Visceral systems Flashcards
structural division of respiratory system
1) upper: nasal cavity, nose, pharynx, larynx
2) lower: trachea, bronchi, bronchioles
functional division of respiratory system
1) conducting: nasal cavity, pharynx, larynx, trachea, bronchi, terminal bronchioles
2) respiratory: respiratory bronchioles, alveolar ducts, alveoli
conducting portion features
- lined by respiratory mucosa
- function: filter, warm and moisten air
respiratory mucosa
1) pseudostratified ciliated (motile to sweep mucus and trapped contaminants towards pharynx for swallowing or expulsion) columnar epithelium with goblet cells (produce mucus) + stem cells
2) lamina propria: loose CT with BVs to warm air + mucous glands
respiratory portion features
- respiratory bronchiole branches from terminal bronchiole, then into alveolar ducts that lead into alveolar sac (made up of alveoli)
- function: where gas exchange takes place
nasal cavity features
- extends anteriorly from nares (nostrils) to choanae posteriorly (continuous with nasopharynx)
- functions: conduct air, filter/warm/humidify air, sense odorants
nasal septum
- divides nose into left and right parts
- formed by perpendicular plate of ethmoid and vomer
nasal cavity subdivision
- superior, middle and inferior conchae separate cavity into air passages (meatuses)
- curved shape keeps air in cavity for longer (swirling around)
- sinuses also connect with nasal cavity
- everything surrounded by mucosa
lateral wall of nasal cavity
- superior and middle nasal conchae (ethmoid)
- lacrimal bone
- inferior nasal concha
- maxilla
- perpendicular plate of palatine
medial wall of nasal cavity
- nasal septum: perpendicular plate of ethmoid, vomer and septal cartilage (hyaline)
roof of nasal cavity
- cribriform plate of ethmoid
- frontal bone
- nasal bone
- sphenoid bone
floor of nasal cavity
- horizonal plate of palatine
- palatine process of maxilla
paranasal sinuses
- lighten mass of skull, increase surface area of respiratory mucosa, create turbulence
- communicate with cavity via ducts
paranasal sinus ducts
1) above superior meatus: sphenoidal sinus
2) into superior meatus: posterior ethmoidal air cells
3) into middle meatus: frontal sinus, maxillary sinus
4) into inferior meatus: nasolacrimal duct
olfaction
- superior part of nasal cavity has olfactory epithelium
- turbulence brings odorants into contact with epithelium, where they dissolve in mucus and stimulate sensory neurons (binding to specific receptors = depolarization)
olfactory organs
1) olfactory epithelium: specialized pseudostratified ciliated columnar
2) underlying lamina propria
cells of olfactory epithelium
1) olfactory sensory neurons: bipolar, dendrites form knob that projects into nasal cavity
2) supporting cells: mechanical and metabolic support to receptor cells
3) basal cells: replace olfactory sensory neurons, decrease with age
olfactory knob
- contains non-motile cilia with olfactory receptors on the surface
olfactory pathway
two neurons:
1) from olfactory epithelium, form CN I and pass through cribriform plate
2) in olfactory bulb, travel in olfactory tract to primary olfactory cortex (temporal lobe), hypothalamus, and limbic system
*thalamus not involved! only exception out of the senses
oral cavity function
- analysis of food
- mechanical processing
- lubrication (saliva)
- limited digestion
oral cavity characteristics
- lined by oral mucosa: stratified squamous non-keratinized epithelium
- buccal fat pads and buccinator muscles support mucosa of cheeks
oral cavity features
1) hard and soft palate
2) palatoglossal arch: extends directly from uvula
3) palatopharyngeal arch: posterior to 2)
4) palatine tonsil: between arches
5) uvula: extends from soft palate
6) superior labial, lingual, inferior labial frenulum
7) fauces: opening to pharynx
8) oral vestibule: space between cheek/lips and teeth
9) gingiva: gums
oral cavity boundaries
1) roof: hard (maxilla and palatine) and soft palate
2) floor: tongue
3) anterior: teeth and lips with orbicularis orbis
4) posterior: palatoglossal arch/folds, palatine tonsil, palatopharyngeal arch/golds
orbicularis orbis
- sphincter muscle continuous around the mouth
soft palate function
- moves up to close off nasopharynx during swallowing
uvula function
- prevents food from entering oropharynx too soon
tongue muscles
1) extrinsic: pass to tongue from bony attachments (to external structures), function to position tongue for speech and swallowing
2) intrinsic: divided by left and right halves by median sagittal septum, within tongue in different orientations, function to alter shape of tongue
extrinsic tongue muscles
1) hyoglossus (3): attach to hyoid bone
2) palatoglossus: palatine
3) genioglossus: chin (genu of mandible)
4) styloglossus: styloid process of temporal bone
innervation of tongue
1) motor: majority by CN XII, palatoglossus by CN X
2) posterior tongue: general sensory and special (taste) by CN IX
3) anterior tongue: special by CN VII and general by CN V3
CN XII lesion
- dysarthria: difficulty speaking
- dysphagia: difficulty swallowing
floor of the mouth
- mandible
- hyoid
- suprahyoid muscles
- salivary glands
suprahyoid muscles
- elevate hyoid and larynx when swallowing
1) digastric (anterior belly, “two bellies”)
2) stylohyoid (styloid process
3) mylohyoid (mandible)
4) geniohyoid (chin)
infrahyoid muscles
- below hyoid
- not part of floor of mouth
1) omohyoid: scapula to hyoid
2) sternohyoid: sternum to hyoid
3) sternothyroid: sternum to thyroid cartilage
4) thyrohyoid: thyroid cartilage to hyoid
salivary glands
- three pairs: parotid, sublingual, submandibular
- multicellular exocrine
- enclosed by dense fibrous CT
- produce/secrete saliva under autonomic control
parotid gland
- duct opens into oral vestibule (by second maxillary molar)
- largest salivary gland
sublingual gland
- below tongue
- numerous ducts open into floor of oral cavity (lateral to that of submandibular gland)
submandibular gland
- below mandible
- ducts open into floor of oral cavity lateral to lingual frenulum
temporomandibular joint (TMJ)
- synovial joint
- mandibular fossa (temporal bone) articulates with head of condylar process (mandible)
- articular surfaces separated by fibrocartilage disc
- loose capsule = highly mobile and easily dislocated
TMJ movements
1) hinge: elevation (close mouth) and depression (open mouth)
2) gliding: retraction (tuck chin), protrusion/protraction (stick chin out), lateral grinding
lockjaw
- dislocated TMJ
- jaw stuck open
muscles of mastication
- produce TMJ movements
- innervated by CN V3
1) temporalis: elevation and retraction
2) masseter: elevation
3) lateral pterygoid: protrusion, side to side movement, opening jaw (mostly by gravity)
4) medial pterygoid: elevation, side to side movement
pterygoid muscle attachments
- to lateral pterygoid plate
pharynx
- common space used by respiratory and digestive systems
- muscular tube extending from base of skull to upper esophageal sphincter
- contracts reflexively during swallowing
- stratified squamous nonkeratinized
pharynx innervation
- motor: CN X
- sensory: CN IX
pharynx parts
1) nasopharynx: pharyngeal tonsils (adenoids), opening of pharyngotympanic tubes (connection to auditory tube)
2) oropharynx: palatine and lingual tonsils, first line of defense
3) laryngopharynx: opens into larynx (air) and esophagus (food)
cricoid caritlage
forms part of larynx (laryngopharynx)
pharyngeal muscles
1) circular: constrict during swallowing (ordered), overlap each other
- superior, middle and inferior pharyngeal constrictor
2) longitudinal:
- stylopharyngeus (styloid process)
- palatopharyngeus (soft palate)
- salpingopharyngeus (pharyngotympanic tube)
pharyngeal muscle innervation
- CN X for all except stylopharyngeus (CN IX)
larynx features
- laryngopharynx opens anterior into larynx and posteriorly to esophagus
- inferiorly into trachea
- function: passage of air, vocalization and prevents food from entering trachea (epiglottis covers larynx)
larynx hyoid connection
- suspended from hyoid bone by thyrohyoid membrane
extrinsic muscles of larynx
- suprahyoid: elevate hyoid bone (and larynx)
- infrahyoid: depress
- during swallowing and speaking
- specifically during swallowing: elevated larynx bends epiglottis over laryngeal inlet
larynx cartilage
- held in place by ligaments and muscles
- three unpaired frameworks:
1) thyroid cartilage: anterior laryngeal prominence (“adam’s apple”), incomplete posteriorly (superior and inferior horn)
2) cricoid cartilage: complete ring, inferior to 1)
3) epiglottis - paired:
1) arytenoid cartilages: associated with corniculate and cuneiform cartilages
larynx cartilage connecting membranes
1) thyrohyoid membrane: dense CT connecting larynx to hyoid
2) cricothyroid membrane: connects thyroid and cricoid cartilage
larynx intrinsic ligaments
- not the same as bone-bone ligaments
- extend between cartilage
1) vestibular ligament: corniculate and thyroid cartilage, along with mucosa forms vestibular folds to protect vocal folds
2) vocal ligament: arytenoid and thyroid, elastic CT, along with mucosa forms vocal folds (avascular, produce sound)
rima glottidis
space between vocal folds
epithelium in the larynx
- above vocal folds: stratified squamous nonkeratinized
- below: respiratory epithelium
sound production (phonation)
- adductor intrinsic muscles adduct arytenoid cartilages
- rima glottidis decreases in size –> air passing through vibrates folds to produce sound waves
vocal folds during respiration
- abductors abduct arytenoid cartilages
tensors and relaxers
- tiny muscles that adjust length of vocal ligaments by tilting thyroid cartilage
what affects sound production?
1) tone: approximation of vocal folds
2) pitch: anterior rocking of thyroid = more tension in vocal fold = higher pitch
3) volume: more air = more speed = louder voice
4) quality: vibration within larynx, pharynx, oral cavity, nasal cavity and nasal sinuses
what happens in whispering?
- arytenoids are adducted, but not fully pulled medially
- all but posterior portion of rima glottidis closed
- more air passes through, vocal folds don’t vibrate as much and thus quieter pitch
thoracic cavity location
above diaphragm
abdominopelvic cavity location
below diaphragm
characteristics of body cavities
- lined by serous membranes
- do not open to the exterior
serous membrane layers
1) visceral layer: around organ
2) parietal layer
- layers are continuous with each other
- layers produce serous fluid (lubricant) that fills serous cavity between them
thoracic cavity subdivision
1) mediastinum: between pleural cavities, includes pericardial cavity with heart
2) right pleural cavity: right lung
3) left pleural cavity: left lung
mediastinum
- sternum anterior, thoracic vertebrae posterior
- bordered laterally by lungs
- further divisions:
1) posterior mediastinum: trachea, primary bronchi, esophagus, great vessels, loose areolar CT
2) middle mediastinum: contains heart
3) anterior mediastinum
tracheal rings
- trachea surrounded by 15-20 tracheal rings (anterior, c-shaped) and muscle (posterior, in front of esophagus)
annular ligaments
- join tracheal rings
- elastic cartilage allows for flexibility
carina of trachea
- bifurcation of trachea into right and left primary bronchi
branching of bronchial tree
1) trachea
2) primary bronchi: enter hilus of each lung, one per lung
3) lobar (secondary) bronchi: one per lung lobe
4) segmental (tertiary) bronchi: one per bronchopulmonary segment
5) bronchioles: each tertiary branches several times to form these
6) terminal bronchioles
trachea structure
- connects larynx to primary bronchi
- lined with respiratory mucosa
- cartilage rings anteriorly
- trachealis muscle (smooth) posteriorly: relaxes with SyNS stimulation for bronchodilation
layers of trachea epithelium
1) respiratory epithelium (mucosa)
2) lamina propria (mucosa)
3) seromucous glands in submucosa
4) perichondrium
5) hyaline cartilage ring
right/left lung lobes
- right = superior, middle and inferior
- left = superior and inferior
bronchopulmonary segments
- 9-10 in each lung
- each has tertiary bronchus
benefit of lung segmentation
- diseased segments can be removed while preserving function of others
bronchi histology
- respiratory mucosa with fewer goblet cells
- amount of cartilage decreases moving through bronchi (inhibit gas exchange)
- circular layer of smooth muscle appears in bronchi (can change size of tube, modulates SA)
- lots of lymphocytes
bronchiole histology
- epithelium becomes simple ciliated columnar/cuboidal, then simple cuboidal/low columnar (bronchiolar exocrine aka club cells)
- no mucosal glands or cartilage
- smaller, less circular lumen than bronchi
- more smooth muscle (prominent bundles lead to distinct shape)
- adjacent to blood vessels
- surrounded by alveoli
- lots of lymphocytes
respiratory portion branching
1) respiratory bronchioles: from terminal bronchioles, decreasing smooth muscle
2) alveolar ducts: no smooth muscle
3) alveolar sac: collections of alveoli
4) alveoli
pulmonary lobule
- branches of pulmonary arteries form capillary beds around alveoli for gas exchange
- pulmonary artery -> pulmonary arteriole -> pulmonary venules -> pulmonary vein -> heart
respiratory bronchiole histology
- lined with bronchiolar exocrine cells
- surrounded by few alveoli
- subdivide into alveolar ducts with simple squamous epithelium
- pulmonary arteries and veins visible
alveoli characteristics
- site of gas exchange, resembles a pouch (open on one side to alveolar duct/sac)
- between alveoli: interalveolar septa with fibroblasts, elastic (spongy) and reticular (maintain shape) fibers + pulmonary capillaries
- two types of cells (pneumocytes) and macrophages
type I alveolar cells
- numerous
- form simple squamous epithelium
type II alveolar cells
- rounded cells, vacuolated cytoplasm
- not as numerous
- secrete surface-active agent (surfactant) to decrease surface tension and maintain alveolar patency (sacs remain open)
alveolar macrophage
- phagocytose particulate matter
- contribute to black remnants on lungs (some in healthy, lots in smoker lungs)
blood-air barrier
- respiratory membrane with:
1) endothelium
2) thin basement membrane
3) alveolar epithelium - gas exchange is rapid due to thinness (~0.5 micrometer) of membrane and small, lipid-solubility of gases
alveoli histology
- lots of empty space
- type I cells: flat, little cytoplasm
- type II: cuboidal/round
- macrophages: darker spots, protrude into spaces
- capillaries: contain RBCs
emphysema
- damaged and permanently enlarged alveoli (destruction of elastic fibers in lungs)
- breathlessness because air becomes trapped in lungs at the end of exhalation (can’t push out, gas exchange inhibited as well)
respiratory epithelium proximal to distal
1) trachea: pseudostratified ciliated columnar with goblet cells
2) bronchi: transition to simple columnar with cilia and few goblet cells
3) bronchioles: transition to simple cuboidal with or without cilia, exocrine cells appear as they branch
4) alveoli: type I/II alveolar cells
respiratory lamina propria proximal to distal
1) trachea: loose CT
2) bronchi: loose CT
3) bronchioles: thin or indistinct
4) alveoli: none
respiratory secretory cells proximal to distal
1) trachea: seromucous glands in submucosa
2) bronchi: seromucous glands in submucosa
3) bronchioles: bronchiolar exocrine cells
4) alveoli: type II alveolar cells
respiratory cartilage rings proximal to distal
1) trachea: c-shaped, joined by annular ligaments
2) bronchi: incomplete, irregular plates
3) bronchioles: none
4) alveoli: none
respiratory smooth muscle proximal to distal
1) trachea: trachealis (at free ends of cartilage)
2) bronchi: discontinuous layer, more prominent as bronchi branch
3) bronchioles: prominent, large layer –> thin, indistinct, small layer
4) alveoli: none
respiratory adventitia proximal to distal
1) trachea: loose CT
2) bronchi: loose CT
3) bronchioles: merges with submucosa
4) alveoli: none
pleura
- serous membrane lining wall of pleural cavity and lungs
- mesothelium: simple squamous epithelium attached to loose areolar CT
- layers: parietal pleura, pleural cavity (small, with pleural fluid), visceral pleural
pleural cavity
- contains transudate (pleural fluid) for lubrication and tension between membranes
pleural recesses
- spaces left behind in pleural cavity to accommodate expansion of lungs during inhalation
1) costodiaphragmatic recess: around costal edge of base of lung
2) costomediastinal recess: extension of cavity between sternum and mediastinum
pleural effusion
- excess fluid in pleural space, shows up as white on x-ray instead of black (empty air)
- two types:
1) transudative pleural effusion: caused by changes in hydrostatic pressure, leads to excess fluid
2) exudative pleural effusion: inflammatory conditions, infection, lung injury or tumour, leads to excess fluid, protein and immune cells –> additional spaces in endothelial cells
lung structure
- cone shape with apex above clavicle and base
- lobes separated by deep fissures
- right lung: superior, middle, inferior lobe
- left lung: superior, inferior
lung lobe surfaces
1) costal: contact with ribs (anterior, lateral and posterior)
2) mediastinal: medial surface
3) diaphragmatic: base, close to diaphragm
lung fissures
1) horizontal: separates superior and middle (right lung)
2) oblique: separates middle and inferior (right) or superior and inferior (left)
root of the lung
- contained in the hilus
- consists of primary bronchi, pulmonary arteries, veins, nerves and lymphatics enclosed in CT
hilus arrangement in R/L lung
- right: veins inferior, arteries anterior to primary bronchi
- left: artery most superior, primary bronchus, veins inferior to other two
grooves and impressions in lung
- right: posterior esophageal impression
- left: posterior groove for aorta, anterior cardiac impression and cardiac notch
thorax bones
- 12 pairs of ribs (flat bones) and costal cartilages
- 12 thoracic vertebrae and intervertebral disks
- sternum
sternum structure
1) manubrium: articulates with clavicles
2) body
3) xiphoid process
intercostal space
between ribs
costal margin
formed by bottom of rib cage
types of ribs
1) true ribs (1-7): attach directly to sternum via a costal cartilage
2) false ribs (8-12): attach indirectly (not their own costal cartilage to sternum OR lack attachment
3) (false) floating ribs (11-12): no anterior attachment or tubercular facets
typical rib structure
1) head: has two articular facets that articulate with body of thoracic vertebrae
2) neck
3) tubercle: has tubercular facet to articulate with transverse process of thoracic vertebra (corresponding)
4) angle
5) costal groove: internal aspect, protects blood vessels and nerves
5) body
6) costal cartilage (for most)
*applies to ribs 3-9
what permits movement of thoracic wall?
articulations of ribs and thoracic vertebrae (synovial joints)
superior/inferior thoracic aperture
- superior: bordered by T1, 1st ribs and superior border of manubrium + contains trachea and blood vessels
- inferior: bordered by T12, ribs 11/12, costal margins and xiphisternal joint + closed off by diaphragm
attachments of rib cage
1) jugular notch
2) clavicular notch: clavicle
3) sternal angle: manubrium and body articulate, forms protrusion
4) costal notches: attachment of costal cartilage
5) xiphisternal joint: body and xiphoid process articulate, has limited movement
6) diaphragm attachment
thoracic wall muscles
- occupy and support intercostal spaces
- overlap each other and fibers run in different directions for added strength
1) external intercostals: do not attach to sternum, fibers run inferiorly and anteriorly, elevate ribs during inhalation
2) internal intercostals: start from sternum, fibers run inferiorly and posteriorly, depress ribs during FORCED exhalation
3) innermost intercostals
costal groove
- contains VAN (vein, artery, nerve –> superior to inferior)
- between inner and innermost intercostals
arteries of thoracic wall
1) thoracic aorta
2) subclavian artery (branches off brachiocephalic)
3) internal thoracic arteries: anterior aspect inside thoracic wall, arises from 1)
4) anterior and posterior intercostal arteries: from 1) and 3), in costal groove, ant/pos anastomose with each other for collateral circulation
5) subcostal artery (last artery)
veins of thoracic wall
1) internal thoracic vein: drains blood anteriorly into brachiocephalic vein and superior vena caba
2) anterior and posterior intercostal veins: most (posterior) drain into azygos venous system
3) subcostal vein
4) azygos and hemiazygos veins: drain back and thoracoabdominal walls and viscera, pathway between SVC and IVC
azygos venous system
1) right intercostal veins drain into azygos
2) left intercostal veins drain into hemiazygos, then azygos
3) azygos drains into superior vena cava
lymphatic drainage in thoracic wall
- lymphatics throughout drain thoracic wall into thoracic duct
inhalation mechanism
- thoracic cavity dimensions and intrathoracic volume increases
- draws air in because of pressure drop
- structure of pleura and lungs enable this to occur: pleural fluid creates tension between membranes, inherent elasticity of lungs allow expansion to remain in contact with thoracic wall
- diaphragm contracts (flattens)
exhalation mechanism
- typically passive process: recoil of lungs and relaxation of muscles
- intrathoracic volume decreases, expelling air out
movements of thoracic wall during inhalation
- diaphragm (flattens) and external intercostals (elevates ribs and sternum) contract
- vertical changes: diaphragm flattens
- lateral changes: ribs elevated, thoracic cavity widens
- anterior/posterior changes: inferior portion of sternum moves anteriorly
movements of thoracic wall during exhalation
- passive process
- vertical changes: diaphragm relaxes, moves up, thoracic cavity narrows
- lateral changes: ribs depressed, thoracic cavity narrows
- anterior-posterior changes: inferior portion of sternum moves posteriorly
diaphragm structure
- forms floor of thoracic cavity
- muscle fibers arranged radially and insert into central tendon
- space for inferior vena cava, esophagus and aorta (posterior)
- crura: attach diaphragm to lumbar vertebrae
diaphragm action and innervation
- contraction increases vertical dimension of thoracic cavity
- innervated by phrenic nerves (C3-C5)
structures that pass through diaphragm
1) internal vena cava: between right dome and pericardial sac
2) esophagus: behind pericardial sac, in front of thoracic vertebra
3) aorta: between thoracic vertebra and left dome
accessory muscles of respiration
- attached to thoracic wall and could be involved in breathing
neural control of respiration
- rate/depth of breathing matched with tissue oxygen and CO2 removal demands
- controlled by brainstem nuclei (pons and medulla)
1) posterior respiratory group (medulla): efferent fibers control inspiration
2) anterior respiratory group (medulla): efferent fibers coordinate innervation of both inspiratory and expiratory muscles
3) CN IX/X (to medulla): modulate feedback based on input from baroreceptors and chemoreceptors
4) pontine respiratory group: receives higher level input (cerebral cortex, limbic system, hypothalamus), outputs to medulla to adjust respiratory pace –> some voluntary control
heart as a double pump
- right side: conveys blood through pulmonary circuit
- left side: conveys blood through systemic circuit
- both sides at the same time
arteries vs veins
arteries carry blood away from heart, veins towards heart
heart chambers
two atria superior to two ventricles
heart position
- left of midline in middle mediastinum
- oblique angle to longitudinal axis of body (slightly rotated to left)
heart shape
- base of heart = posterior surface
- apex located in 5th intercostal space
pericardium
- surrounds heart and roots of the great vessels
- two parts: outer fibrous pericardium and inner serous pericardium (two layers)
- function: stabilize position of heart and prevents overfilling (bc attached to other structures, ex. fibrous attached to diaphragm)
serous pericardium
1) visceral layer: attaches to heart
- potential space (pericardial cavity) containing pericardial fluid (lubrication) between layers
2) parietal layer: attaches to fibrous pericardium
components of heart wall
superficial to deep:
(parietal layer of serous pericardium: mesothelium, areolar CT and pericardial cavity)
1) epicardium (visceral layer of serous pericardium): mesothelium and areolar CT
2) myocardium: cardiac muscle tissue
3) endocardium: unique endothelium and areolar CT
heart surfaces
1) right pulmonary surface: formed by right atrium
2) anterior surface: majority right ventricle
3) left pulmonary surface: left ventricle
4) diaphragmatic surface
external heart sulci
1) coronary sulcus: between atria and ventricles, location of fibrous skeleton
2) anterior/posterior interventricular sulci: between ventricles, overlie interventricular septum
anterior external heart
1) right atrium
2) right auricle (flap)
3) right ventricle
4) left ventricle
5) left auricle
- cannot see left atrium
posterior external heart
1) left atrium
2) right atrium
3) left ventricle
4) right ventricle
right heart input/output
input: deoxygenated blood to right atrium
1) superior vena cava: drains head and upper limbs
2) inferior vena cava: below diaphragm
3) coronary sinus: heart wall
output: from right ventricle
1) pulmonary trunk
2) continues to right and left pulmonary arteries –> lungs
left heart input/output
input: oxygenated blood to left atrium
1) right and left pulmonary veins (two on each side)
output: from left ventricle
1) ascending aorta
2) aortic arch
3) descending aorta
heart borders
1) right border: right atrium
2) left border: left ventricle
3) inferior border: mostly right ventricle, a little left ventricle
internal right atrium
1) input vessels: SVC, IVC, coronary sinus
2) interatrial septum
3) fossa ovalis: remnant of embryonic foramen ovale
4) pectinate muscles: create rough wall
5) crista terminalis: line dividing smooth and rough parts of atrium
embryonic foramen ovale
- direct connection between right and left atrium
- no need for pulmonary circulation as an embryo
internal right ventricle
1) right atrioventricular valve (tricuspid) cusps (3)
2) septomarginal trabecula: extend from septum, attach to papillary muscles and trabeculae carnea
3) pulmonary semilunar valve cusps
4) conus arteriosus
atrioventricular valve structures
1) cusps attach to chordae tendineae
2) attach to papillary muscles
3) trabeculae carneae: rough inner wall (no smooth parts in ventricle)
atrioventricular valve cusp function
- like a parachute: chordae tendinae are strings attached to the papillary muscle (person) –> prevent cusps from everting
- cusp pulled taut in a curved shape
semilunar valve cusp function
- curved shape causes blood to pool in the closed cusps
internal left atrium
1) left atrioventricular valve (bicuspid or mitral) cusps (two)
2) interatrial septum: smooth wall
3) left auricle: lined with pectinate muscles (rough)
internal left ventricle
1) aortic semilunar valve cusps
aorta vs pulmonary trunk
aorta has openings of coronary arteries early on (oxygenated blood goes to heart first)
why is LV wall thicker than RV?
- higher force needed to pump to entire body, not just lungs
valve primary function
- ensure unidirectional flow of blood
fibrous skeleton of heart
- structural foundation for heart valves
- attachment for myocardium
- electrical insulation of atrial myocardium from ventricular (precise coordination of contraction)
fibrous skeleton components
1) pulmonary fibrous ring (anterior): pulmonary semilunar valve
2) aortic fibrous ring (posterior): aortic semilunar valves
3) left atrioventricular fibrous ring
4) right atrioventricular fibrous ring
coronary vessels (arteries)
two major branches:
1) left coronary artery bifurcates almost immediately into circumflex artery and anterior interventricular artery
- circumflex: LA/LV
- anterior interventricular: 2/3 IV septum of LV, anterior wall of LV/RV, connects with posterior interventricular artery at apex
2) right coronary artery gives rise to right marginal artery and posterior interventricular artery, supplies RA/RV
- right marginal: RV
- posterior interventricular artery: posterior 1/3 of IV septum, posterior RV/LV
coronary vessels (veins)
1) great cardiac vein: drains areas supplied by anterior interventricular artery –> drain into coronary sinus
2) small and middle cardia veins: drains RCA area –> drain into coronary sinus
3) anterior cardiac vein: anterior RV –> drain directly into RA
recognizing coronary vessels
- thick wall = aorta
- thinner wall = pulmonary vein
- big, dilated vessel near left side = coronary sinus
conducting system of heart
1) sinoatrial node (pacemaker): automatically depolarize, impulses travel through internodal pathways to…
2) atriovenricular node: impulse slows, atria contract (superior to inferior), fibrous skeleton insulates ventricles from atrial depolarization
3) atrioventricular bundle branches into…
4) L/R bundle branches: conduct impulse through interventricular septum, right bundle transmits to septomarginal trabecula
5) subendocardial plexus: impulse goes upwards from apex, distributed to ventricular myocardium
heart innervation
- autonomic nervous system innervates both SA/AV nodes and myocardium via cardiac plexus
- SNS: increase HR through NE release
- PNS: decrease HR through Ach release (vagus nerve)
- cardiac centers in medulla control based on input from baroreceptors and chemoreceptors
cardiac cycle
1) atrial systole: AV valves open, blood enters ventricles (relaxed)
2) atrial diastole: continues until start of next cycle
3) ventricular systole 1st phase: contraction closes AV valves (“lub”)
4) ventricular systole 2nd phase: ventricular BP rises, SL valves open
5) early ventricular diastole: ventricular BP drops until reverse blood flow closes SL valve (“dub”), passive atrial filling
6) late ventricular diastole: passive ventricular filling, all chambers relaxed
aortic valve regurgitation
- aortic valve that does not fully close
- blood leaks back through during ventricular diastole
- enlarged LV wall to cope with increased afterload
pelvis structure
1) right and left hip bones (os coxae) joined anteriorly by pubic symphysis
2) sacrum (joins to hips by sacro-iliac joints)
3) coccyx
pelvis function
1) support visceral organs
2) attachment point for muscles
3) transfer upper body weight to lower limb
4) attach lower limb to axial skeleton
pelvic girdle
- consists of left and right hip bones
hip bone structure
- three separate bones:
1) ilium (most superior)
2) ischium
3) pubis/pubic bone (anterior to ischium) - acetabulum: where bones fuse together around mid 20s, before separated by hyaline cartilage
- obturator foramen: formed by 2/3, covered with fascia and muscle
ilium features
lateral surface:
1) iliac crest
2) ala
medial surface:
3) iliac fossa
4) arcuate line
for muscle attachment:
5) anterior superior iliac spine
6) anterior inferior iliac spine
7) posterior superior iliac spine
8) posterior inferior iliac spine
other:
9) greater sciatic notch: sciatic (largest nerve) passes through
ischium features
1) ischial tuberosity: “big bump” that are “sit” bones, hamstrings attach here –> lateral view
2) ischial spine: muscle attachment
3) lesser sciatic notch
4) ischial ramus
pubis features
1) pectineal line: medial view, continuous with arcuate line
2) superior pubic ramous
3) pubic tubercle: ligament attachment
4) body of pubis: between rami, forms pubic symphysis
5) inferior pubic ramus
ischiopubic ramus
inferior pubic ramus + ischial ramus
pelvic brim
- formed by:
1) sacral ala and promontory
2) arcuate line
3) pectineal line
4) superior pubic ramus
5) pubic symphysis - shaped differently in males and females (to accommodate childbirth
pelvic inlet
space enclosed by pelvic brim
pelvic outlet
space bordered by:
1) coccyx
2) ischial tuberosities
3) inferior border of pubic symphysis
true vs false pelvis
- true = below pelvic brim, protects and contains pelvic viscera
- false = above pelvic brim, encloses and protects lower abdominal viscera
pelvic diaphragm
- aka pelvic floor
- funnel-shaped sheet of muscle within pelvic outlet
- formed by two major muscles and their fascia:
1) coccygeus
2) levator ani - muscles loop around urethra, vagina (if present) and anus –> controls urination and defecation
- other functions: partitions true pelvis from perineum (contains external genitalia) and supports abdominopelvic viscera
levator ani
- consists of three separate muscles
1) puborectalis: ‘sling’ around rectum
2) pubococcygeus: pubic bone to coccyx
3) iliococcygeus: ilium to coccyx - elevate anus
- torn/stretched in childbirth
coccygeus
- attaches to coccyx
anterolateral abdominal wall
- no bony reinforcements
- consist of fascia, muscles and their aponeuroses (thickening of CT)
- muscle fibers run at right and oblique angles to one another + overlap = increase strength
anterolateral abdominal wall muscles
(listed superficial to deep):
1) external oblique: fibers run inferomedially, same direction as external intercostals
2) rectus abdominis:
vertical and enclosed by rectus sheath
3) internal oblique: fibers run superomedially
4) transversus abdominis: fibers run anteromedially
1-3 = flat, muscular laterally + aponeurotic medially
linea alba
- collagen fibers of anterolateral abdominal wall muscle aponeuroses interlace here
anterolateral abdominal wall muscles actions
1) stabilize vertebral column
2) compress abdominal contents
3) flexion of vertebral column (ex. sit-up motion)
4) rotation of vertebral column
5) lateral flexion of vertebral column
inguinal ligament
- runs from anterior superior iliac spine to pubic tubercle
- formed by lower border of external oblique
- creates space where blood vessels and nerves pass through
rectus abdominis structure
- extends from pubis to thoracic cage
- segmented by three tendinous intersections: these sometimes don’t line up because walls develop independently and later fuse together
- enclosed by rectus sheath
linea semilunaris
- where tendons of the lateral abdominal muscles meet the sheath surrounding the rectus abdominis muscle
rectus abdominis action
1) flexion of vertebral column
2) compress abdominal viscera
rectus sheath
- surrounds rectus abdominis
- anterior layer formed by external oblique and some internal oblique aponeuroses
- posterior layer formed by transversus abdominis and some internal oblique aponeuroses
arcuate line in anterolateral abdominal wall
- posterior to rectus abdominis
- marks transition on rectus sheath where all aponeurotic layers pass anteriorly
- below line: fascia is thinner
posterior abdominal wall structures
1) some bones: lumbar vertebrae, sacrum, ilia, ribs 11/12
2) posterior abdominal wall muscles: attach to vertebrae
3) portion of diaphragm
4) kidneys, suprarenal glands and fascia: lie on top of the wall
5) fat, nerves, blood vessels
posterior abdominal wall muscles
1) diaphragm
2) transversus abdominis: forms belt around abdomen
3) quadratus lumborum: 4 sided, attached to lumbar vertebrae and 12th rib
4) iliacus: fills iliac fossa, continues to lower limbs
5) psoas major: attaches to lumbar vertebrae, continues to lower limbs
*4/5 pass under the inguinal ligament
abdominal wall layers
1) skin
2) superficial fascia
3) muscles/vertebra
4) transversalis fascia: lines inside of abdominal wall, called renal fascia around kidneys
5) extraperitoneal (visceral) fat
6) peritoneum
7) peritoneal cavity
peritoneum
- continuous serous membrane in peritoneal cavity that invests some viscera
- two layers of mesothelium that secrete fluid:
1) visceral
2) peritoneal cavity: doesn’t actually contain organs!
3) parietal
intraperitoneal organs
- surrounded by visceral peritoneum
- suspended by mesenteries to posterior abdominal wall
- ex. stomach, spleen
retroperitoneal organs
- develop posterior to peritoneal cavity
- only partially covered by peritoneum
- ex. kidneys, aorta, IVC, pancreas
arteries of posterior abdominal wall
- branch from aorta
- unpaired visceral branches:
1) celiac trunk
2) superior mesenteric artery
3) inferior mesenteric artery - paired:
4) suprarenal arteries
5) renal arteries
6) gonadal arteries
7) lumbar arteries
veins of posterior abdominal wall
- drain into inferior vena cava
- unpaired:
1) hepatic veins: drain liver (all digestive system blood goes to liver) - paired:
2) suprarenal veins
3) renal veins
4) gonadal veins: left drains into left renal vein, right drains directly into IVC
5) lumbar veins
digestive system function
- mechanically and chemically break down food for absorption
digestive system organ groups
1) gastrointestinal tract: form continuous tube = mouth, pharynx, esophagus, stomach, small intestine, large intestine
2) accessory digestive organs: connected to GI tract = teeth, tongue, salivary glands, liver, gallbladder, pancreas
secondarily retroperitoneal organs
- initially intraperitoneal
- become attached to posterior body wall through development (part of peritoneum disintegrates)
- ex. ascending and descending colon
mesenteries
- double layer of peritoneum with intervening areolar CT
- blood, lymph vessels, nerves sandwiched between
- several types/names
- function: support and stabilize intraperitoneal organs
mesentery examples
1) transverse mesocolon
2) mesentery proper: largest
3) sigmoid mesocolon: helps suspend part of colon
GI tract general layers
1) mucosa: protection, absorption, secretion
2) submucosa
3) muscularis externa
4) serosa or adventitia
GI mucosa
1) epithelium: varies based on tube function
2) lamina propria: areolar CT with mucosal glands, blood vessels, nerves, lymphatics
3) muscularis mucosae: smooth muscle, alters shape of lumen
GI submucosa
- dense irregular or areolar CT
- blood, lymphatics, submucosal plexus
- some regions: lymphatic tissue and submucosal glands
GI muscularis externa
- two layers of smooth muscle (except in esophagus and stomach): inner circular and external longitudinal
- myenteric plexus located between layers
- contraction of layers = segmentation and peristalsis
- circular = compression, mixing, constricting diameter
- longitudinal = shortens length of tube
GI adventitia/serosa
- areolar CT
- intraperitoneal organs = serosa
- others = adventitia
peristalsis
1) contraction of circular muscles behind bolus
2) contraction of longitudinal muscles ahead of bolus
3) wave of contraction in circular muscle layer forces bolus forward
segmentation
- primarily circular muscle layers
- churn and mix contents in digestive tract
- no net movement in particular direction
esophagus
- muscular tube running through neck and posterior mediastinum
- passes through muscular part of diaphragm via esophageal hiatus
- 25cm x 2cm
- secretes mucus (lubrication
- transports swallowed materials from pharynx to stomach
esophagus layers
1) mucosa:
- stratified squamous nonkeratinized epithelium
- lamina propria: lymphatic nodules and esophageal cardiac glands
- thick muscularis mucosae
2) submucosa:
- dense irregular CT
- blood and lymphatics
- lots of elastic fibers (collapsed lumen), assist in closing tube
- submucosal glands
3) muscular layer:
- circular and longitudinal
- proximal to distal: 1/3 skeletal muscle, 1/3 both, 1/3 smooth
4) adventitia: adheres to posterior body wall
esophagus bolus path
- passes through esophageal hiatus to portion located in peritoneal cavity
- pass through lower esophageal sphincter (cardiac sphincter): thickening of circular layer
- goes to stomach
gastroesophageal reflux disease (GERD)
- lower esophageal sphincter fails to close adequately
- HCl from stomach irritates esophageal wall
- long-term: epithelium changes to simple columnar and scar tissues build up, changing function and narrowing lumen
stomach regions
1) fundus: dome shaped
2) cardia: transition zone between esophagus and stomach
3) body: majority
4) pyloric antrum: funnel-shaped
stomach structure
- J-shaped, with four regions
- lesser curvature: lesser omentum (mesentery) attachment
- greater curvature: greater omentum
- rugae (semipermanent folds) formed by mucosa and submucosa, accommodate expansion and filling of stomach
stomach muscularis externa
- three layers:
1) longitudinal
2) circular
3) oblique: additional layer to allow more effective mixing
stomach function
- food (chyme) storage
- mechanical/chemical digestion
- hormone secretion
- little absorption
pyloric sphincter
- thickening of circular layer
- regulates chyme movement from stomach to duodenum
stomach layers
1) mucosa:
- simple columnar epithelium
- mucous cells invaginate into lamina propria = gastric pits
- muscularis mucosae
2) submucosa:
- loose areolar CT with BVs, lymphatics
- no glands!
3) muscularis externa: 3 layers
4) serosa: loose areolar CT
gastric secretions
1) surface mucous and mucous neck cells: mucins, protects mucosa from acid and maintains acidic conditions
2) parietal cells: intrinsic factor (B12 absorption), HCl (denatures proteins, antibacterial, breaks down cell walls)
3) chief cells: pepsinogen (proenzyme –> pepsin with HCl), gastric lipase
4) G cells (enteroendocrine): gastrin into blood stream, stimulates parietal/chief cells and contractions
stomach secretory cell distribution
- gastric pit: mucous cells
- gastric gland: parietal, G, chief
- chief cells more predominant at bottom of gland
- G cells at bottom, not seen on H&E
parietal vs chief cells histology
- parietal = large, central nucleus, eosinophilic
- chief = small, basophilic (proteins)
small intestine function
most digestion and absorption
small intestine regions
1) duodenum (~25cm, shortest): mix chyme with exocrine secretions, proximally intraperitoneal (mobile) and rest secondarily retroperitoneal (anchored)
2) jejunum (2.5m): chemical digestion, nutrient absorption, intraperitoneal
3) ileum (3.6m): controls movement of intestinal contents into cecum, intraperitoneal
mesenteries of small intestine
- duodenum: no mesentery
- jejunum and ileum: fan-shaped mesentery proper (anchor to posterior wall)
small intestine structures
1) circular folds (plicae circulares): permanent, transverse folds of mucosa and submucosa = increase SA and slow chyme
2) intestinal villi: finger-like extensions of mucosa, covered by simple columnar cells, also increase SA
3) microvilli: projections from intestinal villi (brush border), increase SA
small intestine layers
1) mucosa:
- villi, intestinal glands, lymphoid nodules
- muscularis mucosae
- simple columnar with goblet cells
- lamina propria: capillary networks (nutrient-rich blood to liver), lacteals (lipid-protein complexes to venous system), nerves and smooth muscle
2) submucosa: lymphatics, vessels, submucosal neural plexus
3) muscular layer:
- circular and longitudinal
- myenteric neural plexus
4) serosa
small intestine plexuses
- control movement of chyme and secretions
intestinal glands (crypts)
- extend into lamina propria
- enteroendocrine cells: hormone production, ex. CCK
- paneth cells: innate immunity
- stem cells: replenish epithelial cells lost in lumen and MALT
small intestine regional specializations
1) duodenum: mucous secretion and goblet cells, with submucosal (Brunner’s) glands
2) jejunum: nutrient absorption, well developed circular folds
3) ileum: lymphoid nodules (Peyer’s patches, target bacteria from large intestine), goblet cells (lubrication after lots of absorption)
large intestine structure
- from ileocecal valve to anus (1.5m long, 6.5cm wide)
- large = wider (shorter than small)
- three regions
1) cecum: blind ended sac (contents can only go up)
2) colon: ascending, transverse, descending, sigmoid
3) rectum
large intestine function
- reabsorption of water and salts
- absorption of vitamins
- storage of feces
large intestine feactures
1) right colic (hepatic) flexure
2) left colic (splenic) flexure
3) haustra: permit expansion, created by…
4) teniae coli (3 strips): reorganization of external longitudinal layer
5) epiploic (omental) appendages: fatty appendages along teniae coli, function unknown
appendix
- filled with lymphoid nodules and involved in immune function
- attached to cecum
retroperitoneal and intraperitoneal parts of large intestine
1) ascending colon = secondarily retroperitoneal
2) transverse colon = intra
3) descending colon = secondarily retro
4) sigmoid colon = intra
5) rectum = retro
greater omentum connections
- connects stomach to transverse colon
rectum characteristics
- expandable, filling = urge to defecate
- ends as anal canal, opens to outside at the anus
- epithelium changes:
1) simple columnar
2) stratified squamous nonkeratinized
3) keratinized
rectum features
1) anal canal: circular folds hold feces
2) internal anal sphincter: smooth muscle, thickening of inner circular muscular layer = reflex control
3) external anal sphincter: skeletal muscle = voluntary control
large intestine layers
1) mucosa:
- changing epithelium
- no villi or circular folds
- goblet cells, deep intestinal glands
- muscularis mucosae
2) submucosa
3) muscular layer:
- circular layer
- longitudinal layer = teniae coli
4) serosa
large intestine control
- regulated by local reflexes in ANS
- proximally: fecal material moves slowly by peristalsis, segmentation by haustral churning
- mass movements: powerful, peristaltic-like contraction involving teniae coli (infrequently, ~2-3x/day)
- rectal distension consciously sensed = sphincter relaxation
arterial supply of digestive system
1) celiac trunk = foregut:
- left gastric artery: lesser omentum
- splenic artery: greater omentum, spleen, pancreas
- common hepatic artery: liver, gall bladder, proximal duodenum, connects to left gastric artery
2) superior mesenteric artery = midgut: distal duodenum to left colic flexure
3) inferior mesenteric artery = hindgut: descending colon to upper rectum
(also, esophageal arteries, visceral branches of thoracic aorta)
hepatic portal system
1) hepatic portal vein: carries nutrient rich and O2 poor blood from digestive system (all other veins) to liver
2) left gastric vein
3) splenic vein
4) inferior mesenteric vein
5) superior mesenteric vein
6) hepatic veins: drain blood from liver to IVC
*no common hepatic or celiac vein!
portal vein definition
- connects two capillary beds
liver capsule
- covered by fibrous CT capsule and visceral peritoneum, except at bare area
- peritoneum reflects to make ligaments
liver lobes
two major:
1) right
2) left
two smaller (only visible posteriorly)
3) caudate: next to IVC
4) quadrate: next to gall bladder
liver ligaments
1) coronary ligament: attaches to diaphragm
2) falciform ligament: attachment to anterior body wall
3) round ligament: free edge of falciform, remnant of fetal umbilical vein
liver bare area
- close proximity to diaphragm
- coronary ligament around attaches to diaphragm
porta hepatis
- structure in liver containing: BVs, lymph, bile ducts and nerves
- lateral to medial: common hepatic duct, hepatic artery proper, hepatic portal vein (more posterior)
- housed under lesser omentum
liver functions
1) digestive: produce and secrete bile, facilitate fat digestion, buffer acidity in chyme
2) metabolic: regulate circulating levels of nutrients, store fat-soluble vitamins, remove metabolic wastes and toxins
3) hematological: synthesize plasma proteins, phagocytize debris in blood, blood reservoir
lesser omentum attachments
- attaches stomach to liver
liver functional units
- divided by CT (interlobular septum, containing interlobular veins and arteries) into lobules
- commonly hexagonal shaped
- portal triads at periphery: include branches of hepatic portal vein, hepatic artery proper and bile duct
- central vein in the middle
blood flow through liver
1) blood from hepatic portal vein and hepatic artery proper drain into hepatic sinusoids (sinusoidal vessel)
2) drain into central vein
3) central veins merge to form hepatic veins
4) empty into IVC
blood processing in liver
- as blood passes through, it is processed by:
1) hepatocytes: nutrient packaging, metabolism, bile production, blood processing
2) stellate macrophages: vit A and fat storage
liver perisinusoidal space
- separates hepatocytes from endothelial cells
- where functions of the liver take place
bile flow in liver
1) produced by hepatocytes
2) secreted into bile canaliculi
3) bile ductules
4) bile ducts
5) hepatic ducts: one for each lobe, collects all bile ducts
6) common hepatic duct
7) cystic duct to store in gall bladder
8) OR common bile duct: common hepatic + cystic duct –> major duodenal papilla
bile function
- digestion of lipids in duodenum
hepatopancreatic ampulla
- collects from common bile duct and pancreatic duct
- flow controlled by hepatopancreatic sphincter: formed by part of duodenum wall
- lipid/protein-containing chyme stimulates enteroendocrine cell release of CCK
- CCK stimulates gallbladder contraction and hepatopancreatic sphincter relaxation
pancreas characteristics
- posterior to stomach, incurve of duodenum
- secondarily retroperitoneal
- ~15cm long
- head, body and tail (tail near spleen)
- surrounded by thin fibrous CT capsule
- divided into lobules by CT septa
- endocrine and exocrine functions
pancreatic blood supply
1) celiac trunk
2) superior mesenteric artery
pancreas histology
1) pancreatic islets: endocrine = lighter staining
2) acinar cells: make up acini, exocrine = darker staining, eosinophilic lumen
pancreatic cell types and functions
1) pancreatic islets (contain many diff cells): endocrine products, ex. insulin/glucagon –> BVs
2) acinar cells: mucin, digestive enzymes
3) intercalated duct cells: bicarbonate ions, mix with digestive enzymes to go towards small intestine via pancreatic duct
urinary system component
kidneys, ureters, bladder, urethra
urinary tract components and function
- ureters, bladder, urethra
- store and eliminate urine
kidney function
- maintenance of water and electrolyte homeostasis
- elimination of by-products of metabolism: urine production
filtration/reabsorption in kidney
- blood filtered, most reabsorbed
- rest is filtrate converted to urine
urinary system function
- elimination of organic wastes, toxins and some drugs
- conservation of nutrients
- storage/excretion of urine
- regulation of blood volume and pressure
- regulation of erythrocyte production
- regulation of blood electrolyte concentration and pH
kidney location
- either side of VC between T12-L3
- right: posterior to liver, right colic flexure, duodenum
- left: medial to spleen, posterior to stomach, pancreas, left colic flexure, small intestine
kidney structure
1) superior pole: adrenal glands
2) hilium: renal BVs (vein anterior to artery), lymphatics, nerves, renal pelvis
3) ureter
4) inferior pole
renal pelvis
- connection to ureter in kidney
kidney coverings
deep to superficial:
1) fibrous capsule: thin dense irregular CT, maintains shape and protects
2) perinephric fat: cushioning and support
3) renal fascia: dense irregular CT, anchors kidney to surrounding structures and posterior abdominal wall
4) paranephric fat
L/R renal vein and artery differences
- L vein longer bc IVC closer to L
- L artery shorter bc aorta closer to R
internal features of kidneys
1) renal pyramid: renal medulla, has apex and base (abuts renal cortex)
2) renal papilla: formed by apex of renal pyramid, extends into minor calyx
3) renal columns: cortical tissue between pyramids
4) renal lobe: location of renal functional units, includes pyramid and adjacent cortex/columns
5) minor calyx: drains medulla into…
6) major calyx: formed by merging minor
7) renal pelvis: drains major calyxes
8) renal sinus: contains fat
blood supply to kidney
1) R/L renal arteries
2a) accessory artery
2b) segmental artery, divides further
3) interlobar arteries
4) arcuate arteries
5) cortical radiate arteries: branch into afferent arterioles and supply nephrons
*all are end arteries: do not anastamose with others
blood drainage from kidney
- all arteries typically associated with veins
- efferent arterioles drain nephrons (functional unit of kidney)
nephron components
1) renal corpuscle: spherical, contains glomerulus (bundle of BVs) and glomerular capsule
2) renal tubule: PCT, nephron loop, DCT
renal corpuscle function
- filter blood
- produce glomerular filtrate (enters capsular space)
renal tubule function
- modifies glomerular filtrate through reabsorption/secretion
types of nephrons
1) cortical (85%): primarily in cortex, produce glomerular filtrate
2) juxtamedullary nephrons (15%): close to junction between cortex and medulla, extend into medulla, produce filtrate and ALSO create/maintain osmotic gradient in renal interstitium
importance of renal interstitium osmotic gradient
- concentration of urine
- modification of filtrate as it passes through
nephron blood supply
1) renal artery
2) segmental
3) interlobar
4) arcuate
5) cortical radiate
6) afferent arterioles
in nephron:
7) glomerulus
8) efferent arteriole
9) peritubular capillaries or vasa recta
10) venules
11) same veins, except no segmental veins
peritubular capillaries
- around PCT/DCT
- gas, nutrient, waste exchange
vasa recta
- around nephron loop
- gas, nutrient, waste, exchange
afferent vs efferent arteriole
- afferent wider
- creates increased hydrostatic pressure that drives H2O and low MW molecules through filter to form filtrate
urine formation
renal corpuscle:
1) glomerular filtration: movement of substances from blood within glomerulus to capsular space
renal tubule and collecting duct:
2) tubular reabsorption: movement of substances back to blood from tubular fluid (most)
3) tubular secretion: movement of substances from blood to tubular fluid
glomerular capsule layers
1) parietal layer: simple squamous cells
2) capsular space: contains glomerular filtrate
3) visceral layer: specialized cells (podocytes) with bulging nuclei and interlaced digits
glomerulus structure
1) vascular pole: where afferent arteriole and efferent arteriole enter
2) tubular pole: PCT
3) DCT closely associated with arterioles
filtration membrane in kidney
- negatively charged
- three layers:
1) fenestration of glomerular endothelial cells: prevents blood cells, but all other plasma components can flow through
2) basal lamina of glomerulus: blocks larger proteins
3) slit membrane between podocytes (pedicels): blocks medium-sized proteins
PCT characteristics
- located in cortex
- simple cuboidal with very dense microvilli: most absorption in PCT
PCT functions
- active reabsorption of ions, nutrients, vitamins, plasma proteins from filtrate to peritubular fluid (H2O follows passively), peritubular capillaries return these to general circulation
- active secretion of organic acids/bases, metabolites, drugs into PCT lumen
nephron loop characteristics
- descending limb
- ascending limb: impermeable to water, actively pumps Na/Cl out of tubular fluid to concentrate interstitial fluid, drawing water with it (reabsorption), vasa recta returns to circulation
- each has thick (simple cuboidal) and thin (simple squamous) segment
- most water and NaCl reclaimed at this point
DCT characteristics
- in cortex, passes vascular pole in renal corpuscle between afferent/efferent arterioles
- simple cuboidal with FEW, BLUNT microvilli
- smaller diameter than PCT
- shorter than PCT
DCT function
- active secretion of K/H into tubular fluid
- reabsorption of NaCl, H2O when aldosterone and ADH present
PCT vs DCT on H&E stain
- PCT: bigger cells, not every cell has nucleus, fuzzy lumen
- DCT: smaller cells all with nuclei, empty lumen
juxtaglomerular complex function
- regulate glomerular filtration rate (GFR) and blood pressure
- ex. BP drop = lower Na in filtrate = SyNS input and release of renin
juxtaglomerular complex components
1) macula densa: modified epithelial cells in DCT, monitor [Na] in fluid
2) juxtaglomerular cells: modified (contractile to secretory) smooth muscle cells of afferent arteriole, monitor BP and innervated by SyNS for renin secretion (increases BP)
3) extraglomerular mesangial cells: surround and support vascular pole, FN not well understood
juxtaglomerular complex histology
1) macula densa: cells more columnar, contact afferent arteriole
2) juxtaglomerular cells: hard to see, but near afferent arteriole
3) extraglomerular mesangial cells: in space between afferent and efferent arterioles
collecting system function
- transport fluid from DCT to minor calyx
- make final adjustments to osmotic concentrations and volume
- ADH controls permeability ex. dehydration = more ADH = more H2O reabsorption = more concentrated urine
collecting system comonents
1) collecting tubules
2) collecting ducts
3) papillary ducts
collecting system histology
- tubules = simple cuboidal
- ducts = simple columnar
- collecting ducts have pale staining principal cells with few organelles and DISTINCT cell borders
ureter location
- retroperitoneal
- extend from renal pelvis to posterolateral wall of bladder (oblique angle)
ureter layers
1) mucosa: transitional epithelium and lamina propria
2) smooth muscular layer: longitudinal inner, circular outer
3) adventitia (CT)
bladder location
- posterior to pubic symphysis
- retroperitoneal (superior surface covered with peritoneum)
- shape and location differ in M/F
urethra location
- from urinary bladder to exterior
- longer in males
- shorter in females, UTIs more common
bladder features
1) rugae: formed by mucosal folds, allow for greater distension
2) trigone region: smooth, funnels urine from ureters to urethra
3) internal urethral sphincter: only in males, organized smooth muscle
4) detrusor muscle: 3 layers, contract to expel urine
urethra structure in males
1) prostatic urethra: goes through prostate
2) membranous urethra: passes through external urethral sphincter
3) spongy: penis
bladder layers
1) mucosa: transitional epithelium and lamina propria
2) submucosa
3) thick detrusor muscle
4) adventitia
urethra histology
- large longitudinal folds around lumen
- surrounded by bundles of smooth muscle
- females: stratified squamous
- males: changes from transitional –> stratified columnar/pseudostratified columnar –> stratified squamous
micturation control
1) bladder not full: SyNS (T11-L2) inhibit detrusor contraction, stimulate internal urethral sphincter
2) bladder full: baroreceptors and sensory axons (T11-L2) relay info to brain, PSyNS stimulate detrusor contraction and relax internal sphincter, somatic motor (S2-S4) relax external urethral sphincter
exocrine gland
- duct connects gland to external environment
- secretory cells release chemical products onto epithelial surface via duct
- ex. eccrine sweat glands
endocrine glands
- no connection to epithelial layer = ductless
- secrete chemical products (hormones) into surrounding tissue –> blood stream
- ex. endocrine pancreas
endocrine organs
1) CNS: hypothalamus, pituitary gland
2) thoracic cavity: thyroid, parathyroid
3) abdominal cavity: adrenal/suprarenal, pancreas
endocrine system functions
- secrete hormones that act on receptors that modulate the biochemistry of target cells
- maintain homeostasis through endocrine reflexes and feedback loops
characteristics of endocrine organs
- clusters or cords of secretory cells
- surrounded by supportive dense irregular CT
- highly vascularized with fenestrated (most) or sinusoidal capillaries
neural vs endocrine signaling
1) same function = regulate body functions to maintain homeostasis
2) mechanism: electrical signaling and chemical neurotransmitters through nervous system (“wired”) vs chemical hormones distributed through CV system (“wireless”), BOTH act on specific receptors
3) speed: relatively fast vs slow
4) effect duration: short vs long-term
5) recovery: fast vs slow, BOTH regulated by feedback loops
6) location: localized/specific vs widespread/diffuse
types of hormones
1) amino acid derivatives
2) peptide hormones: largest class
3) steroid hormones
endocrine reflex
1) stimulus
2) integrating center
3) hormone 1
4) integrating center
5) hormone 2
6) target tissue
7) response
*feedback can be negative or positive
types of endocrine stimuli
1) humoral: changes in extracellular fluid composition
2) hormonal: changes in hormonal levels
3) neural: presence of neurotransmitter at neuroglandular junction
hypothalamus mechanisms
- coordination center, regulates nervous and endocrine system by:
1) secreting regulatory hormones
2) functioning as an endocrine organ
3) direct neural control (endocrine cells of adrenal gland)
hypothalamus regulatory hormones
- control endocrine cells in anterior pituitary gland
- two classes:
1) releasing: stimulate synthesis and secretion of hormones
2) inhibiting: prevent
hypothalamus endocrine organ function
- neurons directly synthesizing hormones, transport to posterior pituitary
- released at posterior pituitary
- ex. ADH, oxytocin
hypothalamus direct neural control
- ANS centers control autonomic output
- SyNS activation = suprarenal medulla release of hormones into circulation
pituitary gland functions
1) tropic functions: modulate other endocrine glands
2) non-tropic functions: act directly on non-endocrine systems
pituitary structure
1) infundibulum: stalk portion connecting hypothalamus and pituitary glands
2) anterior pituitary (adenohypophysis)
3) posterior pituitary (neurohypophysis, pars nervosa)
4) sella turcica: hypophyseal fossa of spehnoid, houses glands
anterior pituitary divisions
1) pars distalis: most distal
2) pars intermedia: separates anterior/posterior
3) pars tuberalis: forms part of infundibulum
anterior pituitary control
- regulatory hormones from hypothalamus via hypophyseal portal system
hypophyseal portal system
1) superior hypophyseal artery: branch from internal carotid
2) primary capillary plexus: hypothalamic neurons release hormones here
3) hypothalamic portal veins: carry hormones to AP
4) secondary capillary plexus: regulatory hormones modulate AP activity, AP release hormones here
5) hypophyseal veins: drain blood into general circulation via cavernous sinus
anterior pituitary cell types
1) chromophils
i) acidophils: prolactin, growth hormones
ii) basophils: FSH, LH, ACTH, TSH (FLAT)
2) chromophobes: don’t stain well
anterior pituitary histology
- acidophils = eosinophilic
- basophils = basophilic
- chromophobes = don’t stain
- more basophilic (darker) than posterior pituitary
posterior pituitary control
- axons from paraventricular and supraoptic nuclei of hypothalamus travel through infundibulum to PP
- hormones produced by PVN/SON travel along axon to synaptic terminals of PP –> released into interstitium, taken up by capillaries
- SON = ADH
- PVN = oxytocin
posterior pituitary blood supply
1) inferior hypophyseal artery: branch from meningohypophyseal trunk of internal carotid
2) hypohpyseal veins: drain released ADH and oxytocin to general circulation
posterior pituitary histology
1) herring bodies: intense staining clusters = terminal end of axons where hormones are stored
2) blood vessels
3) pituicytes: glial cells
*very eosinophilic
ADH function
- act on kidneys and circulatory system for water reabsorption and increasing BV/BP
oxytocin function
- female reproductive system
- uterine contractions (positive feedback loop)
FSH/LH function
- hypothalamic hormone = GnRH
- follicular cells in ovary, nurse/interstitial cells of testes
- FSH = estrogen secretion, sperm maturation
- LH = testosterone secretion, ovulation
TSH function
- hypothalamic hormone = TRH
- thyroid gland hormone production
prolactin function
- hypothalamic hormone = PRH
- mammary gland milk production
growth hormone function
- hypothalamic hormone = GHRH
- liver, bone, muscle
- growth, protein synthesis, lipid metabolism
ACTH function
- hypothalamic hormone = CRH
- adrenal gland glucocorticoid production
thyroid gland characteristics
- two lobes connected by isthmus, created by surrounding DICT capsule
- butterfly-shaped
- anterior surface of trachea: cartilage ring 2-3
- easily palpable with fingers, especially when enlarged (goiter)
- highly vascularized
thyroid arterial supply
1) external carotid artery –> superior thyroid artery
2) subclavian artery –> thyrocervical trunk, inferior thyroid artery
thyroid venous drainage
1) internal jugular veins –> superior thyroid and middle thyroid veins
2) brachiocephalic vein –> inferior thyroid vein
thyroid gland structure
- enclosed in fibrous capsule that sends trabeculae deep into the gland = irregular lobules
- functional unit = thyroid follicle (spherical)
- follicular cells = thyrocytes
- parafollicular (C) cells between thyroid follicles
thyroid follicle
- simple cuboidal epithelium (can change to columnar if more active)
- cavity filled with colloid (viscous fluid)
thyrocyte functions
1) synthesize thyroglobulin (prohormone)
2) secrete colloid –> become iodinated
3) breakdown to form thyroid hormones: thyroxine (T4, storage) and triiodothyronine (T3, active form)
parafollicular (C) cell function
- secrete calcitonin, which decreases [Ca]:
1) inhibits osteoclast activity
2) stimulates Ca excretion at kidneys
hypothalamus-pituitary-thyroid (HPT) axis
1) low body temperature
2) hypothalamus: releases TRH
3) anterior pituitary: releases TSH
4) thyroid: produces thyroid hormones
5) increase metabolic rate, increase body temperature
6) negative feedback to hypothalamus and anterior pituitary through homeostasis restoration
parathyroid glands location
- 4 pea-sized, located on posterior aspect of thyroid gland
- two superior, two inferior
parathyroid blood supply
- superior = superior thyroid arteries
- inferior = inferior thyroid arteries
- venous drainage same as thyroid gland
parathyroid characteristics
- surrounded by CT capsule that forms irregular lobules
- two specialized cell types:
1) parathyroid cells (chief/principal): produce parathyroid hormone
2) oxyphil cells: immature/inactive parathyroid cells
parathyroid gland control
- humoral stimulus = [Ca] in circulation
- decrease in Ca stimulates PTH secretion
PTH function
1) stimulate osteoclasts and osteoblasts (needed to activate osteoclasts)
2) reduce urinary Ca excretion
3) stimulate calcitriol production (kidney, increases intestinal absorption of Ca)
parathyroid gland histology
- very cellular
- oxyphil cells: more cytoplasm
adrenal (suprarenal) gland characteristics
- pyramid-shaped
- one on each superior pole of kidney (retroperitoneal)
- CT capsule
- highly vascularized
- two regions: cortex (superficial) and medulla (deep)
adrenal arterial supply
1) abdominal aorta –> superior and middle adrenal arteries
2) renal artery –> inferior adrenal arteries
adrenal cortex characteristics
- cells with high lipid content that secrete 24 types of steroid hormones (adrenocortical steroids)
- three layers (superficial to deep):
1) zona glomerulosa: cells in densely packed clusters (“glomeruli), produce mineralocorticoids ex. aldosterone
2) zona fasciculata: cells in radiating cords, separated by fenestrated capillaries, produce glucocorticoids ex. cortisol
3) zona reticularis: reticular network of small cells, produce androgens
adrenal medulla characteristics
- primarily chromaffin cells: large, rounded, resemble sympathetic ganglia neuron (modified postganglionic sympathetic neuron)
- two types of endocrine cells that secrete catecholamines: 80% epinephrine, 20% NE
adrenal medulla innervation
- by sympathetic preganglionic neurons –> splenic nerve –> target cells
adrenal medulla function
- trigger utilization of cellular energy to increase muscle strength and endurance
hypothalamus-pituitary-adrenal (HPA) axis
1) stress
2) hypothalamus releases corticotropin releasing hormone
3) anterior pituitary releases ACTH
4) adrenal cortex releases cortisol
5) stress response
*4/5 act as negative feedback on hypothalamus and anterior pituitary
pancreas characteristics
- retroperitoneal
- head, body, tail
- mixed gland: acini/ducts are exocrine (99%), pancreatic islets are endocrine
pancreas blood supply
- pancreatic branches of:
1) splenic artery
2) pancreaticoduodenal arteries
pancreatic islets characteristics
- aka islet of langerhans
- surrounded by CT
- fenestrated capillaries
- ANS input through celiac plexus
pancreatic islet cell types
1) alpha cells: glucagon
2) beta cells: insulin
3) delta cells: somatostatin, inhibits alpha/beta cell production
4) F cells (least common): pancreatic polypeptide, inhibits gallbladder contraction, regulates enzyme production (overall slows digestion)
*cannot be distinguished on H&E stain
low blood glucose reflex
1) alpha cells release glucagon
2) increased glycogen breakdown in liver
3) increase blood glucose
high blood glucose reflex
1) beta cells release insulin
2) stimulates glucose uptake
3) more glycogen formation in liver
4) decrease blood glucose
reproductive system components
1) primary sex organs = gonads = testes and ovaries
2) accessory organs
gonads function
- produce haploid gametes and sex hormones
- ovary = oocytes, estrogen, progesterone
- testes = sperm, androgens
- gametes fuse to form diploid zygote
activation of reproductive systems
- primarily non-functional until puberty, when hypothalamus releases GnRH
- acts on ant. pituitary = FSH/LH release
- at puberty: external sex characteristics develop, gametes mature and gonads start to secrete sex hormones
components of male reproductive system
1) genital ducts: ductus (vas) deferens, ejaculatory duct, urethra, epididymis
2) external genitalia: penis, scrotum, testes
3) accessory glands: seminal, prostate, bulbourethral
testes descent purpose
- for temperature regulation: sperm must be below body temp to be viable
testes descent time
- between 3rd month of gestation and birth
testes descent
- go from retroperitoneal position to external
- descent from posterior abdominal wall into scrotum
gubernaculum testes
- cord of CT and muscle fibers anchored to scrotum
- does not elongate, eventually shortens
- pulls testes through layers of abdominal wall (via inguinal canal)
testes descent steps
1) testes anchored by gubernaculum to developing scrotum
2) pulled through abdominal wall during growth: deep inguinal ring formed passing through transversalis fascia
3) peritoneum evaginates at deep inguinal ring = processus vaginalis (does not pass through! only guides)
4) evagination continues through inguinal canal: superficial inguinal ring formed passing through external oblique aponeurosis
5) descent complete by birth: processes vaginalis closes off and forms tunica vaginalis
inguinal canal
- between deep and superficial inguinal rings
testes descent: layers of abdominal wall
1) does NOT pass through peritoneum
2) transversalis fascia
3) does NOT pass through transversus abdominis
4) internal oblique muscle
5) external oblique muscle/aponeurosis
spermatic cord
- structures passing between abdominopelvic cavities and the testes and fascial coverings
spermatic cord wall
1) external spermatic fascia
2) cremaster muscle (smooth) and fascia
3) internal spermatic fascia
cremaster muscle function
- temperature control
- contracts to bring testes closer when cold
dartos muscle
- in superficial fascia under scrotum
- temperature control: contracts to bring testes closer
scrotum
- homologous to labia majora
- covers testes
spermatic cord contents
1) ductus deferens and artery to ductus deferens
2) testicular artery and pampiniform plexus
3) branch of genitofemoral nerve and autonomic nerves
4) lymphatics
pampiniform plexus
- extensive vein network
- cools blood entering into testes
abdominal wall –> coverings of spermatic cord
1) peritoneum = tunica vaginalis
2) transversalis fascia = internal spermatic fascia
3) transversus abdominis muscle = nothing, not passed through
4) internal oblique muscle/fascia = cremasteric muscle/fascia
5) external oblique aponeurosis = external spermatic fascia
6) subcutaneous tissue = dartos fascia/muscle
7) skin = skin
inguinal hernias
- weakened parts of abdominal wall result in protrusion of peritoneal sac
- with or without abdominal contents ex. intestine
indirect inguinal hernia
- peritoneal sac enters inguinal canal VIA deep inguinal ring
- passes LATERAL to inferior epigastric vessels
- cause: embryonic processus vaginalis remains open
- commonly congenital
direct inguinal hernias
- peritoneal sac enters inguinal canal DIRECTLY
- passes MEDIAL to inferior epigastric vessels
- cause: weakening in abdominal wall
- commonly acquired
cryptorchidism
- one or both testes fail to descend
- higher proportion of inviable sperm produced
testes structures
1) tunica vaginalis: serous membrane, parietal and visceral layers line scrotal cavity (containing serous fluid)
2) tunica albuginea: fibrous CT capsule, forms septa lobules
3) septa: subdivide internal space into lobules containing…
4) seminiferous tubules: blind end or loop, contain sustentacular and dividing germ cells
5) ducts: straight tubules –> rete testis –> efferent ductule, which goes to epididymis
6) raphe: ridge of tissue extending from anus to scrotum
testes histology
1) outer tunica albuginea
2) seminiferous tubules
3) interstitial cells between = hormone production
seminiferous tubules
- site of spermatogenesis
- complex stratified epithelium containing sustentacular and spermatogenic cells
sustentacular cells
- protection and nourishment for sperm cells
- produce inhibit when sperm count is high (inhibits FSH secretion)
- secured together by tight junctions = blood-testes barrier
blood-testis barrier
- protects sperm from immune system
interstitial cells
- produce androgens ex. testosterone
- located between seminiferous tubules in loose CT along with BVs, nerves, lymphatics
myoid cells
- unique contractile cells
- expel contents of seminiferous tubules
seminiferous tubule histology
1) myoid cells = outer edge, flattened nuclei
2) interstitial cells = outside
3) sustentacular cell = lighter stain, extend entire tubular wall
4) outer to inner (least to most mature):
a) spermatogonium = dark nucleus
b) primary spermatocyte = speckled
c) secondary spermatocyte
d) spermatid = smaller, not speckled
e) spermatozoon = tails
testes duct system function
- store sperm
- transport sperm as they mature and pass out of the body (or die)
- facilitate transport through smooth muscle stimulated by oxytocin
testes duct system components
1) rete testes
2) efferent ductules
3) epididymis: head, body, tail
4) ductus deferens
rete testis
- complex anastomotic network
- simple cuboidal with microvilli
- receive from straight tubule
efferent ductules
- ciliated and non-ciliated columnar
- absorb excess fluid secreted by seminiferous tubules
epididymis function
- accumulation, storage and maturation (learn to swim) of sperm
- uptake and digestion of luminal fluid and degenerated sperm
epididymis structure
- highly coiled tube
- pseudostratified columnar epithelium with LONG microvilli (“sterocilia”)
- principal cells = tall, columnar
- basal cells = small, round
- circular layer of smooth muscle
ductus deferens structure
- thick-walled tube within spermatic cord
- connects epididymis to prostatic urethra
- ends at large ampulla (posterior to bladder)
- unites with proximal seminal vesicle to form ejaculatory duct
- empties into prostatic urethra (common with urine)
ductus deferens layers
1) mucosa: pseudostratified columnar with few stereocilia + lamina propria
2) muscularis: inner longitudinal, middle circular, outer longitudinal
3) adventitia
accessory gland general functions
- produce/secrete ~95% of seminal fluid to support sperm survival
- smooth muscle contraction with SyNS during emission
accessory glands specific functions
1) seminal vesicle/gland: secretions with fructose for energy
2) prostate gland: multiple ducts that secrete milky, nutrient rich fluid
3) bulbourethral glands: clear, viscous mucin for lubrication
accessory gland locations
1) seminal: lateral to vas deferens, empty into ejaculatory duct
2) prostate gland: around prostatic urethra
3) bulbourethral: embedded in urogenital diaphragm, empty into membranous/spongy urethra
perineum
- diamond-shaped area between thighs
- inferior to pelvic diaphragm
- consists of:
1) urogenital triangle: pubis symphysis, ischiopubic rami to ischial tuberosities
2) anal triangle: ischial tuberosities and coccyx
urogenital triangle components
1) base of penis and scrotum OR clitoris
2) urethral and/or vaginal orifices
3) perineal membrane
4) skeletal muscles around external genitalia
anal triangle components
1) anus
penis function
- conduct urine and semen
penis structure
1) bulb connects to body
2) crus of penis: attaches to perineum
3) root: fixed portion in urogenital triangle
4) body: suspended from pubic symphysis
5) glans: expanded, cap-like end of corpus spongiosum (covered by prepuce in uncircumcised person)
6) three parallel erectile columns: homologous to clitoris
penis erectile columns
1) bilateral corpora cavernosa: dorsal (anatomical position = erect), surrounded by tunica albuginea
2) corpus spongiosum: ventral, containing spongy urethra
- all encased in fascia and skin
corpus cavernosa relative anatomy
- diverge as crura of penis
- fuse to ischiopubic rami
- covered by ischiocavernosus
corpus spongiosum relative anatomy
- expands as bulb of penis
- fuses to underside of perineal membrane
- covered by bulbospongiosus
perineal muscles in male
- skeletal
- ischiocavernosus and bulbospongiosus
penis blood supply
1) internal iliac artery
2) branches to dorsal and deep arteries
3) deep arteries branch and open into cavernous spaces of erectile tissue
4) arteriovenous anastomoses between deep artery branches and deep dorsal vein
erectile tissue structure
- vascular spaces with smooth muscle and elastic CT trabeculae
erection
- PSyNS relaxes trabecular and vascular smooth muscles
- tunica albuginea limits filling of cavernous spaces = compression of dorsal veins traps blood
emission
- SyNS input = peristalsis in ductus deferens and accessory glands
ejaculation
- reflexive somatic input = rhythmic contraction of striated muscle surrounding bulb and crura of penis
female reproductive system components
1) two ovaries
2) uterine tube
3) uterus
4) peritoneum creates recesses: vesicouterine and rectouterine pouches
5) external genitalia: mons pubis, clitoris, labia minora/majora
6) vagina
7) vestibule
descent of ovaries
1) ovaries anchored by gubernaculum
2) growth causes ovaries to descend to pelvic brim (stays internal)
3) portion of gubernaculum attaches to uterus, splits to form: ovarian and round ligaments
ovary/uterus ligaments
1) ovarian: ovary to uterus
2) round: uterus to labia majora, travels through inguinal canal
3) broad: drape of peritoneum where anterior and posterior layers connect, connects to ovary at hilum
4) suspensory: ovarian to pelvic wall, contains ovarian BVs, nerves and lymphatics
ovaries
- paired, oval
- anchored by specific cords and sheets of CT
- no peritoneum, in peritoneal cavity
ovary and uterine tube connection
- not directly connected
- space between
broad ligament contents
- subdivisions contain VANs, lymphatics
ovary histology
outer to inner:
1) germinal (surface) epithelium: simple cuboidal (mesothelium)
2) tunica albuginea: dense irregular CT
3) cortex: contains ovarian follicles
4) medulla: areolar CT, BVs, Ls, Ns
oogenesis
- production of primordial germ cells begins before birth (halted in prophase I = primary oocyte)
atresia
- primordial germ cells degenerating throughout childhood (programmed cell death)
ovarian cycle
- post puberty
- monthly sequence of follicular development regulated by GnRH (affects FSH and LH levels)
- follicular (1-14) and luteal phase (15-28)
follicular pahse
- stimulated by increasing FSH
- primordial follicles (many) –> primary –> secondary –> mature (primary oocyte differentiates into secondary and polar body)
primordial follicle
- primary oocyte
- simple squamous follicle cells
- outer surface has thin basal lamina
primary follicle
- simple cuboidal cells that undergo stratification to form granulosa layer (uni to multilaminar)
- surrounding stroma (CT + smooth muscle) forms thecal layers (interna and externa)
- zona pellucida around primary oocyte
zona pellucida
- protective acellular layer around oocyte
- contains sperm receptors
- “clear”
which cells secrete estrogen precursors?
- granulosa
- theca interna
secondary follicle
- primary oocyte
- many granulosa cell layers
- follicular fluid accumulates = become one continuous space = antrum
- granulosa cells form cumulus oophorus: attaches oocyte to follicular wall
- corona radiata: cells of CO that immediately surround oocyte
mature follicle
- one predominant follicle
- extends thickness of cortex
- antrum increases in size
- stratum granulosa thins
- oocyte and cumulus cells loosen from surrounding granulosum = prep for ovulation
- thecal cells become more prominent
- secondary oocyte halted in meiosis II until fertilized
fate of immature follicles
- atresia (majority)
luteal phase
- remaining granulosa cells + theca interna of ruptured follicle = corpus luteum, secretes progesterone and estrogens to prepare uterine lining for implantation
ovulation
- surge of LH causes release of secondary oocyte into peritoneal cavity
corpus luteum vs granulosa/theca interna cells
- increase in size, fill with lipids
end of luteal phase if no sperm
- corpus albicans = dense CT scar from degenerating corpus luteum
- estrogen and progesterone decrease = uterine lining shed
end of luteal phase if there is sperm
- secondary oocyte fertilized, may implant in uterine wall
- pre-embryo produces human chorionic gonadotropic (hCG) hormone
- hCG maintains corpus luteum, which continues to secrete progesterone
- after 3 months: placenta takes over, corpus luteum degenerates
polycystic ovary disease
- multiple follicular cysts
- thickness of tunica albuginea prevents ovulation of mature follicle
uterine tube structure
1) uterine part
2) isthmus
3) ampulla: expanded region where fertilization typically occurs
4) infundibulum: funnel-like area with fimbriae that sweep secondary oocyte into tube
uterine tube histology
1) columnar (ciliated and non-ciliated) epithelium
2) lamina propria
3) smooth muscle: inner circular, outer longitudinal
4) serosa
uterus support
- thick, muscular wall
- pelvic floor (inferior)
- ligaments: cardinal (transverse cervical), uterosacral, round
uterus epithelium
- simple columnar
- transitions to stratified squamous nonkeratinized passing through cervix and vagina
uterus structure
1) fundus
2) body with uterine cavity
3) isthmus: narrowing
4) cervical canal
internal/external os
1) internal = cervical opening from uterus (simple columnar to simple cuboidal)
2) external = cervical opening to vagina (simple cuboidal to stratified squamous nonkeratinized)
cardinal (transverse cervical) ligaments
- under broad ligament
- cervix to pelvic wall
- prevents inferior movement of uterus
uterosacral ligament
- attaches to sacrum (posterior side of uterus)
- restricts inferior and anterior movement of uterus
round ligament of uterus
- anterior side
- attaches to external genitalia
- prevents inferior and posterior movement of uterus
prolapse
- weakness of pelvic floor and/or ligaments causes uterus to fall through into vagina
- varying degrees
uterine wall layers
1) perimetrium: outer, mostly serosa, continuous with broad ligament
2) myometrium: middle, 3 concentric layers of smooth muscle
3) endometrium: innermost mucosa = simple columnar (some ciliated, others secretory) + lamina propria (with uterine glands)
uterine wall blood supply
1) branch from internal iliac artery (from aorta –> 2x common iliac –> internal)
2) uterine artery
3) arcuate artery = myometrium
4) radial artery = myometrium
5) straight artery = basal layer of endometrium
6) spiral artery = functional layer of endometrium
endometrium layers
1) basal: highly cellular lamina propria, uterine glands
2) functional: sparser (spongier) lamina propria, more ground substance, includes most of length of glands and superficial epithelium –> lost during menstruation
menstruation mechanism
- spiral arteries retract
- functional endometrium loses blood supply
uterine cycle
- cyclical changes to endometrial lining under influence of estrogens and progesterone
1-7 = menstrual phase
~10 = proliferative
~14 = secretory
inhibin in females
produced by granulosa cells, inhibits FSH production
menstrual phase
- triggered by decreasing progesterone and estrogen
- spiral arteries contract, superficial becomes ischemic
- degeneration and sloughing of functional layer
proliferative phase
- increasing estrogen from developing follicles
- cellular proliferation to regenerate functional layer (uterine epithelium, glands and spiral arteries)
- glands secrete glycogen and rich mucus
secretory phase
- begins after ovulation, persists as long as corpus luteum is intact
- stimulated by progesterone and estrogen from corpus luteum
- glands enlarge and accelerate secretion rate
vagina structure
- fibromuscular tube with three layers:
1) mucosa: stratified squamous nonkeratinized + lamina propria
2) muscular layer (thinner than uterus)
3) adventitia - greater vestibular glands around vestibule: area between labia minora
vagina acidic environment
- discourages bacterial growth
- necessitates buffering capacity of seminal fluid
vagina connections
- vaginal canal connects cervix to external environment
urogenital triangle in females
- covered by perineal membrane
- provides attachment for erectile tissue of external genitalia (vulva)
female external genitalia arrangement
1) mons pubis = skin and adipose tissue
2) labia majora = paired thickened folds of skin, homologous to scrotum
3) labia minora = paired folds, no hair, more medial than majora
4) vestibule: contains urethral (anterior) and vaginal openings
female erectile tissue
1) clitoris: crura, body, glans = homologous to penis
2) bulbs of vestibule: bilateral, deep to vestibule, connected to clitoris, homologous to bulb of penis
perineal muscles in female
- bulbospongiosus over bulbs of vestibule
- ischiocavernosus over crura of clitoris
- propel blood into body and glans of clitoris
- skeletal muscle
