Lec 3 - Chemical Signals in Animals Flashcards
Regulatory Mechanism
- Nervous system
- Endocrine system
conveys high-speed electrical signals along specialized cells
Nervous system
Specialized cell in nervous system
Neurons
secretes hormones that coordinate slower but longer-acting responses
Endocrine system
are chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body
(Animal) Hormones
Hormones which regulated insect metamorphosis
- Steroid 20-hydroxyecdysone
- Lipid juvenile hormone
Two types of glands
- Exocrine Glands
- Endrocrine Glands
secrete chemicals into ducts and the effect is where the duct empties
- Exocrine glands
secrete chemical messengers (hormones) into the blood for distribution throughout the animal’s body and bind to specific hormone receptors
Endocrine Glands
Conclusion of Arnold Adolph Berthold’s study
Hormones in testes is responsible for crown phenotype
Regulates developments in humans
Signaling Pathways
Activates the signaling pathways
Specific chemical signaling molecules
Only target cells respond to the signal, because it bears receptors for the hormone
Target Cell concept
3 types of intercellular communication
- Endocrine signaling
- Paracrine signaling
- Direct signaling
- secreted molecules diffuse into the bloodstream
- Trigger response in target cells anywhere in the body
Endocrine signaling
special type of endocrine signaling
Nueroendocrine signaling
neurohormones diffuse into the bloodstream and trigger responses
Neuroendocrine signaling
secreted molecules diffuse locally and trigger a response in neighboring cells
Paracrine signaling
Special types of paracrine signaling
- Autocrine signaling
- Synaptic signaling
secreted molecules diffuse locally and trigger a response in the cells that secrete them
Autocrine signaling
neurotransmitters diffuse across synapses and trigger responses in cells of target tissue
Synaptic/neuronal signaling
for some signals to be received, the cells must be in direct contact.
Direct Signaling
signaling that is relative slow
Endocrine signaling
signaling that has quick response
Paracrine signaling
Types of secreted signaling molecules
- Local regulators
- Neutrotransmitters
- Neurohormones
- Phermones
- Hormones
chemical signals that travel over short distances by diffusion
Local regulators
What does local regulators regulaate
- help regulate blood pressure
- nervous system function
- Reproduction
2 types of local regulators
- paracrine
- autocrine
signals act on cells near the secreting cell
Paracrine
signals act on the secreting cell itself
Autocrine
proteins and polypeptides that stimulate cell proliferation
Growth Factors
play a role in immune responses
Cytokines
acts as a neurotransmitter when secreted by neurons
Nitric oxide (NO)
what does nitric oxide do to bacteria and cancer cells
- Kills them when secreted by WBCS
Effects of nitric oxide to blood vessels
- Dilates the wall of blood vessesl when secreted by endothelial cells
modified fatty acids, secreted by placenta to stimulate uterine contractions
Protaglandins (PGs)
secreted by neurons at many synapses
Neurotransmitters
Roles of neurotransmitters
- sensation
- memory
- cognition
- movement
muscle contraction
Acetylcholine
- secreted by neurosecretory cells
- diffuse from nerve cell endings into the bloodstream
Neurohormones
increases water permeability of kidney’s collecting ducts and causes vasoconstriction
ADH (vasopressin)
chemical signals that are released from the body and used to communicate with other individuals in the species
Pheromones
chemicals that transfer information and instructions between cells in animals and
plants
Hormones
Importance of pheromones
- Defining territories
- warning to predators
- Attracting potential mates
Importance of hormones
- regulates metabolism
- regulates growth and development
A hormone can also have different effects in different species
Multiple effects of hormones
The same hormone may have different effects on target cells that have;
- Different receptors for hormones
- Different transduction pathways
- Different proteins for carrying out the response
Epinephrine effects to liver vs skeletal muscle blood vessel with the same α-receptor
- Glycogen breaks down and glucose is released
- Vessel dilates
Epinephrine effects to β- receptor
vessel constricts
Three major classes of molecule functions as hormones in vertebrate
- Polypeptides
- Amines derived from amino acids
- Steroid hormones
Classes of hormones
- steroids, polypeptides, amines
Water soluble
polypeptides and amines
Lipid-solube
- steroid hormones
- other largely non-polar hormone
are secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors
Water-soluble hormones
- diffuse across cell membranes,
-travel in the bloodstream - bound to transport proteins
- diffuse through the
membrane of target cells
Lipid-solube hormones
Epinephrine effects in the body
mediating the body’s response to short-term stress
epinephrine binding sit
- receptors on the plasma membrane of liver cells
epinephrine triggers
release of messenger molecules, release of glucose in the bloodstream
Key events for signaling hormones
- Reception
- Signal transduction
- Amplification
- Response
detection of a signal in
the environment
Reception
activating a series of proteins inside the cell
Signal transduction
change in behavior that
occurs inside the cell
Response
involves the hormone-secreting tissues and organs of the body
Endocrine system
chemical messengers
Hormones
referes to the duration of time required to decrease the concentration of a circulating hormone by half
Half life of a hormone
two factors influencing hormone concentration in blood
- Rate of hormone secreted into the blood
- Rate of the removal of the hormone from the blood
