Control and Coordination in Living Organisms

Action potentials are transmitted to the rest of the heart by gap junctions between myocytes and the annulus fibrosus prevents transmission directly to the ventricles.

These are the cortical areas that are neither motor nor sensory but are thought to be involved in higher processing of information.The idea of a voluntary movement originates in the asso­ci­a­tion cortex.

Amygdala is a limbic structure involved in many brain functions like emotion, learning and memory. It is part of a system that processes reflexive emotions like fear and anxiety.

The pons is a section of the brain lying above the medulla oblongata . It plays important role in arousal, sleep, carrying sensory information between the cerebrum and the cerebellum and helping control of autonomic functions.

It is the compact layer that lacks cell boundaries and grows into the endometrial stroma. It secretes the hormone hCG in order to maintain progesterone secretion and continue the pregnancy.

Body osmolality is sensed in the hypothalamus by osmoreceptors which influence thirst (water intake) and ADH (anti-diuretic hormone or vasopressin) secretion (which influences water output by the kidneys).

The filtration barrier is made up of two layers of cells and the basement membrane which lies between them. These two layers of cells in the filtration barrier are the endothelial cells of the glomerular capillaries and the epithelial cells of Bowman's capsule .

This period of development starts during the ninth week of pregnancy and lasts until birth. The early body systems and structures formed in the embryonic stage continue to develop. In this stage the neural tube develops into the brain and spinal cord. In this stage all the organs of the fetus predicate their specialized functions.

Purkinje fibres lie in the deepest layer of the endocardium and supply the papillary muscles. Hence, the apex of the heart contracts first, followed by the papillary muscles.

Nerve fibres vary in size from 0.5 to 20µm in diameter, the smallest unmyelinated fibre being the slowest conducting and the largest myelinated fibres the fastest conducting.

Stomach secretes intrinsic factor required for absorption of vitamin B12, which is a water-soluble vitamin.

Carbon dioxide and bicarbonate ions are effectively a buffer pair.  If carbon dioxide is added to body fluids, the direct effect is the production of carbonic acid and thus a rise in the pH as some of this carbonic acid dissociates to produce free H+ ions.

The cerebral cortex is the part of the brain that functions to make human beings unique and distinct. Distinct human traits encompassing higher thought, language and human consciousness as well as the ability to think, reason and imagine, all originate in the cerebral cortex.