Respiratory System

• responsible for the exchange of gases between blood and the atmosphere

• improve the quality of the inspired air and regulate its flow

function of the respiratory system

• respiratory passages

  • nose

  • nasopharynx

  • larynx

  • trachea

• site of gaseous exchange

  • lungs

  • bronchial tree

division of respiratory system based on function

• upper respiratory tract

• lower respiratory tract

division of respiratory system based on location

upper respiratory tract

respiratory organs located within the head

lower respiratory tract

structures within the larynx to the lungs

• nose

• nasopharynx

• larynx

• trachea

structures included in the respiratory passages

nose

• formed by nasal bones dorsally, tha maxillae laterally and the palatine processes of the incisive bone, the maxillae and palatine bones ventrally

• it is limited caudally by the cribriform plate of the ethmoid bone

• nasal bones - dorsally

• maxillae and palatine processes - laterally

• maxillae and the palatine bones - ventrally

structures that encloses the nose

external nares (nostril)

the rostral part of the muzzle

• carnivores

• small ruminants

species wherein the nostrils features:

• the specialized area (planum nasale) around the nostril is hairless and are divided by a median groove called philtrum which continues ventrally to divide the upper lip

planum nasale

specialized skin area around the nostril of carnivores and small ruminants

philtrum

• median groove that divides the upper lip and nose

• deep and extend into the nostrils in carnivores and small ruminants

• it is shallow or absent in pig, ox, or horse

porcine/pig

species wherein the nostrils features:

• the disc-like movable point of the muzzle is called rostrum or snout

• it is supported by the rostral bone (os rostrale)

• covered by modified skin which forms the rostral plate (planum rostrale)

rostrum or snout

disc-like movable point of the muzzle of pig

os rostrale

rostral bone that supports the rostrum or snout of the pig

planum rostrale

rostral plate on the rostrum or snout of the pig

bovine/ox

species wherein the nostrils features:

• the integument of the frontal region is modified to form the smooth hairless nasolabial plate (planum nasalabiale or muzzle)

planum nasolabiale or muzzle

smooth hairless nasolabiale plate of ox

equine/horse

species wherein the nostrils features:

• it consist of a normal skin covered with a coat of short hair interspersed with tactile hairs

• porcine/pig

• ruminants

species wherein the nose is kept moist by glands which secrete through pores in the small polygonal fields

carnivores

species wherein the glands that keeps the nose moist is absent

• carnivores

• small ruminants

species wherein the philtrum is deep and extend into the nostrils

• porcine/pig

• bovine/ox

• equine/horse

species wherein the philtrum is shallow or absent

• porcine/pig

• bovine/ox

species wherein the shape of the nostril is oval

small ruminants

species wherein the shape of the nostril are narrow slits

equine/horse

species wherein the shape of the nostril is semilunar

equine/horse

species wherein the muscles of the nostrils are well developed and can transfer the normally semilunar nostrils to become circular

• carnivores

• porcine/pig

species wherein the muscles of the nostrils that can transfer the normally semilunar nostrils to become circular are poorly developed

equine/horse

species wherein there are dorsal and ventral groove present near the nostrils; the dorsal leads into a blind cutaneous pouch, the nasal diverticulum (or false nostril), the ventral leads into the nasal cavity

nasal diverticulum or false nostril

blind cutaneous pouch where the dorsal groove near the nostril leads

nasal cavities

• extends from the nostrils to the cribriform plate of the ethmoid bone

• divided by the nasal septum into left and right sides

• lined with mucous membrane and contains the nasal conchal bone (dorsal and ventral nasal conchal bones) which serves to increase the respiratory surface area

nasal septum

divides the nasal cavities into left and right side

nasal conchal bone

bone that serves to increase the respiratory surface area

nasal septum

• divides the nasal cavity into right and left halves

• it consists of:

  • osseous part

  • cartilaginous part

osseous part of nasal septum

part of nasal septum that consists of the vomer venntrally and perpendicular plate of the ethmoid bone caudally

vomeronasal organ

• a pair of blind sacs that lie in the floor of the nasal cavity septum

• they perform special olfactory functions notably the investigation of the urinary phenomena; this seems to be related to the ‘flehmen’ reaction, a peculiar, sustained retraction of the upper lip

lateral nasal gland

• absent in ox, not very large in other domestic animals

• well developed in avian species and are called salt gland

• the secretion of the lateral nasal gland moistened the inhaled air and also believed to play a role in the functioning of the vomeronasal organ

salt gland

lateral nasal gland in avian species

bovine/ox

species where the lateral nasal gland is absent

vomeronasal organ

the secretion of the lateral nasal gland moistened the inhaled air and also believed to play a role in the functioning of the ___

nasal conchae (nasal turbinates)

cartilaginous or ossified scrolls covered with nasal mucosa that occupy most of the nasal cavity

• dorsal nasal meatus

• middle nasal meatus

• ventral nasal meatus

• common nasal meatus

division of the dorsal and ventral nasal conchal bones

dorsal nasal meatus

• space between the roof of the nasal cavity and the dorsal conchal bone

• it is longest in domestic animals

bovine/ex

species wherein the caudal 2/3 of dorsal nasal meatus encloses the dorsal conchal sinus

equine/horse

species wherein the caudal part of the dorsal nasal meatus encloses the dorsal conchal sinus, which combines with the frontal sinus to form the conchal frontal sinus

conchal frontal sinus

in horse, the caudal part of dorsal nasal meatus encloses the dorsal conchhal sinus, which combines with the frontal sinus to form the

middle nasal meatus

space between the dorsal and ventral conchal bone

nasomaxillary orifice

the opening into the paranasal sinuses is found in this caudal part of the middle nasal meatus

ventral nasal meatus

• this is the main pathway for airflow leaading to the pharynx

• largest

• it is the space between ventral conchal bone and the floor of the nasal cavity

common nasal meatus

• longitudinal space between conchal bone and nasal septum

• it communicates with all the other nasal meatus

paranasal sinus

• diverticula of the nasal cavity

• form air-filled cavities between the external and internal lamina of the bones of the skull

• it is lined by respiratory mucosa

• nasal

• maxilla

• incisive

• frontal

• lacrimal

• zygomatic

• perpendicular plate of the palatine

structures that make up the wall of the nasal cavity

• incisive

• palatine process of the maxilla

• horizontal plates of the palatine bone

structures that make up the floor of the nasal cavity

nasopharynx

• after leaving the nasal cavity, the inspired air passes through the choanae into the ____

• along the wall of this is the pharyngeal opening of auditory (Eustachian tube)

guttural pouch

• in the horse, the auditory (Eustachian) tube is greatly dilated to form this

equine/horse

species wherein the auditory (Eustachian) tube is greatly dilated to form the guttural pouch

larynx

• short, bilaterally symmetrical musculocartilaginous tube that connects the lower part of the pharynx with the trachea

• it contains the organ of phonation and also function to protect the entrance to the traches thus preventing aspiration of foreign material into the lower RT

• consists of several cartilages lined on the inside with the nervous membrane; the cartilages are connected to each other to the hyoid bone and to the trachea by ligaments and muscles

vocal folds

the cavity of the larynx is constricted by __

cranial laryngeal nerve

innervates the mucous membrane of the larynx

caudal (recurrent) laryngeal nerve

innervated the laryngeal muscles except the cricothyroideus

• cricoid (unpaired)

• thyroid (unpaired)

• epiglottis (unpaired)

• arytenoids (paired)

cartilages of the larynx

• cricoid

• thyroid

• epiglottis

unpaired cartilages of the larynx

arytenoids

paired cartilages of the larynx

cricoid cartilage

• caudal

• hyaline cartilage that closes the entrance into the larynx during swallowing

• it forms a complete ring at the caudal end of the larynx

thyroid cartilage

• lateral and ventral

• hyaline cartilage

epiglottis

• rostral

• elastic cartilage

• resembles a leaf with a small stalk and a large blade

arytenoids

• dorsal

• hyaline (body)

• elastic (vocal and corniculate processes)

• muscular process

• vocal process

• corniculate process

• cuneiform process

processes of the arytenoid cartilage

• aditus laryngis

• laryngeal ventricles

• vestibular fold

parts of the laryngeal cavity and mucosa

aditus laryngis

inlet to the laryngeal cavity

laryngeal ventricles

lateral evaginations of the laryngeal mucosa

• canine/dog

• porcine/pig

• equine/horse

species where the laryngeal ventricles is present

ruminants

species where the laryngeal ventricles is absent

• porcine

• ruminants

species where the vestibular fold is absent

• cricothyroideus

• dorsal cricoarytenoideus

• lateral cricoarytenoideus

• transverse arytenoid

• thyroarytenoid

muscles of the larynx

cricothyroideus

the only laryngeal muscle innervated by the cranial laryngeal nerve

dorsal cricoarytenoides

• innervated by the caudal (recurrent) laryngeal nerve

• main abductor of the vocal folds (widening the glottic cleft)

lateral cricoarytenoideus

• innervated by the caudal (recurrent) laryngeal nerve

• constriction of this muscle narrows the glottic cleft

transverse arytenoid

• innervated by the caudal (recurrent) laryngeal nerve

• adducts the two arytenoid cartilages, thus narrowing the glottic cleft

thyroarytenoid

in the horse and dog, this is divided into the ventricular and the vocal muscles

left recurrent laryngeal nerve

• paralysis results in a stertorous sound produced at inspiration in affected animal

• the condition is called laryngeal hemiplegia or “roaring”

laryngeal hemiplegia / roaring

a stertorous sound produced at inspiration in affected animal

trachea

• non-collapsible tube, which continues the respiratory pathway from the cricoid cartilage to the root of the tongue where it bifurcates into right and left principal bronchia

• it is accompanies by the common carotid arteries vagosympathetic trunks, internal jugular veins, caudal laryngeal nerves, and tracheolarymphatic trunks

equine/horse

species where the internal jugular veins is often absent

• caprine/goat

• ovine/sheep

species where the internal jugular veins is always absent

tracheal cartilages

open dorsally and is completed by the trachealis muscle

• horse, ox, sheep, goat - 48 to 60

• dog - 42 to 46

• cat - 38 to 43

• pig - 29 to 36

number of tracheal cartilages in each species

structure of trachea

• consists of varying number of hyaline cartilaginous rings that are incomplete dorsally for most animals, (except in chickens where it is complete) where it is completed by connective tissue and trachealis muscle (smooth muscle)

• avian/chickens

species wherein the hyaline cartilaginous ring of trachea is complete

• carnivores

• porcine

• ruminants

• equine

species wherein the hyaline cartilaginous ring of trachea is incomplete

carnivores

species wherein the trachealis muscle lies outside the cartilage

• porcine

• ruminants

• equine

species wherein the trachealis muscle lies below the cartilage

• porcine

• ruminants

species wherein a tracheal bronchus or epibronchus is given off to the cranial lobe of the right lung

• lungs

• bronchial tree

structures included in sites of gaseous exchange

lungs

• left and right

• connected with each other at the bifurcation of the trachea

• these are elastic, air-filled organs shaped like a semi-cone with a base and an apex

• located within the pleural sacs which come together medially to form the mediastinum

• its color depends on the amount of blood it contains

• on the average, the lungs represent 1 to 15% of the total body weight, its size varies depending on the amount of air it contains

pink

color of the lungs under complete bleeding

dark red

color of the lungs under partial bleeding

true

true or false:

the lungs is always heavier after inspiration

true

true or false:

the right lung is always larger than the left lung (4:3) during expiration

• costal surface

• medial (mediastinal) surface

• diaphragmatic surface

surfaces of the lungs