5/31 – 6/3
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5/31 – 6/3. Chemical senses Web Quest Digestive system begin lecture HW: parts of dissection mini-packet (whatever is not completed in class). The Digestive System and Body Metabolism. Digestion Breakdown of ingested food Absorption of nutrients into the blood Metabolism - PowerPoint PPT PresentationTRANSCRIPT
Chemical senses Web Quest Digestive system begin lecture HW: parts of dissection mini-packet
(whatever is not completed in class)
Digestion› Breakdown of ingested food› Absorption of nutrients into the
blood Metabolism
› Production of cellular energy (ATP)
› Building and breaking down cellular activities
Two main groups› Alimentary canal – continuous coiled
hollow tube In adults, the alimentary canal is about 30 feet long.
Other names for the alimentary canal include the gastrointestinal (GI) tract, digestive tract, alimentary tract
› Accessory digestive organs
Figure 14.1
Mouth Pharynx Esophagus Stomach Small intestine Large intestine Anus
Lips – protect the anterior opening
Cheeks – form the lateral walls› Keep food in mouth
Hard palate – forms the anterior roof
Soft palate – forms the posterior roof› Keeps food out of nasal passage
Uvula – fleshy projection of the soft palate. Helps you not to choke on food
Figure 14.2a
Vestibule – space between lips externally and teeth and gums internally
Oral cavity – area contained by the teeth
Tongue – strong muscle which mixes & moves food in the correct direction
Figure 14.2a
Mastication (chewing) of food Mixing masticated food with saliva Initiation of swallowing by the
tongue Allowing for the sense of taste
Figure 14.2a
Serves as a passageway for air and food
Food is propelled to the esophagus by two muscle layers
Food movement is by alternating contractions of the muscle layers (peristalsis)
Runs from pharynx to stomach through the diaphragm
Conducts food by peristalsis (slow rhythmic squeezing)
Passageway for food only (respiratory system branches off after the pharynx)
Located on the left side of the abdominal cavity
Food enters at the cardioesophageal sphincter
Food empties into the small intestine at the pyloric sphincter
Rugae – internal folds of the mucosa
Acts as a storage tank for food Churns food into a paste called
chyme. Chemical breakdown of protein
begins
Simple columnar epithelium› Mucous neck cells – produce a sticky
alkaline mucus› Gastric glands – secrete gastric juice› Chief cells – produce protein-
digesting enzymes (pepsinogens)› Parietal cells – produce hydrochloric
acid› Endocrine cells – produce gastrin
Gastric pits formed by folded mucosa
Glands and specialized cells are in the gastric gland region
The body’s major digestive organ
Site of nutrient absorption into the blood
Suspended from the posterior abdominal wall by the mesentery (connective tissue sheet)
Duodenum› Attached to the stomach› Curves around the head of the
pancreas Don’t worry about the other 2
Bile enters from the gall bladder- breaks down lipids
Fingerlike structures
Give the small intestine more surface area-pull out more nutrients from food.
Figure 14.7a
Small projections of the plasma membrane
Found on absorptive cells
Figure 14.7c
Absorptive cells Blood capillaries
Figure 14.7b
Larger in diameter, but shorter than the small intestine
Frames the internal abdomen
Figure 14.8
Absorption of water Eliminates indigestible food from the
body as feces Does not participate in digestion of
food Goblet cells produce mucus to act as
a lubricant
Appendix› Accumulation of lymphatic tissue
that sometimes becomes inflamed (appendicitis)
Colon› Ascending› Transverse› Descending› S-shaped sigmoidal
Rectum Anus – external body opening
In class complete the following in the mini-packet› NOTE: YOU WILL BE JUMPING AROUND!
The human digestive tract pg 175 › DO NOT DO pg 176
Stomach and small intestine: both sides If you do not finish this it will become
homework If you have time color Overview of the
System- it is not required BUT if you do a nice job and complete the entire thing in colored pencil or crayon you can earn EC
Put packet into bin. You’ll get it back today for your HW
Finish digestion lecture (quick!) Final Dissection- digestive system HW: finish digestion mini-packet
Salivary glands Teeth Pancreas Liver Gall bladder
Saliva-producing glands› Parotid glands – located anterior to
ears Mixture of mucus and serous fluids Helps to form a food bolus Contains salivary amylase to begin
starch digestion Dissolves chemicals so they can be
tasted
The role is to masticate (chew) food Humans have two sets of teeth
› Deciduous (baby or milk) teeth› 20 teeth are fully formed by age
two
Permanent teeth› Replace deciduous teeth beginning
between the ages of 6 to 12› A full set is 32 teeth, but some
people do not have wisdom teeth
Incisors Canines Premolars Molars
Crown – exposed part› Outer enamel› Dentin› Pulp cavity
Neck› Region in contact
with the gum› Connects crown to
rootFigure 14.10
Root› Periodontal
membrane attached to the bone
› Root canal carrying blood vessels and nerves
Figure 14.10
Produces a wide spectrum of digestive enzymes that break down all categories of food
Enzymes are secreted into the duodenum
Alkaline fluid introduced with enzymes neutralizes acidic chyme
Largest gland in the body Located on the right side of the body
under the diaphragm Connected to the gall bladder via the
common hepatic duct Produces bile which breaks down
fats
Sac found in hollow of liver Stores bile from the liver & releases
in the presence of fatty food Gallstones can cause blockages and
PAIN
Ingestion – getting food into the mouth
Propulsion – moving foods from one region of the digestive system to another
Food must first be well mixed Rippling peristalsis occurs in the
lower stomach
Figure 14.15
The pylorus meters out chyme into the small intestine (30 ml at a time)
The stomach empties in four to six hours
Figure 14.15
Peristalsis – alternating waves of contraction down esophagus, large intestine
Segmentation – moving materials back and forth to aid in mixing, small intestine
Sluggish peristalsis Mass movements
› Slow, powerful movements› Occur three to four times per day
Presence of feces in the rectum causes a defecation reflex› Internal anal sphincter is relaxed› Defecation occurs with relaxation of the
voluntary (external) anal sphincter
Mechanical digestion› Mixing of food in the mouth by the
tongue› Churning of food in the stomach› Segmentation in the small
intestine
Chemical Digestion› Enzymes break down food molecules
into their building blocks› Each major food group uses different
enzymes Carbohydrates are broken to simple sugars
Proteins are broken to amino acids Fats are broken to fatty acids and alcohols
Absorption (diffusion of macromolecules)› End products of digestion are
absorbed in the blood Defecation
› Elimination of indigestible substances as feces
Figure 14.11
Digestive system & associated organs Check out the kidneys Check out reproductive if there is time Thank your pig, place you pig in the bag
and then in the garbage.
HW: finish mini-packet Thursday: pizza lab! FYI Juniors: you take your final with
seniors which is next week.