Chapter 9 Fetal Circulation and Respiratory System Review

A set of 60 vocabulary flashcards covering fetal circulation, respiratory mechanics, gas exchange, lung anatomy, and alveolar cell types based on the lecture notes.

Placenta

A large-volume, low-resistance system that provides oxygen to the fetus and allows blood to flow through easily, keeping fetal SVR low.

Ductus venosus

A shortcut blood vessel branching from the umbilical vein that carries most oxygenated blood past the liver directly into the IVC.

Umbilical vein

Blood vessel that carries oxygen-rich blood from the placenta into the fetus.

Foramen ovale

Opening between the right and left atria that moves oxygenated blood from the right atrium into the left atrium, allowing it to skip the lungs.

Ductus arteriosus

Blood vessel connecting the pulmonary artery to the aorta that shunts blood away from high-resistance fetal lungs into the low-resistance aorta.

Systemic Vascular Resistance (SVR)

How difficult it is for blood to flow through the body's blood vessels.

High resistance

A vascular condition where blood has difficulty flowing through the blood vessels.

Low resistance

A vascular condition where blood flows easily through the blood vessels.

Right atrium

Upper-right heart chamber that receives blood from the IVC and ductus venosus.

Inferior Vena Cava (IVC)

A large vein that carries blood into the right atrium of the heart.

Left atrium

Upper-left chamber of the heart that receives oxygenated blood passed from the right atrium via the foramen ovale.

Aorta

Main artery carrying oxygenated blood from the heart to the body.

Pulmonary artery

Blood vessel carrying blood away from the right side of the heart toward the lungs.

Pulmonary Vascular Resistance (PVR)

How difficult it is for blood to flow through the lungs' blood vessels.

In utero fetal lungs

Fetal organs that have high PVR due to low $PaO_2$ and because they are not breathing air.

Gas exchange

The primary function of the respiratory system, consisting of continuous absorption of oxygen and elimination of carbon dioxide.

External respiration

Gas exchange between alveolar gas and blood, where oxygen moves from alveoli into blood and carbon dioxide moves from blood into alveoli.

Internal respiration

Gas exchange between blood and tissue cells at the cellular level, where oxygen moves into cells and carbon dioxide moves into blood.

Diffusion

Passive movement of gases across a membrane from an area of higher pressure to lower pressure.

Alveolar-capillary membrane

A thin wall separating the alveoli from pulmonary capillaries that controls fluid exchange and allows gas exchange.

Embryonic period

The first 8 weeks of pregnancy during which the baby's major organs begin developing.

Surfactant

Substance that decreases surface tension inside the alveoli to keep them open and prevent collapse.

Surfactant production timeline

Begins around 24 to 28 weeks of pregnancy.

Respiratory distress syndrome (RDS)

A condition in premature babies caused by insufficient surfactant production leading to alveolar collapse.

Single alveolus

One small open space in the lung dedicated to gas exchange.

Collapsed alveolus

An alveolus whose walls fold inward, leaving little room for air.

Bucket-handle movement

Rib movement upward and outward during inhalation that increases lateral space and makes the chest wider side-to-side.

Pump-handle movement

Movement of upper ribs and sternum upward and forward during inhalation that increases AP diameter from front to back.

Rib pair 1

Rib pair that raises slightly and pulls the sternum upward during inhalation.

Rib pairs 2-7

Rib pairs that perform both pump-handle and bucket-handle movements during inhalation.

Rib pairs 8-10

Rib pairs that mainly move outward to increase side-to-side space during inhalation.

Diaphragm

The main breathing muscle that performs about 75% of the work of breathing.

Passive exhalation

Normal exhalation where breathing muscles relax, the diaphragm moves up, and air flows out naturally.

Forced exhalation

Process where abdominal and internal intercostal muscles pull ribs down and push air out faster.

Inhalation

Process where the diaphragm contracts and moves down while external intercostals lift ribs, creating negative pressure that pulls air into lungs.

Accessory muscles of inhalation

Scalene and sternocleidomastoid muscles that help when breathing becomes difficult or the body needs more air.

Phrenic nerve

Nerve arising from C3, C4, and C5 that carries brain signals to control one side of the diaphragm.

C3, C4, and C5

Third, fourth, and fifth cervical spinal nerve levels in the neck area that join to form the phrenic nerves.

Abdominal compression

Increased intra-abdominal pressure created by prolonged diaphragmatic contraction concurrent with abdominal muscle contraction for coughing, vomiting, bowel movements, and childbirth.

Spinal cord injury at or above C3

Injury that interrupts brain signals to breathing muscles, causing loss of independent breathing control and requiring mechanical ventilation.

Diaphragmatic paralysis

Condition where the diaphragm cannot contract normally due to interrupted nervous signals.

Pulmonary circulation resting flow rate

Blood flow supplied from the right heart to the lungs equal to the entire blood volume each minute at rest.

Pulmonary capillary coverage

Tiny blood vessel network covering approximately 90% of the alveolar surface.

Pulmonary arteries

Vessels carrying oxygen-poor blood from the right heart to the lungs.

Pulmonary veins

Vessels carrying oxygen-rich blood from the lungs to the left heart.

Pulmonary non-respiratory functions

Production, processing, and clearance of chemicals and filtering small blood clots from the bloodstream.

Left lung structure

Lung consisting of 2 lobes and 8 to 10 bronchopulmonary segments, having less space because the heart sits partly on the left side.

Right lung structure

Lung consisting of 3 lobes and 10 bronchopulmonary segments.

Bronchopulmonary segment

A smaller section of a lung lobe supplied by its own segmental bronchus.

Segmental bronchus

An airway branch that delivers air to an individual bronchopulmonary segment.

Terminal bronchioles

The last conducting airways that only move air and mark the end of anatomic dead space.

Anatomic dead space

Conducting airways containing no alveoli where gas exchange does not occur.

Anatomic dead space volume

Volume of conducting airways measuring approximately $2\,mL/kg$ of lean body weight, or around $150\,mL$ in an adult.

Anatomic dead space structures

Includes the nose, mouth, trachea, bronchi, and terminal bronchioles.

Alveoli

Saclike growths on respiratory bronchioles, alveolar ducts, and alveolar sacs whose primary function is gas exchange.

Type I pneumocytes

Very flat, thin cells covering approximately 93% of the alveolar surface that form tight joints and facilitate gas exchange.

Type II pneumocytes

Cuboidal-shaped cells, twice as numerous as Type I cells, that manufacture/store surfactant, reduce surface tension, and increase compliance.

Compliance

A measure of how easily the lungs expand.

Type II cell repair capability

The ability of Type II cells to divide and differentiate into new Type I cells when Type I cells are damaged.

Alveolar macrophages

Immune cells in the alveoli that provide defense by removing germs, dust, and other unwanted particles.

Club cells

Cells found mainly in the bronchioles (formerly Clara cells) that protect airways and manufacture/store surfactant-like material.