· Consists of paired lungs and a series of air passages
· For gas exchange (respiration)
· Air conduction
· Air _filtration___________
· Upper respiratory system
· Develops embryologically from ___________ (primitive oral cavity)
· Nasal cavities, paranasal sinuses, nasopharynx, and oropharynx
· Lower respiratory system
· Develops embryologically from endoderm (primitive __________)
· Larynx, trachea, bronchii, and lungs
· Conducting Portion
· Upper part + larynx, trachea, bronchi, and most of the bronchioles
· Respiratory Portion
· Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli
· Paired cavities divided into vestibules, respiratory regions and _olfactory_________ regions
· Respiratory region lined by respiratory mucosa; warms/moistens/filters air
· Ciliated, pseudostratified columnar epithelium
· Columnar cells – cilia for motility
· Goblet cells – secrete _mucus_______
· Brush cells – sensory innervation
· Small granule cells – endocrine function
· Basal cells – pluripotential stem_____ cells
· Olfactory region lined by pseudostratified olfactory epithelium; nasal roof
· Lacks goblet cells
· Olfactory receptor cells – bipolar neurons with immotile cilia_______
· Supporting cells + brush cells + basal cells + Bowman’s glands
Pharynx and Larynx
Pharynx is a continuation of the _oral_____ and _nasal______ cavities
- Passes food to esophagus and air to larynx
Larynx – connection between pharynx and trachea
· Contains _vocal_______ folds which are covered by stratified squamous epithelium
· The remainder of the larynx is lined by respiratory mucosa
Extends from the larynx to mediastinum and divides into the two main bronchi
Wall of trachea has four layers
· Mucosa - ciliated pseudostratified epithelium
· Submucosa – dense irregular connective tissue
· Cartilaginous layer – C-shaped _hyaline__________ cartilage
· Adventitia – binds trachea to adjacent structures
Bronchi and Bronchioles
Right and left main bronchi enter lungs
· Lined by respiratory mucosa, w/ __cartilage_____ plates, & surrounded by smooth muscle
Bronchioles are branches of the bronchi < 1 mm in diameter with no cartilage or glands
· Composed simple cuboidal epithelium containing Club cells – for gas exchange
Bronchioles → alveolar ducts → alveolar sacs → clusters of alveoli
· Alveoli are the terminal__________ air spaces – septa allow gas exchange with the blood
· Alveolar epithelium composed of Type I and II alveolar cells (pneumocytes)
· Type I – thin squamous cells, line 95% of surface to form a barrier
· Type II – secretory cells for _surfactant___________ to prevent collapse of alveoli
· Air-blood barrier is the interalveolar septum
· Composed of layer of surfactant, a Type I cell, and a capillary endothelial cell,
The thyroid gland is located in the neck, develops from the endodermal____________ lining of the floor of the primitive pharynx (foramen caecum). It consists of two lateral lobes and an isthmus.
Consists mainly of thyroid follicles, the functional unit of the gland, which generally are formed from simple cuboidal follicular epithelium. The lumen follicles are filled with a gel-like mass called colloid, which contains thyroglobulin, an inactive storage form of thyroid hormones.
Follicular epithelium contains two types of cells:
· Follicular cells that produce thyroid hormones _T4___ and T3___ (Thyroxine)
· In response to TSH stimulation, follicular cells resorb colloid and transport
T4 and T3 into circulation.
· Thyroxine regulates tissue metabolism and influence growth & development
· Parafollicular cells that produce calcitonin___________
· Calcitonin is a physiologic antagonist to PTH, thought to regulate serum calcium
Essential functions of the kidneys:
· Homeostasis via control of:
· Electrolyte and water balance
· Plasma pH
· Tissue osmolality
· Blood pressure
· Excretion of metabolic waste products
· Endocrine activities:
· Secretion of hormones to regulate bone marrow erythropoiesis (erythropoietin),
· __Blood Pressure_____ _________ (renin)
· Ca2+ metabolism (activation of vitamin D).
GENERAL STRUCTURE OF THE KIDNEY
Each kidney is surrounded by a connective tissue capsule
Contains an outer cortex and inner __________ which is divided into 8 to 12 renal pyramids.
· Exhibits renal corpuscles and their associated convoluted and straight tubules.
· Aggregation of straight tubules and collecting ducts form the medullary rays
· Extends into medulla to form renal columns; these separate the renal pyramids
· A renal lobe includes the renal pyramid and its associated cortical tissue
· Characterized by straight tubules.and collecting ducts from the medullary rays
Has a specialized capillary network (vasa recta)
· Medullary tubules form conical pyramids
STRUCTURE AND FUNCTION OF NEPHRONS
The nephron is the basic structural and functional unit of the kidney; 1,000,000 each kidney
The nephron consists of the renal corpuscle and a tubular system:
- Starts at Bowman’s capsule
- Proximal thick segment - (proximal convoluted___________ tubule and proximal straight tubule)
- Thin segment - (thin part of the loop of Henle)
- Distal thick segment (distal straight tubule and distal convoluted tubule). The distal
convoluted tubule connects to the collecting tubule that opens at the renal papilla.
The spherical renal corpuscle contains the _glomerulus___________ surrounded by a double layer of the Bowman capsule.
The filtration apparatus of the kidney consists of the glomerular endothelium, glomerular basement membrane (GBM), and the Bowman capsule _podocytes_________.
The negatively charged GBM, which contains type IV and XVIII collagens, sialoglycoproteins, noncollagenous glycoproteins, proteoglycans, and glycosaminoglycans, acts as a physical barrier and an ion-selective filter.
Podocytes extend their processes around the capillaries and develop numerous secondary processes called pedicels (foot processes), which interdigitate with other foot processes of the neighboring podocytes. The spaces between the interdigitating foot processes form filtration slits that are covered by the filtration slit diaphragm.
The GBM in the renal corpuscle is shared among several capillaries to create a space for mesangial cells and their extracellular matrix.
Mesangial cells are involved in phagocytosis and endocytosis of residues trapped in the filtration slits, secretion of paracrine substances, structural support for podocytes, and modulation of glomerular distention.
The juxtaglomerular apparatus includes the macula densa (monitors Na+ concentration in tubular fluid), juxtaglomerular cells (secrete renin), and extraglomerular mesangial cells. It regulates blood pressure by activating the renin–angiotensin–aldosterone system (RAAS).
KIDNEY TUBULE FUNCTION
The glomerular ultrafiltrate from the Bowman capsule passes through a series of tubules and collecting ducts lined by epithelial cells that secrete and absorb various substances to produce the final urine.
The proximal convoluted tubule receives the glomerular ultrafiltrate from the Bowman capsule.
This tubule is the initial and major site for reabsorption of glucose, amino acids, polypeptides, water, and electrolytes.
Reabsorption of the ultrafiltrate continues as it flows from the proximal convoluted into the proximal straight tubule (the thick descending limb of the _distal straight tubule ___ __ _____) that descends into the medulla.
The loop of Henle, with both the descending limb (highly permeable to water) and ascending limb (highly permeable to Na+ and Cl−), concentrates the ultrafiltrate.
The distal straight tubule (thick ascending limb) ascends back into the cortex_______ to reach the vicinity of its renal corpuscle, where it makes contact with the afferent arteriole. In this area, the epithelial cells of the tubule form the macula densa.
The distal convoluted tubule empties the ultrafiltrate into the cortical collecting duct that lies in the medullary ray, which further adjusts the concentration of Na+ and K+ in the ultrafiltrate.
The medullary collecting duct is lined by cuboidal cells, with a transition to columnar cells as the duct increases in size. The collecting ducts possess aquaporins and antidiuretic hormone (ADH)–regulated water channels that regulate water reabsorption.
The collecting ducts open at the renal papilla, and the modified ultrafiltrate, now called urine, flows sequentially via the excretory passages.
Adrenal (Suprarenal) Gland
The adrenal glands are paired triangular organs embedded in the perirenal fat at the upper poles
of the kidneys. They secrete _steroid hormones_______ __________ and catecholamines.
· Cortex, a steroid-secreting portion that developed from the mesoderm; 90% of weight
· zona glomerulosa (outer) –produce mineralcorticoids like aldosterone
· zona fasciculata___________ (thick middle) –produce glucocorticoids (e.g., cortisol) that regulate glucose synthesis and glycogenesis
· zona reticularis (inner), which communicates with the medulla. These produce weak androgens
· Medulla, a catecholamine-secreting portion that develops from neural crest cells.
· Medulla contains chromaffin___________ cells that synthesize epinephrine and norepinephrine to prepare the body for a “fight-or-flight” response.
· Many myelinated, presynaptic sympathetic nerve fibers pass directly to the chromaffin cells.
· Upon impulse, the cells release norepinephrine and epinephrine
· Increase __heart rate____ ____, BP, respiration rate, decrease digestion
The eye is a specialized sensory organ for sight
Composed of tissues from:
· Neuroectoderm - retina
· ___________ ectoderm – lens, epithelium of the cornea
· Mesoderm – sclera, corneal stroma, vascular coat
Three structural layers
· Outer corneoscleral or fibrous coat – transparent cornea + white opaque sclera
· Middle vascular coat – choroid, ciliary body, and iris
· Inner layer – the _retina________
Chambers in the eye
· Anterior chamber – filled with aqueous humor
· Posterior chamber – filled with aqueous humor
· Vitreous chamber - filled with the _vitreous body__________ _____ (a transparent gel)
· Corneal epithelium – nonkeratinized stratified squamous epithelium
· Corneal stoma – thick avascular lamina propria and makes up 90% of the cornea
· Corneal endothelium – a single layer of __squamous__________ cells
· Here is where the metabolic exchanges occur
· Many cell organelles: mitochondria, rER, Golgi apparatus and vesicles
Sclera – contains flat collagen bundles and is divided into three layers
· Episclera – external layer of loose connective tissue
· Substantia propria – thick _collagen__________ fiber network makes up the investing fascia
· Extraocular muscles attach by tendons here
· Superchoroid lamina – located adjacent to the choroid
· Consists of thinner collagen fibers + elastic fibers
· Cellular components – melanocytes, macrophages, fibroblasts
· An episcleral space added to the surrounding periorbital fat allow eye rotation
· Contains the pupil and forms a contractile ______________
· Adaptation is the size change of the pupil responding to amount of light
· Consists of a highly vascularized CT stroma
· Posterior surface is highly pigmented melanin___________ and determines eye color
· Located between choroid and iris
· Contains the ciliary process
· Secretes _aqueous humor___________ __________
· Anchors suspensory lens fibers (zonula fibers)
· Contains the ciliary muscle that alters lens shape for focusing
· Transparent, avascular, _biconvex__________
· Suspended between the edges of the ciliary body
· Consists of :
· Lens capsule
· Subcapsular epithelium
· Lens fiber cells
· Part of vascular coat
· Choriocapillary layer provides the retina nutrients via vascularity
· Bruch’s membrane is the _basal lamina____ _____ for endothelial and retinal pigment epithelial cells
· Consists of two basic layers (that then can be divided into 10 cellular layers)
· Neural layer – inner layer with the photoreceptor cells
· Retinal pigment epithelium – outer layer for attachment to the choroid
· Most numerous, (120 million cylindrical segments) detect light intensity________
· Contain rhodopsin
· 7 million, conical__________ segments detect colors (RGB)
· Contain iodopsin
· Conducting neurons – bipolar neurons + ganglion cells which send axons to form optic nerve (CN II)
· Association cells- also neurons
· Supporting cells- neuroglial cells/astrocytes
· Eyelids – skin cells
· Orbicularis oculi muscles
· Tendon fibers of a levator muscle
· Palpebral conjunctive
· Stratified columnar epithelium with goblet cells
· Lacrimal gland
· Produces tears to moisten cornea
· Flows to _nasal____________ duct and into nasal cavity
The ear is a specialized sensory organ for both sound and balance
Composed of tissues from:
· Surface ectoderm – epithelial lining of the membranous labrynth
· First pharyngeal _groove_____ – external auditory meatus
· Pharyngeal pouch (endoderm) – auditory (Eustachian) tube, middle ear cavity
· 1st Pharyngeal arch – malleus, _incus_____, anterior part of the auricle
· 2nd Pharyngeal arch – stapes and posterior part of the auricle
Three structural components
· External Ear
· Middle Ear
· Inner Ear
- Auricle – collects and amplifies sounds
- External acoustic meatus – extends from auricle to the __tympanic membrane______ _________
Lined by integument with hair follicles and glands
- Sebaceous glands
- Ceruminous glands – produce cerumen (earwax)
Middle Ear – an air-filled space lined by mucous membrane. Separated by the eardrum from the
external auditory meatus.
- Ossicles – Malleus, incus, stapes
- Eustacian tube – connects middle ear to _nasopharynx__________
Tympanic membrane - 3 layers: integument/thin CT/mucous membrane of middle ear
- Ossicles cross middle ear and connect the tympanic membrane to the _oval window___ _________
Compartments of the Internal Ear (both within the temporal bone)
· Bony labrynth – consists of semicircular canals, vestibule, and cochlea
· Membranous labrynth
· A series of communicating sacs: _utricle_______, saccule, and endolymphatic sac
· Also a series of endolymph containing ducts – three semicircular ducts, a cochlear duct, endolymphatic duct, and ductus reuiens
Inner Ear – has three fluid filled spaces
· Endolymphatic space – within the membranous labrynth
· Perilymphatic space – lies between the wall of the bony and membranous labrynth
· Cortilymphatic space – lies within the tunnels of the Organ of _Corti______ (in the cochlea)
· Hair cells are mechanoreceptors
· Contain hair bundles (rows of stereocilia), overlaid with gel otolithic membrane
· Movement of the _otoliths_________ causes an ionic channel flow of an action potential
· Cochlear canal is divided into three parallel compartments
· Scala media (cochlear duct) – contains spiral Organ of Corti
· Composed of hair cells with stereocilia
· Hair cell movement stimulates electrical impulses
· These impulses transmitted to the _vestibulocochlear_______________ nerve
· Scala vestibule
· Scala tympani
· Sound waves transmitted to tympanic membrane → ossicles → oval window → produce waves in the scala vestibule → deflects Organ of Corti → electrical impulse