Physiology Flashcards
Which part of the digestive tract contains striated muscle?
Pharynx,
Upper 1⁄2 Oesophagus
External Anal Sphincter
What are the 3 important features for splanchnic circulation?
Large blood flow
Large reservoir function
Perfuses a diversity of organs
What percentage of blood is funneled to the liver by the Hepatic portal vein?
70% - deoxygenated blood
In which part of the digestive tract is a serosa missing?
Oesophagus & Distal rectum
What percentage of blood is coming from the Hepatic artery to the liver?
30%
What percentage of the nerve fibres in the Vagus are afferents?
75%
Where do motor neuronal cell bodies in the cranial division reside and what do the project via?
They reside in the medulla oblongata and project via the Vagus nerve
At what level is the Enteric nervous system present in the hierarchy of neural organization ?
Level 1
Fill in the blanks.” Motor neuronal cell bodies in the sacral s.c. project in the _________ to colon , rectum and internal sphincter.”
Pelvic nerve
What substance is released by parasympathetic Motor neuronal cell bodies in the sacral s.c. ?
Acetylcholine
What substance is released by the sympathetic postganglionic neurone when they synapse on other neurone of the ENS, blood vessels, mucosa and sphincters?
Nor-epinephrine
What are the two nerve networks by which the enteric nervous system works by?
Submucous plexus- Meissner’s plexus
Myenteric Plexus - Auerbach’s plexus
Where is the Myenteric plexus found?
Between the middle circular and outer longitudinal layers.
Where is the submucosal plexus found?
Between the submucosa & muscularis propria
What are the types of Neurones found in the Enteric Nervous system?
Sensory neurons - respond to stretch , tonicity and chemicals
Motor neurons- Innervate smooth muscles to elicit movement
Secretory neurons - Regulate endocrine and exocrine secretions.
Interneurones- innervate both plexuses
What substances are released that causes excitatory nerves to innervate muscles?
Acetylcholine (Ach) and Substance P ( SubP)
What substances are released that causes inhibitory nerves to innervate the muscles?
Nitric Oxide (NO) and Vasoactive intestinal polypeptide(VIP)
What is the function of the Submucousal plexus ( Meissner’s plexus)?
It has an exocrine & endocrine function
What is the function of the Myenteric plexus?
It controls peristalsis and other motor activities
Which substances are involved with Paracrine secretions for the GI tract ?
Histamine
Somatostatin
What substances are involved in Neurocrine secretions for the GI tract?
Vasoactive intestinal polypeptide(VIP)
Gastrin releasing peptide ( GRP)
Enkephalins
Gastrin, CCK, Secretin , GIP (Glucose- dependent intsulinotropic peptide), motilin and ghrelin are what type of secretory substances?
Endocrine secretions
Where is Ghrelin secreted from and what is its function?
It is secreted by epithelia in body of stomach and is a hormone that regulates food intake.
What are Neurocrines?
These are peptide released from nerve endings in the gut in response to a stimulus.