Physiology and Homeostasis

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Questions and Answers

Briefly explain the concept of homeostasis and why it is crucial for the normal functioning of the human body.

Homeostasis is maintaining a stable internal environment despite external changes. It's crucial because cells function optimally within a narrow range of conditions; deviations can lead to dysfunction or disease.

Describe the roles of the respiratory and cardiovascular systems in maintaining homeostasis.

The respiratory system obtains oxygen and removes carbon dioxide, while the cardiovascular system transports these gases, nutrients, and waste products throughout the body, facilitating exchange between cells and the environment.

How do the nervous and endocrine systems coordinate to regulate body functions?

The nervous system provides rapid, short-term control through electrical and chemical signals, while the endocrine system uses hormones for slower, longer-lasting effects. They often work together to maintain homeostasis.

The gastrointestinal tract and the urinary system both play key roles in maintaining homeostasis, explain their roles.

The gastrointestinal tract digests food to provide the body with nutrients. The urinary system eliminates waste, regulates blood volume, and blood pressure. Signup and view all the answers

Explain how understanding physiology can help in clinical applications and problem-solving within healthcare.

Physiology provides the foundation for understanding how the body works in health and disease. This knowledge is essential for diagnosing, treating, and preventing illnesses by addressing the underlying physiological mechanisms. Signup and view all the answers

How does the number of neurons in the efferent pathway differ between the somatic and autonomic nervous systems, and what implication does this have for signal modulation?

The somatic nervous system uses a single neuron, while the autonomic nervous system uses two neurons (preganglionic and postganglionic). This allows for greater modulation of the signal in the autonomic system via synapses in the ganglia. Signup and view all the answers

Contrast the effects of denervation (nerve damage) on skeletal muscle (somatic nervous system) versus smooth muscle and glands (autonomic nervous system).

Denervation of skeletal muscle leads to flaccid paralysis and atrophy. Denervation of smooth muscle and glands in the autonomic nervous system leads to muscle tone and function persistence and denervation hypersensitivity. Signup and view all the answers

If a drug selectively blocked nicotinic receptors on skeletal muscle, what specific effect would you expect to observe?

You would expect to observe muscle paralysis because acetylcholine would not be able to bind and activate the nicotinic receptors located on the motor end plates of the skeletal muscle. Signup and view all the answers

How do the neurotransmitter and receptor combinations differ in preganglionic versus postganglionic neurons within the autonomic nervous system, and what is the functional significance of this difference?

All preganglionic neurons release acetylcholine (ACh) activating nicotinic receptors on postganglionic neurons which can release either ACh or norepinephrine activating different receptors. This divergence allows for a wider range of effects on target organs. Signup and view all the answers

The sympathetic and parasympathetic divisions often have complementary roles. Describe how these divisions work in opposition, giving a specific example of an organ system they both affect.

The sympathetic system generally prepares the body for 'fight or flight,' while the parasympathetic system promotes 'rest and digest.' For example, the sympathetic nervous system increases heart rate, while the parasympathetic nervous system decreases it. Signup and view all the answers

How does norepinephrine affect blood pressure through α2 receptors, and what type of feedback mechanism is involved?

Norepinephrine, when binding to α2 receptors, leads to decreased release of norepinephrine, which in turn lowers blood pressure. This is a negative feedback control mechanism. Signup and view all the answers

Explain why the adrenal medulla secretes mostly epinephrine instead of norepinephrine, contrasting its function with typical sympathetic postganglionic neurons.

The adrenal medulla secretes mainly epinephrine (80%) and some norepinephrine (20%) because it functions as a specialized ganglion in the sympathetic nervous system that releases hormones into the bloodstream for a systemic effect, as opposed to postganglionic neurons that release neurotransmitters directly at the effector organ. Signup and view all the answers

Describe how the activation of α1 receptors leads to the dilation of the eye pupil, detailing the specific muscle and its action.

Activation of α1 receptors in the radial muscle of the iris causes the muscle to contract. This contraction leads to the dilation of the pupil. Signup and view all the answers

What are the primary effects of stimulating β1 receptors in the heart, and how do these effects influence cardiac function?

Stimulating β1 receptors in the heart increases heart rate (SA node), conduction velocity (AV node), and the force of ventricular contraction. These effects increase cardiac output and blood pressure. Signup and view all the answers

How does the activation of muscarinic receptors affect heart rate and what branch of the autonomic nervous system is responsible for this?

Activation of muscarinic receptors decreases heart rate. This effect is mediated by the parasympathetic nervous system, which promotes a 'rest and digest' state. Signup and view all the answers

Briefly explain the 'fight or flight' response, naming three specific physiological changes and the receptors involved.

The 'fight or flight' response involves increased heart rate (β1), increased blood glucose (α1 in liver), and bronchodilation (β2). This helps prepare the body for intense physical activity. Signup and view all the answers

Explain how the activation of α1 receptors in the sphincters of the gastrointestinal tract (GIT) and bladder affects digestion and urination.

Activation of α1 receptors in the sphincters of the GIT and bladder causes contraction, slowing down the passage of food and urine, respectively. Signup and view all the answers

How does norepinephrine cause vasoconstriction via α1 receptors, and in which tissues is this effect most prominent?

Norepinephrine causes vasoconstriction via α1 receptors by activating G-proteins, increasing cytoplasmic Calcium, and contracting smooth muscle in blood vessels. This is prominent in smooth muscles and blood vessels. Signup and view all the answers

Describe the action of epinephrine and norepinephrine when they bind to receptors, and what subsequent cellular event leads to a change in cell activity?

When epinephrine and norepinephrine bind to their receptors, they activate coupled G proteins. This activation leads to a change in the cell, ultimately resulting in an action. Signup and view all the answers

How does stimulation of β receptors in the smooth muscle of blood vessels in skeletal muscle contribute to the 'fight or flight' response?

Stimulation of β receptors in the smooth muscle of blood vessels in skeletal muscle causes vasodilation, increasing blood flow to these muscles. This provides more oxygen and nutrients, supporting increased physical activity during the 'fight or flight' response. Signup and view all the answers

Flashcards

Physiology

The study of the functions of the human body.

Homeostasis

Maintaining a stable internal environment for cells.