Question

Histological adrenal cortex is divided into how many layers? (a) 1 (b) 2 (c) 3 (d) 4

Short answer

The histological adrenal cortex is divided into 3 layers.

Step-by-step solution

Understand the adrenal cortex

The adrenal cortex, part of the adrenal gland, is the outer layer of the gland. It produces crucial hormones to regulate physiological processes.

Discover the layers of the adrenal cortex

Histologically, adrenal cortex is divided into three layers. These are the zona glomerulosa, the zona fasciculata, and the zona reticularis.

Match the number of layers with the options

The adrenal cortex has three layers. So, the correct answer matches with option (c)

Key concepts

Adrenal Gland Structure

The adrenal gland is a vital component of the endocrine system that sits atop each kidney. It is composed of two main parts: the adrenal cortex and the adrenal medulla. The more superficial adrenal cortex is responsible for producing a variety of crucial hormones essential for maintaining homeostasis in the body. It is histologically divided into three distinct layers:

• Zona Glomerulosa: This is the outermost layer of the adrenal cortex. It primarily produces the hormone aldosterone, which plays a key role in regulating blood pressure and electrolyte balance by controlling sodium and potassium levels.
• Zona Fasciculata: Situated beneath the zona glomerulosa, this layer is responsible for producing glucocorticoids, mainly cortisol. Cortisol is significant for the body's response to stress, maintaining glucose metabolism, and influencing the immune system.
• Zona Reticularis: The innermost layer of the adrenal cortex, which produces androgens. Although androgens are considered minor compared to those produced by the gonads, they are still important for the development of male characteristics and reproductive functions.

The adrenal medulla, the inner part of the adrenal gland, is involved in producing catecholamines like adrenaline and noradrenaline, which are critical for the body’s fight-or-flight response.

Hormonal Regulation

Hormonal regulation is a complex process that ensures the body's internal environment remains stable. The adrenal cortex plays a critical role in this regulation by producing steroid hormones that influence various physiological processes. Each layer of the adrenal cortex secretes specific hormones under regulated mechanisms.

The regulation of steroids like aldosterone includes signals from the renin-angiotensin-aldosterone system (RAAS), which responds to fluctuations in blood pressure or blood volume changes. On the other hand, cortisol secretion is regulated by the hypothalamus-pituitary-adrenal (HPA) axis. The pituitary gland releases adrenocorticotropic hormone (ACTH), in response to signals from the hypothalamus, which then stimulates the adrenal cortex's zona fasciculata to produce cortisol. This intricate feedback loop helps the body adapt to stress and manage energy use.

• Regulation of aldosterone: Mainly through RAAS, responding to body fluid balance.
• Regulation of cortisol: Controlled via HPA axis, crucial for stress response and metabolic processes.

The precise regulation of these hormones plays a fundamental role in keeping physiological functions balanced and responding efficiently to environmental changes.

Physiological Processes

The adrenal cortex's hormones are integral to a variety of physiological processes critical for homeostasis. Understanding these hormones and their impacts can help elucidate the significance of the adrenal cortex in maintaining the body's balance.

Aldosterone, produced in the zona glomerulosa, helps regulate blood pressure by retaining sodium and excreting potassium in the kidneys. This process ensures that blood pressure remains within a healthy range, preventing conditions such as hypertension or hypotension. Cortisol, from the zona fasciculata, influences numerous processes including metabolism, the immune response, and anti-inflammatory actions. It helps the body manage energy levels by increasing blood glucose availability, suppressing immune function during acute stress, and reducing inflammation. Androgens, secreted by the zona reticularis, contribute to both male and female physiology by influencing sexual differentiation and reproduction functions. In females, they are known to influence libido and some aspects of sexual health.

• Aldosterone: Regulates electrolyte balance and blood pressure.
• Cortisol: Manages energy, stress responses, and immune system modulation.
• Androgens: Affect sexual development and reproductive health.

Each of these hormones ensures that our body's internal conditions remain stable, enabling it to react and adapt to external stressors efficiently.