1. 3.2 – Human Organs & Systems
Circulatory, Digestive, Respiratory, Nervous, Skeletal, Muscular, Immune, Endocrine, Reproductive, Urinary, Integumentary

2. Cell  Tissue  Organ
Organs contain all 4 types of tissue in order to function properly:
Epithelial
Muscle
Nervous
Connective
Stomach organ

3. Organelle  Cell  Tissue  Organ  System
Some cells have more organelles than others
ex: muscle cells are packed with mitochondria, WBC are packed with lysosomes, etc.
Together, specialized cells form tissues that perform special functions
Tissues form organs that are part of a system
organs work together so the organism can survive

4. Example: the Circulatory System
Consists of the heart, arteries, veins, & blood
cells: RBC, WBC, platelets, etc.
tissues: all 4 (E, M, N, C)
organs: heart, blood vessels
system: circulatory
All function to transport nutrients, gases, and wastes to and from cells in the body

5. Humans Have 11 Organ Systems!
Circulatory
Respiratory
Digestive
Urinary
Skeletal
Muscular
Nervous
Immune
Endocrine
Reproductive
Integumentary

6. Main Function of Each System
1. Circulatory System  transports blood, nutrients, gases & wastes
2. Respiratory System  controls breathing and exchanges gases in the lungs
3. Digestive System  takes in food, breaks it down, absorbs nutrients and removes waste
4. Urinary System  removes liquid wastes
5. Nervous System  detects changes in the environment and sends signals to parts of the
body to respond
6. Skeletal System  supports, protects, & works with muscles to move parts of the body
7. Muscular System  works with bones to move parts of the body
8. Immune System  defends against infection
9. Endocrine System  makes & releases hormones to keep systems working properly
10. Reproductive System  produces offspring
11. Integumentary System  creates a waterproof barrier around body (skin, hair, nails)

7. Circulatory System Picks up and transports oxygen & nutrients to cells
See Figure 3.20A on p. 100
Picks up and transports oxygen & nutrients to cells
Carries wastes to kidneys for elimination from the body
Heart contractions produce pressure so that blood can move around the body
Heart valves close after blood is pushed through them to prevent blood from flowing backwards
Arteries carry oxygenated blood
Veins carry deoxygenated blood and wastes like CO2 that need to be removed from body
remember the exception! (explained in the video)
artery = away from heart
vein = towards heart

9. Remember…
Blood flows through the 4 chambers of the heart & through the lungs before being dispersed through the body

10. Blood in the Heart & Lungs
Blood returning from the body is deoxygenated
carries CO2 waste from cellular respiration
Blood returning from the lungs is oxygenated
bright red due to the high O2 content
See Figure 3.20B on p. 100

11. The Path of Blood in the Body
Blood from body:
Vena cava 
Right atrium 
Right ventricle 
Pulmonary arteries 
Lungs 
Pulmonary veins 
Left atrium 
Left ventricle 
Aorta 
Blood circulates to body

13. Capillaries
KAP-ill-air-eez
These are networks of very thin blood vessels (1 epithelial cell thick!)
They deliver oxygen & nutrients and pick up waste materials from tissues in every organ in the body
Trace the path of blood with your finger, starting at one point and returning to it

15. Quiz time! Name the 2 major functions of the circulatory system.
Name the 4 main chambers of the heart.
What do the valves in the heart do?
With a partner, explain the path that blood takes through the body from your fingertip or your toe, back to that same body part.
What are capillaries? What do they do?

16. The Same, but Different
Read the top half of p Then with a partner, answer the following questions.
1. a) What is the difference between an open and closed
system with regards to circulation?
b) Give an example of an animal that would have an
open system, and one that would have a closed one.
2. How is a fish’s heart different from a human’s?
3. a) How many chambers does an amphibian’s heart
have?
b) What does this mean then?

17. Respiratory System Consists of the lungs & airways
Responsible for gas exchange (O2 in, CO2 out)
Is connected to the circulatory system so that it can exchange gases in the blood (through capillaries)
The diaphragm is a muscle that contracts when you breathe
allows room for your lungs to expand so they can take in air
rib cage moves up & out, causing air to be pulled into your body through your nose or mouth

19. Use Your Nose!
The air your breathe in passes by epithelial cells in your nasal cavity
cells have tiny, hair-like projections called cilia
they also secrete mucus
Both cilia & mucus keep foreign particles like allergens, bacteria, and toxins out of your body

20. Pharynx  Trachea  Bronchi
Air moves from the pharynx (throat) to your trachea
a small flap called the epiglottis opens and closes so no food ends up in the trachea
From the trachea, the single pipe splits into two, called bronchi
each bronchi goes to a lung

21. Bronchi  Bronchioles  Alveoli
Bronchi then branch out into smaller tubes called bronchioles
bronchioles are embedded within the lung tissue
Bronchioles divide into tiny sacs called alveoli
Capillaries surround the alveoli
it is here that gas exchange takes place
See Figure 3.26 on p. 104

22. Alveoli Tiny clusters of air sacs in the lung (sing. = alveolus)
have a very thin epithelial layer
gases can cross, but bacteria and other harmful substances cannot
O2 and CO2 are exchanged with blood in the capillaries
O2 to RBC from alveoli
CO2 to alveoli from RBC
RBCs contain hemoglobin, which binds O2 so that it can be carried through the body

23. Alveoli are the tiny heroes of the respiratory system!

24. Alveoli       Mouth
When your diaphragm & chest muscles relax, you exhale
CO2 in the alveoli is released into the air in the opposite way O2 came in
When CO2 levels get too high, breathing rate increases so CO2 can be expelled quicker

25. The Same, but Different… again
Birds, reptiles, & amphibians have lungs just like humans do
these creatures have an effective gas exchange system, but it is different than ours
Instead of alveoli, fish have gills
Read over Figure 3.28 on p and summarize with a classmate how gills perform gas exchange just like alveoli in humans

26. Quiz… yahoo!!
Trace the path of a breath of air in through your nose and out through your mouth.
Why should you always breathe in through your nose?
What is the structure in the lung where gas exchange takes place? Name 2 gases that are exchanged with blood in capillaries here.
Why does your breathing rate increase when you’re exercising?

27. Digestive System
Mechanically & chemically breaks down food so the body can use nutrients
The major organs are the stomach, liver, pancreas, and intestines
See Figure 3.14A on p. 97

28. Mouth  Pharynx  Esophagus
Teeth break down food into smaller pieces
Enzymes (protein) in saliva begin chemical digestion
Swallowed food passes through the pharynx to the esophagus
Esophagus
Is a muscular tube that contracts & relaxes to push chunks of food down to the stomach
Waves of muscle contraction is called peristalsis

29. Stomach
Contains liquids called gastric juices that chemically break down the food more
are highly acidic
Stomach muscles mix the contents, which continues the mechanical breakdown of food
churning action of stomach & gastric juices cause food to break down into a liquid
Food is pushed into small intestine

30. Small Intestine Divided into 3 sections: 1. duodenum  where the rest
of digestion takes place
2. jejunum
3. ileum  where absorption
of nutrients takes place
Pancreas, liver, and gall bladder release digestive enzymes into the duodenum via small tubes called ducts
Walls of the small intestine are covered with little projections called villi (& microvilli)
they increase the surface area so that more nutrients and water can be absorbed into the bloodstream
See Figure 3.15 on p. 98
See Figure 3.16 on p. 98

31. Large Intestine Includes the colon, rectum, & anus (oh geez)
Absorbs water, vitamins salts from digested food
achieved by bacteria in the gut like E.coli
Remaining (undigested) food is eliminated as feces

32. Sooooo… let’s recap The path of a meal from start to finish:
mouth  pharynx  esophagus  stomach  small intestine  large intestine
Weird facts:
it takes 24 to 33 hrs for a meal to go from beginning to end of this system
the small intestine is between 6 – 10 m in an adult

33. Quizzy, quizzy… Identify the structures A. – E.
Name 3 organs that help digest food that enters the small intestine.
Name the 3 sections of the small intestine.
Give 4 organs in the digestive system that chemically break down food and explain how each occurs.
Which part of the digestive systems mechanically breaks down food?

34. Urinary (Excretory) System
Composed of the kidneys, ureter, bladder, urethra, and blood vessels
Eliminates liquid wastes from the body
Interacts closely with the circulatory & digestive systems

35. Kidneys: Liquid Waste’s Last Stop
As blood passes through the kidneys, it is filtered and wastes are removed
Remember nephrons? Those are the tiny structures within the kidneys that do the filtering
Urine forms from excess water and unneeded salts in the blood (called urea)
Urine is stored in the bladder and then excreted through the urethra

36. Nephrons

37. Urine trouble if you don’t know the answers to these questions!
Name the 4 major structures that compose the urinary system.
How is the urinary system different from the digestive system?
What tiny structure in the kidney is responsible for filtering blood of its wastes?