1-Compare and contrast the operation of negative and positive feedback mechanisms in maintaining homeostasis. Provide two examples of variables controlled by negative feedback mechanisms and one example of a process regulated by a positive feedback mechanism.
#2-Compare and contrast skeletal, cardiac, and smooth muscle tissue relative to structure, body location, and specific function.
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1. Negative and positive feedback mechanisms in maintaining homeostasis
Negative feedback is a process that helps to maintain a stable internal environment by counteracting changes in a variable. For example, if blood sugar levels rise, the pancreas releases insulin, which helps to lower blood sugar levels. This negative feedback loop helps to keep blood sugar levels within a healthy range.
Positive feedback is a process that amplifies changes in a variable. For example, during childbirth, the release of oxytocin causes the uterus to contract. This contraction then causes the release of more oxytocin, which causes the uterus to contract even more. This positive feedback loop helps to bring about the birth of the baby.
Examples of variables controlled by negative feedback mechanisms
Blood sugar levels
Body temperature
Blood pressure
Blood pH
Heart rate
Example of a process regulated by a positive feedback mechanism
Childbirth
Blood clotting
Immune response
2. Skeletal, cardiac, and smooth muscle tissue
Skeletal muscle is attached to bones and is responsible for voluntary movement. Skeletal muscle cells are long and striated, and they contain many nuclei.
Cardiac muscle is found in the heart and is responsible for pumping blood throughout the body. Cardiac muscle cells are also long and striated, but they have only one nucleus per cell.
Smooth muscle is found in the walls of hollow organs, such as the stomach, intestines, and bladder. Smooth muscle cells are short and spindle-shaped, and they do not have striations.
Structure
Type of muscle Structure
Skeletal muscle Long and striated cells with many nuclei
Cardiac muscle Long and striated cells with one nucleus per cell
Smooth muscle Short and spindle-shaped cells without striations
Body location
Type of muscle Body location
Skeletal muscle Attached to bones
Cardiac muscle Heart
Smooth muscle Walls of hollow organs
Specific function
Type of muscle Specific function
Skeletal muscle Voluntary movement
Cardiac muscle Pumping blood throughout the body
Smooth muscle Contraction of hollow organs
