Unit2 Flashcards
Describe homeostasis.
Homeostatis aims to maintain a constant internal environment (equilibrium) in response to stress (anything that disrupts homeostasis). It is the ability to adjust cellular and physiological processes (dynamic).
What are the types of stressors? Give an example for each of them.
- Physical -> ex. Sun brings light and heat, this may disrupt body temperature
- Environmental -> you see a bear while you are walking in the forest, it can threaten your life (fight or flight)
- Emotional -> you are stressed before a final exam, production of cortisol that will help you secrete more glucose in the blood that will go to your brain and help you function and think (+ run if muscles needed).
Name the components of a feedback loop.
- Variable
- Receptor (sensor)
- Integrator
- Effector(s)
Describe the process of homeostasis (steps).
- Stimulus causes change/stress
- Change detected (sensor)
- Response initiated (control)
- Cells respond (effector)
- Return to normal
True or false. A negative feedback loop decreases the original stimulus. Explain your answer.
False. In a negative feedback loop, the response cancels or counteracts the original stimulus. It puts an end to the initial stimulus or at least reduces it.
You are very hot, so your body temperature rises. In response to this change, your blood vessels dilate and your salivary glands secrete fluid to increase evaporation from your tongue, mouth and throat. Is this a negative or positive feedback loop?
Negative feedback loop, because your body is trying to decrease your body temperature to bring it back to normal.
How does the male body use homeostasis to regulate hormonal changes?
If the body too much testosterone and FSH, the Sertoli cells in the testis will produce and release inhibin. This hormone will tell the anterior pituitary to stop producing FSH. If the body has too much LH, the production of testosterone will increase. Therefore, the body has too much testosterone. The testosterone will tell the anterior pituitary to stop producing LH and the hypothalamus to reduce the production of GnRH
True or false. A positive feedback loop increases the original stimulus.
True. A positive feedback loop strengthens or reinforces the initial stimulus.
Which one of the following is not an example of a positive feedback loop?
Blood clotting, ovulation, blood sugar regulation, childbirth
Blood sugar regulation is a negative feedback loop because the pancreas secretes insulin to decrease blood sugar levels and glucagon to increase the concentration of sugar in the blood.
Describe the process of childbirth. Is it a negative or positive feedback loop?
The baby pushes against the cervix, causing it to stretch.
The stretching of the cervix causes nerve impulses to be sent to the brain.
The brain stimulates the pituitary to release oxytocin.
Oxytocin the uterus to contract.
And the cycle continues.
This is a positive feedback loop because it reinforces the stretching of the uterus is reinforced.
What is the mechanism of control of the endocrine and nervous system?
Nervous:
- Sends electrical signals (impulses within neurons)
- Neurotransmitters: between neurons and target cells
Endocrine:
-Sends messages as hormones in the bloodstream
What cells are affected by the nervous and endocrine system?
Nervous:
-Neurons, glands and muscle cells
Endocrine:
-All the cells of the body (mitosis)
What is the type of action/result in the nervous and endocrine system?
Nervous:
- Neurons: Neural stimulation -> activate a neuron
- Glands: Hormone production -> neurons tell glands in the kidney to release adrenalin (quick)
- Muscle cells: contraction
Endocrine:
-Messages change metabolic activity (metabolism)
What is the onset of actions in the nervous and endocrine system? How quick are the responses?
Nervous:
-Instantly (milliseconds)
Endocrine:
-Longer (seconds-days)
What is the duration of actions in the nervous and endocrine system?
Nervous:
-Lasts only briefly -> ex. contraction of muscle
Endocrine:
-Lasts longer (minutes-days) -> ex. menstrual cycle, ex. cortisol when stressed before an exam (access to glucose, takes time to dissolved)
