DAT Lymphatic and Digestive Systems Flashcards
Osmoregulation
maintenance of
osmotic pressure of fluids by control of
water and salt concentrations
Marine fish osmoregulation
body is hypotonic
to the environment → water is
constantly lost by osmosis, so these
fish are constantly drinking water,
rarely urinating, and secreting
accumulated salts through gills
freshwater fish osmoregulation
body is
hypertonic to the environment →
water moves in, so the fish are rarely
drinking water, constantly urinating,
and absorbing salt though gills
Annelids excretory system
excrete CO2 directly through
moist skin
Nephridia (metanephridia)
functional unit of excretion that occur
in pairs within each segment of
annelids (earthworms).
Platyhelminthes excretory system
possess flame cells/
flame bulbs, which are bundles of flame
cells that combine to form
protonephridia; they are distributed
along a branched tube system that
permeates the flatworm
Arthropods excretory system
CO2 is released from
tissue via trachea, which lead to the
external air via spiracles
Malpighian tubules
found in most
terrestrial arthropods and are
tubules that attach at the junction
between the midgut and the
hindgut. They collect body fluids
from the hemolymph that bathes
the cells. The fluids are deposited at
the junction of the midgut and
hindgut
what is nitrogenous waste usually converted to?
converted
to ammonia, which is also toxic.
4 places excretion occurs in humans
lungs, liver,
skin, and kidney:
Lungs
CO2 and H2O (gas) diffuse from
the blood and are continually exhaled
Liver
largest internal organ that
processes nitrogenous wastes, blood
pigment wastes, other chemicals,
produces urea via the urea cycle
Skin
sweat glands in the skin excrete
water and dissolved salts to regulate
body temperature
what is the largest overall organ
skin
Kidney
i. Excrete waste via the path - kidneys
→ ureter → bladder → urethra
ii. Maintain homeostasis of body fluid
volume and solute composition
iii. Regulate blood pressure
regions of the kidney
i. The outer cortex
ii. Inner medulla
iii. Renal pelvis which drains to the
ureter
nephrons
composed of a renal
corpuscle and renal tubule, and function to
reabsorb nutrients, salts, and water.
Renal corpuscle
contains
the glomerulus, which acts as a sieve, and
Bowman’s capsule, which encloses the
glomerulus.
2 arterioles of Bowmans capsule
an afferent
arteriole that leads into the glomerulus,
and an efferent arteriole that leads out of
the glomerulus
what happens in the renal corpuscle
Hydrostatic pressure forces plasma
through the fenestrations (small
pores) of the glomerular endothelium
and into Bowman’s capsule. These
fenestrations screen out blood cells
and large proteins from entering
Bowman’s capsule, After the efferent arteriole passes out
of the glomerulus, it just webs around
the entire nephron structure as the
peritubular capillaries (which surround
the proximal convoluted tubule and
distal convoluted tubule and reabsorb
materials) and vasa recta (which
surrounds the Loop of Henle in the
kidney’s medulla and maintains the
concentration gradient) before
dumping back into the renal branch
of the renal vein
When substances are reabsorbed from
the tubules (or secreted into them), it takes place in…
the interstitium. It is this network of capillaries that lets
us reabsorb into/secrete from the blood.
the renal corpuscle leads to…
Renal tubule
components of the renal tubule
Proximal convoluted tubule (PCT), Loop of Henle, Distal convoluted tubule, Collecting duct
Proximal convoluted tubule (PCT)
where active reabsorption of almost
all glucose, amino acids, and some
NaCl, as well as passive reabsorption
of K+ and HCO3
-, begins. Water
follows these ions out so the cortex is
not salty. Most reabsorption takes
place here.
Loop of Henle compnenets
ascending loop and descending loop
largest component of the nephron?
loop of henle
Descending loop
only
permeable to water (but this
water is picked up by the vasa
recta so the medulla stays salty)
via lots of aquaporins. The
solute concentration in the tube
increases as a result
Ascending loop
makes the
renal medulla salty: first
passively and then actively by
pumping out NaCl. The
ascending loop is also
impermeable to water! Solute
concentration in the tube
decreases as a result.
Distal convoluted tubule
(DCT)
more reabsorption of
glucose, ions and water occurs here
so the cortex isn’t salty.
Collecting duct
collects the
remaining filtrate. What happens here
(concentrated or dilute urine) is highly
dependent on what hormones are
acting on it.
Path of urea through collecting duct:
- Urea first descends to the medulla
(salty part) where antidiuretic
hormones (ADH/vasopressin) can
make more water leave from urine
by increasing permeability of the collecting duct (via increased
aquaporins) → urine is even more
concentrated. Note that one
collecting duct is shared by many
nephrons.
entire process of urine formation can be
summarized in four overarching steps:2. Aldosterone can also act on the
collecting duct by increasing Na+
reabsorption, resulting in water
passively following Na+ - By the time urine emerges, it usually
has varying amounts of: H2O, urea,
NaCl, K+, and creatinine
entire process of urine formation can be
summarized in four overarching steps:
filtration,
reabsorption, secretion, and concentration
filtration (urine formation)
the fluid that goes through
the glomerulus (afferent arteriole →
glomerulus → efferent arteriole) to the
rest of the nephron is called filtrate,
which is pushed into Bowman’s capsule.
Particles that are too large to filter
through the glomerulus (such as blood
cells or albumin) remain in the circulatory
system.
i. This is a passive process that is driven
by the hydrostatic pressure of blood.
Reabsorption
glucose, salts, and amino
acids are reabsorbed from filtrate and
return to the blood. This process takes
place primarily in the PCT via active
transport.
Secretion
substances such as acids,
bases, ammonia, drugs, and ions are
secreted by both passive and active
transport from the peritubular capillaries
and into the nephron
Concentration
when we’re dehydrated,
the volume of fluid in the bloodstream is
low, so we need to make small amounts
of concentrated urine (and increase our
blood fluids). ADH prevents water loss; it
increases water retention by making the
collecting duct more permeable to water.
When blood pressure is low, aldosterone
increases reabsorption of Na+ by the
DCT and collecting duct, which increases
water retention
where does filtration occur?
renal corpuscle
where does reabsorption/secretion occur?
PCT
filter becomes more conc as it moves thru what part of loop of henle
down loop
where does DCT dump into
collecting duct
macula densa,
monitor the
filtrate pressure in the DCT.
Osmolarity Gradient
created by the entering and exiting of
solutes, and increases from the cortex to the
medulla
Aquatic animals nitrogenous waste
excrete NH3 and
NH4 directly into the water
Mammals, sharks, and amphibians nitrogenous waste
convert NH3 into urea
Birds, insects, reptiles nitrogenous waste
secrete uric
acid (is insoluble in water and is
excreted as a solid to conserve water)
Excretion in Plants
Excess CO2, waste O2, and H2O (gas) leave via
diffusion through the stomata and lenticels via
transpiration
Intracellular digestion
takes place
within the cells and occurs in amoeba,
paramecium, and porifera. Food is
usually phagocytized, and fuses with food
vacuoles and lysosomes to break down
nutrients
Extracellular digestion
takes place
outside the cells usually in a food
compartment continuous with the
animal’s body
Amoeba digestive system
food capture via phagocytosis
→ food vacuoles → fuse with lysosomes
Paramecium digestive system
cilia sweep food into the
cytopharynx. Food vacuoles form and
move toward the anterior end of the cell
Invertebrate Digestion
rely on either physical breakdown or chemical breakdown
Cnidarians digestion
hydra rely on intracellular
and extracellular digestion
Annelids digestion
earthworms have a one-way
digestive tract
i. Crop - food storage
ii. Gizzard - grind food
iii. Intestine - contains typhlosole to
increase surface area for absorption
Arthropods digestion
- also have jaws for
chewing and salivary glands
Molluscs digestion
have radula, a tongue/tooth
structure that is located in the mouth
and breaks down food
Four groups of molecules are encountered in the
digestive system:
starches, proteins, fats, nucleic acids
Mouth (digestion)
salivary amylase breaks down
starch into maltose by breaking starch’s
a-glycosidic bonds. Chewing creates a
bolus which is swelled, and also increases
the surface area of food, thus exposing it
to more enzymes
Pharynx (throat) (digestion)
- area where food and
air passages cross; epiglottis, a flap of
tissue that blocks the trachea so only
solid and liquid enter, is located here
Esophagus (digestion)
tube leading to stomach,
food travels by contractions (wave
motion peristalsis via smooth muscle),
and saliva lubricates this
Stomach (digestion)
secretes gastric juice
(digestive enzymes and HCl) and food
enters the stomach through the lower
esophageal/cardiac sphincter. The
stomach contains exocrine glands (local
secretion by way of duct) within gastric
pits (indentation in stomach that denote
entrance to the gastric glands) which
contain secreting chief cells, parietal
cells, G cells, and mucous cells (secrete
mucus to prevent backwash)
storage (stomach
stomach contains
accordion-like folds that allow 2-4
liters of storage
mixing (stomach)
mixes food with H2O and
gastric juice, forming chyme, a
creamy medium
Physical breakdown (stomach)
muscles are
activated to break down food
Chemical breakdown (stomach)
pepsin
(secreted by chief cells) digests
proteins; pepsinogen → pepsin
activated by HCl, which is secreted
by parietal cells
Peptic ulcers
caused by failure
of mucosal lining to protect
stomach.
Controlled release (stomach)
chyme enters
the small intestine via the pyloric
sphincter
Mucous cells
secrete mucus that
lubricates and protects stomach’s
epithelial lining from acid
environment.
Chief cells
- secrete pepsinogen
Parietal cells
secrete HCl;
intrinsic factor that assists ileum’s
B-12 absorption.
G cells
secrete gastrin, a large
peptide hormone which is
absorbed into blood and
stimulates parietal cell to secrete
HCl
acetylcholine,
which increases
secretion of each cell.
ECL cells
neuroendocrine cells in
the digestive tract; gastrin
stimulates them to release
histamine which in turn stimulates
parietal cells to produce gastric
acid
Stomach pH
full stomach has a
pH of 2, which is extremely acidic
and beneficial for killing ingested
bacteria, and is the optimal pH for
pepsin!
Rugal folds
stomach contains
these folds / rippled areas to
increase the surface area of the
stomach lumen
Overall note
protein digestion
begins in the stomach, but no
absorption whatsoever occurs in the
stomach
Food goes from the stomach to the small
intestine through…
the pyloric sphincter.
3 portions of the small intestine
the duodenum,
jejunum, and the ileum.
Duodenum
continues breakdown of
starches and proteins as well as
remaining food types (fats and
nucleotides)
Jejunum
absorption of nutrients
Ileum
absorption of nutrients, longest
portion and contains Peyer’s patches,
which are large aggregates of lymphoid
tissue
90% of digestion and absorption occurs in the
small intestine
what connects small intestine to large intestine
the ileocecal valve.
Structure of small intestine
wall has finger-like
projections called villi that increase
the surface area to allow for greater
digestion and absorption. Each villi
has a lacteal, a lymph vessel
surrounded by a capillary network
that functions for nutrient absorption.
Villi have microvilli, allowing for
greater surface area.
Pancreas
Secretes bicarbonate and acts as an exocrine
gland releasing major enzymes from acinar cells
via pancreatic duct → duodenum
Liver
Produces bile, which contains no enzymes but
emulsifies fats and contains sodium
bicarbonate that helps neutralize stomach acid.
Chyme moves through intestines via
peristalsis
Large Intestine (colon)
Here is where water and salts are reabsorbed to
form feces; is 1.5 m long,
4 parts of large intestine
ascending, transverse, descending, and sigmoid
Gastrin
produced by stomach lining
when food reaches the stomach or
upon sensing of food
Secretin
- local peptide hormone from
SI, produced by cells lining duodenum
in response to HCl; stimulates pancreas
to produce bicarbonate (neutralizes the
chyme)
Cholecystokinin
- secreted by small
intestine in response to fat digestates;
stimulates gallbladder to release bile
and pancreas to release its enzymes.
Also decreases motility of stomach →
more time for duodenum to digest fat
Gastric Inhibitory Peptide
produced
in response to fat/protein digestates in
duodenum; effect = mild decrease of
stomach motor activity
Grehlin
secreted from stomach wall,
initiates hunger
Leptin
- secreted from adipose tissue,
inhibits hunger
Peptide YY
secreted from small
intestine and is concerned with hunger
and lack of hunger
Insulin
secreted from pancreas,
encourages storage of glucose as
glycogen in the liver
Epinephrine
suppresses hunger
Intracellular digestion plants and fungi
store primarily
starch in seeds, stems, and roots; when
nutrients are required, polymers are
broken down (into glucose, fatty acid,
glycerol, and amino acids) by enzymatic
hydrolysis
Extracellular digestion fungi (rhizoids of bread molds)
secrete enzymes into bread,
producing simple digestive products
which are then absorbed by diffusion
into rhizoid
Blood filtration (liver)
Kupfer cells
(specialized macrophages in liver)
phagocytize bacteria picked up in
intestines
Carbohydrate metabolism (liver)
liver
maintains normal blood glucose levels
via gluconeogeneis (production of
glycogen and glucose from
noncarbohydrate precursors),
glycogenesis, and storage of glycogen
Fat metabolism liver
liver synthesizes bile
from cholesterol and converts
carbohydrates and proteins → fat. Fat
metabolism oxidizes fatty acids for
energy, and also forms lipoproteins.
Protein metabolism liver
liver deaminates
amino acids, forms urea from ammonia in
blood, synthesizes plasma proteins and
nonessential amino acids
Detoxification liver
detoxifies chemicals
which are then excreted by the liver as
part of bile
Erythrocyte destruction
Kupfer cells
destroy irregular erythrocytes
Vitamin storage liver
stores vitamin A, D,
and B12. The liver also stores iron by
combining it with apoferritin → ferritin
Glycogenesis
(formation of glycogen)
glycogenolysis
(if blood glucose
levels decrease → glycogen broken down
to glucose for release)
