Dr kellys digestion Flashcards
one example of essential breakdown by digestion
Linoleic acid converted by enzyme fatty acid desaturase to g-linoleic acid, an essential precursor for
phospholipids and prostaglandins
Mammalian accessory glands
Are the salivary
glands, the pancreas, the liver, and the
gallbladder
what does saliva contain?
Saliva (exocrine secretion from salivary glands) contains mucus, a viscous mixture of water, salts, cells, and
glycoproteins, and amylase, which breaks down starch
pharynx
Is the junction that opens to both the esophagus and the trachea
Swallowing causes the which part of the body to block entry to the trachea, and the bolus is guided by the larynx, the
upper part of the respiratory tract
Epiglottis
what causes peristalsis?
Valves called sphincters
regulate the movement of
material between
compartments
what two names should I remember for the GI tract?
Serosa,
Submucosa
Chyme
The mixture of ingested food and gastric juice.
gastric juice is made form what?
-is made up of hydrochloric acid (HCl) and pepsin (a
protease that breaks peptide bonds to cleave
proteins into smaller peptides)
what produces the ions separately?
Parietal cells secrete hydrogen and chloride ions
separately into the lumen (cavity) of the stomach
what cells secrete inactive pepsinogen
Chief cells
Cell division adds a new epithelial layer every how many days?
three days
Gastric ulcers, lesions in the lining, are caused mainly caused by what bacteria?
Helicobacter pylori
what converts pepsinogen
to pepsin
HCl
where does most enzymatic hydrolysis of macromolecules
from food occur?
The small intestine
what happens in the duodenum?
Here, chyme from the stomach mixes with
digestive juices from the pancreas, liver,
gallbladder, and the small intestine itself
the pancrease produces what?
Trypsin and
chymotrypsin, which are activated in the
lumen of the duodenum for neutralising acidic chyme
what digests fats?
Bile salts, Bile also destroys nonfunctional red blood cells
what vein carries
nutrient-rich blood from
capillaries of the villi to
the liver, then to the heart
and onwards to all organs
the hepatic portal vein
How does bile break up fat molecules?
Bile salts break
up fat globules,
increasing
exposure of
triglycerides to
hydrolysis.
The enzyme
lipase breaks
triglycerides
down to fatty
acids and
monoglycerides.
After monoglycerides?-
Monoglycerides
and fatty acids
diffuse into
epithelial cells and
are re-formed into
triglycerides.,
Triglycerides
are incorporated
into water-soluble
particles called
chylomicrons
Chylomicrons
enter lacteals and
are carried away
by lymph.
The alimentary canal ends with the (3)
includes the colon, caecum, and rectum
The cecum aids what?
The fermentation of plant material
and connects where the small and large
intestines meet
the appendix does what?
appendix plays a minor role in immunity
how many sphincters between the rectum and the anus?
Two sphincters between the rectum and anus
control bowel movements
NUCLEIC ACID DIGESTION
Pancreatic nucleases → Nucleotides
→ Nucleotidases → Nucleosides
→ Nucleosidases & Phosphatases → Nitrogenous bases, sugars, phosphates
Endocrine system
Gastrin, CCK, secretin
Gastrin stimulates production of
gastric juice
CCK stimulates release
digestive enzymes and bile
Secretin stimulates release of
bicarbonate (neutralises acid)
If chyme is high in fat, what happens
. If chyme is high in fat, digestion is slowed (peristalsis and gastric juice secretion is
inhibited)
Fat stores how many days energy?
about two months
carbohydrates are stored as what?
Glycogen
what are the rules of fat storage?
In humans, energy is stored first in the liver and muscle cells in the polymer glycogen
Excess energy is stored in fat in adipose cells
When fewer calories are taken in than expended, the human body expends liver glycogen first, then muscle glycogen and fat
what is the absorptive state?
-Fed state
– Glucose is plentiful and serves as major
energy source
– Insulin is major hormone of absorptive
state
Postabsorptive state
Fasting state
Endogenous energy stores are
mobilized to provide energy
Glucagon is major hormone of
postabsorptive state
where is the site glucose homeostasis
Liver
what is the only part of the body that are an exception; they can take up glucose
whether or not insulin is present
brain cells
what type of systems does the body have to prevent Metabolic syndrome
Hormones regulate long-term and short-term appetite by affecting a
“satiety center” in the brain
Ghrelin, a hormone secreted by the stomach wall, triggers feelings
of hunger before meals
Insulin and PYY, a hormone secreted by the small intestine after
meals, both suppress appetite
Leptin, produced by adipose (fat) tissue, also suppresses appetite
and plays a role in regulating body fat levels
GLP-1 receptor agonists what do they do ?
GLP-1 receptor agonists are a type of medication that mimic the action of a natural hormone called GLP-1 (Glucagon-Like Peptide-1). GLP-1 is an incretin hormone released from the gut after eating, which helps regulate blood glucose levels.
they can lead to slow gastric emptying aswell as liposyis
what is unique about the guts microbiome
Each individual has unique enteric bacterial fingerprint
common features to all organs
Blood supply
Nerve supply
Presence of immune
cells (resident cells and
cells that infiltrate from
blood)
adaptive immunity what is different about them?
it is slow
innate immunity is then
it is then rapid response
what can we say about ALL stressors
ALL stressors induce the same general
nervous and endocrine response (which
impacts the immune system)
Effects of
mineralocorticoids( aldosterone)
Increases sodium (Na⁺) reabsorption in the kidneys (mainly in the distal tubules & collecting ducts)
Increases water retention (follows sodium → increases blood volume & blood pressure)
Increases potassium (K⁺) excretion in the urine Increases hydrogen ion (H⁺) excretion → helps regulate acid-base balance
effects of glucocorticoids?
Proteins and fats broken
down and converted to
glucose, leading to increased
blood glucose
Partial suppression of
immune system
(a) Stress Response & Adrenal Medulla
The adrenal medulla is the inner part of the adrenal glands. It handles the immediate, short-term “fight or flight” stress response.
Hormones released:
Adrenaline (epinephrine)
Noradrenaline (norepinephrine)
Effects: ↑ Heart rate
↑ Blood pressure
↑ Respiratory rate
↑ Blood glucose levels (for quick energy)
Dilates pupils
Redirects blood to muscles & brain (away from digestive system)
key:This is a fast, nervous system-driven response via the sympathetic nervous system.
(b) Stress Response & Adrenal Cortex
The adrenal cortex is the outer part of the adrenal glands. It handles the slower, longer-term stress response through hormone release.
Hormones released:
Glucocorticoids → mainly Cortisol
Mineralocorticoids → mainly Aldosterone
Androgens (less relevant for stress)
Effects of Cortisol: ↑ Blood glucose levels (by promoting gluconeogenesis)
Suppresses immune response (anti-inflammatory)
Breaks down fats & proteins for energy
Inhibits non-essential functions (like reproduction, growth)
Effects of Aldosterone: Increases sodium & water retention
Increases blood volume & pressure
This is a hormonal, endocrine response triggered by the Hypothalamic-Pituitary-Adrenal (HPA) axis
sedentary is what?
<1.5 mets
METS
metabolic equivalent. Ratio
of activity to resting metabolic
rate
what is weird about elite athletes
they have a higher rish of upper respitory infections- why-Heavy exercise causes a short-term drop in immune function (especially after long sessions, like marathons).
This is known as the “Open Window” theory — there’s a window of time (3-72 hours) after intense exercise when the immune system is suppressed
what is inflammaging
Increased inflammation as we age
why does inflammatiging happen?
Accumulation of Cell Debris & Damage
Over time, we build up damaged cells, misfolded proteins, and dead cell debris.
This activates the immune system constantly (almost like tiny “danger” signals).
Senescent Cells
Old cells stop dividing and become senescent but don’t die.
These cells release pro-inflammatory cytokines → called the SASP (Senescence-Associated Secretory Phenotype).
Mitochondrial Dysfunction
As we age, mitochondria become less efficient → more reactive oxygen species (ROS) → causes cellular damage & inflammation.
Reduced Autophagy
Autophagy = the process of clearing out damaged cell components.
With age, this process slows down → more waste → triggers inflammation.
exercising does what for the body?
Increase in Anti-inflammatory cytokines (IL-10)
A decrease in Pro-inflammatory cytokines (IL-1β, TNF-⍺)
An increase in Synaptic plasticity
what is synaptic plasticity?
Synaptic plasticity is the ability of the connections between neurons (synapses) to change in strength or efficiency over time
