anatomy

How long do carbohydrates stay in the stomach?

About 1–2 hours

How long do proteins stay in the stomach?

About 2–4 hours

How long do fats (lipids) stay in the stomach?

About 4–6 hours

Function of carbohydrates

Main quick source of energy

Function of lipids (fats)

Long-term energy storage, insulation, part of cell membranes

Function of proteins

Build and repair tissues; form enzymes and hormones

Calories per gram of carbohydrates

4 kcal per gram

Calories per gram of lipids

9 kcal per gram

Calories per gram of proteins

4 kcal per gram

Functions of the respiratory system

Gas exchange (O2 in, CO2 out), regulates pH, sound production, smell

Pharynx

Throat; passageway for air and food

Larynx

Voice box; produces sound and keeps airway open

Trachea

Windpipe; carries air to lungs

Epiglottis

Flap that prevents food from entering airway

Nasopharynx

Upper part behind nose; air only

Oropharynx

Middle part behind mouth; air and food

Laryngopharynx

Lower part; leads to larynx and esophagus

Right lung

3 lobes; larger

Left lung

2 lobes; smaller due to heart

Visceral pleura

Covers the lungs

Parietal pleura

Lines the chest wall

Pleural fluid

Reduces friction between pleura layers

External respiration

Gas exchange between alveoli and blood (O2 in, CO2 out)

What happens during inspiration?

Diaphragm contracts and flattens; intercostals contract; chest expands

Tidal volume (TV)

Normal breathing air (~500 mL)

Inspiratory reserve volume (IRV)

Extra air inhaled after normal breath

Expiratory reserve volume (ERV)

Extra air exhaled after normal breath

Residual volume (RV)

Air remaining after maximum exhale

Functional residual capacity (FRC)

the amount of air that reaches respiratory zone 350ml

Inspiration

Breathing in; active process

Expiration

Breathing out; usually passive

Pleurisy

Inflammation of pleura causing painful breathing

Atelectasis

Collapse of lung or alveoli

Chronic bronchitis

Inflamed bronchi with excess mucus

Emphysema

Damage to alveoli reducing gas exchange

Where does gas exchange occur?

In the alveoli

Main functions of the digestive system

break down food and absorb nutrients

Alimentary canal

Continuous, coiled, hollow tube of the digestive system

Ingestion

Taking food into the mouth

Propulsion

Movement of food through the digestive tract (alimentary canal )

Absorption

Passage of nutrients into blood or lymph

Defecation

Elimination of indigestible waste

Mechanical digestion

Physical breakdown of food (chewing, churning); occurs in mouth and stomach

Chemical digestion

Breakdown of food using enzymes; occurs in mouth, stomach, and small intestine

Bile

Substance that destroys fats; produced by liver and stored in gallbladder

Epiglottis

Cartilage flap that ensures food enters esophagus, not the airway

Peristalsis

Wave-like contractions that move food through the digestive tract

Parotid glands

Salivary glands located near the ears

Submandibular glands

Salivary glands located under the jaw

Sublingual glands

Salivary glands located under the tongue

Where are digestive enzymes secreted?

Mouth, stomach, and small intestine

Rugae of mucosa

Folds in stomach lining that allow expansion and increase surface area

Digestion in the stomach

Both mechanical (churning) and chemical (enzymes and acid)

Lower esophageal (cardiac) sphincter

Prevents acid reflux into esophagus

Pyloric sphincter

Controls movement of food from stomach to small intestine

Function of the small intestine

Most digestion and absorption of nutrients

Duodenum

First part of small intestine; receives bile and digestive enzymes

Jejunum

Middle section; primary site of nutrient absorption

Ileum

Last section; connects to large intestine

Function of the large intestine

Absorbs water and forms feces

Order of the alimentary canal

Mouth → Pharynx → Esophagus → Stomach → Small intestine → Large intestine → Rectum → Anus

Small intestine vs large intestine

Small intestine: longer (~20 ft), smaller diameter; Large intestine: shorter (~5 ft), larger diameter