Human Organ Systems and Biodesign

The brain uses electrical and chemical signals to send and receive information.
The brain's memory capacity is equivalent to 2.5 million gigabytes.
The brain has three main parts: cerebrum, cerebellum, and brainstem.
- Cerebrum: responsible for higher functions like touch, vision, hearing, and speech.
- Cerebellum: responsible for fine-tuning muscle movements.
- Brainstem: connects the brain to the spinal cord and helps with involuntary actions.

The nervous system helps the body's parts communicate with each other.
The nervous system has two main parts: central nervous system (CNS) and peripheral nervous system (PNS).
CNS consists of the brain and spinal cord.
PNS consists of nerves that branch off from the spinal cord and extend to all parts of the body.

A neuron sending a signal releases a neurotransmitter, which binds to a receptor on the receiving neuron.
Electroencephalogram (EEG) measures electrical activity in the brain.
EEG is used to diagnose brain disorders, especially epilepsy.

Robotic prosthetic limbs are designed to replace missing limbs and restore lost functions.
They use advanced mechatronics, intelligent sensing, and control systems.

Deep brain stimulation (DBS) involves surgically implanting a neurotransmitter that sends electrical impulses to specific areas of the brain.
DBS has helped people with Parkinson's disease reduce symptoms.

The human eye is similar to a camera, with a diaphragm, lens, and image sensing system.
The eye has a refractive system that bends light to form an image.
The retina has two types of photoreceptors: rods and cones.

Refractive errors occur when light bends incorrectly as it enters the eye.
Eyeglasses and contact lenses are used to correct refractive errors.
Cataracts are a clouding of the lens of the eye that can be treated with surgery.

Bionic eyes are electrical prostheses that are surgically implanted into the eye.
They allow people with severe vision loss to perceive light.

The heart is a dual-pump system that receives blood from the body and pumps it to the lungs and vice versa.
The heart beats around 70-80 times per minute.
The heart can pump blood up to 30 feet.

The sinus node generates an electrical stimulus that triggers the heart to beat.
The electrical stimulus travels through the conduction pathways and causes the heart's ventricles to contract.

Electrocardiogram (ECG) monitoring systems are used to monitor the heart's rhythm.
ECG monitoring systems are used in hospitals, homes, and outpatient ambulatory settings.

Coronary artery disease is a common heart condition that occurs when the heart's arteries struggle to supply enough blood.
Cholesterol deposits and inflammation can cause coronary artery disease.

Pacemakers are small devices that are implanted in the chest to control the heartbeat.
They are used to prevent the heart from beating too slowly.
Pacemakers have two parts: a pulse generator and leads (electrodes).

Defibrillators are devices that send an electric shock to the heart to restore a normal heartbeat.
They are used to prevent or correct an arrhythmia.
There are three types of defibrillators: automated external defibrillators (AEDs), implantable cardioverter-defibrillators (ICDs), and wearable cardioverter-defibrillators (WCDs).

The respiratory system's main job is to move fresh air into the body and remove waste gases.
The lungs are responsible for gas exchange, where oxygen is moved into the bloodstream and carbon dioxide is removed.
The respiratory system also performs other roles, including bringing air to the proper body temperature and moisturizing it, protecting the body from harmful substances, and supporting the sense of smell.### Lung Architecture
Lung parenchyma is composed of air-containing passages, alveolar ductal lumens, alveoli, alveolar septa, and small pulmonary vessels, occupying 10% of total parenchymal volume.
The primary function of the lungs is gas exchange.
Lungs also perform non-respiratory functions, vital for normal physiology, including acting as a reservoir of blood, fine-tuning preload to the left heart, and optimizing cardiac output.

Lungs act as a filter against endogenous and exogenous emboli, preventing them from accessing systemic circulation.
Pulmonary epithelium forms the first line of defense against inhaled particles.
Pulmonary endothelial cells are responsible for the uptake, metabolism, and biotransformation of several exogenous and endogenous substances.

Air enters the body through the mouth or nose and passes through the pharynx, larynx, and trachea, which branches into left and right bronchus, further dividing into smaller bronchioles.
Bronchioles end in tiny air sacs called alveoli, which inflate when a person inhales and deflate when a person exhales.
During gas exchange, oxygen moves from the lungs to the bloodstream, while carbon dioxide passes from the blood to the lungs.
Gas exchange occurs between the alveoli and a network of tiny blood vessels called capillaries, located in the walls of the alveoli.

Spirometry uses a machine called a spirometer to measure lung function, specifically the amount and/or speed of air that can be inhaled and exhaled.
Spirometry is used to diagnose conditions that affect breathing, such as asthma and chronic obstructive pulmonary disease (COPD).
Requirements of an acceptable spirometer include accumulating volume for ≥15 s, measuring volume of ≥8 L, accuracy of reading at least ±3% (or ±0.05 L), and total resistance to airflow at 14 L per s.