HNSC 1210 Ch. 3: The Remarkable Body

What do cells need to do work?

Energy, oxygen, water and nutrients

What do genes affect?

Affect how nutrients are handled

What does body fluid supply to?

Tissues

Purpose and path of blood

Carries water-soluble nutrients; goes from small intestine -> liver -> heart

Purpose and path of lymph

Carries fat-soluble nutrients; goes from small intestine via the lymphatic system -> thoracic duct where lymph enters bloodstream near the heart

Arteries

Carry oxygen and nutrients to the tissues

How does blood circulate?

By capillaries

Where does blood return to?

Returns to the heart via veins

How is carbon dioxide removed?

By the lungs in exchange for oxygen

Where does bllod circulate to when removing waste?

Kidneys; filtered by nephrons

Where is waste excreted in?

Urine

Regulation

The communication between organs and cells

Hormones

Chemical messengers

How is blood glucose regulated?

Insulin - takes excess glucose from blood

Glucagon - tells liver to break down glycogen into glucose

How does the nervous system tell you you're hungry?

Hypothalamus - keeps track of nutrients and water in the body

Cortex - receives sensation of hunger

What is the combination of hormone and nervous system during fight or flight reaction?

Epinephrine (hormone) and body responses/movements -metabolism speeds up, pupils dilate, muscles tense up

Digestion

The breakdown of nutrients into their smallest subunits for absorption into the body

What are carbs, proteins, and fats after being broken down?

Carbs - glucose

Protein - amino acids

Fat - fatty acids

These subunits are what gets absorbed to use for synthesis

What body parts does digestion consist of?

1. Mouth

2. Esophagus

3. Stomach

4. Small intestine

5. Large intestine

6. Rectum

Purpose of mouth

Taste buds guide food acceptability, chew, and mix food with saliva

Purpose of esophagus

Passes food to the stomach via peristalsis (wave-like muscular squeezing along digestive tract)

Purpose of stomach

Churns and mixes food to a liquid mass called chyme

Layers of muscle in the stomach

Inner, middle, and outer

What is movement of food controlled by?

Cardiac sphincter - opening into the stomach; also prevents stomach contents from seeping back into the esophagus

Pyloric valve - opening into the small intestine

What is the gastric juice made up of?

Hydrochloric acid, enzymes and fluid

Gastric Juice

pH of 2, denatures protein, kills microorganisms and mucus protects the stomach wall

Heartburn

Burning sensation in the chest caused by backflow of stomach acid into the esophagus

Temporary heartburn relief

Antacids

Prevention/reduction of heartburn

- Eat smaller meals

- Do not drink liquid with food, do it before or after the meal

- Wear loose fitting clothing

- Do not lie down after eating

- Avoid smoking

Major site of digestion

Small intestine

Length of small intestine

20 feet long with large absorption area

Pancreas do what when hormones are released?

Secrete bicarbonate that neutralizes acidic contents from the stomach

Enzymes (from pancreas) and small intestine digest what?

CHO, protein and fat

Bile purpose

Emulsifies fat to assist digestion

Absorption

Movement of nutrients from small intestine; into the blood or the lymph

How is the environment of absorption?

Large absorptive area created by folds of villi and smaller projections of microvilli

When is absorption completed?

Before intestinal contents reaches the colon

Where is fibre in absorption?

Fibre stays in small intestine and passes into the large intestine (colon)

Purpose of large intestine (colon)

Reabsorbs water and minerals, passes waste and some water to rectum (fibre, bacteria, any unabsorbed nutrients)

Purpose of rectum

Stores wastes as feces prior to elimination

Tim in small intestine

7-8 hours

Time in large intestine

12-14 hours

Problem in the lower gut

Diarrhea, constipation, and food and intestinal gas

Where are energy-containing nutrients stored?

- Fat - fat cells or adipose tissue - large amounts and no limits

- CHO - as glycogen in liver and muscle - smaller amounts and limited

- Other nutrients - other tissues

Alcohol effects

Acts as a lipid solvents and easily penetrate cell's outer lipid membrane - denatures cell's protein structure

Clories in alcohol

7cal/g - not a nutrient but provide energy

What happens when alcohol enters the body?

- Diffuses through the stomach wall into bloodstream (food delays diffusion and stomach emptying)

- Vomiting protects against high dose of toxin - body's defense mechanism

- Absorbed rapidly in small intestine

Physical effects of alcohol

- Increase urine output

- Mineral loss

- Slow drinker = alcohol collected by the liver and processed

- Rapid drinker = some alcohol flows through the rest of the body and brain

Alcohol and the brain

- Depressant: reducing functional or nervous activity

- Brain cells are sensitive to excessive alcohol exposure

- "Passing out" helps protect against consumption of lethal dose

- Sedates nervous cells - judgement and reasoning; voluntary muscle control; respiration and heart action

What does the liver do with alcohol?

Detoxify (metabolizes) - major organ for toxifying alcohol

Do females have less or more ADH?

Less

Percentage breakdown of alcohol in liver

80% alcohol dehydrogenase (ADH)

10% microsomal ethanol oxidizing (MEOS system)

10% excreted through breath and urine

Alcohol dehydrogenase (ADH)

Removes hydrogen

Microsomal Ethanol Oxidizing (MEOS system)

Exchange of enzymes that oxidize alcohol and breaks it down

Alcohol stimulates what in the liver?

Fat synthesis - acutely and chronically

Liver deterioration

Fatty liver -> fibrosis (scar tissue) -> cirrhosis (loss of function) -> once hardened -> liver transplant (only cure)

Length for the body to metabolize one alcoholic drink

1.5 hours

Hangover

- Toxic effects of congeners - other substances in alcoholic beverages

- Dehydration and rehydration of the brain

- Accumulation of formaldehyde

Formaldehyde produced from

The breakdown of ethanol

Long-term effects of alcohol (7)

- Amino acid metabolism in liver cells

- Synthesis of blood lipids increase - interferes with uric acid

- Toxic to muscle

- Increased blood pressure

- Dementia - due to damage in brain cells

- Increased risk of cancer

- Increase risk of death in younger people

How does alcohol lead to malnutrition?

- Inadequate food intake

- Impaired nutrient absorption and metabolism

- Thiamin deficiency - nerve impairment (Wernicke-Korsakoff syndrome)

Alcohol as calories and a nutrient

Provides empty calories and displaces nutrients

Health effects of wine

- High potassium may lower high blood pressure

- Antioxidant properties - may protect against events thought to trigger heart disease

- Dealcoholized wine all contains similar phytochemicals without potential dangers of alcohol

Alcohol effects on appetite

- Reduces appetite

- Small doses of wine may improve appetite for elderly individuals

- Improves muscle, morale and stimulates social interaction