Digestive System Overview

The digestive system is a complex process by which the body breaks down and absorbs nutrients from food.

Mouth:
- Mechanical digestion: teeth break down food into smaller pieces
- Chemical digestion: salivary enzymes break down carbohydrates
Esophagus:
- Muscular tube that transports food to the stomach
- Peristalsis: wave-like muscle contractions that move food through the esophagus
Stomach:
- Mechanical digestion: stomach muscles mix food with stomach acid and enzymes
- Chemical digestion: stomach acid and enzymes break down proteins and fats
Small Intestine:
- Absorption: nutrients are absorbed into the bloodstream through the walls of the small intestine
- Chemical digestion: enzymes from the pancreas and bile from the liver break down carbohydrates, proteins, and fats
Liver:
- Produces bile, which helps break down fats
- Filters toxins from the blood
Pancreas:
- Produces enzymes that break down carbohydrates, proteins, and fats
- Produces hormones that regulate blood sugar levels
Large Intestine:
- Absorption: water and electrolytes are absorbed into the bloodstream
- Elimination: waste products are prepared for elimination from the body
Rectum:
- Stores waste products until they are eliminated from the body
Anus:
- Elimination: waste products are eliminated from the body through the anus

Ingestion: food is taken into the mouth
Mechanical digestion: food is broken down into smaller pieces by teeth and tongue
Chemical digestion: salivary enzymes break down carbohydrates in the mouth
Swallowing: food is swallowed and passes through the esophagus into the stomach
Gastric digestion: stomach acid and enzymes break down proteins and fats in the stomach
Small intestine: nutrients are absorbed into the bloodstream and chemical digestion continues
Large intestine: water and electrolytes are absorbed, and waste products are prepared for elimination
Elimination: waste products are eliminated from the body through the anus

Mouth
- Mechanical digestion: teeth break down food into smaller pieces
- Chemical digestion: salivary enzymes break down carbohydrates
Esophagus
- Muscular tube that transports food to the stomach
- Peristalsis: wave-like muscle contractions that move food through the esophagus
Stomach
- Mechanical digestion: stomach muscles mix food with stomach acid and enzymes
- Chemical digestion: stomach acid and enzymes break down proteins and fats
Small Intestine
- Absorption: nutrients are absorbed into the bloodstream through the walls of the small intestine
- Chemical digestion: enzymes from the pancreas and bile from the liver break down carbohydrates, proteins, and fats
Liver
- Produces bile, which helps break down fats
- Filters toxins from the blood
Pancreas
- Produces enzymes that break down carbohydrates, proteins, and fats
- Produces hormones that regulate blood sugar levels
Large Intestine
- Absorption: water and electrolytes are absorbed into the bloodstream
- Elimination: waste products are prepared for elimination from the body
Rectum
- Stores waste products until they are eliminated from the body
Anus
- Elimination: waste products are eliminated from the body through the anus

Ingestion: food is taken into the mouth
Mechanical digestion: food is broken down into smaller pieces by teeth and tongue
Chemical digestion: salivary enzymes break down carbohydrates in the mouth
Swallowing: food is swallowed and passes through the esophagus into the stomach
Gastric digestion: stomach acid and enzymes break down proteins and fats in the stomach
Small intestine: nutrients are absorbed into the bloodstream and chemical digestion continues
Large intestine: water and electrolytes are absorbed, and waste products are prepared for elimination
Elimination: waste products are eliminated from the body through the anus

The brain is the control center of the body, responsible for processing and integrating information from sensory receptors, controlling voluntary movements, and regulating various bodily functions.

Divided into two hemispheres: left and right.
Each hemisphere is further divided into four lobes: frontal, parietal, temporal, and occipital.
Functions of each lobe:
- Frontal lobe: motor control, decision-making, problem-solving, and language processing.
- Parietal lobe: sensory processing, spatial awareness, and attention.
- Temporal lobe: auditory processing, memory, and language comprehension.
- Occipital lobe: visual processing.

Located at the base of the brain.
Functions: coordinates muscle movements, balance, and posture, and regulates learning and memory of motor skills.

Connects the cerebrum to the spinal cord.
Functions: controls automatic functions, such as breathing, heart rate, blood pressure, and body temperature, and regulates consciousness and sleep.

Chemical messengers (neurotransmitters) transmit signals between neurons.
Types of neurotransmitters:
- Excitatory: stimulates the next neuron to fire.
- Inhibitory: reduces the likelihood of the next neuron to fire.
- Modulatory: influences the strength of synaptic transmission.

The ability of neurons to change and adapt in response to experience.
Types of synaptic plasticity:
- Long-term potentiation (LTP): strengthens synaptic connections.
- Long-term depression (LTD): weakens synaptic connections.

Electrical activity in the brain, measured using EEG.
Types of brain waves:
- Alpha waves: relaxed, closed eyes.
- Beta waves: active, focused attention.
- Theta waves: drowsy, sleep.
- Delta waves: deep sleep.