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
What are the weaknesses of sexual repdocution
- more time-consuming and energetically expensive
what are the weaknesses of asexual repdroduction
hinders genetic diversity
What is meiosis?
A type of cell division where a cell divides twice to make 4 haploid cells (gametes)
What happens in meiosis 1
the chromosomes in the homologous pair separate and are pulled to opposite poles of the cell
what happens in meiosis 2?
the chromatids in the double chromosome are pulled apart forming a single chromosome, and the haploid gametes are produced
what is crossing over?
the exchange of genes between homologous chromosomes, which results in a mixture of parental characteristics in offspring
What are the four stages of somatic cell nuclear transfer
- enucleation: The removal or destruction of the nucleus from a donated egg cell to produce an enucleated egg cell
-extraction: The donated somatic cells nucleus (cell of the animal wanted to be cloned) is extracted
-insertion: The somatic cells nucleus, is inserted into the enucleated egg cell
-development: following insertion, the cell can now divide and develop into an embryo, which is then implanted into a surrogate mother, and pregnancy continues are normal
what is embryo splitting?
Ø After the successful fertilization of an egg cell, once it begins its formation as an embryo during the early stages it can be split, and each individual embryo will develop independently, meaning the offspring will be genetically identical.
Ø This process naturally occurs in the production of identical twins in humans, embryos can be artificially split for agricultural applications.
Ø These artificially split embryos are then implanted into surrogates, where they can develop independently.
Embryo splitting must occur when it only has between 6-8 cells, in which all cells are totipotent, and are capable of developing into viable embryos.
what is osmoregulation?
Osmoregulation is the homeostatic regulation of osmolality in the body, via the alteration of water and solute balance.
what does the body do when its water levels decrease?
receptor: baroreceptor
osmoreceptor
Modulator: Kidney cells release renin
Hypothalamus releases ADH
Effector: Increased sodium reabsorbtion
Greater presence of aquaporins
thirst centre stimulated
Response: Increased water consumption
Increased water reabsorbtion
what does the body do when its water levels increase?
Receptor: Baroreceptor
osmoreceptor
Modulator: Hypothalamus suppresses the release of ADH
Effector: Decreased sodium reabsorbtion
Thirst center suppressed
Response: Decreased water consumption
Decreased water reabsorbtion
What are the three types of adaptions
Behavioral- : Adaptions that are the actions or activities of an organism that enable it to survive in its environment.
Structural- Physical (external) features or parts of an animal or plant which help it survive in its environment
Physiological- Internal or cellular feature that helps an organism survive in its environment.
What is a keystone species?
An organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether.
What is an apex predator
A predator that has no natural predators and is at the top of its food chain
What is an ecosystem engineer?
An organism that creates, significantly alters or maintains the structure of an environment.
What is symbiosis?
An interaction between two organisms of different species living in close proximity to each other.
What is competiton?
Describes interactions between two or more organisms rivalling for the same pool of resources (food, mate, shelter etc). When two organisms compete for the same limited resource, the availability of the resource in the environment decreases
What are the two types of competition
Interspecific competition: Competition between two individuals of a different species
Intraspecific competition: Competition between two individuals from the same species.
What are the 6 types of relationships?
Mutualism (+/+)- both benefit
Commenalism (+/0)
Predatation (+/-) Involves one organism hunting and killing the other for food
Paratism (+/-) Interactions where an organism obtains nutrients at the expense of a host
Amensalism (0/-)
Competition (-/-)
can cancer cells grow exponentially?
yes
can cancer cells migrate to other parts of the body?
yes- only malignant however
what is a stem cell?
an undifferentiated cell with the capacity of differentiating into specialized cells
what are totipotent cells?
stem cells that can differentiate into any cell type
- zygote
what are pluripotent cells?
can differentiate into multiple cell types
blasocyst
what are multipotent cells?
can diffrentiate into a limited number if specialised cell types
- bone marrow
-umbilical cord
-
what are the four stages of apoptosis?
1 healthy cell
2 shrinkage
3 blebbing
4 apoptotic bodies
5 phagocytes digest the apoptotic bodies by phagocytosis
what is the intrinsic pathway?
initiated by the detection of internal cellular damadge by mitochondria
what is the extrinsic pathway?
initiated by the reception of extracellular death signalling molecules
where is bile produced?
liver
where is bile stored?
gall bladder
where are digestive enzymes produced?
pancreas
is the gall bladder, pancreas apart of the digestive tract
no they are accessory organs
where is water reabsorbed in the nephron
loop of henle
collecting duct
where are salts reabsorbed in the nephron
loop of henle
where is glucose reabsorbed in the nephron
proximal convolnted tube
is urea reabsorbed in the nephron
no
