lecture 33: digestive 1

Question 1

main parts of the tooth

Answer 1

• enamel (no cells, crystaline rods)
• dentin (like bone but odentoblasts occur near pulp and not scattered)
• pulp (soft tissue with nerves, blood + lymphatic vessels)
• cementum: callcified connective tissue covering root)
• periodontal ligament (collagen fibres linking alveolar bone socket to cementum, rapid turnover)

Question 2

scurvy

Answer 2

• lack of vitamin c.
• rapid turnover of periodontal ligament cannot occur so connection to cementum is bad and the teeth can fall out

Question 3

tongue papillae

Answer 3

• fungiform: mushroom shaped (some taste buds)
• filiform: sharp and bendy
• vallate: have a moat/trench surronding and in that border are most taste buds

Question 5

intrinsic muscles of the tongue

Answer 5

• superior and inferior longitudinal (A->P) that withdraw the tongue
• vertical that flatten the tongue
• tranverse that narrow tongue

Question 6

the three major salivary glands and their functions

Answer 6

• parotid: only serous cells (watery enzyme secretion)
• sublingual: mixture of serous and mucous, but motly mucous
• submandibular: mixed serous and mucous cells

Question 7

enzymes in saliva

Answer 7

• amylase to break down starchy debris around teeth
• lysozyme for antibacterial functions

Question 8

digestion

Answer 8

chemical breakdown of ingested food into absorbable molecules requires secretion

Question 9

absorption

Answer 9

movement of nutrients water and electrolytes through epithelial lining of gut into blood or lymph

Question 10

secretion

Answer 10

salivary gland: enzymes (for various) and mucous for lubrication

Question 11

methods to increase surface area of epithelium in digestive system

Answer 11

• gross convolutions
• luminal folds (circular): longitudinal in stomach, circular in intestines
• evaginations: projections into lumen (SI has villi)
• glands/invagination: project away from lumen (SI and LI = intestinal glands)

Question 12

four layers that generally make up the gut tube

Answer 12

• mucosa (mucous membrane)
• submucosa
• muscularis externa (ext. smooth muscle)
• serosa (or visceral peritoneum)

Question 13

tissue components and functions of mucosa

Answer 13

• epithelium: can specialise for protection/absorption/secretion also is a physical barrier of external environement
• lamina propria: fibrous connective tissue with nervous and blood supply (support)
• muscularis mucosae: two layers of smooth muscle that moves mucosa alone (squeee glands or lymph)

Question 14

tissue components and functions of submucosa

Answer 14

• blood vessels that provides structural and blood/nervous support to external muscle and mucosa
• glands that are controlled by submucosal nerve plexus
• loose connective tissue

Question 15

tissue components and functions of muscularis externa

Answer 15

• two large layers of smooth muscle
• inner layer is cicular, outer is longitudinal
• myecentric nervel plexus inbetween inner and outer layers that coordinates their movement
• two layers produce peristalsis (gut movement)

Question 16

peristalsis

Answer 16

the contraction of muscle in the digestive tract, starting int he oesophagus. a wave like motion where the outer layer of muscularis externa contracts longitudinally and inner layer contracts circularly. under controll of enteric nervous system, influenced by autonomic

Question 17

tissue components and functions of serosa

Answer 17

• interchangeable with visceral peritoneum
• bed of connective tissue lined with mesothelial cells
• does not cover oesophagus
• outermost connective tissue is called adventitia when not in contact with body cavity (oesophagus)