Download Give an example of negative feedback in detail

Random Chapter review
38-40, 43-45, 48-49, 51
52-56 is ecology (not going to review)
II. Sexual reproduction of Angiosperms: Alternation of Generations
Plant Hormones
•
•
•
•
•
•
Auxin
Cytokinins
Giberrellins
Abscisic Acid
Ethylene
Brassinosteroids
Plant responses
• Phototropism
• Photoperiodism
• Defense
Give an example of negative feedback in detail
Urine Formation
• Filtration – blood pressure drives
filtration at the glomerulus
– The filtrate (stuff that came out of the blood)
continues flowing through the renal tubule.
– 180 liters of fluid every 24 hours.
• Reabsorption
– Selectively reclaims just eh right amounts of
substances, such as water, electrolytes, and
glucose that the body requires.
• Secretion
•
Hydrogen ions and certain toxins are removed
from the blood
• Urinary excretion
Glomerular filtration + tubular secretion – tubular reabsorption = Urine
Countercurrent
Mechanism
Urine Formation: Collecting Duct
• Reabsorption of water
• Antidiuretic Hormone
controls the
concentration of your
urine.
– Hypothalamus monitors
– Posterior pituatary
gland secretes it
– It changes the water
permeability of the
collecting duct (see
next slide)
Effect of ADH on urine formation
Immune System
• 1st line of defense
– Barrier
– skin
– Traps
– mucous membranes, cilia,
hair, earwax
– Elimination
– coughing, sneezing, urination,
diarrhea
– Unfavorable pH
– stomach acid, sweat, saliva, urine
– Lysozyme enzyme
– digests bacterial cell walls
– tears, sweat
• 2nd line of defense
– attack pathogens, but don’t
“remember” for next time
• leukocytes
– phagocytic white blood cells
– macrophages, neutrophils,
natural killer cells
• complement system
– proteins that destroy cells
• inflammatory response
– increase in body temp.
– increase capillary
permeability
– attract macrophages
Immune System
• 3rd line of defense
– Specific defense with
memory
• lymphocytes
– B cells
– T cells
• antibodies
– immunoglobulins
– Responds to…
• antigens
– cellular name tags
» specific pathogens
» specific toxins
» abnormal body cells
(cancer
• Major histocompatibility
(MHC) proteins
– proteins which constantly
carry bits of cellular
material from the cytosol
to the cell surface
– “snapshot” of what is
going on inside cell
– give the surface of cells a
unique label or
“fingerprint”
Endocrine System
In addition, it increases heart rate, stroke volume (amount of blood
pumped from ventricles) and dilates the bronchioles in the lungs
Simple Hormone Pathway
Negative Feedback
• The response leads to
the reduction in the
stimulus and the
pathway shuts off.
• Here, release of
bicarbonate raises the
pH in the duodenum
• Negative feedback is
when the response
REDUCES the stimulus
Simple Hormone Pathway
Positive Feedback
• Oxytocin in mammals
regulates milk release
during nursing.
• Oxytocin also induces
target cells in the
uterine muscles
• Positive feedback is
when the response
REINFORCES the
stimulus
Antagonistic Hormones
• Two hormones that
operate in a simple
endocrine pathway
regulated by negative
feedback.
• Diabetes Type I
• Diabetes Type II
• Insulin and Glucagon
controlling blood
glucose levels
• Blood Glucose
– Insulin released which
triggers the uptake of
glucose from the blood
• Blood Glucose
– Glucagon promotes the
release of glucose into
the blood
Post-synaptic membranes or Motor Endplates 
Neurotransmitter binds to Neurotransmitter receptor 
Neurotransmitter receptor changes shape 
Sodium Channel opens 
Sodium flows in 
Other Sodium Channels open = “Threshold” 
Potassium Channels open slowly 
Sodium Channels close 
Potassium Channels close.
Resting
“polarized”
Na+ channel open
“depolarized”
Na+ closed, K+ open
Resting
“repolarization” “polarized”
G. How this communication takes place:
1. Action potential moves down the neuron through the axon, then
through the axon terminals (“telodendria”), and finally
through the synaptic end bulbs.
a. Synaptic end bulbs contain vesicles of neurotransmitter
2. Voltage-gated calcium channels in the membrane of the
end
bulb open.
3. Calcium diffuses in.
4. Calcium’s presence causes the synaptic vesicles to fuse
with
the cell membrane to release neurotransmitter (exocytosis) into the
synaptic cleft.
5. Neurotransmitters diffuse across the synaptic cleft and
bind
to neurotransmitter receptors on the membrane on
the opposite
side of the cleft.
6. Neurotransmitters are broken down by enzymes in the
synaptic cleft.