wastes on its individually.
• Some communication between cells is possible by
  excretion/diffusion.

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Evolution

• The most basic circulatory systems are found in
  the phylum mollusca and anthropoda.
• The system is called an open circulatory system
  because fluid is not always contained within
  vessels, it is free to bathe tissues directly.

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Evolution

• A circulatory system where the fluid is kept
  within vessels is called a closed circulatory
  system.
• The most basic of these is seen in fish.

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Evolution

• Amphibians and some reptiles have a 3-chambered
  heart.
• Oxygenated and deoxygenated blood can mix.
• The blood flow to the lungs can be selectively
  turned off. This is done for poikilotherm heat
  control.

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Evolution

• Mammals have a 4-chambered heart.
• Oxygenated and deoxygenated blood never mixes.

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Mammalian Circulatory System

• There are two sections to the system.
• The Pulmonary Circuit takes deoxygenated blood
  from the heart through the lungs and oxidizes it.

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Mammalian Circulatory System

• There are two sections to the system.
• The Systemic Circuit takes the oxygenated blood
  from the left heart through the body and then
  back to the right heart.

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Mammalian Circulatory System
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Circulatory System

• There are three elements to the circulatory
  system
• Vessels
• The pipes that connect everything.
• Veins, arteries, capillaries.
• Medium
• The fluid that is transported.
• The blood.
• Pump
• The motor that forces the medium through the
  vessels.
• The Heart

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Circulatory System

• There are three elements to the circulatory
  system
• Vessels
• The pipes that connect everything.
• Veins, arteries, capillaries.
• Medium
• The fluid that is transported.
• The blood.
• Pump
• The motor that forces the medium through the
  vessels.
• The Heart

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Vessels

• Vessels are the pipes and tubes that set the
  framework for the circulatory system.
• There are three main types of vessels
• Arteries
• Veins
• Capillaries

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Arteries

• An artery is any blood vessel that contains blood
  flowing from the heart.
• The smaller arteries are known as arterioles.

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Arteries

• Most arteries and arterioles carry oxygenated
  blood.
• An important exception is the pulmonary artery
  the artery that carries deoxygenated blood from
  the right side of the heart to the lungs.

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Arteries

• Arteries are made of three layers.
• Outer connective tissue and some elastic fibers
• Middle thick, alternating smooth muscle and
  elastic fibers
• Inner single layer of cells smooth to reduce
  friction with blood

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Arteries

• Arteries are thick-walled and built strong in
  order to withstand the pressure of blood straight
  from the heart.

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Arteries

• The elastic fibers and smooth muscle are designed
  to be able to expand when high-pressure blood
  enters and to then snap back to normal size,
  keeping the blood flowing the proper direction.

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Arteries

• In total, arteries hold about 30 of the systemic
  blood in the body.

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Veins

• Veins are the blood vessels that return blood to
  the heart.
• Smaller veins are known as venules.

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Veins

• Most veins and venules carry deoxygenated blood.
• Again, an important exception is the pulmonary
  vein the artery that carries oxygenated blood
  from the lungs to the left side of the heart.

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Veins

• Veins contain the same layers as arteries.
• However, the layers are thinner and more flexible.

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Veins

• Veins contain blood that is at a much lower
  pressure than arterial blood.
• Because of this, veins do not need to be as rigid.

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Veins

• As venous blood is at a lower pressure, the blood
  is more at risk to flow backwards.
• To counteract this, veins have one-way valves
  that only allow blood flow in the proper
  direction.

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Veins

• The flow of blood through the veins is helped
  somewhat by gravity.
• The major factor, however, is muscle movement.

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Veins

• Venous blood flow is slower and less pressurized
  than arterial blood flow.
• 65 of systemic blood is contained in the veins.

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Arteries and Veins
Note the relative size of the interior space
(lumen) and wall thickness (vwvein wall,
awartery wall).
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Capillaries

• Capillaries are very small blood vessels that are
  the link between arteries, veins and the bodies
  tissues.
• Capillaries are the site of nutrient/waste
  exchange.

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Capillaries

• Capillaries are one endothelial cell thick with
  an average diameter of 8 µm.
• This allows them to reach every remote region of
  the body.

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Capillaries

• Capillaries are so narrow that red blood cells
  will often have to travel through single-file.

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Capillaries

• Nutrients and wastes are transferred between the
  blood and the surrounding tissues.
• Examples include
• Oxygen
• Carbon Dioxide
• Glucose
• Amino Acids
• Urea

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Capillaries

• Remember that the human circulatory system is
  closed. No blood ever leaves the vessels. Only
  nutrients and wastes transfer back and forth.

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Capillaries

• Note the thinness of the capillary wall and the
  small diameter of the vessel.

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Circulatory System Vessels
Points to Consider What is the purpose of the
circulatory system? What are the differences
between open and closed circulatory
systems? What are the components of a
circulatory system? How are a vein and artery
similar? How do they differ? How are capillaries
designed for substance exchange with body
tissues.

• Chapter 9, pp. 304-307

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Unit 3 Maintaining HomeostasisTopic IIIThe
Lymphatic System and The Blood

• Biology 2201

80
Review

• Last time we introduced the concept of the
  circulatory system. This is a vital network
  designed to maintain homeostasis throughout
  complex organisms.
• The circulatory system consists of three
  components

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Review

• There are three elements to the circulatory
  system
• Vessels
• The pipes that connect everything.
• Veins, arteries, capillaries.
• Medium
• The fluid that is transported.
• The blood.
• Pump
• The motor that forces the medium through the
  vessels.
• The Heart

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Vessels Review

• In the last lesson we discussed how capillary
  beds link the arteries, veins and tissues of the
  body.
• However, there is also another system at work.

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Lymphatic System

• The Lymphatic system is an open system that
  connects directly to the space within tissues.

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Lymphatic System

• Instead of blood, the fluid in the system is
  known as lymph. As well, there is no pump for the
  lymphatic system.

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Lymphatic System

• Lymph circulates throughout the body until it
  reaches a lymph node.
• Lymph eventually joins up with the blood in the
  subclavian vein.

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Review

• There are three elements to the circulatory
  system
• Vessels
• The pipes that connect everything.
• Veins, arteries, capillaries.
• Medium
• The fluid that is transported.
• The blood.
• Pump
• The motor that forces the medium through the
  vessels.
• The Heart

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The Role of Blood

• Blood is the tissue through which all of the
  uptake, storage, transport, and delivery takes
  place in the circulatory system.
• It is made of several types of specialized cells
  and compounds suspended in liquid.

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Blood composition

• To analyze the composition of a persons blood, a
  centrifuge is used.
• This instrument spins test tubes filled with
  blood at very high speeds.

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Blood composition

• The high speeds force the heavier cells to the
  bottom while the leftover fluid remains on top.
• This allows scientists and doctors to see how
  much of the blood is made up of cells.

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Blood composition

• The blood normally contains
• Plasma
• (55)
• White Blood Cells (1)
• Red Blood Cells (44)

91
Blood composition

• The blood normally contains
• Plasma
• (55)
• White Blood Cells (1)
• Red Blood Cells (44)

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Red Blood Cells

• Red blood cells are called erythrocytes.
• On average, people have between 4.5 - 5.5 million
  RBCs per millilitre of blood.

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Red Blood Cells

• Red blood cells are specialized for oxygen
  transport.
• Mature red blood cells lack a nucleus.
• The average life span is about 3-4 months.

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Hemoglobin

• In order to meet the high levels of oxygen needed
  by the body, RBCs have a special oxygen-carrying
  protein known as hemoglobin.

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Hemoglobin

• Each hemoglobin protein contains 4 sites for
  Oxygen-binding, the heme groups.
• Oxygen is bound reversibly so that it can be
  picked up and released when needed.

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Oxygen Binding

• Each heme site will not have an Oxygen bound at
  all times.
• In tissues where oxygen is low, oxygen is more
  easily released.

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Oxygen Binding

• The binding of oxygen to hemoglobin is designed
  to take up oxygen at high oxygen areas (lungs)
  and release oxygen at low oxygen areas (tissues).

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Oxygen Binding

• High acidity also encourages the release of
  oxygen from hemoglobin.
• High carbonic acid levels are the result of
  metabolic activity.
• Thus highly active tissues take up even more
  oxygen for fuel.

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Oxygen Binding

• Hemoglobin releases oxygen more slowly at cold
  temperatures.
• Little effect on warm-blooded animals.
• Cold-blooded animals cannot be as active when it
  is cold.

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Blood composition

• The blood normally contains
• Plasma
• (55)
• White Blood Cells (1)
• Red Blood Cells (44)

101
Blood composition

• The blood normally contains
• Plasma
• (55)
• White Blood Cells (1)
• Red Blood Cells (44)

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White Blood Cells

• White blood cells are called leucocytes and are
  involved in immune defense.
• White blood cells make up only 1 of the blood,
  but can double during an infection.

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White Blood Cells

• Unlike red blood cells, white blood cells have a
  nucleus.
• They appear colorless.

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White Blood Cells

• An important white blood cell is the macrophage.
• Macrophages can pass through capillary walls to
  engulf and digest invaders.

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White Blood Cells

• Macrophages have a short lifespan of only a few
  hours to a few days.
• Macrophages much larger than red blood cells.

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White Blood Cells

• Another white blood cell type are the
  lymphocytes.
• These are medium-sized cells.
• Their lifespan is currently not known.

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White Blood Cells

• Lymphocytes play a role in the bodies acquired
  immune response.
• They aid in the formation of antibodies which
  label pathogens for destruction or removal.

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Platelets

• A third major component of blood are platelets.
• These are not cells but are formed from fragments
  of bone marrow cells.

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Platelets

• Platelets have a short lifespan of 7 10 days.
• Platelets play an important role in preventing
  blood loss.

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Clotting

• Platelets prevent blood loss by clotting.
• Clotting is a complicated process.

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Clotting Process

1. Broken blood vessels release substances that
   attract platelets.
2. The platelets collect at the wound.
3. The platelets rupture releasing chemicals that
   react with clotting agents in the plasma.
4. This reaction activates thromboplastin.

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Clotting Process

1. Thromboplastin reacts with prothrombin,
   converting it to thrombin. Calcium ions catalyze
   this reaction.
2. Thrombin converts fibrinogen into fibrin.
3. Fibrin collects to form a mesh of strands that
   plug the wound, preventing blood loss.

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Clotting Process
115
Blood composition

• The blood normally contains
• Plasma
• (55)
• White Blood Cells (1)
• Red Blood Cells (44)

116
Blood composition

• The blood normally contains
• Plasma
• (55)
• White Blood Cells (1)
• Red Blood Cells (44)

117
Blood Plasma

• The fluid portion of the blood is called the
  plasma.
• The plasma carries all the bloods cells,
  nutrients, and wastes.
• Important proteins in the plasma
• Clotting proteins
• Serum Albumin (blood pressure and volume
  regulation)
• Serum Globulin (some act as antibodies to fight
  disease)

118
Blood Plasma

• The plasma carries carbon dioxide in the form of
  carbonic acid.
• The plasma also contains many needed ions and
  nutrients (metals, chlorine, phosphates, sugars,
  etc).
• Hormones and other signalling molecules travel in
  the plasma.

119
Circulatory System Blood
Points to Consider What is the typical
proportion of RBCs, WBCs and plasma in the
blood? What is the main function of RBCs? What
is the main protein involved in this
function? What are types and roles of
WBCs? What are the role of platelets? How is
blood loss prevented? What functions does the
plasma perform?

• Chapter 9, pp. 308-312

120
Unit 3 Maintaining HomeostasisTopic IVThe
Heart

• Biology 2201

121
Review

• There are three elements to the circulatory
  system
• Vessels
• The pipes that connect everything.
• Veins, arteries, capillaries.
• Medium
• The fluid that is transported.
• The blood.
• Pump
• The motor that forces the medium through the
  vessels.
• The Heart

122
Review

• There are three elements to the circulatory
  system
• Vessels
• The pipes that connect everything.
• Veins, arteries, capillaries.
• Medium
• The fluid that is transported.
• The blood.
• Pump
• The motor that forces the medium through the
  vessels.
• The Heart

123
The Hearts Workload

• The human heart has a very challenging job.
• Pumping about 70 times per minute constantly for
  80 years
• 160000 km of piping to pump fluid through
• Unconscious control
• Able to adapt and adjust pumping
• Able to pump two types of fluid in two directions
  without mixing

124
Basic Layout

• The basic path of blood through the body
• Tissues to right heart.
• Right heart through lungs to left heart.
• Left heart to tissues.

125
The Flow of Blood Through the Heart

• Blood from the body enters the heart from the
  vena cava.
• Blood collects in the right atrium.
• The atria contract, forcing the blood into the
  right ventricle.

126
The Flow of Blood Through the Heart

• The ventricles contract. The tricuspid valve
  prevents blood returning to the atrium. The blood
  is forced out of the heart into the pulmonary
  artery.

127
The Flow of Blood Through the Heart

• The pulmonary artery takes the blood to the lungs
  where it receives oxygen.
• Upon exiting the lungs, the blood flows back to
  the heart in the pulmonary vein.

128
The Flow of Blood Through the Heart

1. The oxygenated blood collects in the left atrium.
2. Again, the atria contract and the blood moves
   into the left ventricle.

129
The Flow of Blood Through the Heart

• 9. The ventricles contract. The bicuspid valve
  prevents blood from returning to the left atrium.
  The blood leaves the heart through the aorta to
  reach the bodys tissues.

130
The heartbeat

• The sound of a heart beating, lub-dup, is
  caused by the valves of the heart snapping shut.

131
The heartbeat

• Lub
• Softer sound
• Atrioventricular valves shutting.
• Dup
• Sharper sound
• Valves between the ventricles and arteries
  shutting.

132
The heartbeat

• The heartbeat is controlled by a pacemaker.
• A small bundle of muscle tissue in the right
  atrium stimulates the heart to beat.
• This is the sinoartrial node, or S-A node.

133
The heartbeat

• As the atria contract, another node, the
  atrioventricular node (A-V node).
• The A-V node is in between the ventricles and
  stimulates the muscles to contract the
  ventricles.

134
The heartbeat

• The heart rate can be adjusted by the brain.
• The medulla oblongata controls the rate by
  nerves.

135
The heartbeat

• To increase the heart rate, the nerves release
  noradrenaline, which stimulates the S-A node.
• To decrease heart rate, the nerves release
  acetylcholine to inhibit the S-A node.

136
Output and fitness

• The amount of blood the heart pumps is known as
  the cardiac output.
• Two factors
• Heart rate (average 70 beats/min)
• Stroke volume (average 70 mL)
• CO HR x SV
• A low resting heart rate is associated with good
  fitness. This means the stroke volume is high.

137
Heart Defects

• The septum is the wall that separates the
  ventricles.
• If a hole exists, blood from the ventricles can
  mix, leading to poor oxygen delivery.

138
Heart Defects

• A heart murmur occurs if one of the valves of the
  heart cannot open or close properly.
• This can be heard in the heartbeat.

139
Circulatory System The Heart
Points to Consider Describe the flow of blood
through the heart. What do the atrioventular
valves do? What causes the sounds of the
heartbeat? What controls the heart rate? What
is cardiac output and how is it related to
general fitness? How can defects in the septum
and valves effect the heart?

• Chapter 9, pp. 314-321

140
Chapter Nine Review

• READ
• Page 298 -321
• REVIEW
• Lab, Worksheets
• QUESTIONS
• p. 303 1-3,6
• p. 312 1,5
• p. 321 1,2,4,8a