Human Anatomy & Physiology

Respiratory System

Nasal cavity → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli

Bronchi are further divided up by:

Primary Bronchi → secondary bronchi → Tertiary Bronchi → Bronchioles

Bronchioles are further divided like:

Tertiary bronchi → Terminal bronchioles → Respiratory bronchioles → Alveoli

Nasal cavity - where the air is warmed, humidified, and filtered by mucus and hair

Pharynx - Junction for both air and food

Larynx - voice box

Trachea - Cylinder tube with rings of cartilage that provide support

The pharynx acts as the crossroads for food and air where the food is supposed to go to the esophagus and the air is supposed to go to the pharynx

Epiglottis - stops food from going into our trachea

There are two main bronchi: Right and Left

Bronchioles - smaller branches of bronchial airways

Alveoli - tiny air sacs in the lungs at the end of the bronchioles that allow for rapid gaseous exchange

• Alveoli are surrounded by clusters of alveolar sacs. In these sacs are the actual sites of where gas exchange occurs

There are two lungs: Right and left.

• Lungs are divided into sections called lobes.

  • The right has 3 lobes

  • The left has 2 lobes

The left lung has an indention at the bottom called the cardiac notch where it makes space for the heart. This contributes to the smaller size of the left lung. You can remember which lung has the smaller amount of lobes because less lobes = smaller. The left is smaller because of the heart and your heart is on the left side

Conducting zone - The areas in which air is transported between from the outside to the site of the gas exchange. It’s commonly referred as the “dead space” as no gas is actually exchanged in this area.

• The conducting zone includes the nose all the way to the bronchus. (Nose/mouth → pharynx → larynx → trachea → Bronchus)

Respiratory zone - Structures in the lungs where gas exchange occurs

• Includes Respiratory Bronchioles, Alveoli, and Alveoli ducts

The Respiratory System works with:

• The cardiovascular system

  • Red blood cells carry the oxygen throughout the body and picks up the CO2

• Skeletal system

  • protects lungs through our ribcage

• Nervous system

  • Voluntary and involuntary control of respiratory by using pH

• Muscular system

  • Work together to expand and contract the thoracic cavity, aiding in breath

    • intercostal muscles (muscles in between ribs)

    • Diaphragm (beneath our lungs)

    • Abdominal wall

Inspiration - Air drawn into lungs or inhalation

• Diaphragm and intercostal muscles contract

Expiration - air pushed out of the lungs

• Diaphragm and intercostal muscles relax

Diaphragm pushes down and thoracic cavity volume increases during inhalation

• Causes negative pressure relative to the atmosphere, causing air to flow in

Diaphragm rises and thoracic cavity volume decreases during inhalation

• Increases pressure compared to the atmosphere, causing air to flow out

pH scale - A measure of how acidic or alkaline a solution is

Acid - Substances that increase concentration of hydrogen ions

Base - substances that decrease concentration of hydrogen ions

Increase in acidity of blood signal the brain to increase respiration

• Higher levels of CO2 will lead to higher levels of hydrogen ion concentration causing blood acidity to rise

• Lower levels of CO2 will cause lower levels of hydrogen ion concentration causing blood to become alkaline

More CO2 = more hydrogen ions

pH scale is from 1-14

• <6 is acidic (1-6)

• >8 is alkaline (8-14)

• 7 is neutral

Perfusion - delivering blood to the body’s tissues, organs, and cells

Ventilation - movement of air in and out of the lungs (breathing)

Hyperventilation - Fast breathing

• Blood pH is basic → not getting enough CO₂

• increased O2 = hyperoxia

• decreased CO2 + hypocapnia

When there’s too much O2, blood becomes basic

Hypoventilation - slow breathing

• pH is acidic → too much CO2

• lower O2 = hypoxia

• higher CO2 = hypercapnia

Hyperventilation and hypoventilation disrupt the normal process of breathing as well as the balance of oxygen and carbon dioxide in the body

Cardiovascular System

Blood - red liquid that circulates in the arteries and veins of humans and other vertebrate animals

Primary function: maintain homeostasis

• pH

• Temperature

• Osmotic pressure

Transports:

• Hormones

• Nutrients

• Gases

The cardiovascular system carries oxygen and carbon dioxide to and from the tissue of the body

Blood is always red in color

• the brighter the blood, the more oxygen it has

Blood is composed of:

• Plasma

• Platelets

• Erythrocytes

Plasma - liquid portion consisting of lipids, salt, protein, and water

Erythrocytes and cells:

• Red blood cells

  • Transports

• White blood cells

  • fight infection

Platelets - help w/ clotting

Hemoglobin - what gives blood its red hue

Arteries carry blood AWAY from the heart, typically oxygen rich

• A in Away stands for Arteries

Veins - carry blood back to the heart, typically oxygen poor

• VERB - Veins Efficiently Return Blood

Pulmonary arteries carry oxygen-poor blood

Pulmonary veins carry oxygen-rich blood

Capillaries - tiny blood vessels where gas exchange for oxygen and carbon dioxide happen

Heart

Atrium at the top, Ventricle at the bottom

• A comes before V in the alphabet

Heart valves prevent backflow

Atria have thin walls while ventricles have thick walls

Right of the heart usually carries deoxygenated blood

Left of the heart usually carries oxygenated blood

Blood flow: deoxygenated blood goes to the lungs to get reoxygenated

• Blood comes from tissues and re-enters heart through the superior or inferior vena cava

  • Inferior vena cava is blood from the lower parts of the body while Superior vena cava comes from the higher parts of the body

Superior/Inferior Vena Cava → Right Atrium → tricuspid valve → right ventricle → pulmonic valve → pulmonary artery → Lungs

Oxygenated blood moves from the lungs to the heart and back to the tissues

Lungs → Pulmonary veins → Left Atrium → Bicuspid/mitral valve → Left ventricle → aortic valve → Aorta

Coronary Arteries

• Right coronary artery

• Left coronary artery

• Circumflex artery

• Right Marginal Artery

• Left Anterior descending artery

• Posterior interventricular Artery or posterior descending artery

Coronary arteries originates from the aorta and delivers nutrients and oxygen to the heart

Coronary veins

• Great cardiac vein

• Small cardiac vein

• Coronary sinus

• Middle Cardiac vein

Coronary veins carry deoxygenated blood return to right atrium from coronary sinus

Interatrial Septum - thin, muscular membrane structure that consists of two parts: fossa ovalis and the limbus of the fossa ovalis

• Separates the right and left atrium

Atrial Septal Defect (ASD) - a congenital heart defect where there is an abnormal opening in the interatrial septum, allowing blood to flow between the two atria

Interventricular septum - Thick, muscular wall that consists of two parts: a membranous and muscular portion

• Separates the right and left ventricles

Ventricular Septal Defect (VSD) - A congenital defect characterized by one or more holes. in the interventricular septum, allowing to mix between ventricles

The Interatrial Septum and the Interventricular septum separate the oxygen-rich blood from the oxygen-poor blood between the chamber

Electrical Conduction System of the Heart

Sinoatrial node (SA)

• Main Pacemaker

• Starts electrical impulse

• Triggers atrial contraction

• 60-100 BPM

• Situated in the right atrium where it meets the Superior vena cava

Bachmann Bundle - brings signal from SA to the left atrium

Internodal Pathways

• Three routes: Anterior, middle, posterior

• Signal from SA node goes to AV node

Atrioventricular node (AV)

• Secondary Pacemaker

• In the right atrium but near the tricuspid valve and coronary sinus

• Relay signals from SA node

• Allow atria to contract → allows ventricles to fill

• 40-60 BPM

The AV has a delay on the relay of signals which allows the atria to fully contract and that blood reaches the ventricles

Bundle of His

• Only route between atria and ventricles

• Two branches:

  • Right bundle branch - signal to right ventricle

  • Left bundle branch - signal to left ventricle

Purjinke Fibers

• Last ditch pacemaker

• Connect w/ myocytes

• Initialize depolarization → leads to contraction

• 20-40 BPM

Depolarization - contraction

Repolarization - Relaxation

ECG Basics

P Wave: Atrial depolarization

• Signifies Atrial contraction

QRS Complex: Ventricular Depolarization

• Signifies ventricular contraction

• Normal range: .06-.12 seconds

T Wave: Ventricular Repolarization

• Signifies Ventricular relaxation

Atrial Repolarization happens concurrently with the QRS complex

Systolic Pressure - Contraction of the heart

• “Lub” sound

• Top # on the reading lowest pressure in arteries

• Lower than 120

Diastolic Pressure - relaxation of the heart

• “Dub” sound

• Bottom # on reading lowest pressure in arteries

• Lower than 80