Homeostasis and Body Systems
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Review of Systems
Homeostasis, Feedback Systems
Endocrinology/Cell communication
Nervous System
Immune System
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Respiratory Systems of Vertebrates
*Lung
surface area
and moist
outer skin
p.975
Fig 45.5
• Fish: Gill countercurrent exchange; swim bladder for bouyancy
• Become more efficient: Increased surface area
• Birds are Most efficient- 2 cycles of inhalation and exhalation to
support a one-way flow of air through the lungs. Highly efficient
Text-p974-975
Gas Exchange in Animals
CIRCULATORY…
“Double Pump”
More efficient O2
distribution; not
all separate
Heart
Structure
differences
in
Vertebrates
• Advantage:
Separation
of O2 rich
and poor
blood- more
O2 available
to tissues
DIGESTIVE
Mechanical
And
Chemical
EXCRETORY
Nephron
Osmoregulation
Nitrogenous
Wastes:
NH3
• NH3 Ammoniahighly toxic- directly
into water in aquatic
species; converted to
urea in the liver.
• Uric Acid- insoluble
‘paste’
• Urea- produced in
the liver from toxic
ammonia(NH3 + CO2)
Text p1016 Fig 47.6
Do Fish Drink?
*ABSORB
DRINK
MusculoSkeletal
Anatomy and Physiology
SYSTEMS:
Endocrine, Nervous, Immune
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HOMEOSTASIS
Requirements of Organisms:
• water – most abundant chemical in body; many functions;
required for metabolism & transport of substances
• nutrients (food) – for energy, structural support, cellular
reactions
• oxygen – for cellular respiration to create energy, which
drives metabolism
• heat – to maintain normal body temperature (~98˚F or
37˚C) – helps to maintain normal reaction rates
• pressure – normal atmospheric pressure required for
proper breathing; normal hydrostatic pressure maintained
in blood
Ch. 48 Endocrine Regulation
Homeostasis
• The body has the ability to regulate its internal
environment (job of the Nervous and Endocrine systems)
dynamic equilibrium
• Homeostasis involves regulating:
–
–
–
–
–
–
Blood levels of vital substances (Oxygen, glucose)
Heart rate and blood pressure
N-waste and removal
Body temperature
Rate and depth of breathing
etc
• Regulation is accomplished by Feedback Mechanisms of
two types:
1. Negative Feedback “NFM”
2. Positive Feedback “PFM”
Positive and Negative Feedback 14.0
Negative Feedback Mechanisms
• Most F.M. are negative
• Maintain some physiological function or keep
blood chemicals within a safe range
• Decrease or shut off original stimulus/reduce
intensity; return from too high/too low
• Return stimulus back to a setpoint (proceed in
the opposite direction)
• Ex: Control of Glucose levels, Body temperature
Regulation of Blood Glucose Levels by Negative Feedback
2
3
1
1
3
Diabetes and Insulin 7.24
2
Plasmids, Recombinants 4.14
Anti-Diuretic Hormone (ADH)
Hormonal Controls of Ionic Ca++ levels in Blood
1
2
1. Stimulate Thyroid
(calcitonin): when
Ca++ too HIGH
(and slows PTH)
2. Stimulate
Parathyroid (PTH):
when Ca++ too
LOW.
• TARGETS?
– Bone
– Kidney
– Digestion/SI
Positive Feedback Mechanisms
• Control episodic (infrequent) events that do not
require continuous adjustments
• Result in enhancing or exaggerating the original
stimulus so that the activity (output) is accelerated
• Accelerates in the same direction until the original
stimulus is gone. (the change proceeds in the same
direction)
• Set off a series of events that may be selfperpetuating
• Ex: Blood-clotting, enhancement of labor
contractions during giving birth
Positive feedback loop…
enhancing original stimulus
*Also released during breast feeding….contraction of smooth muscle, milk glands /uterus
“Classic” endocrine signaling
Hormones -transported by the blood (some dissolved in plasma,
some bound to proteins) and produce a response only after they
reach target cells and bind with specific receptors. Target cellsanother endocrine gland or another organ. Hormones are
removed from the blood by the liver (inactivates) and by the
kidney (secretes).
• Reception
• Transduction
• Response
animation
Hormones that work through secondary messengers
1. First messenger (ligand) binds a cell
surface receptor (membrane protein)
2-3. Creates a series of membranebound reactions to activate an
effector (G-protein-relay-enzyme)
4. Generates/activates the second
messenger molecule- cAMP )
5.
Text p 1035 Fig 48-5
Signal Transduction Pathways 9.24
Lipid/Steroid Hormone vs Protein Hormones
1. Master Glandsecretes hormones
that manage the
other glands
2. Regulates Ca++
levels in blood
3. Increase metabolic
rate; lowers Blood
Ca ++ levels
4. Consists mostly of
“T” cells; role in
immune system
5. Stress; metabolic
rate; HR/BP
6. Endocrine AND
digestion *Glucose
7. Sex characteristics
1.
and Hypothalamus
( Links NS/End.sys)
3.
2.
(Whole gland)
(four dots)
4.
Thymus
5.
6.
Islets of Langerhans
7.
8.
Chapter 48 p1037-8
Endocrine
System
Locations
Anterior Lobe of the Pituitary
• Most use classical
endocrine
signaling
• Regulated by the
hypothalamus
(oxytocin, ADH)
Thyroid Hormone
• Increases the overall
metabolic rate, regulates
growth and development
as well as the onset of
sexual maturity, plays a
role in the regulation of
calcium.
Hormone Cascade Pathway- stimulus to response -
Handout
How the Mammalian Kidney Concentrates Urine
Reabsorption
to blood
Filtration
Secretion
Secretion
Glomerular Filtration
(180L/24hrs; 99% reabsorbed)
a)
b)
c)
d)
e)
Counterflow of fluid
Text p 1022
Reabsorption (~65%);
secretion (local cells)
Descending loop:
Permeable to H2O, less to
NaCl (Concentrates urine)
Ascending loop: more
permeable to NaCl (reset
Concentration Gradientdilutes urine)
Reabsorption; secretion
(local cells)
Collecting ductconcentrates urine
How the Mammalian Kidney Concentrates Urine
Text p 1023
Hormonal Regulation of the Kidney: ADH
Thirst
(dehydrated; rise in
Na+ in blood)
• Cells of distal tubule and collecting duct become more
permeable to water, so more water is reabsorbed back in to
the bloodstream.
Chemical Signals - Communication
• Coordinated by nervous and endocrine systems
• Chemical Signals:
– Hormones: Between organs of the body
Ductless glands > Blood stream > receptor on target cell
(shape specific) *Homeostasis
– Pheromones: Between Individuals of same species
Chemical signal, small amounts, social behavior
– Local Regulators: *short range; between cells. Diffuses
through interstitial fluid and acts on same cell/nearby
cells. Other messengers: neurotransmitters, growth
factors, nitric oxide gas, histamine, prostaglandin
*immune system
Relationships between Nervous & Endocrine systems
• Structural
– Many endocrine glands possess nerve tissue;
nervous system helps regulate endocrine responses.
• Chemical
– Some hormones used as signals in both systems
(Example- norepinephrine)
• Functional
– Each system can affect the output of the other
– Endocrine system responds slower than the nervous
system, has a wider range of target cells, but has a
longer lasting response.
The
Nervous
System
Chapter
40
3
1
4
2
5
7
8
9
or
6
Neuron
*
-
*
*
Reflexes:
Involuntary responses to sensory information
Reflex Arc
(1): Sensory (PAIN!!) to (2) Afferent neuron
(3): Association neuron/spinal cord
(4): Efferent neuron to (5) Motor (MOVE!!)
White Matter: Myelinated Grey Matter: Cell bodies/Unmyelinated
Synaptic Cleft - Neurotransmitters
In Note
Packet
Action Potential
Depolarization:
Na+ gates open
Na+ Rushes in…
Repolarization:
Na+ gates close
K+ gates open
K+ Rushes out
Action Potential 5:39
*Neuro-Muscular Action Potential in Packet, p2
ACTIVE TRANSPORT: Na-K Pump
THREE Sodium in, TWO Potassium out…. Normal function(INSIDE of the cell overall NEGATIVE CHARGE at ‘resting potential’….important for Action Potential)
*ONE Pump: does 450:300 Sodium OUT:Potassium IN every SECOND
The Immune
System
• First Line of
Defense:
– Barriers to
pathogens
– Nonspecific
• Second Line of Defense:
The Inflammatory Response
– nonspecific
• Third Line of Defense:
– Specificity and Diversity
TEXT- Chapter 48
Lymphatic System
• Vessels that transport fluids back
to the blood
– One way system; valves
• Lymphoid Organs:
– Nodes
– Tonsils, Thymus, Spleen
– Peyer’s patches- Intestines
• Lymphoid Tissues: (MALT)
– Mucosa/Walls of lungs & intestines
– appendix
• Immune System Cells:
– WBC “leukocytes” (5-10,00/mm3)
Lymphocytes: NK, T, B cells
(circulate in lymph and blood)
Phagocytes: Neutrophils (50-70%)
Macrophages (APC’s)
Dendritic cells (APC’s)
• A myeloid stem cell matures
into a myeloid blast. The blast
can form a red blood cell,
platelets, or one of several
types of white blood cells.
• A lymphoid stem cell matures
into a lymphoid blast. The
blast can form one of several
types of white blood cells,
such as NK, B or T cells.
Recognizing Self vs Non-self cells
Body’s cells must have:
– “Self-markers” a collection of molecules called MHC
(Major Histocompatibility complex- a protein complex)
• Imbedded in the cell membrane
• No two complexes are alike* …A biochemical ‘fingerprint’
• 2 classes of MHC
molecules:
Class I on all
nucleated cells
Class II on
macrophages and B cells
MHC + Antigen =
Antigen Presenting Cell
(APC)
Impaired System?
First, Second and Third Lines of Defense
• Nonspecific Mechanisms: Responds to all invaders; 1st (external) & 2nd (internal)
• Specific: responds to specific invader; “True immune system”
– Works simultaneously with 2nd line of defense
– Phagocytes- APC’s, Lymphocytes- “The STARS of the IS”: B cells and T cells
*Chart in Note Packet
PATHOGEN INVADES
NONSPECIFIC (INNATE)
SPECIFIC (ADAPTIVE)
“third line of defense”
Second line of
defense: Inside
Chemical Mediators- ’Reinforcements’- Phagocytosis; Inflammation
Cytokines: interleukins (‘between’ WBC’s), interferons (antiviral)
Complement: 20 different; chemotaxis, cell lysis
Pyrogens: Body Temperature (fever)
‘B’
‘T’
2.19
WBC’s:
Neutrophils (70%)
~20 pathogens/die
Monocytes- Dendritic;
Macrophages
~100 pathogens/die
NK cells NK cells 3.02
Basophils- Allergy
Eosinophils- Parasite
Inflammatory Response
Dilates vessels,
Increase blood
flow, more
permeable- leads
to swelling
*If there is a severe infection (systemic)• Stimulates Bone marrow - release more WBC’s
• Fever- Pyrogens released by WBC’s
The Third Line
of Defense
*Antibodies immobilize pathogens until
phagocytes and “complement” chemicals
destroy them
*Cells already infected. T cells bind to
and destroy infected cells/cancer cells
Antigen-Antibody Binding site
Third Line of Defense: Specificity and Diversity
• Antigen
Pathogen
1
macrophage
2
• Macrophage
• “APC”
3
(MHC + antigen = APC)
• T Helper:
“Th”
• B cell
4
5
• T Cytotoxic
“Tc”
• Active
“effector”
vs Memory
6
8
7
“Call 911”
Cytotoxic T cell
.17
Central Role of Helper T-cells
Interleukin-1 and 2
and other cytokines
activate Th cells, B
cells, and Tc cells
(In Note Packet)
• T cells produced in the bone marrow; mature in the thymus
gland. Helper T (Th or CD4*) Cytotoxic C (Tc or CD8)
AIDS
HIV Lifecycle 4.52
Aids and the Plague 7.26
Clonal Selection
of B cells
Proliferation to
form a clone
Secreted into circulation
• Produced and
mature in the bone
marrow
• Once activated by
the matching
antigen,
differentiates into
plasma or memory
cells
• One plasma cell can
produce > 1 mill.
antibody/hr
The Immune
Response:
Third Line of
Defense:
B Cells
(Humoral)
Antibody
Production
1st and 2nd
Lines of
Defense
APOPTOSIS (Cell Death) vs LYSIS (Cell Bursting)
Induced/Adaptive Immunity
You get sick >
make AB’s,
memory cells
Ex- Chicken
pox, measles
Flu, shingles
vaccine,
infant
vaccines
Fetus gets AB’s
from mother
infant through
placenta,
breast milk
-Injection of Gamma
globulin after
exposure to
dangerous disease
(viral hepatitis)
-Antitoxin after
being bitten by
poisonous snake