The document summarizes the key functions of the digestive and endocrine systems. It describes the multi-step process of digestion that begins in the mouth and involves mechanical and chemical breakdown of food through the actions of organs like the stomach, liver, pancreas and intestines. The endocrine system maintains homeostasis through glands like the pituitary, thyroid and adrenals that release hormones regulating processes like metabolism, growth and stress response. Hormones travel through the bloodstream and trigger responses in target cells through negative feedback loops.

1. The Digestive and
Endocrine Systems

2. Following the Digestion of a
Meal
Functions of the Digestive System
• Main function is to disassemble the
food you eat into its component
molecules s that it can be used as energy
(ATP) by your body.

3. All of these organs work together to break
down food into simpler compounds that can be
absorbed by the body.

4. • Steps of Digestion
1. System takes ingested food & begins
moving it through the digestive tract. As
food moves it breaks down mechanically
and chemically
2. The system absorbs the digested food &
distributes it to your cells
3. It eliminates undigested materials from
the body

5.  The Mouth
- The disassembly line STARTS at the
mouth
• What happens when you chew?
– Your tongue moves food around & helps position
it b/t your teeth
– Chewing is a form mechanical digestion = the physical
process of breaking down food into smaller pieces.
This prepares food for chemical digestion
– Chemical digestion = the process of changing food on
a molecular level through the action of enzymes

7. • Chemical Digestion begins in
Mouth
• Saliva in mouth contains digestive
enzymes, called amylase, which breaks
down starch into smaller molecules
• In the stomach, amylase continues to
digest food for about 30 min.

8. Starch

9. • Swallowing Your Food
• Chewed food becomes a ball and is swallowed
• Swallowing forces food into throat and then to
the esophagus = a muscular tube that
connects the mouth to the stomach
– Food moves through the esophagus by peristalsis
= a series of involuntary smooth muscle
contraction along the walls of the digestive tract

10. Peristalsis

12. • The epiglottis = a flap of cartilage that closes
over the opening to the respiratory tract as you
swallow, keeping food out
– After food passes, epiglottis opens again
– If you talk or laugh as you swallow, food may
enter the upper portion of the respiratory tract
– Your response is to choke & cough, forcing food
out of the respiratory tract

14.  The Stomach
Stomach = a muscular pouchlike
enlargement of the digestive tract
• Muscle Churning
– The walls of the stomach are composed of 3
layers of involuntary muscles
– When the muscles contract, they work to
physically breakdown food, creating smaller
pieces
– The pieces mix with digestive juices produced by
the stomach

16. • Chemical Digestion in the stomach
• The lining of the stomach contains
millions of glands that secrete a mixture
of chemicals called gastric juice
• Gastric juice contains pepsin &
hydrochloric aced
– Pepsin = an enzyme that begins the
chemical digestion of proteins in food

17. • The lining of the stomach secretes mucus
that forms a protective layer b/t it and
the acidic environment of the stomach
• Food remains in stomach for about 2-4
hrs
• When food leaves it is the consistency of
tomato soup (YUMMY!)

18.  The Small Intestine
- Small intestine = a muscular tube
about 6 m long
Called “small” because of how narrow it
is (only 2.5 cm in diameter)
- Digestion is COMPLETED here
- First 25 cm of the small intestine
called the duodenum

20. • Secretions of the
Pancreas
• Pancreas = soft, flattened gland that
secretes both digestive enzymes &
hormones
– The mixture of enzymes it releases break
down carbs, proteins, & fats

21. • Secretions of the Liver
• Liver = large, complex organ that produces bile
• Bile = chemical substance that helps break down fats
– Made by the liver, but stored in the gallbladder
– From the gallbladder, bile passes into duodenum
– Bile causes further digestion by breaking large drops
of fat into smaller droplets
– Gallstones form when bile in the gallbladder becomes
too concentrated due to high levels of cholesterol in
you diet

22. LIVER

23. • Absorption of Food
• Liquid food stays in the intestine for 3-5 hrs. as it is
moved through
• As food moves it passes over thousands of tiny
fingerlike structures called villus = a single projection
on the lining of small intestine that function in the
absorption of food
• Now that food is in the form of small molecules, it
can be absorbed directly into the cells of the villi
(plural for villus)
• Food then diffuses into blood vessels of the villus &
enter the bloodstream
* Villi are the link between the digestive system & the
circulatory system

25.  The Large
Intestine
- All indigestible material from a meal then
moves into the large intestine = a
muscular tube that is also called the colon
- Large intestine is only about 1.5 m long,
but it is much wider that the small intestine (
about 6.5cm in diameter)

26. • Water Absorption
• As indigestible mixture passes through
the large intestine, water and salts are
absorbed by the intestinal walls,
leaving behind a more solid material
• This way water in NOT wasted

27. • Bacteria in the large intestine make
some B vitamins and Vitamin K,
which are absorbed as needed by the
body
–These bacteria also stop harmful
bacteria from colonizing, reducing the
risk of intestinal infections

28. • Elimination of
Wastes
• After 18-24 hrs in the large intestine,
the remaining indigestible material,
now called feces, reaches the rectum
• Rectum = the last part of the digestive
system

29. YOUR ENTIRE MEAL’S
JOURNEY THOUGH THE
DIGESTIVE TRACT HAS
TAKEN BETWEEN 24-33
HOURS!

30. mouth
esophagus
stomach
liver
gall bladder pancreas
small intestinelarge intestine
appendix rectum
anus
colon

31. • Ch. 35.2: Nutrition
 The Vital Nutrients
• - Six basic kinds of nutrients can be found:
–1. Carbohydrates
» Main source of energy
–2. Fats
» Used to store energy
–3. Proteins
» Form part of muscles and many cell
structures, including the cell membrane

32. –4. Minerals
» Serve as structural materials
–5. Vitamins
» Needed for growth and metabolism
–6. Water
» Facilitates chemical reactions, helps
dissolve materials and helps maintain
the body’s temperature
Ca
B12
CrMg
Vitamin C
Vitamin D

33. USDAUSDA
Food Guide PyramidFood Guide Pyramid

34. The Endocrine System
• Control of the Body
–Internal control of the body is
directed by 2 systems:
•The Nervous System
•The Endocrine System

36. –The Endocrine System is made up of
a series of glands called endocrine
glands
•These glands release chemicals directly
into the bloodstream
•The chemicals act as messengers,
relaying information to other parts of
the body

37. • Interaction of the Nervous & Endocrine
Systems
– The endocrine system and the nervous system
work together to maintain homeostasis within
the body
– Hypothalamus = the portion of the brain that
receives messages from other areas of the brain
& internal organs
• When a change in homeostasis is detected, the
hypothalamus stimulates the pituitary gland

38. • pituitary gland = the main gland
of the endocrine system and is
located in the skull just beneath the
hypothalamus
–The pituitary gland releases its own
chemicals or stimulates other glands
to release theirs

40. • Endocrine Control of the Body
–Hormones = the chemicals secreted by
endocrine glands
• Hormones are chemicals released in one part
of an organism that affects another part of
the organism
• They convey information to other cells in
your body, giving them instructions regarding
your metabolism, growth, development, and
behavior

41. • Hormones travel in the bloodstream and
attach to specific binding sites of target
cells
• These binding sites are called receptors

42. Lock and Key Analogy
Hormone = key
Receptor = lock
Like a key with a lock, hormones only fit certain
receptors. Even a close fit won’t turn the lock.

43. • Example of Endocrine Control (hGH)
– Human growth hormone (hGH) is a good
example of an endocrine system hormone
– When your body is growing, blood glucose
levels are slightly lowered as the growing cells
use up the sugar in your cells
– The low blood glucose level is detected by the
hypothalamus, which stimulates the production
& release of hGH from the pituitary gland into
the bloodstream

44. – hGH binds to receptors on liver cells,
stimulating liver cells to release glucose into the
blood
– Your cells need this glucose in order to continue
growing
LOW
GLUCOSE
detected by
hypothalamus
(endocrine
system)
Pituitary
gland
releases hGH
hGH
stimulates
liver to release
extra glucose
Homeostasis
restored 
glucose level is
NORMAL

45. 1. Hypothalamus tells
pituitary to release
hGH
2. hGH signals liver to
release stored glucose
3. Higher glucose level
signals hypothalamus that
homeostasis is restored

46. • Negative Feedback Control
–When homeostasis is disrupted the
regulation of the endocrine system is
controlled most often through one type
of internal feedback mechanism called a
negative feedback system
–In this system the hormones, or their effects,
are fed back to inhibit the original signal
(normal signal)
–Once homeostasis is reached, the signal is
stopped & the hormone is no longer released

47. • Feedback Control of Hormones
–The majority of endocrine glands operate
under negative feedback systems
–Information regarding the hormone level
or its effect on target cells is “fed back” to
the hypothalamus or pituitary gland to
regulate the production of the hormone

48. • Control of Blood Glucose Levels (sugar)
– When you have just eaten & your blood glucose
levels are high, your pancreas releases the
hormone insulin
– Insulin signals liver & muscle cells to take in
glucose, thus lowering blood glucose level
– When blood glucose levels become too low, the
pancreas releases the hormone glucagon
– Glucagon binds to liver cells, signaling the release
of stored glucose

49. Glucose Feedback Loop
Blood Glucose Blood Glucose
HIGH LOW
Glucagon
release
secretesecrete
Insulin
pancreas
liver
Glucose
Target tissue
Glucose
stimulates
stimulates
stim
ulates
absorption
absorption

50. • Hormone Action
2 Basic types of Hormones:
1. Steroid hormones = made from lipids
(fats)
• Diffuse freely into cells thru the plasma
membrane
• Then travel to the cell nucleus where thy
activate the production of mRNA
• mRNA then produces the required proteins

51. Steroid Hormones

52. 2. Amino Acid hormones = made from
amino acids
–Don’t diffuse easily through the plasma
membrane
–Must bind to receptors in the plasma
membrane of target cells to enter the cell
–Once inside they activate enzymes which
will alter the behavior of other molecules
in the cell

53. Amino Acid Hormones

54. • Adrenal Hormones and Stress
–Adrenal glands play an important role in
preparing your body for stressful
situations.
•Adrenal glands are located on top of the
kidneys and consist of two parts
–1. Outer Portion: secretes steroid hormones
that help the body combat stresses by raising
blood pressure
» Ex: fright, temperature extremes, bleeding,
infection, even test anxiety

55. – 2. Inner Portion: secretes two amino acid
hormones
• Epinephrine (sometimes called “adrenaline”) &
Nonepinephrine
» These hormones increase heart rate, blood pressure, &
rate of respiration
» They increase efficiency of muscle contraction &
increase blood sugar levels
* You may have experienced these symptoms if
you have ever had to perform in front of a large
audience and had an “adrenaline rush”

56. • Thyroid and Parathyroid Hormones
– The Thyroid Gland:
– Located in the neck
– Regulates metabolism, growth, and development
– Main metabolic & growth hormone of the thyroid is
thyroxine
» Thyroxine affects the rate at which the body uses
energy and determines your food intake requirements
– Thryroid also secretes calcitonin
» Calcitonin regulates calcium levels in the blood by
causing an increase in the release of calcium when
necessary

57. –The Parathyroid Hormones
•Parathyroid glands: are attached to
the thyroid gland and are involved
in mineral regulation
–Ex: they regulate the absorption of
calcium, phosphate, magnesium, etc.

58. * Hormones that are associated with the
endocrine system are responsible for
controlling many different functions in your
body.
* Different hormones may play more
important roles during some periods in your
life than others.