Human Body
Biology – Human Body
Table of Content:
Page 2 – Digestion and Nutrition
Page 8 – Metabolism
Page 11 – Nervous System
Page 16 – Muscles and the Skeletal System
Page 21 – Genetics
Page 23 – Ageing and Neoplasm
Page 27 – Immune Defences
Page 29 – Vaccination and Infection Control
, Human Body
Digestion and Nutrition
Digestive tract: Accessory organs:
• Mouth • Teeth
• Pharynx • Tongue
• Oesophagus • Salivary glands
• Stomach • Liver
• Small intestine • Gallbladder
• Large intestine • Pancreas
Layers:
• Mucosa
o Membrane of epithelium, lamina propria and
muscularis mucosae
o Secretion, absorption and folding
• Submucosa
o Binds mucosa to muscular layer
Mucosa
o Contains nerves network Submucosa
• Muscular layer Muscular Layer
Serosa
o Smooth muscle creates patterns of contraction
and relaxation
o Important for movement of substances
• Serosa
o Membrane allows attachment to abdominal walls
Function: Function steps:
• Supply the body with nutrients, 1. Ingestion
electrolytes and water I. Material enters digestive tract via mouth
2. Propulsion
• Supply of nutrients is dependent I. Movement of food along the GIT
on the food ingested 3. Mechanical breakdown
I. Easier to propel along tract
• GI tract optimises conditions for II. Increases surface area to allow easier breakdown
digestion and absorption 4. Chemical digestion
I. Chemical breakdown of food for absorption
• Ingested food broken down into II. Larger molecules broken down into small molecule
substrates available for cells 5. Absorption
I. Movement of substrates, electrolytes, vitamins and
water across epithelium into interstitial fluid
6. Defecation
I. Removal of indigestible waste products from the
body
Movement of substances: Autonomic nervous system:
• Peristalsis • Controls digestion via sympathetic and parasympathetic divisions
o Waves of muscular contraction • Acts on enteric nervous system in the digestive tract wall
o Circular muscles push forward • Parasympathetic divisions stimulates
o Longitudinal muscles shorten • Sympathetic division inhibits
o Propels substance forward at different
speeds Oral cavity:
• Segmentation • Tongue provides sensory analysis of material before swallowing
o Cycles of contraction • Mechanical processing - teeth, tongue and palatal surfaces
o Churn and fragment food • Lubrication - mixes food with mucus and saliva
o Mix food with intestinal secretions • Limited digestion
o Food comes in contact with absorptive o Mechanical processing and chemical digestion provide limits to
layer digestion. Salivary amylase and lingual lipase
, Human Body
Saliva: Oesophagus:
• Produce 1.0-1.5L of saliva per day • Hollow muscular tube
• Composed of 99.4% water • Conveys food or medications to stomach by peristalsis
o 0.6% IgA, lysozyme, • Pierces diaphragm through oesophageal hiatus
enzymes, buffers, mucins, • Upper and lower sphincters
electrolytes and waste. o Prevents air from entering the oesophagus
• Begins chemical digestion o Prevents reflux from the stomach
o Lubrication of mouth and • Deglutition
pharynx o Buccal phase: voluntary, bolus -> oropharynx
o Cleanse mouth and teeth o Buccal phase – upper oesophageal sphincter is contracted and tongue presses
o Moistening food against the palate, forces food into oropharynx
o Dissolve food and o Pharyngeal phase: involuntary, pharynx -> oesophagus -> stomach
chemicals o Pharyngeal phase: tongue blocks the mouth, palate and uvula rise closing the
nasopharynx, larynx rises so epiglottis blocks the trachea and food enters
oesophagus
Stomach: Breakdown in stomach:
• Muscularis • Mechanical breakdown
o 3 layers of smooth muscle o Mixing waves every 15-25 seconds
• Rugae o Forms chyme, chyme forms into
o Mucosal folds and gastric duodenum
• Mixing chamber • Chemical digestion
o Carbohydrate digestion o HCl unravels proteins
halts, protein digestion o Pepsinogen: HCl converts to pepsin
begins and fat digestion and hydrolyses peptide bonds
continues o Gastric lipase: hydrolyses
triglycerides
Stomach mucosa: Regulation of gastric activity:
Secretory glands form gastric glands which line • Involves CNS, ENS and hormones
gastric pits • 3 overlapping phases:
• Mucous cells o Cephalic phase – CNS and brain prepares stomach for food arrival
o Important for protection o Gastric phase – builds on cephalic phase, begins when food arrives in
o COX-1 pathway stomach
• Parietal cells o Intestinal phase – starts when chyme arrives in duodenum
o HCl • Cephalic phase
o Intrinsic factor o Sight, smell, taste or thought of food
• Chief cells o Prepares stomach for food arrival by increasing gastrin secretion
o Pepsinogen • Gastric phase
o Gastric lipase o Arrival of food into stomach
• G cells o Stretch receptors and chemoreceptors
o Gastrin hormone stimulates • Intestinal phase
parietal and chief cells to o Chyme enters duodenum (small intestine)
increase secretions and motility o Enhanced secretion of secretin (reduces gastric secretion), CCK (inhibits
gastric emptying) and GIP (inhibits gastric secretions)
o Slows exit of chyme from stomach
Hormonal control of food intake:
• Ghrelin
o Appetite stimulant, when body is ready for a meal
• Leptin
o Appetite suppressant secreted by adipose tissue
o Inhibits appetite stimulant NPY
• Insulin and CCK
o Released during food absorption
o Act as satiety signals to depress hunger
Biology – Human Body
Table of Content:
Page 2 – Digestion and Nutrition
Page 8 – Metabolism
Page 11 – Nervous System
Page 16 – Muscles and the Skeletal System
Page 21 – Genetics
Page 23 – Ageing and Neoplasm
Page 27 – Immune Defences
Page 29 – Vaccination and Infection Control
, Human Body
Digestion and Nutrition
Digestive tract: Accessory organs:
• Mouth • Teeth
• Pharynx • Tongue
• Oesophagus • Salivary glands
• Stomach • Liver
• Small intestine • Gallbladder
• Large intestine • Pancreas
Layers:
• Mucosa
o Membrane of epithelium, lamina propria and
muscularis mucosae
o Secretion, absorption and folding
• Submucosa
o Binds mucosa to muscular layer
Mucosa
o Contains nerves network Submucosa
• Muscular layer Muscular Layer
Serosa
o Smooth muscle creates patterns of contraction
and relaxation
o Important for movement of substances
• Serosa
o Membrane allows attachment to abdominal walls
Function: Function steps:
• Supply the body with nutrients, 1. Ingestion
electrolytes and water I. Material enters digestive tract via mouth
2. Propulsion
• Supply of nutrients is dependent I. Movement of food along the GIT
on the food ingested 3. Mechanical breakdown
I. Easier to propel along tract
• GI tract optimises conditions for II. Increases surface area to allow easier breakdown
digestion and absorption 4. Chemical digestion
I. Chemical breakdown of food for absorption
• Ingested food broken down into II. Larger molecules broken down into small molecule
substrates available for cells 5. Absorption
I. Movement of substrates, electrolytes, vitamins and
water across epithelium into interstitial fluid
6. Defecation
I. Removal of indigestible waste products from the
body
Movement of substances: Autonomic nervous system:
• Peristalsis • Controls digestion via sympathetic and parasympathetic divisions
o Waves of muscular contraction • Acts on enteric nervous system in the digestive tract wall
o Circular muscles push forward • Parasympathetic divisions stimulates
o Longitudinal muscles shorten • Sympathetic division inhibits
o Propels substance forward at different
speeds Oral cavity:
• Segmentation • Tongue provides sensory analysis of material before swallowing
o Cycles of contraction • Mechanical processing - teeth, tongue and palatal surfaces
o Churn and fragment food • Lubrication - mixes food with mucus and saliva
o Mix food with intestinal secretions • Limited digestion
o Food comes in contact with absorptive o Mechanical processing and chemical digestion provide limits to
layer digestion. Salivary amylase and lingual lipase
, Human Body
Saliva: Oesophagus:
• Produce 1.0-1.5L of saliva per day • Hollow muscular tube
• Composed of 99.4% water • Conveys food or medications to stomach by peristalsis
o 0.6% IgA, lysozyme, • Pierces diaphragm through oesophageal hiatus
enzymes, buffers, mucins, • Upper and lower sphincters
electrolytes and waste. o Prevents air from entering the oesophagus
• Begins chemical digestion o Prevents reflux from the stomach
o Lubrication of mouth and • Deglutition
pharynx o Buccal phase: voluntary, bolus -> oropharynx
o Cleanse mouth and teeth o Buccal phase – upper oesophageal sphincter is contracted and tongue presses
o Moistening food against the palate, forces food into oropharynx
o Dissolve food and o Pharyngeal phase: involuntary, pharynx -> oesophagus -> stomach
chemicals o Pharyngeal phase: tongue blocks the mouth, palate and uvula rise closing the
nasopharynx, larynx rises so epiglottis blocks the trachea and food enters
oesophagus
Stomach: Breakdown in stomach:
• Muscularis • Mechanical breakdown
o 3 layers of smooth muscle o Mixing waves every 15-25 seconds
• Rugae o Forms chyme, chyme forms into
o Mucosal folds and gastric duodenum
• Mixing chamber • Chemical digestion
o Carbohydrate digestion o HCl unravels proteins
halts, protein digestion o Pepsinogen: HCl converts to pepsin
begins and fat digestion and hydrolyses peptide bonds
continues o Gastric lipase: hydrolyses
triglycerides
Stomach mucosa: Regulation of gastric activity:
Secretory glands form gastric glands which line • Involves CNS, ENS and hormones
gastric pits • 3 overlapping phases:
• Mucous cells o Cephalic phase – CNS and brain prepares stomach for food arrival
o Important for protection o Gastric phase – builds on cephalic phase, begins when food arrives in
o COX-1 pathway stomach
• Parietal cells o Intestinal phase – starts when chyme arrives in duodenum
o HCl • Cephalic phase
o Intrinsic factor o Sight, smell, taste or thought of food
• Chief cells o Prepares stomach for food arrival by increasing gastrin secretion
o Pepsinogen • Gastric phase
o Gastric lipase o Arrival of food into stomach
• G cells o Stretch receptors and chemoreceptors
o Gastrin hormone stimulates • Intestinal phase
parietal and chief cells to o Chyme enters duodenum (small intestine)
increase secretions and motility o Enhanced secretion of secretin (reduces gastric secretion), CCK (inhibits
gastric emptying) and GIP (inhibits gastric secretions)
o Slows exit of chyme from stomach
Hormonal control of food intake:
• Ghrelin
o Appetite stimulant, when body is ready for a meal
• Leptin
o Appetite suppressant secreted by adipose tissue
o Inhibits appetite stimulant NPY
• Insulin and CCK
o Released during food absorption
o Act as satiety signals to depress hunger
