medulla

Examples of medulla in the following topics:

• Adrenal Medulla

  • The adrenal medulla is the core of the adrenal glands, and is surrounded by the adrenal cortex.
  • The adrenal medulla produces is responsible for the production of catecholamines, derived from the amino acid tyrosine.
  • The adrenal medulla secretes approximately 20% noradrenaline (norepinephrine) and 80% adrenaline (epinephrine).
  • Chromaffin cells are the neuroendocrine cells found in the medulla, they are modified post-synaptic sympathetic neurons that receive sympathetic input.
  • The adrenal medulla sits below the three layers of the adrenal cortex and is innervated by nerve fibers.

• Medulla Oblongata

  • The medulla oblongata controls autonomic functions and connects the higher levels of the brain to the spinal cord.
  • The medulla oblongata is the lower half of the brainstem.
  • An open or superior part where the dorsal surface of the medulla is formed by the fourth ventricle.
  • During development, the medulla oblongata forms from the myelencephalon.
  • Describe the location and function of the medulla oblongata region of the brain stem

• Internal Anatomy of the Kidneys

  • The cortex and medulla make up two of the internal layers of a kidney and are composed of individual filtering units known as nephrons.
  • There are three major regions of the kidney: renal cortex, renal medulla, and renal pelvis.
  • The renal cortex is a space between the medulla and outer capsule.
  • The medulla is the inner region of the parenchyma of the kidney.
  • Distinguish between the cortex and medulla in the internal anatomy of the kidney

• Neural Mechanisms (Respiratory Center)

  • The medulla and the pons are involved in the regulation of the ventilatory pattern of respiration.
  • The medulla oblongata is the primary respiratory control center.
  • There are two regions in the medulla that control respiration:
  • The medulla also controls the reflexes for nonrespiratory air movements, such as coughing and sneezing reflexes, as well as other reflexes, like swallowing and vomiting.
  • The pons is the other respiratory center and is located underneath the medulla.

• Control of Autonomic Nervous System Function

  • The medulla oblongata, in the lower half of the brainstem, is the control center of the autonomic nervous system.
  • Within the brain, the ANS is located in the medulla oblongata in the lower brainstem .
  • The medulla's main functions are to control the cardiac, respiratory and vasomotor centers, to mediate autonomic, involuntary functions, such as breathing, heart rate and blood pressure, and to regulate reflex actions such as coughing, sneezing, vomiting and swallowing.
  • The medulla is a subregion of the brainstem and is a major control center for the autonomic nervous system.

• Medulla Injury

  • Medulla injury results in a wide variety of deficits including numbness, difficulty swallowing, slurred speech, and poor coordination.
  • Lateral medullary syndrome, also called Wallenberg syndrome and posterior inferior cerebellar artery syndrome, is a disease that presents with a constellation of neurologic symptoms due to injury to the lateral part of the medulla in the brain, resulting in tissue ischemia and necrosis, typically from blood clot (stroke) impeding the vertebral artery and/or the posterior inferior cerebellar artery .
  • MRI image showing an acute infarct in the left dorsal lateral medulla.
  • Describe the effects of injury to the medulla in the brainstem

• Functions of the Brain Stem

  • The three components of the brainstem are the medulla oblongata, midbrain, and pons.
  • The medulla oblongata (myelencephalon) is the lower half of the brainstem continuous with the spinal cord.
  • The medulla contains the cardiac, respiratory, vomiting, and vasomotor centers regulating heart rate, breathing, and blood pressure.
  • The pons (part of metencephalon) lies between the medulla oblongata and the midbrain.
  • It contains tracts that carry signals from the cerebrum to the medulla and to the cerebellum.

• Overview of the Adrenal Glands

  • Each adrenal gland has two distinct structures, the outer adrenal cortex and the inner medulla, both of which produce hormones.
  • The cortex mainly produces mineralcorticoids, glucocorticoids and androgens, while the medulla chiefly produces adrenaline and nor-adrenaline.

• Chemoreceptor Regulation of Breathing

  • Central chemoreceptors: These are located on the ventrolateral surface of medulla oblongata and detect changes in the pH of spinal fluid.
  • For the respiratory rate, the chemoreceptors are the sensors for blood pH, the medulla and pons form the integrating center, and the respiratory muscles are the effector.
  • In response, the chemoreceptors detect this change, and send a signal to the medulla, which signals the respiratory muscles to decrease the ventilation rate so carbon dioxide levels and pH can return to normal levels.
  • The chemoreceptors are the sensors for blood pH, the medulla and pons form the integrating center, and the respiratory muscles are the effector.

• Pons

  • It is above the medulla, below the midbrain, and anterior to the cerebellum.
  • The white matter of the pons includes tracts that conduct signals from the cerebrum down to the cerebellum and medulla, and tracts that carry the sensory signals up into the thalamus.
  • Most of it appears as a broad anterior bulge rostral to the medulla.
  • $$Structure of the brainstem showing the location of the pons in relation to the midbrain and medulla.