Body Organization
• Cells form Tissues • Tissues form Organs • Organs form Systems (e.g., digestive)
Cell Processes
• Constant turnover of substances • Require energy to continue to function • Require nutrients
Cell
Cell Membrane
Cell Membrane
• Double layer of lipid, carbohydrate, and protein • Controls passage of substances • Contains distinct identification structures
Organelles
• Cytoplasm • Mitochondria---Power plant
– Major site for energy production
• Endoplasmic reticulum---Communication
network – Rough endoplasmic reticulum - protein synthesis – Smooth endoplasmic reticulum - fat synthesis
Organelles
• Golgi Complex
– Packaging site for protein
• Lysosomes
– Cell’s digestive system
• Peroxisomes
– Detoxify harmful chemicals
Nucleus
• Double membrane • Genetic material DNA • DNA directs protein synthesis and cell division
DNA
Genetics
• • • • • • • Human Genome Project Cardiovascular disease Hypertension Obesity Diabetes Cancer Osteoporosis
Four Types of Tissues
• Epithelial
– Lines the outside surfaces and external passages
• Connective
– Holds structures together
• Muscle
– Contracts to cause movement
• Nervous
– Transports nerve impulses
Body Systems Work Together
Cardiovascular and Lymphatic Systems
• • • • • Heart and blood vessels Blood Pulmonary circulation Systemic circuit Lymphatic system
Cardiovascular System
Capillary and Lymph Vessels
Portal Circulation
• Transports water soluble nutrients • From the small intestine • Delivers to the liver
Blood Circulation
Lymphatic System
• Contains lymph • Immune cells • Passage for large particles • Empties into veins leading to the heart
Nervous System
• Regulatory system • Central Nervous System – Brain and the spinal cord • Peripheral Nervous System – Branches out to organs • Basic unit is Neuron – Responds to electrical and chemical signals
Sending Signals
• Change in sodium and potassium concentration • Neurotransmitter
– Secretion of dopamine, epinephrine, and norepinephrine
• Dependent on nutrient supply
Endocrine System
• • • • • Secretes regulatory substances (hormones) Target cells with receptor proteins Body’s messenger Insulin Estrogen
Immune System
Immune System-- The Skin
• Continuous barrier • Effects of nutritional deficiencies are clearly seen • Lysozyme
Immune System--The Intestinal Cells
• • • • Barrier to invading microbes Immunoglobulins Muscosal membrane Effects of nutritional deficiency are clearly seen
Immune System--White Blood Cells
• Attack microorganism • Phagocytes • Cell-mediated immunity
– Antibodies – Antibody-antigen response – Template (memory) made
The Digestive System
The Mouth
• Mastication • Taste • Saliva
– Solvent – Enzymes – Mucus
The Esophagus
• • • • Long tube Epiglottis Peristalsis Lower esophageal sphincter
The Stomach
• • • • • • Sphincters Expands and contracts as needed Gastric juices Holding ―tank‖ Formation of chyme Prevention of autodigestion
Physiology of the Stomach
Stomach Acid
• • • • • Destroys activity of protein Activates digestive enzymes Partially digests dietary protein Assists in calcium absorption Makes dietary minerals soluble for absorption
The Small Intestine
• • • • • Approximately 10 feet long Folded walls Villi Absorptive cells Rapid cell turnover
The Small Intestine
Nutrient Absorption
• • • • Passive diffusion Facilitated diffusion Active absorption Phagocytosis and pinocytosis
Nutrient Absorption
The Large Intestine
• • • • Indigestible food stuff No villi or enzymes Mucus-producing cells Absorption of water, some minerals, vitamins • Bacteria • Elimination
Rectum
• • • • Stool Elimination Muscle contraction Anal sphincters
Peristalsis
Accessory Organs
• Pancreas • Gallbladder • Liver
The Liver
• Bile • Enterohepatic circulation
The Pancreas
• Digestive enzymes • Hormones
– Glucagon and insulin
• Pancreatic juices
– Bicarbonate
The Urinary System
• • • • • • Kidneys Ureter Bladder Urethra Waste products Blood acid-base balance (pH)
Storage Capabilities
• • • • • Maintaining reserves Adipose tissue Glucose Amino acids Vitamins and minerals
– Calcium in bones
Common GI Tract Problems
Ulcers
Heartburn
• Gastroesophageal reflux disease (GERD)
Constipation
• Difficult or infrequent evacuation • Causes
– Ignoring normal urges – Muscle spasms – Certain medications
• Treatment
– Fiber – Avoid dehydration – Regular physical activity
Laxatives
• Irritate the intestinal nerve • Draw water into the intestine • Regular use is harmful
Hemorrhoids (piles)
• Swollen veins of the rectum and anus • Intense pressure and straining • Dietary recommendation:
– Fiber and fluid
Irritable Bowel Syndrome
• Symptoms
– Cramps, bloating, increased frequency, diarrhea, constipation
• Causes
– Altered intestinal peristalsis – Decrease pain threshold
• Individualized treatment
– Moderate caffeine – Low-fat, small, frequent meals – Stress reduction
Diarrhea
• Fluidity and frequency • Causes
– Infections – Poorly absorbed substances
• Treatment:
– Plenty of fluid until subsides
Gallstones
• •
•
Major cause of illness and surgery Solid material in the gallbladder—primarily cholesterol
Excess body weight a risk. especially in women.
• •
•
Lead to pain in the upper abdomen and bloating Surgical removal of the gallbladder most common
Prevention of gallstones: avoid overweight, limit animal protein, high fiber diet, regular physical activity