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Animal Systems

Animal Systems

Animal Systems Questions

Bring on the tough stuff

1. Explain how activating suppressor T cells could be used as therapy for organ transplants.

2. Describe hormone cascade pathway associated with growth hormone release.

3. What is the difference between regulated and constitutive hormone release. Give an example of each.

4. Why is the hypothalamus essential for neuroendocrine responses?

5. How is melatonin released based on a circadian rhythm?

6. What are two ways the nervous system can communicate with the immune system?

7. What is the difference between the innate and adaptive immune systems?

8. Describe the events in neurotransmission.

9. What is a hormone cascade pathway?

10. How are both the immune and nervous systems implemented in multiple sclerosis?

Possible Answers

1. Explain how activating suppressor T cells could be used as therapy for organ transplants.
If the immune system does not recognize a transplanted organ and launches an immune response against it, natural suppressor T cell activity can quiet the attack. Because these immune cells act to regulate the over activity of the immune system, their activation leads to decreased inflammation and decreased leukocyte activation.

2. Describe hormone cascade pathway associated with growth hormone release.
Although growth hormone itself is released from the pituitary gland, it's the hypothalamus that controls its release. Growth hormone-releasing hormone is secreted from the hypothalamus and stimulates the pituitary to release the actual growth hormone.

3. What is the difference between regulated and constitutive hormone release. Give an example of each.
Regulated hormone release occurs when hormones are stored in vesicles before release. When the endocrine gland gets the signal to release a hormone, it can release it right away without having to make it. Peptide hormones are usually secreted via regulated hormone release.

Steroid hormones are typically released through constitutive hormone release. Here, the endocrine glands don't store extra hormone, and when they get the signal that the steroids are needed, the gland first has to produce the hormone and then secrete it.

4. Why is the hypothalamus essential for neuroendocrine responses?
The hypothalamus is part of the nervous system as a part of the brain, and is also an endocrine organ that largely regulates hormone release from the pituitary gland. Because it belongs to both systems, it's their point of contact, serving to relay various messages between the two systems.

5. How is melatonin released based on a circadian rhythm?
Melatonin is a pineal gland hormone that is specifically secreted in response to the dark. Every night as our eyes sense the darkness outside, the pineal gland is stimulated to release this hormone that helps us sleep.

6. What are two ways the nervous system can communicate with the immune system?
The nervous system sends nerves that connect the brain with various tissues, including the bone marrow and thymus of the immune system. To send messages from the brain to the immune system, the nervous system activates these neural pathways to simulate or inhibit activity in the bone marrow or thymus.

The nervous system also uses the endocrine system to indirectly talk to the immune system. Usually, the brain directly sends messages to the hypothalamus, which controls several hormone cascade pathways like the HPA axis. The end product of this process is cortisol, an anti-inflammatory agent.

7. What is the difference between the innate and adaptive immune systems?
The innate immune system is the first to respond to a pathogen attack. It includes physical barriers, like the skin and eyebrows, and leukocytes that mount a wide-spread attack on anything out of the ordinary. The adaptive immune system is the second immune system to respond to an attack, and it consists of B and T cell lymphocytes that recognize and respond to particular pathogens.

8. Describe the events in neurotransmission.
Neurotransmission occurs between an axon of one cell and a dendrite of another cell, and is the way that neurons communicate with each other. When a cell receives an electrical signal, the presynaptic cell releases specific neurotransmitters at a synapse. The other side of the synapse, the postsynaptic cell, contains receptors that are activated by that particular neurotransmitter. Depending on the neurotransmitter and postsynaptic receptors, different chemical pathways are activated.

9. What is a hormone cascade pathway?
The release of some hormones is regulated by the presence of other hormones. Without one, you won't get release of the other. Therefore, a hormone cascade pathway describes the multiple endocrine glands and hormones required to release particular hormones.

10. How are both the immune and nervous systems implemented in multiple sclerosis?
Multiple sclerosis is caused by an autoimmune response to the myelin that covers axons. For an unknown reason, the immune system believes that the myelin is a pathogen, and immune cells attack it, destroying some of the myelin. Because myelin is essential for the nervous system's fast-acting communication, its loss slows down the ability for the brain to talk to itself and other parts of the body.

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