Homeostasis Flashcards
What is homeostasis?
the body’s self regulating ability to maintain internal stability due to adusting from internal and external conditions to help it survive
What is a stimulus?
A change in the external or internal environment
What is a receptor?
A receptor detects the stimulus and transfers this stimulus into a chemical or electrical signal for the modulator
What is a modulator
The modulator compares the information received by the receptor to the ideal condition the body aims to achieve/maintain, and will release molecules to go an alter the function of an effector to reach the ideal condition again.
A modulator is most commonly the brain, however it can also be a specific cell type
What three neurons make up the modulator?
sensory neuron
relay neuron
motor neuron
What is an effector
A molecule (hormone), cell or organ that responds to a signal from the modulator and produces a response
What is a response?
Any change in the function of a target cell, organ or organism after stimulation from an initial signal.
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What is a positive feedback system?
A positive feedback system occurs when the response increases/supports the initial stimulus, instead of trying to counteract it (rare in the body and do not form part of homeostasis), positive feedback systems are drawn with arrows creating a loop
what is an example of a positive feedback system
pregnancy
a baby takes up space in the uterus
stretch receptors detect the change in space, and how it has shrunk
the body then causes uterine muscles to contract, and the contractions continue to get stronger until the baby is delivered.
what is a negative feedback system
a negative feedback system occurs when the response counters the stimulus, meaning the response attempts to revert the system back to the state it was in before the stimulus occured
What is thermoregulation
the homeostatic process of maintaining a constant internal temperature, which occurs via negative feedback
what is the stimulus response model for when the core body temperature decreases?
Receptor: thermoreceptor
Modulator: hypothalamus
effector: Skeletal muscle cells
small blood vessels in the skin
cerebral cortex
arrector pili muscles
cells
brown fat
response ( in respect to the order of effector)
shivering
constriction of arterioles
change in behavior
lifting of the hair
increase in metabolic rate
burning of triglycerides
What is the stimulus response model for when the bodys core temperature increases:
receptor: thermoreceptors
modulator: hypothalamus
Effector: sweat glands
small blood vessels in the skin
cerebral cortex
arrector pili muscles
cells
Response (in respect to the order of the effector):
sweating
dilation of arterioles
change in behavior
flattening of hair
decrease in metabolic rate
What does the body do when its blood glucose levels decrease?
receptor: alpha cells
Modulator: secretes glucagon
Effector: liver cells
Response: glycogen breakdown
What does the body do when its blood glucose levels increase?
receptor: beta cells
Modulator: secrete insulin
Effector: liver cells
skeletal muscles
Response (in respect to effector order)
increased uptake of glucose
increased production of glycogen
Does oxygen diffuse via simple diffusion
yes
Can carbon dioxide diffuse easily through the membrane?
yes
Can sugars diffuse easily through the membrane?
no
can animo acids diffuse easily through the membrane?
no
What characteristics define asexual reproduction?
- does not require the fusion of gametes
- commonly occurs in unicellular and simple, multicellular organisms
- only one parent is involves
- Offspring are genetically identical4 to parents
What characteristics define sexual reputation?
- involves the fusion of two haploid gametes, in a process known as fertilization
- forms a single, genetically unique diploid zygote
-each parent makes a genetic contribution to the offspring via DNA from their gametes
What are the strengths of sexual reproduction
- increases genetic diversity of a population
- Reduces the risk of birth defects and genetic diseases
what are the strengths of asexual repdocution
- more frequent and energy efficient (uses less energy)
- fine tuned to thrive in a steady environment, as offspring are clones