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Biology II – BIO 51

WELCOME TO BIOLOGY II

Course Outline
Topics:
1
...
Urinary
3
...
Reproductive
5
...
Muscular
7
...
Immunity

Week 1
▪ The Digestive system

Functions of the Digestive System
Five major functions:
1
...


Propulsion (propel food)
• food must be moved from one organ to the next for processing

Functions of the Digestive System
Five major functions:
3
...


*Absorption• movement of chemically digested food molecules into
blood

5
...


Alimentary canal
• continuos coiled hollow tube
• a
...
a gastrointestinal (GI) tract
...

• Connected to Alimentary Canal
• assisted int he function of digestion

Organs of the Alimentary Canal

mouth
pharynx
esophagus

stomach
large intestines
small intestines
rectum
anus

Accessory Digestive Organs
salivary gland
teeth

liver
gall bladder
pancreas

Mouth (Oral Cavity) Anatomy

▪ Lips (labia) – protect anterior opening

▪ Cheeks – form lateral walls

▪ Hard palate – forms anterior roof

▪ Soft palate – forms posterior roof

▪ Uvula – fleshy projection of soft palate

Mouth (Oral Cavity) Anatomy
▪ Vestibule – space between lips and
teeth/gums internally
▪ Oral cavity – area contained by teeth

▪ Tongue – attached
to skull

Figure 14
...
Palatine tonsils

3
...
Lingual tonsil
• back of tongue

• (adenoid)- roof of
nasopharynx

4
...
at opening of auditory tubes
into pharynx

* serves defense function*

Mouth (Oral Cavity) Anatomy

Functions of the Mouth
1
...
Swallowing (propulsion)
3
...
Chemical digestion
▪

saliva contains salivary amylase which begins digestion
of starch
4
...
Buccal Phase
2
...
Buccal phase
▪ Voluntary
▪ Occurs in mouth
▪ Food is formed into bolus (using teeth,
tongue and saliva)
▪ bolus(ball of food) is forced towards
pharynx by tongue(wave like movement)

Swallowing
2
...
Pharyngeal-esophageal phase (continued)
▪
▪

Peristalsis moves bolus toward stomach
Cardioesophageal sphincter(circular muscle) is
opened when food presses against it

Swallowing

Figure 14
...
4a

Lining of the Stomach

gastric pit

gastric gland

Figure 14
...
Enzymes
2
...
Gastrin (hormone that stimulates stomach to
secrete hydrochloric acid)

• stomach lining also produces mucous to protect
stomach wall from gastric juice(acid like substance)

Stomach Functions
1
...
Mechanical breakdown by churning of 3 layers
of muscles(turning bolus into liquid)
3
...
Delivers chyme (processed food (bolus mixed
with gastric juice)) to small intestine

Propulsion in the Stomach
▪ Food must first be well mixed
▪ Rippling peristalsis occurs in lower stomach

Figure 14
...
15

Organs of the Alimentary Canal
▪ Mouth
▪ Pharynx
▪ Esophagus
▪ Stomach
▪ Small intestine
▪ Large intestine
▪ Anus

Small Intestine
▪ The body’s major digestive organ
▪ Muscular tube extending from pyloric sphincter to
ileocecal valve
▪ Food moved by peristalsis

Subdivisions of the Small Intestine
Duodenum
- attached to stomach
- curves around the head of pancreas

Jejunum
- 2nd part, starts at duodenum and ends at ileum
Ileum
- 3rd part extends from jejunum to large intestine

Subdivisions of the Small Intestine

Duodenum
Jejunum
Ileum

pancreas

Anatomy of the Small Intestine
▪ Fingerlike structures on folds of inside
intestines called villi on mucosa
▪ Give small intestine more surface area to absorb more
food

Figure 14
...
Chemical Digestion

2
...
enzymes from intestinal (wall) cells
2
...
bile from gall bladder

Function of the Small Intestine

Figure 14
...
Cecum
▪ saclike first part
2
...
Colon
▪ Ascending(up)
▪ Transverse(across)
▪ Descending(down)
▪ Sigmoid (s-shaped)
4
...
Anus
▪
▪

external body opening
Has two sphincters:
1
...
voluntary external anal sphincter

Large Intestine
traverse colon

ascending colon

descending
colon

ileocecal valve

cecum
appendix

sigmoid colon
anus

rectum
Figure 14
...


2
...


Parotid glands

▪ located anterior to ears
Submandibular glands
Sublingual glands

▪ Both empty into floor of mouth

Salivary Glands

Saliva
▪ Mixture of mucous and serous fluids
▪ Helps form a food bolus
▪ Contains salivary amylase to begin starch
digestion
▪ Dissolves chemicals so they cab be tasted

Teeth
▪ role is to masticate (chew) food
Humans have two sets of teeth:
1
...


Permanent teeth
• replace deciduous teeth between the ages of 6 to 12
• a full set is 32 teeth

Classification of Teeth
canines
(tear)

incisors
(cut)

canines
(tear)
premolars
(tear &grind)

premolars
(tear &grind)
molars
(grind)

molars
(grind)
wisdom teeth

-deciduous teeth include incisors, canines and pre molars
...
Lipase- digest lipids
2
...
Amylase- digest carbohydrates
4
...
Main pancreatic duct- joins with a duct that
comes out of the liver to form the Hepatopancreatic
ampulla
▪2
...


Pancreas

Liver
▪ largest gland in body
▪ located on right side of body under diaphragm
▪ connected to gal bladder
▪ hepa=liver

Liver
liver
gall
bladder

Role of the Liver
Several roles in digestion:
▪
▪
▪
▪
▪

produces bile(from liver) that helps lipase(from pancreas) in lipid digestion
detoxifies drugs and alcohol
degrades hormones
produce cholesterol, blood proteins
plays a central role in metabolism

Liver
Hepatic Ducts
1
...
Common hepatic duct
▪ formed by joining of right and left hepatic ducts
3
...
Hepatopancreatic duct
▪ empties bile and pancreatic enzymes into
duodenum

Liver

Gall Bladder
▪ located under liver on right side
▪ stores bile from the liver by way of Cystic duct
▪ bile is introduced into duodenum when fatty
food is there

Liver

Aging and the Digestive System
▪ Metabolism decreases with old age
▪ Middle age digestive problems
▪ ulcers
▪ gall bladder problems
▪ Activity of digestive tract in old age
▪ fewer digestive juices
▪ peristalsis slows
▪ Cancer is more common

Assignments
Text book reading:
chapter 14
pg

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