Ch 9 ­ Homeostasis and Circulation
Homeostasis
• a relatively stable internal physiological environment
• does not mean that there are no changes going on; rather a dynamic equilibrium
• achieved by internal control mechanisms that continuously work to oppose small changes
• body systems must work together to maintain homeostasis
List a few things that must be kept at a constant level within us.
• temperature
• blood sugar
• blood pressure
• heart rate
• CO2 levels • O2 levels
• cholesterol
• water
List the body systems that work to maintain homeostasis.
• Circulatory System
• Respiratory System
• Digestive System
• Excretory System
• Immune System
• Nervous System
• Endocrine System
• Reproductive System
• Muscle System
• Skeletal System
• Integumentary System
How many could you get?
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To maintain a constant internal environment, we use:
• Physiological Mechanisms ex. increase metabolic activity to produce heat on inside (to warm up)
• Behavioral Mechanisms ex. curl up in a blanket to warm up from the outside!
Often, these mechanisms work through Negative Feedback Loops
Negative Feedback Loop
• process that detects and reverses deviations from normal body constants
• involves three parts: a sensory receptor, an integrator, and an effector
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Negative Feedback Loop
Functions of each part:
• sensory receptor detects changes in internal conditions + sends this info to integrator
• integrator (brain usually)
processes information from receptor and sends directions to effector • effector an organ or gland or part that responds to try to return conditions to normal
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Activity: Imagine our body is like a house and our temperature is regulated like the temperature in a house. Think of the parts involved and determine which things in a house would be the receptor, integrator and effector in the negative feedback loop. Draw an actual loop to show how the mechanism works.
Perturbing Factor: Temp drops outside
Perturbing Factor: Sunny + hot outside
Stimulus
Stimulus
Sensor
Sensor
Integrator
(­)
Integrator
Effector
Effector
Response
Response
(­)
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Activity: Imagine our body is like a house and our temperature is regulated like the temperature in a house. Think of the parts involved and determine which things in a house would be the receptor, integrator and effector in the negative feedback loop. Draw an actual loop to show how the mechanism works.
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Animation
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Perturbing Factor: Ate a candy bar
Stimulus
Sensor
Integrator
(­)
Effector
Response
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Regulation of Body Temperature in Animals
Homeotherm = Endotherm = Warm­blooded
• organisms that maintain a relatively constant body temperature
• adjust metabolic rate to release more or less heat inside (physiological)
• also use behavioral mechanisms like poikilotherms do
• only birds and mammals
Poikilotherm = Ectotherm = Cold­blooded
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organisms whose body temperature changes ~ environment
rely a great extent on behavioral mechanisms to regulate temp
go near sun to warm, shade or water to cool
habitat is limited by temperature range
ex. fish, amphibians, reptiles
Many animals fall somewhere between the two. We'll focus on humans!
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Regulation of Body Temperature in Humans
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The Circulatory System and Homeostasis
The circulatory system plays a major role in maintaining homeostasis. This is because it provides a pathway for the distribution of materials (and heat) throughout the body. Brainstorm Activity:
Think of some of the specific things it carries and what other jobs it has to help the body maintain a relatively constant environment and meet all of its requirements.
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Were all of these on your list? If not, add them!
Functions of the human circulatory system in maintaining homeostasis:
1) carries O2 from lungs to heart to body tissues
2) transports nutrients from villi of small intestine to rest of body tissues
3) carries CO2 from tissues to heart to lungs for excretion
4) carries other wastes fr cells to organs of excretion (liver,kidneys, skin)
5) helps fight disease (carries WBCs to attack invaders, antibodies to direct response)
6) helps regulate temperature (carries warm blood to extremities)
7) carries hormones to target tissues so they can coordinate body activities
8) helps heal wounds by forming clots
"Without the bloodstream to serve as a pathway for these substances, the body would be unable to respond effectively to fluctuations in its internal or external environment, and the finely­balanced mechanisms that keep the many different components of the organism functioning together would quickly breakdown" ­ McGraw­Hill Ryerson p313
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Do all organisms have a circulatory system?
Unicellular organisms like euglena exchange materials with environment by diffusion.
More complex, multicellular organisms require a transport / circulatory system. Why?
All cells must receive nutrients and oxygen and get rid of waste materials. Since the inner cells are not in direct contact with the environment, transport is accomplished by a circulatory system.
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Types of Circulatory Systems
Open Circulatory System
ex. clam, grasshopper
• may have pump and vessels
• these open into sinuses (open spaces)
• blood bathes tissues there
Closed Circulatory System
ex. earthworm, human
• have pump and vessels
• vessels connected by capillaries
• blood never comes out of vessels
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What is required in a closed circulatory system?
• a system of tubes (blood vessels) or spaces for the fluid to move through
• a fluid to carry the materials (blood)
• a mechanism to move the blood through the tubes (heart)
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Part 1: The Transport Vessels
Artery
Capillary
Vein
1. Match the label to the right with the appropriate vessel above.
2. Note the different layers each vessel has and their thickness.
a) Which one has the least layers? How many layers thick is it?
b) Which one has the thickest layer of muscle (2nd layer in)? c) Which one has the largest diameter?
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Types of Blood Vessels
Connective Tissue (Outer)
Smooth Muscle (Middle)
Endothelium (Inner)
Endothelium Only
1. Artery
2. Vein
3. Capillary
thick, muscular wall
small diameter
thin, muscular wall
large diameter
very thin wall, 1 cell thick
lg surface area for diffusion
carry blood away fr heart
carry blood twds heart
join arteries and veins together
carry O2 rich blood (most)
carry CO2 rich blood (most)
where O2 and CO2 are exchanged
have a pulse
no pulse
no pulse
no valves
have valves
no valves
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Q: Which picture shows the arterial system? the venous system?
Q: Why is one system depicted in red and the other blue?
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Q: Which picture shows the arterial system? the venous system?
Q: Why is one system depicted in red and the other blue?
Arterial System Venous System
Arteries usually carry oxygenated (O2 rich) blood. When blood is rich in oxygen, the hemoglobin that is carrying O2 reflects a brighter red. When hemoglobin is not carrying as much O2 (deoxygenated blood), it and the blood is a bit darker, so veins are shown as blue.
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artery ­­­ arteriole ­­­ capillary ­­­ venule ­­­ vein
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venule end
arteriole end
What substances move out at the arteriole end?
What substances are absorbed at the venule end?
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Blood is forced through arteries due to action of heart.
How do veins carry blood back towards the heart?
* no pump forcing blood like there is for arteries
* most have to work against force of gravity (exception: those in head region or raised above heart)
* solution: valves and skeletal muscles around veins work together to force blood back to heart
You should be able to sketch this for the test! I'll show you again during review when I return.
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Think About It...
Why does your arm go weak if you hold it above your head for a long time?
Why do you sometimes feel faint if you stand still for a long period of time?
Why is it beneficial to move your legs a bit while you are writing a test?
Why don’t we need valves in the veins in our brains?
What causes you to blush? go pale? bruise?
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Part 2: The Transport Medium
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Blood Plasma
Functions
• suspends and carries cellular components and plasma proteins
• carries nutrients, hormones, minerals, enzymes, antibodies to destination tissues
• carries CO2 and cellular wastes to organs of excretion
Plasma Proteins
• albumins ­ maintain blood volume and blood pressure
• globulins ­ act as antibodies to help provide protection against invaders
• fibrinogens ­ involved in blood clot formation Serum • blood plasma from which fibrinogens and other clotting agents have been removed
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Q: Which ones in the table are red blood cells? white blood cells?
Q: What are the two most important disease­fighting WBC types and what are their functions? (p 311)
Q: Where are the cellular components produced (origin)? (table p308)
RBCs
WBCs
granulocytes
agranulocytes
(lymphocytes)
Platelets
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How are blood clots formed?
Note: good test question!
Try doing your own sketch or schematic diagram. See Fig 9.15 in book and question #5 p313.
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Questions:
1. What category or type of molecules are the special "factors" on the outside of red blood cells determine your blood type?
2. Which "factors" are found on the outside of each blood type?
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3. What type of blood can be given to a person of each different blood type?
4. What does it mean to be + or ­ ?
5. Which type(s) are most common? rarest?
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Most common: O+, A+
Least common: AB­
NOTE: differences exist ~ race and ethnic background
In General: those with ­ cannot receive blood from those with + blood (+ have Rhesus factor protein as well). ex. A+ can receive A+ and A­, O + and O­
A­ can only receive A­ and O­
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Part 3: The Heart
Features
• roughly size of your fist
• surrounded + protected by pericardium (fluid filled membrane)
• 4 chambers ­ 2 atria, 2 ventricles
• acts like 2 pumps
• left and right side completely separated by septum (wall of tissue)
• allows for complete separation of O2 rich and O2 poor blood
• valves prevent backflow of blood during contractions
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Parts of the Heart
(Move boxes to reveal)
aorta
superior
vena cava
pulmonary arteries
left atrium
pulmonary vein
bicuspid or mitral valve
right atrium
left ventricle
tricuspid valve
right ventricle
inferior vena cava
right semilunar or pulmonary valve
left semilunar valve
or aortic valve
septum
Q: What is another name for the tricuspid and bicuspid valves?
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Parts of the Heart
(Move boxes to reveal)
aorta
superior
vena cava
pulmonary arteries
left atrium
pulmonary vein
bicuspid or mitral valve
right atrium
left ventricle
tricuspid valve
right ventricle
inferior vena cava
right semilunar or pulmonary valve
left semilunar valve
or aortic valve
septum
Q: What is another name for the tricuspid and bicuspid valves?
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Blood Flow Through the Heart
to body tissues
Color your diagram to indicate where blood is oxygenated and deoxygenated.
from head region
to lungs
to lungs
back from lungs
Pulmonary Circulation
• carries blood between heart and lungs
• deox to lungs, ox back to heart
back from lungs
Systemic Circulation
• carries blood between heart and body
• ox to tissues, deox back to heart
from lower
body region
*Be able to trace blood flow through the heart or draw a schematic diagram using words and arrows.
Animation of Heart Contraction and Blood Flow
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Q: What causes the characteristic "lubb dubb" sound? Be specific!
Your Heart's Electrical System Animation
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>Know what happens during each part of the wave.
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Factors that Affect Blood Pressure
• Diet high in salt retain water, higher blood volume, more pressure to pump
• Diet high in cholesterol cause clogging of arteries, less elastic and narrower vessels
• Reg use of artificial stimulants that cause increased heart rate, constriction of blood vessels
caffeine (coffee, etc)
nicotine (smoking)
alcohol • Heredity • Lack of exercise
• Obesity
• Age (tends to increase as you age)
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Factors that Affect Blood Pressure
do so by altering one of 3 things:
1) Arteriolar Resistance
cause vasodilation (lowers) or vasoconstriction (raises)
2) Blood Composition
modify viscosity (thickness) or volume
more viscous (thick) or higher vol, higher bp
3) Cardiac Output
alter stroke volume or heartrate
larger stroke volume or faster heartrate, higher bp
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Lymphatic System complements Blood Vascular System
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Functions of the Lymphatic System:
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helps maintain balance of fluids in the body
absorbs excess interstitial fluid and returns it to the circulatory system (vessels near heart)
carries fatty acids and glycerol from small intestine to the circulatory system
lymph nodes provide lymphocytes (WBCs) and house macrophages to help fight infection
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The Right Drainage Area removes lymph from the:
• Right side of the head and neck • Right arm • Upper right quadrant of the body. lymph from these areas:
­> right lymphatic duct ­> right subclavian vein (circulatory system)
The Left Drainage Area removes lymph from the:
• Left side of the head and neck • Left arm and the left upper quadrant • Lower trunk • Both legs Lymph from these areas:
­> thoracic duct
­> left lymphatic duct
­> left subclavian vein (circulatory system)
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