Compare and contrast isotonic and isometric skeletal muscle contractions and the
ID: 3517431 • Letter: C
Question
Compare and contrast isotonic and isometric skeletal muscle contractions and their physiological mechanisms.Describe the concepts of positive and negative feedback pathways. Provide detail for two specific examples of negative feedback pathways involving the hypothalamus and pituitary gland(no made-up examples)
Describe the control of the thyroid gland and the physiological effects of the hormones that it secretes. What roles do the thyroid hormones have in controlling the body’s metabolic rate? Compare and contrast isotonic and isometric skeletal muscle contractions and their physiological mechanisms.
Describe the concepts of positive and negative feedback pathways. Provide detail for two specific examples of negative feedback pathways involving the hypothalamus and pituitary gland(no made-up examples)
Describe the control of the thyroid gland and the physiological effects of the hormones that it secretes. What roles do the thyroid hormones have in controlling the body’s metabolic rate?
Describe the concepts of positive and negative feedback pathways. Provide detail for two specific examples of negative feedback pathways involving the hypothalamus and pituitary gland(no made-up examples)
Describe the control of the thyroid gland and the physiological effects of the hormones that it secretes. What roles do the thyroid hormones have in controlling the body’s metabolic rate?
Explanation / Answer
1. ANS:
Difference between isometric and isotonic muscle contractions:
Isotonic muscle contraction:
An isotonic contraction is in which the muscle maintains the same tension as it shortens.
Examples
Walking, running or lifting a light object.
Isotonic contractions occur in two varieties
1 .Concentric 2. Eccentric
In the concentric contraction, the muscle shortens when its tension is greater than the force opposing it like your biceps does when performing an arm curl.
In an eccentric contraction, the force is greater than the muscle tension, causing the muscle to elongateExample:
Going down stairs or sitting down in a chair
The effects of gravity add to the opposing force.
Isometric muscle contraction:
Isometric means the same length and in contractions of this variety, the muscle does not shorten and its tension never exceeds the opposing force.
Examples:
Holding a weight in place above the ground or pushing against a stationary object.
The entire muscle does not change length during an isometric contraction.
The individual muscle fibers will shorten so the isometric exercises can help to strengthen a muscle.
2. ANS:
Feedback is the information gained from a reaction to a product, that allows the modification of the product. Feedback loops are hence the process whereby a change to the system results in an alarm which will trigger a particular result.
Feedback loops are crucial as they allow living organisms to maintain homeostasis.
Positive Feedback Loops
A positive feedback loop takes place when the product of a reaction leads to an increase in that reaction. For instance, look at a system of homeostasis, a positive feedback loop moves a system away from the target of equilibrium.
Negative Feedback Loops
A negative feedback loop takes place when the product of a reaction leads to a decrease in that certain reaction. That is why a negative feedback loop brings a system closer to a target of stability or homeostasis.
Example:
Estrogens and progesterone have negative feedback regulation on FSH and LH through the anterior pituitary and hypothalamus. This is known as hypothalamic-pituitary-gonadal (HPA) axis.
The corticotropin-releasing hormone (CRH) from the hypothalamus acts on the anterior pituitary to release the ACTH, which stimulate the release of adrenal cortical hormones from the adrenal cortex. If the blood levels of the hormones reach normal levels, these hormones act on hypothalamus to decrease the release of CRH, thus, inhibiting the further release of the hormones. This is the negative feedback loop of the “hypothalamic-pituitary-adrenal axis.”
3. ANS:
Thyroid hormones control metabolism, muscle strength, growth, body temperature, appetite and not only this, they also monitor the overall health of heart, brain, kidneys, and reproductive system.
Iodine is absorbed by only Thyroid cells and with the help of iodine, it creates T4 (thyroxine) and T3 (triiodothyronine) hormones.
T3 and T4 levels
The thyroxine regulates the metabolism and these thyroid hormones regulates the function of body and see the overall physical development.
Our body needs to maintain T3 and T4 levels at correct proportions. T3 and T4 present in our body will travel in our bloodstream to reach almost every cell in the body and these hormones regulate the speed with which the cells will work and perform.
Like regulating our heart rate and digesting our food, if these hormones are less all these processes are affected.
Hyperthyroidism occurs due to too much T3 and T4 in your body: Which results in Anxiety, Hand trembling (shaking), Missed or light menstrual periods, Sweating or sensitivity to high temperatures, Nervousness, hyperactivity, Irritability or moodiness, Hair loss etc
Hypothyroidism occurs when too little T3 and T4 produced in our body: Trouble sleeping, Joint and muscle pain, Tiredness and fatigue, Sensitivity to cold temperature, Frequent, heavy periods, Difficulty concentrating, Dry skin and hair, Depression etc.
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