#9 What is disease? Concepts and applications Flashcards
What are four perspectives of a disease?
- Physician: learn underlying cause of symptoms to treat
- Patient: want to get better
- Pathogen: survive and reproduce like coughing/sneezing to spread pathogens
- Host: populations, groups to adapt and reproduce
Biological phenomena have 2 general types of explanations. What are they?
How are they different?
proximate: immediate physiological reason for phenomenon
ultimate: evolutionary reason for the phenomenon
What is a tissue? Give an example.
Tissue: a group of specialized cells that have a similar shape and function like muscle or connective or epithelial or nervous
What is an organ? Give an example.
Organ: a group of tissues which work together to perform a more complex function. Like nervous tissue that compromises the brain
What is robustness? Give an example
Robustness: is a characteristic that defines how resistant that system is to the transition from the healthy to an unhealthy state. Ex: bone
What is resilience? Give an example
Resilience: a characteristic that defines how easily the system can return from an unhealthy state back to the healthy state. Ex: skin
Humans are a mosaic of organs and tissues that are robust and resilience. Describe an example of an organ/tissue that has high robustness but low resilience. Describe an example of an organ/tissue that has low robustness but high resilience. Suggest an explanation for why these trade-offs exist.
Bones are highly robust but have low resilience because they are hard to break but take a long time to repair.
Skin is not robust but has high resilience because its easy to break but easy to repair too.
These trade offs with robustness and resiliency exist because there is a cost for every mechanism that allows for resilience and robustness and if the costs are too high it hurts the person.
Give an example of a fixed feature or function in humans. Give an example of an adjustable feature or function.
Fixed functions are insensitive to environmental changes like DNA replication, transcription, cytoskeleton function, and major features of the body plan.
Adjustable functions are sensitive to environmental changes like glucose metabolism.
What is disease incidence? What is disease prevalence? Briefly give an example of disease that has increased in prevalence. Why has the prevalence changed?
Disease incidence: the number of newly diagnosed cases per time period
Disease prevalence: the fraction of a population afflicted with a given disease
A disease with increased prevalence is type 2 diabetes because there is an environmental mismatch of the nutrients we evolved to consume and what we consume today.
The transition to modern environment has led to a decrease in extrinsic mortality. What is one disease related outcome of an increased lifespan?
Increased lifespan has caused more cancer and neurodegenerative diseases.
As an illustrative example, consider a Swiss-Webster mouse consuming a diet whose principal source of calories is the disaccharide sucrose, hydrolysed in the small intestine by the brush border enzyme sucrase to yield the monosaccharides glucose and fructose, which are then taken up across the brush border membrane into cells by the transporters SGLT1 and GLUT5, respectively. Thus, sucrase operates in collaboration with SGLT1 and GLUT5. The mouse’s dietary intake is 7.5 mmol sucrose day−1, yielding upon hydrolysis 6 mmol day−1 each of glucose and fructose. The brush border contains enough sucrase to split 19.5 mmol sucrose day−1 (the Vmax value for sucrase) in this system.
What is the built in safety factor for sucrose metabolism by sSucrase in the small intestines? Hint: It will be on the exam!
The built in safety factor is that the brush border contains enough sucrase to split 19.5 mmol sucrose a day so there is a built in max amount of sucrase the mouse can digest so doesn’t overconsume sucrase.
