Download Lecture # 5 Date ______

This unit covers chapters: 7,11,43,44,45
Evolution
• Pathway similarities suggest that ancestral
signaling molecules evolved in prokaryotes
and were modified later in eukaryotes
• The concentration of signaling molecules
allows bacteria to sense local population
density
Cell Membrane structures that
aid in communication Ch. 7
• Animal and plant cells have cell junctions that
directly connect the cytoplasm of adjacent
cells
a. Tight Junctions
b. Desmosomes
c. Gap Junctions
• Tight Junctions-prevent leakage of extra
cellular fluid by making a tight seal around
adjacent cells. Ex: skin cells
• Desmosomes-acts like a rivet, attaching cells
together. Ex: muscle cells, if a muscle tears
then a desmosome has ruptured.
• Gap Junctions- in animals and Plasmodesmata
in plants allows ions, amino acids, and sugars
to transport between cells
Membrane Protein functions
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Transport
Signal Transduction
Cell to Cell recognition
Intercellular joining
Attachment to cytoskeleton
Feedback
• Positive Feedback
Negative Feedback
Which is an example is each:
a. Temperature regulation _______________
b. Lactation in mammals _________________
c. Blood Clotting ______________________
d. Secretion of Insulin __________________
SOOOO……
• How would you describe Positive Feedback?
• How would you describe Negative Feedback?
Chapter 11
Cell Communication
Signal-Transduction Pathway
• Signal on a cell’s surface is
converted into a specific cellular
response
• Local signaling (short distance) Paracrine (growth factors);
Synaptic (neurotransmitters)
• Long distance - hormones
Stages of Cell Signaling
3 steps:
• Reception: target cell detection
• Transduction: single-step or series of
changes
• Response: triggering of a specific
cellular response
Immunity and Cell
Communication
Ch 43
Types of immune responses
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Humoral immunity
B cell activation
Production of antibodies
Defend against bacteria, toxins, and viruses
free in the lymph and blood plasma
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Cell-mediated immunity
T cell activation
Binds to and/or lyses cells
Defend against cells infected with bacteria,
viruses, fungi, protozoa, and parasites;
nonself interaction
Immunity in Health & Disease
• Active immunity/natural: conferred
immunity by recovering from disease
• Active immunity/artificial: immunization and
vaccination; produces a primary response
• Passive immunity: transfer of immunity from
one individual to another
• natural: mother to fetus; breast milk
• artificial: rabies antibodies
The Inflammatory Response
1- Tissue injury; release of chemical signals~
• histamine (basophils/mast cells): causes Step 2...
• prostaglandins: increases blood flow & vessel
permeability
2/3- Dilation and increased permeability of capillary
4- Phagocytosis of pathogens~
• fever- leukocyte-released molecules increase body
temperature
Nervous System and cell
communication
Ch 48
Parts of Neuron-Nervous System Cell
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Neuron~ structural and functional unit
Cell body~ nucelus and organelles
Dendrites~ impulses from tips to neuron
Axons~ impulses toward tips
Myelin sheath~ supporting, insulating layer
Schwann cells~PNS support cells
Synaptic terminals~ neurotransmitter releaser
Synapse~ neuron junction
Neurotransmitters- chemical messengers that pass
information from transmitting to receiving neurons
• Sensory Receptors~ dendrites receive
stimulus and send to CNS which will relay to
Effector cells
• Effector cells~ muscle or gland cells that will
produce a desired response
• Nerves~ bundles of neurons wrapped in
connective tissue
• Central nervous system (CNS)~ brain and
spinal cord
• Peripheral nervous system (PNS)~ sensory
and motor neurons
• Sensory neuron: convey information to spinal
cord
• Motor neurons: convey signals to effector cell
(muscle or gland)
• Reflex: simple response; sensory to motor
neurons.
Is typically -60 to -80 millivolts
Endocrine and cell
communication
Ch 45
Regulatory systems
• Hormone~ chemical signal secreted into body fluids
(blood) communicating regulatory messages
• Target cells~ body cells that respond to hormones
• Endocrine system/glands~ hormone secreting
system/glands (ductless);
• Exocrine glands~ secrete chemicals (sweat, mucus,
enzymes) through ducts
• Neurosecretory cells~ actual cells that secrete
hormones
• Feedback mechanisms ~ negative and positive
Mode of Action: Chemical
Signaling
1- Plasma membrane reception
• signal-transduction pathways
(neurotransmitters, growth factors, most
hormones)
2- Cell nucleus reception
• steroid hormones, thyroid hormones, some
local regulators
Hypothalamus~regulates
the pituitary gland
Pituitary gland
Pineal gland
Thyroid gland
Parathyroid glands
Thymus
Adrenal glands
Pancreas
Gonads -ovary, testis
• Pineal-secretes serotonin which regulates the
sleep/wake cycles
• Thyroid- regulates metabolism
• Parathyroid- control calcium level in bones and
blood
• Thymus-secretes hormones that produce
antibodies
• Adrenal- secretes aldosterone and cortisol
which creates a fight or flight response
• Gonads-secrete testosterone, esterogen, or
progesterone
• Pancreas- secretes Insulin and Glucagon to
regulate blood sugar levels
Examples of Hormone Regulation
• Pituitary: Regulates other glands
• Oxytocin: uterine and mammary gland cell
contraction
• Antidiuretic (ADH):retention of water
by kidneys
Pituitary Gland regulates
• Growth (GH)~bones
• Disorder: gigantism/dwarfism
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• Prolactin (PRL)~mammary glands;
milk production
• Follicle-stimulating (FSH) – this causes the sex cells
to finish meiosis and prepare for sexual reproduction
• Luteinizing (LH)~ovaries/testes- helps maintain levels
of sex hormones in the body
• Thyroid-stimulating (TSH)~ regulates
metabolism
• Adrenocorticotropic (ACTH)~ aids in body’s
response to stress
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• Melanocyte-stimulating (MSH) has effects on
skin pigmentation
• Endorphins~natural ‘opiates’; brain pain
receptors
MSH
• Interesting fact about MSH : However, in
many red headed people, and other people who
do not tan well, there are variations in their
hormone receptors, causing them to not
respond to MSH in the blood.
The pancreas (organ)
Hormones secretes by the pancreas to regulate
Blood Sugar
• glucagon~ raises blood glucose levels
• insulin~ lowers blood glucose levels
Ch 44 Excretory
• With focus on the Kidneys, Ureter, Bladder,
and Urethrea
• Other organs involved in excretory would be
skin and lungs
The Kidneys (organ)
Role of ADH
• When the brain detects dehydration it will
secrete ADH.
• ADH will reduce amt of water in urine.
• Secretion stops when the blood volume
returns to homeostasis.