*Peripheral Nervous System and Endocrine System

Peripheral Nervous System (PNS)

  • The PNS coordinates with the brain to ensure the body is functioning appropriately.

Components of the Peripheral Nervous System

  • Somatic Nervous System: Responsible for voluntary control of body movements via skeletal muscles.

  • Autonomic Nervous System: Regulates involuntary body functions, including heart rate and digestion.

Divisions of the Autonomic Nervous System

  • Sympathetic Nervous System (SNS):

    • Function: Mobilizes the body’s resources during stress or danger.

    • Effects: Rapidly activates organs and glands under its control to prepare the body for a fight-or-flight response.

  • Parasympathetic Nervous System (PNS):

    • Function: Balances the actions of the SNS, promoting relaxation and normalization after stress responses.

    • Effects: Acts to restore and maintain normal functions, essentially reversing the effects of the SNS and "braking" arousal.

Regulation of the Endocrine System

  • The Endocrine System consists of glands that produce and release hormones into the bloodstream, which are chemical messengers that regulate various bodily functions.

  • The endocrine system is closely linked to the immune system.

Key Endocrine Glands and Functions

  • Adrenal Glands:

    • Produce epinephrine/adrenaline, which responds to stress.

  • Thyroid:

    • Secretes thyroxine, which regulates metabolism and energy.

  • Pituitary Gland:

    • Produces various regulatory hormones that control several bodily functions.

  • Gonadal Glands:

    • Produce sex hormones such as testosterone (in males) and estrogen (in females).

Hypothalamic-Pituitary-Adrenal (HPA) Axis

  • Described as a major neuroendocrine system that manages the body’s response to stress and regulates many crucial body processes.

  • Processes Controlled Include:

    • Digestion

    • Immune system responses

    • Mood and emotions

    • Sexuality

    • Energy storage

Functions of the Components of HPA Axis

  • Hypothalamus:

    • Produces corticotropin-releasing hormone (CRH).

  • Pituitary Gland:

    • Releases adrenocorticotropic hormone (ACTH) which activates the adrenal glands.

  • Adrenal Glands:

    • Produce cortisol, a hormone vital for the stress response.

Implications of HPA Axis Dysfunction

  • Changes or dysfunctions in the HPA axis are implicated in various psychological disorders, often linked to anxiety and stress-related conditions.