A & P Exam 2 Flashcards
What kind of muscle is in the heart?
Cardia: involuntary, striated
What type of tissue is in the heart?
Epithelial, connective, muscle, nervous
Can cardiac muscle contract without external stimulation?
Yes
Groups of cardiac muscle cells can adopt the contraction rate of the …… cell in the group
Most rapid
Pumps blood through vascular system Delivers O2 and nutrients to cells Transports hormones Delivers antibodies Removes waste products
Heart
How is the heart positioned in the chest?
In the center, a little to the left
The space between the two pleural cavities that contain the lungs
Surrounded by loose connective tissue
Mediastinum
What else besides the heart is in the mediastinum?
Trachea, esophagus, vascular structures, nerves, lymphatic structures
The mediastinum is fenestrated (holes) in what 3 species?
Dog, horse, sheep
Thin layer of serosal membrane that lines the thoracic cavity and covers the organs in it
Pleura
What types of pleura are there?
Visceral and parietal
Excessive fluid in a body cavity
Effusion
Excessive fluid in tissue
Edema
Blood in thoracic cavity
Hemothorax
What are the 4 layers of the heart?
Pericardium
Epicardium
Myocardium
Endocardium
Outermost layer of heart
Fibrous connective tissue
Protects the heart
Loosely attaches the heart to the diaphragm
Fibrous Pericardium
Parietal layer of the pericardium
Fused to the fibrous pericardium
Serous pericardium
Fluid filled cavity between the parietal and visceral layers of the serous pericardium
Pericardial space
Visceral layer of the serous pericardium
Epicardium
Excessive amount of pericardial fluid
Pericardial effusion
What are some causes of pericardial effusion?
Infection, inflammation, hemorrhage
Excessive pericardial fluid builds up and the heart becomes unable to expand
Cardiac tamponade
What is the TX for pericardial effusion?
Pericardiocentesis
Heart wall located inside the sac formed by the pericardium
Thickest layer of hear tissue
Myocardium
Membranous lining between the myocardium and chambers of the heart
Endocardium
The top or cranial portion of the heart
Base
The point or caudal portion of the heart
Top of the left ventricle
Points to the left
Apex
The largest and most visible parts of the atria from the outside of the heart
Auricles
What does auricle mean?
Ear
Long and narrow, thick walled, terminates at the apex of the heart
Left ventricle
Broader surface area, wraps around the left ventricle
Right ventricle
Borders of the ventricles are externally separated by what structure?
Contains fats and blood vessels that are part of the coronary circulation of the heart
Interventricular sulci (grooves)
What structure externally separates the atria from the ventricles?
Coronary groove
The myocardium (muscle of the heart) has its own blood supply called….
They branch off the aorta and supply oxygenated blood to the heart
Located in the coronary groove and Interventricular grooves
Coronary arteries
Coronary arteries branch into: arterioles > capillaries > venules > cardiac veins > ……. …….. which empties into the right atrium
Coronary sinus
These arteries emerge from the external rig ventricle as the pulmonary trunk
They quickly divide into right and left …….. arteries traveling to each lung
Pulmonary arteries
The pulmonary arteries emerge from the external right ventricle as the ………. ……….
This structures is larger and more curved than the vena cavae
Pulmonary trunk
The largest artery in the body
Aorta
The walls of the aorta are the thinnest or thickest of any blood vessel?
Thickest
The aorta emerges from the ……. …….. into the aortic arch
Left ventricle
The brachiocephalic trunk and left subclavian artery branch off the …… just after the ……. valve
Aorta
Aortic
What are the chambers of the heart
Right atrium, left atrium, right ventricle, left ventricle
Which chamber of the heart has the thickest walls to aid in forceful contraction?
Left ventricle
Do the valves of the heart work one way or both ways?
One way
The right atrioventricular valve is also called what?
It has 3 flaps
It connects the right atrium to the right ventricle
Tricuspid valve
The left atrioventricular valve is also known as what? (2)
It has 2 flaps
It connects the left atrium to the left ventricle
Mitral or bicuspid
What are the 2 semilunar valves?
Pulmonary valve: 3 flaps
Aortic valve: 3 flaps
What does lunar mean?
Moon
What valve in the heart has only 2 flaps?
Left AV, mitral, bicuspid
Valves have these that originate from a fibrous ring of the valve
Flaps
Increased blood pressure in the chambers during contraction forces flaps to
Open
The AV flaps are prevented from bending back into the atrium by the
Chordae tendinae
Chordae tendinae connect the free edges of the AV flaps to the ……… muscles.
These muscles attach to the Interventricular septum
Papillary muscles
What 2 structures are the papillary muscles connected to?
Chordae tendinae and Interventricular septum
Band of tissue present in the right ventricle that originates at the Interventricular septum
Provides additional structural support to the wall of the right ventricle
Acts as a primary conduction path
Not attached to flaps of tricuspid valve
Moderator band
What chamber of the heart is the moderator band located in?
The right ventricle
This type of vessel leaves the heart and carries blood to systemic circulation or away from the heart
Arteries
This type of vessel carries blood from systemic circulation to the heart
Vessels
Nutrient and oxygen rich blood leaves the heart through the
Aorta
The aorta branches into smaller
Arteries
Arteries branch into
Arterioles
Arterioles branch into
Capillaries
At the capillary level, nutrients and O2 are exchanged for
Waste and CO2
Capillaries branch into
Venules
Venules branch into
Veins
This vein carries blood from the caudal part of the body to the right atrium of the heart
Caudal vena cava
This vein carries blood from the cranial part of the body to the right atrium
Cranial vena cava
The cranial and caudal vena cava carry what type of blood to the right side of the heart?
Deoxygenated
Veins typically carry deoxygenated blood with these 2 exceptions
Pulmonary veins
Umbilical vein
This vein carries oxygenated blood to the heart
Pulmonary vein
This vein carries oxygenated blood to the fetus
Umbilical vein
The heart pumps deoxygenated blood through the ………. …….. to the lungs to pick up O2.
Pulmonary artery
Oxygenated blood enters the left side of the heart through the
Pulmonary vein
Arteries typically carry what type of blood?
Oxygenated
2 arteries do NOT carry oxygenated blood
Pulmonary artery
Umbilical artery
This artery carries deoxygenated blood away from the heart to the lungs
Pulmonary artery
This artery carries deoxygenated blood away from the fetus
Umbilical artery
What chamber of the heart do the cranial and caudal vena cava empty into?
Right atrium
From the right atrium, blood flows to which chamber?
Right ventricle
From the right ventricle where does the blood go?
Lungs via the pulmonary artery
From the pulmonary arteries, blood passes through branching vessels to the pulmonary capillaries of the …., where O2 exchange takes place
Alveoli
Where does O2 exchange take place?
Pulmonary capillaries of the alveoli
Is the blood in the pulmonary veins oxygenated?
Yes
From the lungs where does the blood go?
What vessel carries the blood there?
Left atrium
Pulmonary vein
Where does the blood go from the left atrium?
Left ventricle
From the left ventricle, where does the blood go?
To the body via the aorta
These arteries, which branch from the aorta, deliver oxygenated blood to the lungs
Bronchial arteries
What is the valve that is located between the right atrium and right ventricle?
Right AV or tricuspid
What valve is between the right ventricle and pulmonary artery?
Pulmonary valve
What valve is located between the left atrium and the left ventricle?
Left AV, mitral, bicuspid
What valve is located between the left ventricle and the aorta?
Aortic valve
Problems with the right side of the heart cause blood to backup into the caudal vena cava which causes
Ascites, abdomen fills with fluid
Problems with the left side of the heart cause blood to backup where?
Into the lungs
Fluid in the lungs
Pulmonary edema
This type of pulmonary edema is caused by left heart failure
It is perihilar and symmetrical
Cardiogenic
Each complete contraction and relaxation of the heart is called a
Cardia cycle
What are the 2 main parts of the cardiac cycle?
Systole
Diastole
Part of cardiac cycle in which the heart is relaxed
Diastole
Atria relax and fill with blood to be ejected during systole
Atrial diastole
Ventricles relax and fill with blood to be ejected during the next systolic contraction
Ventricular diastole
Heart muscle contracts
Systole
Atria contract and blood is ejected from the atria to the ventricles
Atrial systole
Ventricles contract and blood is ejected from the ventricles to the arteries
Ventricular systole
Blood flow through the heart starts with atrial and ventricular …….
The AV valves are …… And the semilunar valves are ……..
Diastole
AV: open
Semilunar: closed
During atrial …… the contraction of the atria ejects even more blood into the ventricles
Systole
There is a slight …… between atrial systole and ventricular systole
Delay
When the ventricles enter systole, it causes the AV valves to …… And the semilunar valves to …..
AV: shut
Semilunar: open
When the ventricles stop contracting and enter diastole, the semilunar valves ……
Shut
The pressure in the ventricles drops, allowing ……. to open
AV valves
What is unique about cardiac muscle cells?
They contract without any external stimulation
Groups of cardiac muscle cells adopt the contraction rate of the
Most rapid cell in the group
Does the heart need nervous input for the muscle cells to contract?
No
What does the nervous system modify?
Contraction rate and strength
The impulse for a heartbeat comes from where?
Sinoatrial node
Specialized area of cardiac muscle cells located in the right atrium deep to the endocardium
Pacemaker
Generates electrical impulses that triggers repeated beating of the heart
Contraction rate of the muscle cells in this area is faster than those in the walls of the atria or ventricles, therefore it “sets the pace”
Sinoatrial node (SA node)
Charge inside the cell is different than the charge outside the cell. This is called
Membrane potential
The inside of the cell is more negatively charged than the outside of the cell
There is more …… outside the cell and more ……. inside the cell
Outside: sodium
Inside: potassium
Sodium channels open causing sodium to flow in
As these positively charged ions enter the cell, this makes the charge inside the cell more positive
The charge inside the cell has now changed from net negative to net positive
This change is charge is called
Depolarization
Depolarization of cardiac cells in the …. node generates an electrical impulse which travels across the atria to the AV node
SA node
This causes contraction of the cardiac cells
Depolarization
The …… node will then depolarize and generate an electrical impulse which travels down the bundle of His and up the purkinje fibers
AV node
This allows for systole of the heart
Depolarization
Soon after sodium channels open, they close
Now potassium channels open
Since there is more potassium inside the cell, it will flow out
As these positively charged ions leave the cell, this changes the charge back to net negative charge inside the cell
This is called
Repolarization
When the cells are repolarizing, the heart is in
Diastole
When sodium and potassium are on opposite sides of the cell than they were originally, this pump will pump 3 sodium ions out of the cell at the same time it pumps 2 potassium ions back into the cells
Now the cell is ready to depolarize again
Sodium/potassium pump
When sodium channels allow sodium to rush into the cell, these channels also also open in the sarcolemma (plasma membrane) and the sarcoplasmic reticulum (ER)
Calcium
The increase of calcium in the cells allows for …… filaments to bind to …… filaments and slide across each other, shortening the cell and causing contraction of the cell
Myosin and actin
The impulse from the SA node travels quickly down the muscle fibers to the …… node located in the interatrial septum
Atrioventricular node
From the AV node, electrical impulses spread through the ……….
These are fibers in the ventricles that travel down the Interventricular septum to the bottom of the ventricles
Bundle of His
These fibers carry impulses from the Bundle of His up into the ventricular myocardium
Purkinje fibers
Impulse also spread across this from the Bundle of His
Moderator band
Ventricle contraction of systole begins at the …. of the heart and travels to the …..
Starts at apex up to base
After ……… systole, AV valves snap shut and semilunar valves pushed open
Blood is ejected from the ventricles into the pulmonary artery and aorta
Ventricular
This sound is heard at the closure of the AV valves at the beginning of the ventricular systole
“Lub”: S1
Mitral valve is loudest where?
L side of chest
Tricuspid valve is best heard where?
R side of heart
This normal heart sound is at the closure of the semilunar valves at the beginning of ventricular diastole
“Dub”: S2
The S2 sound (dub) is best heard where?
L side of chest
The only two heart sounds heard in small animals are
S1 and S2
These heart sounds can only be heard in large animals along with S1 and S2
S3 and S4
Heart sound heard in large animals
Sound of rapid ventricular filling
S3
Heart sound heard in large animals
Sound of contraction of atria
S4
There are several bypasses in the fetal circulation, why?
The fetus receives oxygenated, filtered blood from the mother through the placenta.
Keeps most blood out of pulmonary circulation and liver circulation
Oxygenated blood flows from the placenta through the
umbilical vein
What other vein besides the umbilical vein in the body carries oxygenated blood?
Pulmonary vein
In the fetus: Oxygenated blood from the umbilical vein flows through the liver and this structure which allows some blood to bypass the liver into the caudal vena cava.
Ductus venosus
In the fetus: most of the blood from the right atrium can flow where to bypass the lungs?
Directly into the left atrium through the foramen ovale
In the fetus: blood from the pulmonary artery may flow into the lungs or directly into the aorta through another type of bypass known as the
ductus arteriosus
In the fetus: deoxygenated blood is sent back to the placenta through the
umbilical arteries
After birth, the ductus venosus constricts and becomes the
ligamentum venosum
After birth, the foramen ovale closes and becomes the
fossa ovalis
After birth, the ductus arteriosus closes and becomes the
ligamentum arteriosus
If the foramen ovale stays patent in the newborn the condition is called
atrial septal defect
With an atrial septal defect, blood will shunt into the right atrium, causing a volume overload to the right atrium, right ventricle, and pulmonary vasculature, which can sometimes lead to
pulmonary hypertension
Atrial septal defect can also can
generalized cyanosis
If the ductus arteriosus remains patent in the newborn is called what?
Patent ductus arteriosus (PDA)
Patent ductus arteriosus can lead to
left side heart failure with pulmonary edema
Why would fetal blood bypass the liver?
Liver filters toxins and the blood has already been filtered by the dam’s liver
If the ductus venosus stays patent in the newborn, what happens?
Blood is not filtered by the liver causing a build up of toxins.
If the ductus venosus stays patent in the newborn, what is this condition called?
Portosystemic shunt (liver shunt)
The amount of blood that leaves the heart per minute
cardiac output
Cardiac output depends on what 2 things?
Stroke volume and heart rate
The amount of blood ejected with each heartbeat (cardiac contraction) dependent upon: strength of contraction; size of heart; blood pressure; blood volume
Stroke volume
Frequency of heart contractions
Heart rate
SV (stroke volume) X HR (heart rate) =
CO (cardiac output)
What would result in increased CO (cardiac output)?
Increased HR or increased SV
Increased HR can be a result of what nervous system?
Sympathetic nervous system
What would result in decreased cardiac output?
Decrease in stroke volume and or heart rate
What nervous system causes the HR to decrease?
Parasympathetic
When a chamber of the heart is depolarizing, it is in what?
Systole, contracting
When a chamber of the heart is repolarizing, it is in what?
Diastole, rest
Force of contraction
inotropy
Medications that increase the force of cardiac contractions are termed:
Positive inotropes
Medications that weaken the force of cardiac contractions are termed:
Negative inotropes
Rate of contraction
Chronotrophy (chronotracking for races)
These drugs may change the HR by affecting nerves controlling the heart or by changing the rhythm produced by the SA node
Chronotropic drugs
What condition would you use a positive inotrope for? (increases strength of heart contraction)
heart failure
What condition would you use a negative inotrope for? (decreases strength of heart contraction)
high bp
Medications that increase HR
positive chronotropes
What are 2 examples of positive chronotropes? (increase HR)
atropine, epinephrine
Medications that decrease HR
Negative chronotropes
When would negative chronotropic drugs be used? (decreases HR)
Increased HR, heart failure
Increased filling of the heart (increased pre-load) results in increased force of cardiac contraction and increased stroke volume.
Starling’s Law
Instrument which measures electrical current using electrodes attached to skin
Electrocardiograph
Because cardiac contractions are the result of _______, an instrument the detects this may be used to measure the electrical activity of the heart
electrical currents
What wave of the EKG does this represent: depolarization of the atria
P wave
What wave of the EKG does this represent: waves created by ventricular depolarization, atrial repolarization is taking place as well
QRS complex
What wave of the EKG does this represent: repolarization of the ventricles
T wave
Blood in the systemic circulation is under higher or lower pressure than blood in the pulmonary or coronary circulation?
Higher - more pressure is needed to carry blood throughout the body
Blood in what encounters more resistance to flow
systemic circulation
What is the largest artery in the body, with the largest diameter and thickest walls of any blood vessel
Aorta
What are the 3 layers of the arterial walls?
Outer fibrous layer
Middle smooth muscle layer
Endothelium
Which two arteries have a middle layer that contains more elastic fibers than muscle fibers?
This allows vessels to stretch slightly as they receive high-pressure blood from ventricles
Aorta and Pulmonary arteries
What part of the circulatory system does not have a muscle layer in the walls?
Capillaries
Since venous blood is under lower pressure than arterial blood, vein has ______ walls than arteries
thinner
What structure in veins ensure that blood travels only in the direction of the heart
Valves
In the cat, the left subclavian and brachiocephalic arteries branch of the
aorta
In the cat, the right subclavian branches of the
brachiocephalic artery
Subclavian arteries travel toward the
thoracic limbs
In the cat, the carotid arteries branch off the
right subclavian artery
The main trunk of the aorta arches dorsally then travels
caudally
The main trunk of the aorta splits at the hind limbs into the
external and internal iliac arteries
This artery emerges at the caudal aorta
Coccygeal artery
These veins carry blood to the cranial vena cava then back into the heart
Jugular veins
Veins in the hind limbs merge into the right and left
internal and external iliac veins
This vein is on the craniomedial aspect of the forelimb. Used for IV catheter placement
Cephalic vein
Vein on the lateral aspect of the hind limb. Can be used for blood draw on dogs and ferrets
Saphenous
Vein on the medial aspect of the hind limb. Used for venipuncture in cats
Femoral vein
Veins on the ventral aspect of each side of the neck in the jugular groove, close the the carotid arteries
Jugular veins
Care must be taken to avoid accidental injection into the carotid artery, esp in what species?
Equine
This vein is also called the “milk vein”. Easily seen in lactating dairy cattle on the ventral aspect of each side of the abdomen. Thin-walled, superficial, prone to hematoma formation - DO NOT USE!!
Caudal epigastric vein
Vein on the ventral midline of the tail. Used for venipuncture in ruminants, lizards, and small rodents.
Coccygeal vein
The cranial vena cava is used for venipuncture in what 2 species?
Pigs and ferrets
What is the primary function of the respiratory system?
Bring O2 into the body and take CO2 out
Phonation, regulation of body temp, regulation of acid-base balance, sense of smell.
These are all functions of what system?
Respiratory
Part of the respiratory system that includes structures from nares to trachea
Upper respiratory tract
Part of the respiratory system that includes structures from the bronchi to the alveoli
Lower respiratory tract
The respiratory system works in conjunction with what other system?
Cardiovascular
This structure of the upper resp tract is the external opening of the respiratory tube. They lead to the nasal passages
Nares (nostrils)
Structures of the upper resp tract between the nostrils and the pharynx
Nasal Passages
Structure of the upper resp tract that separates the left and right nasal passage
nasal septum
2 sets of thin, scroll-like bones in each nasal passage covered by epithelium. There are R, L, dorsal, ventral
Turbinates
The nasal turbinates divide each nasal passage into 3 main passageways called
Dorsal, middle, and ventral meatus
The 4th meatus is located on either side of the nasal septum and is continuous with the other 3 meatuses
common nasal meatus
What type of epithelial tissue lines the nasal passages?
Ciliated Pseudostratified columnar epithelium
Cilia project from the cell surfaces up into a layer of mucus and beat causing the mucus to move toward the:
pharynx where it can be swallowed or coughed up
Mucus is secreted by what 2 cells/glands in the nasal passages?
Mucous glands and Goblet cells
Air in the nasal passages is warmed by what?
blood flowing through blood vessels just beneath the nasal epithelium
Air in the nasal passages is humidified by what?
mucus and other fluids on the epithelial surface
Turbinates do what?
increase surface area and filter air
Particles do not readily pass through the air but become trapped in the
mucous layer
Ciliated outpouchings of the nasal passages contained within spaces in certain skull bones
Paranasal Sinuses or sinuses
The 2 sinuses are located within the frontal bones. They are common in most species
Frontal sinuses
These 2 sinuses are located within the maxillary bones. They are common in most species
Maxillary sinuses
Some animals, including humans, have two more sinuses called
sphenoid and ethmoidal sinuses
The openings from the sinuses into the nasal passages can swell shut or become plugged with inflammatory debris as a result of allergies, infections, tumors, etc. Fluids in the sinus have nowhere to go and the resulting buildup of pressure is very painful. Tx: antibiotics, decongestants, sx
Sinusitis
Structure in the upper resp tract. Common passageway for respiratory and digestive systems
Pharynx
This structure separates the nasal passages from the oral cavity
Hard palate
Respiratory passageway of the pharynx, dorsal
nasopharynx
Digestive passageway of the pharynx, ventral
oropharynx
This structure divides the pharynx into the dorsal and ventral pharynx
soft palate
Caudal end of pharynx opens dorsally into the _____ and ventrally into the _____
Esophagus
Larynx
Congenital defect of the hard palate, tissue does not completely close
cleft palate
Congenital defect of the soft palate
elongated soft palate
What happens if the soft palate is too long?
soft palate gets trapped in the larynx obstructing airflow
What breeds is the elongated soft palate common in?
Brachycephalic breeds
What can be done to fix elongated soft palate?
Surgically remove excess soft palate tissue
What controls actions of the muscles around the pharynx
reflexes
What 2 structures work together to prevent swallowing from interfering with breathing and vice versa?
Larynx and pharynx
Does breathing stop when we swallow?
Yes
Short irregular tube connecting the pharynx with the trachea. Composed of segments of cartilage that are connected to each other and surrounding tissues by muscles. Supported by hyoid apparatus.
Larynx
Larynx cartilage: single, leaf-shaped cartilage; projects forward from the ventral portion of the larynx
Epiglottis
During swallowing, this structure is pulled back to cover the opening of the larynx
epiglottis
Larynx cartilage: paired cartilages; form boundaries of the glottis along with the vocal cords
Arytenoid cartilages
Opening of the larynx
glottis
Larynx cartilage: Adam’s apple, largest cartilage in the larynx
thyroid cartilage
Larynx cartilage: ring shaped cartilage, most caudal
cricoid cartilage
Functions of what structure: voice production; prevention of foreign material being inhaled; control airflow to and from the lungs
larynx
2 connective tissue bands attached to the arytenoid cartilages. Stretched across lumen of larynx parallel to each other. Vibrate as air passes over them
Vocal cords
Muscles attache to the _______ cartilages control the tension of the vocal cords
arytenoid
complete relaxation opens the glottis wide. What does this produce?
no sound
Tightening the tension of the vocal cords produces
higher-pitched sounds
Lessening the tension of the vocal cords produces
lower-pitched sounds
During swallowing, ______________ __________ pull the larynx forward and fold the epiglottis back over its opening
muscle contractions
Short, wide tube that extends from the larynx into the thorax. Divides into the 2 main bronchi that enter the lungs.
Trachea
When the trachea divides into the 2 main bronchi that enters the lungs. What is this called?
Bifurcation
What type of muscle is found on the dorsal side of the trachea?
smooth muscle
What type of cartilage makes up the rings in the trachea?
Hyaline cartilage
What type of epithelium lines the trachea?
ciliated epithelium
Cilia in the trachea move trapped material toward the
larynx
What shape are the rings of hyaline cartilage in the trachea of most species?
C-shaped
Which species have complete tracheal rings?
birds & reptiles
What causes a collapsing trachea?
weakened cartilage rings
In what animals is a collapsing trachea common?
toy breeds of dogs
What is the Tx for a collapsing trachea?
weight loss, restrict activity, use harness instead of collar, bronchodilators, cough suppressants, sx
What structures are part of the lower resp tract?
bronchi, bronchioles, alveolar ducts, alveoli
Air passages that lead from the bronchi to the alveoli
bronchial tree
R & L primary bronchus formed by the bifurcation of the trachea
bronchi
Do the bronchi contain cartilage?
yes
Each bronchus divides into smaller bronchi, which divide into even smaller bronchi, and then tiny
bronchioles
Can the diameter of the bronchi and bronchioles be adjusted?
Yes, they contain smooth muscle fibers in the walls
What nervous system controls smooth muscle fibers in the wall of the bronchial tree?
Autonomic nervous system
What effect does the sympathetic nervous system have on the airways?
Dilates them
Bronchial smooth muscle relaxation.
Aids respiratory effort during intense physical activity.
Bronchodilation
Bronchial smooth muscle partially contracts. Reduces size of air passage. Irritants in inhaled air can cause this.
Bronchoconstriction
Bronchioles subdivide into _________ which end in ____________
Alveolar ducts
Alveoli
Do bronchioles and alveolar ducts contain cartilage?
No
These are the smallest air passageways. They are microscopic and end in groups of alveoli
Alveolar ducts
Alveoli are arranged like what?
bunches of grapes
Groups of alveoli are called
alveolar sacs
Tiny, thin-walled sacs composed of simple squamous epithelium.
Alveoli
Alveoli are surrounded by networks of _______ composed of simple squamous epithelium
Capillaries
Do alveoli contain muscle or cartilage to prevent them from collapsing when air moves in and out during breathing?
No
Alveoli are lined with fluid that contains _________ which reduces surface tension and prevents alveoli from collapsing as air moves in and out
surfactant
What is the site of external respiration?
Alveoli
Exchange of O2 & CO2 between the air inhaled into the lungs and the blood flowing through the pulmonary capillaries
External respiration
Exchange of O2 & CO2 between the blood in the systemic capillaries and all the cell and tissues of the body
internal respiration
O2 and CO2 movement from higher concentration to lower concentration is an example of what?
simple diffusion
Hemoglobin that is carrying oxygen. One oxygen molecule is associated with each iron molecule.
Oxyhemoglobin
Hemoglobin that has released its oxygen.
Deoxyhemoglobin
What influences the ability of the hemoglobin molecule to carry oxygen? (4)
pH, temperature, O2 & CO2 levels
CO2 diffuses into RBCs & is transformed into
carbonic acid
What is the relative pH of venous blood compared to arterial blood?
more acidic
What vessel carries deoxygenated blood to the lungs?
Pulmonary artery (splits into L & R pulmonary arteries -> pulmonary arterioles -> capillaries
Oxygenated blood returns to the left side of the heart via the
pulmonary veins
Pulmonary arteries bringing deoxygenated blood to the lungs for gas exchange with the alveoli
Pulmonary circulation
Bronchial arteries arise from the aorta and supply O2 to the parenchyma (tissue) of the lung itself.
bronchial circulation
The tissue of the lung itself
Parenchyma
This part of the lung lies directly on the cranial surface of diaphragm. It is in the caudal part of the thoracic cavity.
Base
This part of the lung lies in the cranial portion of the thoracic cavity
Apex
The lateral surface of each lung is convex or concave?
convex
In the cat, dog, cow, goat, sheep, and pig, name the lobes of the left and right lungs
Left lung: cranial & caudal
Right lung: cranial, middle, caudal & accessory
What species has 1 lobe on the left lung, and a main and accessory lobe on the right lung.
Horse
_____ are distinguished by the major branches of the bronchi
Lobes
Small, well-defined area on medial side of lung where airways, blood vessels, lymph vessels, and nerves enter and leave the lung.
Hilus
This is the only area of the lung that is attached to the body
Hilus
What is the dorsal boundary of the thoracic cavity?
Thoracic vertebrae
What are the lateral boundaries of the thoracic cavity?
Ribs & intercostal muscles
What is the ventral boundary of the thoracic cavity?
sternum
What is the caudal boundary of the thoracic cavity?
Diaphragm
The area between the lungs is called
mediastinum
What lives in the mediastinum?
heart, trachea, esophagus, blood vessels, nerves, lymphatic structures
The thin membrane that lines the thoracic cavity and covers the organs & structures in the thorax
Pleura
The pleural layer that covers thoracic organs and structures
Visceral layer
The pleural layer that lines the cavity
parietal layer
space between the 2 pleural layers is filled with a small amount of
pleural fluid
What is it called when there is too much fluid in the pleural space?
Pleural effusion
What are some causes of pleural effusion?
trauma, infection, neoplasia
Presence of air in the thorax; this buildup of air puts pressure on the lung, so it cannot expand as much as it normally does when you take a breath resulting in a collapsed lung. What is this condition called?
Pneumothorax
A collapsed lung is called
atelectasis
Causes of pneuomothorax
penetrating wound into thorax
trauma to airways/lungs
TX for pneumothorax
thoracocentesis, chest tube
Pressure within the thorax in negative with respect to atmospheric pressure, therefore a partial _____ exists within the thorax
vacuum
Is the the pressure within the thorax positive or negative?
negative
The vacuum in the thorax does what?
pulls lungs tight out against the thoracic wall
This type of pressure helps draw blood through veins and into the atria
negative intrathoracic
Lungs follow passively as movements of the _____ ____ and ________ alternately enlarge and reduce the volume of the thorax.
Thoracic wall
Diaphragm
The process of drawing air into the lungs
inhalation
What are the 2 main muscles of inspiration?
External intercostal muscles
Diaphragm
Thin, dome-shaped muscle sheet with a right and left crus; forms caudal boundary of thorax; separates thorax from abdomen
Diaphragm
What species don’t have a diaphragm?
birds, reptiles
process of pushing air out of lungs
exhalation
What are the 2 main expiratory muscles?
Internal intercostal muscles & abdominal muscles
Volume of air inspired and expired during one breath (ml/breath)
Tidal volume
Tidal volume = ___ml/kg
10
What is tidal volume used to determine?
size of bag on anesthesia machine
Bag size = _____ x tidal volume
5-6
What sizes do bags come in for the anesthesia machine?
1/2 L, 1 L, 2 L, 3 L
Is it better to have a bag too small or too big on an anesthesia machine?
too big
volume of air inspired and expired during 1 min of breathing
Minute Volume
MV (ml/min) =
TV (tidal volume) x breaths/min
volume of air remaining in the lungs after maximum expiration. Lungs cannot be completely emptied of air
Residual volume
Are the respiratory muscles smooth or skeletal?
Skeletal
Is breathing voluntary or involuntary?
involuntary but can be overriden
Breathing is controlled by an area in the ______ _____ of the brain stem known as the ______ _____
Medulla oblongata
Respiratory center
Within the ______ _____ are individual control centers for inspiration, expiration, and breath holding
respiratory center
What part of the brain controls respiratory muscle contractions?
Respiratory center
What 2 systems send feedback to the respiratory center?
Chemical and Mechanical control systems
Stretch receptors in the lungs set limits on routine resting inspiration and expiration. What control system does this?
Mechanical control system
This system monitors the blood & only affects the breathing pattern if something gets out of balance. Receptors located in the carotid arteries, aorta, & brain stem monitor CO2, pH, & O2 in blood
Chemical control system
What is the normal pH of blood?
7.4
The more CO2 in the blood, the ______ the blood pH. (higher or lower)
lower, more acidic
Increased CO2 in blood causes decreased blood pH and triggers respiratory center to:
increase rate & depth of respiration
Decreased CO2 in blood causes increased blood pH and triggers respiratory center to:
decrease rate & depth of respiration
Decrease in blood O2 level is called
Hypoxia
Slight hypoxia triggers respiratory center to:
increase rate & depth of breathing
Neurons of the respiratory center can become so depressed that adequate nerve impulses cannot be sent to the respiratory muscles. Can cause breathing to decrease or stop completely. What condition is this?
Severe hypoxia
What happens if we are breathing for an animal that is under anesthesia?
O2 increases & CO2 decreases telling respiratory center to slow respiration
Bagging hyperventilates the patient causing more ____ than normal to be eliminated from the lungs. Decreased ____ causes the patient to stop breathing until the ____ level rises back into normal range
CO2
