GI and Respiratory Revision

Question 1

overview the GI tract

Answer 1

Mouth

Esophagus -• Epithelium –Stratified squamous non-keratinised • Submucosa –CT + glands • Muscularis externa –Rapid peristalsis

Stomach - mucosa secret gastric acid and digesitve enzymes, Musucularis mucoasae, submucoasa, Muscularis externa, rugae (pronounced folds)

Duodenum of small intestine (pancreas secretes digestive enzymes- tyrpsin, lipases, pancreatic amylase to stomach and intestine from here) - also secretes bicarb rich muchs to neutralise stomach chyme
liver secrets bile here

Jejenum of small intestine - has crypts
Illeum of small intestine
both have adaptions to maximise absorbtion of fats , glucose - pilcae circulares and villi and microvilli

Cecum of large intestine
Large intestine

Anus

layers of the gut wall

lumen
Musocsa (epithelium, lamina propria, musuclaris mucosa)
Submuscosa - has veins, nerves, arteiris, lymph, glands
muscularis - circular and longnitudunal for contraction wave - peristalsis
Serosa - the double ballon that lines every organ

Question 2

overview respiratory tract

Answer 2

Conducting portion –No gas exchange, only conduit
• Nasal cavity
• Pharynx
• Larynx

• Trachea - Pseudostratified ciliated epithelium Goblet cells secrete mucus –Muco-ciliary escalator Submucosal glands –Secrete mucus and bacteriostatic/-cidalproteins

• Primary, secondary and tertiary bronchi
- Still pseudostratified epithelium with goblet cells • Cartilage in full rings in primary bronchi, then amount of cartilage reduced as bronchial diameter decreases

• Bronchioles - Epithelium –Ranges from pseudostratified to simple columnar ciliated to simple cuboidal
No cartilage–Patency maintained by surrounding alveoli (radial traction)
Goblet cells give way to Clara cells–Secrete a surfactant lipoprotein and abundant Clara cell protein

• Terminal bronchioles

• Respiratory portion –Open onto alveoli, site of gas exchange
• Respiratory bronchioles
• Alveolar ducts

• Alveoli -
Adaptations for gas exchange:
Simple squamous epithelium
Abundant capillaries
Moisture + surfactant
Type I pneumocyte –Squamous cell for gas exchange • Type II pneumocyte –Secretes surfactant
Alveolar macrophage– Phagocytoses microbes and debris