Lecture 30/10/24 Flashcards
Digestive system
Components of digestive system
mouth, pharynx, oesophagus,
stomach, small intestines, large intestines and anus
Accessory organs of digestive system
salivary glands, teeth,
liver, gallbladder and pancreas, tongue
Function of digestive system
Physical/chemical food breakdown
Absorb nutrients
Eliminate waste
What is alimentary canal
The continuous hollow tube of digestive tract
Structure of alimentary canal
Two muscle layers
Inner circular - has thickened parts (sphincters)
Outer longitudinal
Separated by neurovascular/lymphatic vessels
How does peristalsis work
longitudinal acts as a wave, circular prevents going backwards
Function of mouth
starts the process of chemical and mechanical digestion.
Mixing food with enzymes
making food swallowable
borders of mouth
Anteriorly – lips
Posteriorly – oropharyngeal isthmus
Laterally – cheeks / buccal surfaces (buccinators muscle)
Superiorly – palate (hard/soft)
Inferiorly - tongue and floor
Floor of mouth structure
Mylohyoid and geniohyoid muscles
U shaped diaphragm
Floor of mouth function
Supports tongue
Soft palate structure and function
Posterior ⅓. Mobile muscular fold. Uvula – fold of muscle; saliva, speech, gag reflex
Hard palate structure and function
Anterior ⅔ . Made of Maxilla and palatine bones.
Tongue structure
Base attached to hyoid bone and to floor by lingual frenulum.
Skeletal muscle fibres (voluntary) intrinsic and extrinsic
Tongue function
Taste
Speech
Mastication
Swallowing
Teeth function
Speech
Mastication
Salivary glands structure
Three bilateral pairs of glands that release saliva into mouth through ducts.
Name the 3 salivary glands
Parotid, submandibular and sublingual
What is the pharynx split into
Naso, oro and laryngopharynx
oesophagus function
transport food or chyme from mouth to stomach.
structure of oesophagus
A muscular tube resistant to damage.
begins distally to the mouth, lies posterior to trachea but anterior to spine.
passes through diaphragm posterior to central tendon at T10
stomach function
mix or pummel food into chyme
supports further mechanical and chemical digestion
stomach structure (general)
Collapses when empty.
C or J shaped
sections of stomach
- greater and lesser curvature
- Main body
- Pylorus - pyloric antrum (superior) and pyloric canal (inferior)
- Cardia - connects to oesophagus
- Fundus - often has gas in it
two stomach sphincters
lower oesophageal sphincter
pyloric sphincter
3 regions of small intestine
duodenum
jejunum
ileum
function of duodenum
breaks down food using enzymes
receives, chyme, digestive juices and bile
structure of duodenum
c shaped
4 regions:
superior
descending
horizontal
ascending
jejunum function
majority of absorption
peristalsis
jejunum structure
villi that have a capillary bed and lacteals
microvilli - brush border - contains enzymes
ileum structure
mesenteric fat
small thin lumen, less distinct circular folds
peyers patches
ileum function
absorb vitamin B12 and bile salts and anything else left over
what is anesmosis
cut out diseased section of bowel and sew two ends together
structure of large intestine
goblet cells make lubricant mucous
haustra
tenia coil - 2 bands of longitudinal muscle
sections of large intestine
caecum
ascending colon - more posterior, right side
transverse colon - more anterior
descending colon - more anterior, left side
sigmoid colon - S shape, more anterior
rectum - anterior
anal canal structure
internal sphincter - smooth muscle
external sphincter - skeletal muscle
liver structure
wedge shape
Covered by fibroelastic capsule made of visual peritoneum. Underneath has blood and lymph vessels. Posterior cranial aspect not covered by peritoneum so bare area.
liver lobes
4 lobes.
2 main lobes right and left divided by falciform ligament.
The right is larger and divided into caudate and quadrate lobes. Round ligament and coronary ligament
liver function (digestive)
make bile
gallbladder structure
sac like, on inferior liver surface
right and left hepatic duct
cystic duct
common bile duct
sphincter of oddi
gallbladder function
store and concentrate bile
exocrine vs endocrine
exo - duct
endo - blood
pancreas function
make pancreatic juices
make insulin and glucagon
what is pancreatic juices made of
water, salts, sodium bicarbonate, enzymes
what is segmentation
localised mixing contractions
define ingestion
taking in food
define propulsion
moving food
define digestion (mechanical and chemical)
breakdown
define absorption
going through gi tract barrier into blood
define Egestion or elimination
waste expelled
segmentation process
- Contraction of circular muscle
- Constricts intestine → segments
- Muscle fibres in middle of each segment contract which divides segment further
- First fibres relax creating large segment again
- Repeats so chyme is sloshed back and forth
where is amylase made
salivary glands and pancreas
where is protease made
pancreas
where is lipase made
pancreas
