BI111 Lecture Notes - Lecture 12: Ct Scan, Punnett Square, Motility
Biology Exam review 2014 grade 11
Levels of organization of life-
Least complex → most complex:
1. Cells
2. Tissues
3. Organs
4. Organ systems
5. Organism
Tissue: a group of similar cells that perform the same function
• 4 types:
1. Epithelial: protective covering inside and outside of body
2. Connective: for support and structure
3. Muscle: responsible for movement
4. Nervous: communication between organ systems
Organ: structure that is composed of different kinds of tissue that performs a specific
job
Organ system: group of organs that work together to carry particular functions- there
are 11
CAT scan (computed Axial Tomography): outlines bone, soft tissue and blood vessels
inside the body (bone injuries, lung and chest, cancer detection)
MRI (Magnetic Resonance Imaging): soft tissue evaluation, structure and function
(ligament and tendon injury, spinal cord, brain tumors etc.) Does not use radiation like
CAT scan.
The Digestive system
Is the break down of large macromolecules into smaller molecules so that they
can be absorbed by the circulatory system and used by cells. Consists of:
4 steps to digestion
1. Ingestion- the taking in of nutrients
2. Digestion- the mechanical and chemical break down of food into
molecules
3. Absorption- the passing of the broken down molecules into the
bloodstream (mostly in small intestine)
4. Elimination- the removal of undigested food from the body
Processes:
o Mechanical / physical: involves chewing and breaking food into smaller
pieces and physical movement of food
o Chemical: involves enzymes to break food down into macromolecules
and nutrients
Pathway of food:
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1. Mouth (ingestion, digestion, mechanical and chemical)
• Mechanical digestion begins; teeth chew and break down food into
smaller particles so chemical digestion happens faster
• Chemical digestion begins; mouth secretes saliva containing…
o Mucus- keeps food moist
o Amylase (ENZYME): begins to break down starch
• Tongue pushes food to back of mouth, going down the pharynx. Next,
the tong blocks the mouth, the soft palate closes off the nose and the
epiglottis closes over the trachea
2. Esophagus
• Swallowing reflex moves the bolus down the esophagus. Bolus is
moved to the stomach by peristalsis.
o Peristalsis: are rhythmic smooth muscle contractions; food is
slowly propelled down the esophagus
• Cardiac sphincter lets food into the stomach and it controls the
amount
3. Stomach (digestion, mechanical and chemical)
• Cardiac sphincter: controls movement of bolus into the stomach and
prevents stomach acid fro re-entering the esophagus
• Salivary amylase: swallowed from mouth, continues to digest starch
(carbs) until the pH gets to low (AMYLASE DOES NOT FUNCTION AT
LOW PH LEVELS)
• Mechanically the stomach churns, contracts together to mix and
separate the food into pieces
• Glands in the stomach secrete gastric juice (chemical) containing
o Hydrochloric acid (HCl): has a pH at 1-3, helps digestion.
LOW PH ALO KILLS PATHOGENS
▪ Stomach lining is protected by a regenerating coating
mucous
o Pepsin: HCl converts pepsinogen into pepsin
▪ Pepsin digests proteins (proteins → polypeptides)
▪ Senses can increase the production/ secretion of these
gastric juices
▪ Carbs and fats are broken down
▪ If its too acidic enzymes will not function
• Partially digested liquid food is a chyme
4. Small intestine (digestion, chemical, absorption)
• The pyloric sphincter regulates movement of chyme into the small
intestine in small amounts
• Divided into 3 sections:
o Duodenum: digestion of proteins and carbs, digestion of fat
begins
o Jejunum
o Ileum
• Organs:
o Liver: produces bile to dissolve fats
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o Gall bladder: stores bile until needed. A common bile duct
connects the liver and gall bladder to the duodenum to release
bile into small intestine
o Pancreas: produces pancreatic juices which is released in the
duodenum in the pancreatic duct
▪ When HCl enters the small intestine, prosecretin is
converted to secretin (HCl + prosecretin= secretin)
• Secretin is absorbed in blood and signals
pancreas to make bicarbonate ions. These ions
neutralize chyme, leaving the small intestine
basic. This is how small intestine is protected
from acids- pepsin is inactivated because it is
basic
o Then, trypsinogen + enterokinase= trypsin
▪ Trypsin breaks down long polypeptides into shorter
chains (peptides)
o Then, erepsin is released to break down the peptides into
amino acids
o Amylase is released to complete carbohydrate digestion
o Lipases are enzymes released to break down fats into glycerol
and fatty acids
o Inner walls of intestine are covered small projections called
villi and these are covered with even thinner projections
called microvilli. The villi is extended into the small intestine
which increases surface area for absorption
o Liver: filters (removes) toxins and it stores bile until needed
o CCK (cholecystokinin): a hormone is released in the small
intestine when fats enter the small intestine to the duodenum
to release bile
▪ CCK is absorbed into the blood and carried to the gall
bladder in order to signal the release of bile salts
5. Large intestine
• Ileocaecal valve prevents waste products from re-entering the small
intestine.
o Water and minerals are absorbed from undigested food
o Bacteria helps to further the breakdown of undigested food
o Organs:
▪ Ascending colon
▪ Transverse colon
▪ Descending colon
6. Rectum and anus (elimination)
• Rectum stores waste which is then expelled
LIVER FUNCTIONS
Synthesis
→ Produces bile salts that are made in the gall bladder and
the emulsify fats breaking them into smaller droplets
→Makes blood protein from amino acids, found in blood
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Document Summary
Least complex most complex: cells, tissues, organs, organ systems, organism. Tissue: a group of similar cells that perform the same function: 4 types, epithelial: protective covering inside and outside of body, connective: for support and structure, muscle: responsible for movement, nervous: communication between organ systems. Organ: structure that is composed of different kinds of tissue that performs a specific job. Organ system: group of organs that work together to carry particular functions- there are 11. Cat scan (computed axial tomography): outlines bone, soft tissue and blood vessels inside the body (bone injuries, lung and chest, cancer detection) Mri (magnetic resonance imaging): soft tissue evaluation, structure and function (ligament and tendon injury, spinal cord, brain tumors etc. ) Is the break down of large macromolecules into smaller molecules so that they can be absorbed by the circulatory system and used by cells.