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Parts of respiratory system
- Pulmonary ventilation- breathing
- External respiration- gas exchange at air sacs, alveoli
- Transport of respiratory gases- cardiovascular system
- Internal respiration- gas exchange at capillaries
- -provides airway for respiration
- -moistens and warms incoming are
- -filters air
- -resonating chamber for speech
- -houses olfactory receptors
- External nose-apex, septal lateral and alar cartilage, ala is made of dense fibrous tissue
the nasal cavity
- air enters through external nares (nostrils), which are divided by nasal septum.
- nasal cavity is covered by ciliated mucus secreting cells. This area is the vestibule and the air flows through the meatus of the conchae which warms, and moistens air
- Air exits to the nasopharynx through the choanae (internal nares).
The respiratory mucosa
- made of pseudostratified, ciliated, columnar expithelium. Secretes mucus with lysozyme which degrades bacteria and goes to stomach to get destroyed.
- Has rich plexuses of capillaries and thin veins to warm air when cold and is why nose bleeds can occur
Connects the nasal cavity and mouth to the larynx and esophagus. consists of skeletal muscle but different mucosal linings
- consists of nasopharaynx, oropharanyx, and laryngopharanyx
- most superior part of pharnyx that begins at choanae and ends at hard palate and uvula,an extension of the soft palate at the back of the mouth.
- Only for nasal air and has pharyngeal tonsil, or adenoids, on posterior wall.
- posterior to mouth cavity. from soft palate to epiglottis.
- Epithelium changes to stratified squamous epithelium
- has paired palatine tonsils on lateral walls of fauces, or throat. and lingual tonsil on posterior tongue.
- also common passageway for food and air and covered in stratified squamous epithelium
- posterior to the larynx and continuous with larynx and esophagus
The larynx (locations and cartilages)
- between hyoid bone and trachea.
- -produces vocalizations, provides an open airway, acts as switching mechanisms for route between air and food.
- thyroid cartilage-"adam's apple" largest, and anterior, looks like open book
- cricoid cartilage- around entire trachea, connects thyroid to trachea
- arytenoid cartilage- superior to cricoid and posterior to thyroid cartilages for attachment to vocal cords (cornicate and cuneiforms cartilages)
- epiglottis- closes glottis when swallowing
The Larynx (voice production)
- vocal folds (true vocal cords): ligaments extending across upper opening of larynx from thyroid to arytenoid cartilages, and vibrate to form sounds. with medial opening is glottis
- vestibular folds (false vocal cords): horizontal mucosal folds superior to vocal cords.
- All of larynx, mouth, lips, pharynx nasal cavity are part of resonance and shaping sounds
- goes from larynx till dividing into main bronchi.
- lines with pseudostratified columnar epithelium containing 16-20 cartilagenous "C"'s that allow for flexibility posteriorly.
- carina internal ridge that marks division with bronchi. associated with cough reflex
Bronchi and subdivisions
- primary (main) bronchi- first branch after tracheal bifurcation.
- Secondary (lobar) bronchi- 3 on right, 2 on left, for each lobe of the lung
- tertiary (segmental) bronchi- third division, goes up to 23 until you reach bronchioles.
- Less cartilage as subdivisions get smaller, epithelium get thinner, smooth muscle becomes important to control gas exchange
- respiratory bronchioles become alveoli ducts which have alveolar sacs (groups of alveoli) attached
- wall of alveolus and capillary wall (Type 1 cell made of squamous epithelium) make respiratory membrane that oxygen can easily travel across as blood rushes past. (type II cells secrete surfactant: reduces surface tension)
- fine elastic fibers, alveolar pores (equalize), and alveolar macrophages (remove dust particles)
- serous membrane of the lungs.
- Visceral pleura- internal layer, covers external lung surface.
- parietal pleura- covers internal thoracic wall.
- pleural cavity filled with pleural fluid, lubricated between pleura and attaches them together to help expand lung during chest expansion.
lung infections- (like pnemonia) cause inflammation of pleura
lung gross anatomy
- apex, base, hilum, cardiac notch, lobes and fissures (oblique and horizontal), lobule
Lung blood supply and innervation
- Pulmonary arteries branch posterior to bronchi counterpart. Pulmonary capillary networks around the alveoli, pulmonary veins are anterior to bronchi.
- Innervation through pulmonary plexus enter at lung root and lie along bronchial tubes
Mechanism of Inspiration (breathing in)
- Negative pressure
- Diaphragm contracts and flattens down expanding lungs downward and lower ribs laterally
- Intercostal muscles contract- raise ribs to be horizontal expanding lungs laterally.
- Collapsed lung happens when air enter pleural cavity and lung no longer stick to thoracic walls.
Lung expiration (breathing out)
- Usually a passive process when muscles relax
- When forced caused by contraction of abdominals, lowering ribs. Surfactant from type II cells keep alveoli from collapsing.
- Respiratory distress syndrome- surfactant isnt produced, alveoli collapse and a respirator is needed to provide positive pressure to lungs
Neural control of ventilation
- central breathing control is ventral respiratory group, located in medulla oblongata, with input from pons. Modifications from limbic system (emotions), cerebral cortex (conscious breathing), and blood concentration of oxygen (via chemoreceptors from vagus and glossopharageal nerves)
- phrenic nerve- innervates diaphragm to control rate of breathing
Disorders of Lower Repiratory structure (Bronchial asthma, Cystic fibrosis, chronic obstruction pulmonary disease COPD)
- Bronchial Asthma- allergic inflammation from hypersensitivity of irritants or stress.
- Cystic Fibrosis- inherited, gene prevents chloride channels into epithelial cells, surface becomes salty, bacteria thrive and mucus obstructs respiratory passageways
- COPD- flow of air is obstructed and difficult. Often from bronchitis and emphysema, permanant enlargement of alveoli from smoking
Disorders of upper respiratory tract
- Epitaxis-nose bleed, mostly from highly vascularized anterior part of nose
- epiglottis- inflammation from ages 2 to 7. Caused by bacteria.
Alimentary canal v. accessory digestive organs
- Alimentary canal- lies "outside the body" connected to outside on both ends. Mouth, pharynx, esophagus, stomach, small intestine, large intestine.
- Accessory digestive canal- inside the body connected to canal via ducts. Teeth, tongue, salivary glands, gallbladder, pancreas, liver.
- Ingestion- taking food into mouth
- Propulsion- peristalsis, involuntary alternate contraction and relaxation of muscle the pushes food through tracts.
- Mechanical digestion- chewing, churning (stomach), segmentation (small intestine)
- chemical digestion-food is broken down to building blocks by enzymes
- absorption- digested end product from lumen into blood and lymphatic capillaries
- defecation- elimination of indigestible substance
Four tissue layers of alimentary canal
- Mucosa, submucosa, muscularis externa, serosa
- Mucosa- epithelium (absorbs nutrients, secretes mucus, continuous with glands) Lamina propia (connective tissue, absorbs nutrients, contains MALT) muscularis mucosae (thin smooth muscle, for local movements)
- submucosa- connective tissue with elastin, contains major blood and lymphatic vessels.
- muscularis externa- two layers of smooth muscle (circular and longitudinal layer), forms sphincters
- serosa or adventitia- simple squamous epithelium or connective tissue
- Digestive organs are all surrounded by serous membranes, the largest of which is peritoneum.
- Visceral peritoneum- covers external surface of most digestive organs.
- Parietal peritoneum- lines the body wall.
- peritoneal cavity- filled with serous fluid allowing for smooth gliding of organs
- a double layer of peritoneum that extends from body wall to digestive organs that holds them in place, sites of fat storage, routes for circulatory vessels and nerves.
- Ventral mesenteries- falciform ligament (binds anterior liver to abdominal wall), lesser omentum (from liver to lesser curvature of stomach and duodenum)
dorsal mesenteries- greater omentum (covers abdominal viscera), mesentery (jejunum and ileum) transverse mesocolon (transverse colon), sigmoid mesocolon (sigmoid colon)
most of duodenum, ascending/descending colon, rectum and pancreus lose their mesenteries during development, secondarily retroperitoneal
- Oral vestibule-between lips and teeth
- lips- "labia" red margin lacks mucosa and sweat glands, labial frenulum is medial connection of lips to gums.
- Palate-roof of mouth. palatal rugae is ridges of ard palate. soft palate closes off nasopharynx during swallowing (also provides suction), uvula hangs off end
- Cheeks- buccinator muscle, stratified squamous epithelium
- moves food around, forms bolus. symetrical intrinsic and extrinsic muscles
- lingual frenulum- secures and limits tongue movements
- filiform papillae- roughen tongue, whitish
- fungiform papillae- "mushroom shaped" scattered widely and taste buds are in epithelium and on top.
- circumvallate papillae- V shaped on posterior tongue, anterior to sulcus terminalis.
- posterior 1/3 of tongue has lingual tonsil in oropharynx.
- Deciduous teeth, primary dentition (20 teeth) are replaced by permanent dentition (32 teeth). Sit in sockets "alveoli", innervated via trigeminal nerve
- Incisors- for cutting, four upper and four lower, with a single root
- canines- "fangs", pierce and tear, single root. 2 upper, 2 lower
- premolars (bicuspids) and molars- "millstone", 8 premolars, 12 molars
- cusp-irregular chewing surface on molars and premolars for crushing food
- root-anchors root in alveoli, contains pulp and root canal which supplies nutrients, blood vessels and nerves to teeth.
- enamel and dentin- hard material of teeth, enamel is hardest in body.
- Cementum is continuous with periodontal ligament and gums/gingiva which all anchors tooth.
- tubuloalveolar structures secrete saliva that breaks down starches, lubricates food and oropharynx, is antimicrobial. intrinsic glands are small and everywhere.
- Extrinsic glands:
- parotid gland- largest, "near ear", inferior and anterior to external ear. mumps causes inflammation of parotid gland.
- submandibular gland- inferiomedial to mandible body, opens lateral to lingual frenulum
- sublingual gland- in floor of oral cavity
- Gross anatomy: from larynx to stomach, passes through esophageal hiatus, ends with cardiac orifice and cardiac sphincter, which prevents reflux stomach acid.
- "J" shaped, food is churned and turned into chyme. secretes pepsin which breaks down proteins. secretes hydrochloric acid which kills microorganisms. Can absorbs water, electrolytes and some drugs. Food stays in stomach for 4 hours. Sends food to small intestine via pyloric sphincter.
- cardiac region- region attached to esophagus
- fundus-superior portion, touches diaphragm
- body- major portion, inferior to fundus
- greater and lesser curvatures
- gastric rugae- folds of inner stomach that allow for stretching
- pyloric region-terminal part of stomach leading to duodenum via pyloric sphincter
Stomach microscopic anatomy
- Have extra layer of muscularis extera, oblique layer that pushes food to small intestine.
- has epithelial layer secretes bicarbonate buffered mucus that protects lining from acidic environment.
- millions of gastric pits have glands with:
- Mucus neck cells- secrete special mucus
- parietal (oxyntic) cells- secrete HCl
- Chief (zymogenic) cells- secrete pepsinogen which is activated into pepsin with HCl
Gross anatomy of small intestine
- Has food for 3-6 hours. absorbs nutrients with help from pancreas enzymes.
- 2.7-5 meters long from pyloric sphincter to large intestine.
- Duodenum- 5%, C-shaped, receives pancreatic enzymes (main pancreatic duct) and bile from liver and gallbladder (bile duct) via the major duodenal papilla
- Jejunum- ~40%, relatively larger lumen, has more plicae circulares
- ileum-~60%, contain numerous lymphatics in walls
- Food enters large intestine via ileocecal valve, a sphincter
microscopic anatomy of small intestine
- plicae circulares, circular folds- transverse ridges that increase surface area and spin chyme
- Villi- 1mm high, have absorptive cells, lamina propia contains lymphatic capillary, lacteal, for absorbing fats, have muscle that allow for movement
- microvilli- are exceptionally long and densely packed
- goblet cells (mucus-secereting), enterendocrine cells (signal emzyme secretion), epithelial walls are renewed every 3-6 days
Large intestine: gross anatomy
- food there for 12-24 hours, absorbs electrolytes and water.
- teniae coli- longitudinal strips of muscularis externa, which cause formation of small sacs, haustra.epiploic appendages-fat accumulations on visceral peritoneum of large intestine.
Cecum and vermiform appendix
- iliocecal valve opens into cecum, a saclike part. veriform appendix opens in posteriolateral cecum to the appendix which has lymphoid tissue
Colon, rectum and anal canal
- Ascending colon, at right colic (hepatic) flexure, turns and become transverse colon, at left colic (splenic) flexure, turns and becomes descending colon.
- Inferiorly colon becomes intraperitoneal and becomes S-shaped sigmoid colon.
- rectum- following sigmoid colon, allows for strong muscular contractions, inferior half of sacrum
- anal canal- 3cm long, internal anal sphincter (involuntary), external anal sphincter (voluntary) on surface of canal.
- Produces bile which emulsifies fats, stores glycogen, processes fats and amino acids, detoxifies poisons and drugs.
- right and left lobes seperated by falciform ligament that connects liver to diaphragm.
- quadrate lobe located next to gallbladder.
- caudate lobe located deep near vena cava.
- right/left hepatic ducts form common hepatic duct which collects bile for duodenum via cystic and common bile ducts.
Liver: Microscopic anatomy
- over a million liver lobulesm size of sesame seeds, hexagonal, each corner has portal triad (artery, vein, duct). Has plates of hepatocytes, between which are liver sinusoids, which carry blood.
- Kupffer cells- in sinusoids, destroy bacteria and toxins, destroy worn-out blood cells
- stores and concentrates bile made by the liver.
- secretes duct via cystic duct which joins common hepatic duct to create bile duct
- shaped like tadpole with head in C-shaped duodenum.
- Main pancreatic duct empties into duodenum via major duodenal papilla.
- acinar cells- create 22 pancreatic enzymes for digestion, stored as zymogen granules.
- Pancreatic islets (islets of langerhans) secretes glucagon and insulin
digestive system embryonic development