Anatomy and Physiology: Key Terms and Definitions
Regions of the Diencephalon
Located atop the brain stem and enclosed by the cerebral hemispheres, the diencephalon has three main parts:
- Thalamus: Relay station for sensory impulses.
- Hypothalamus: Regulates body temperature, controls water balance, regulates metabolism, and contains the limbic center.
- Epithalamus: Houses the pineal body.
Schwann Cells
These cells form a myelin sheath and provide support.
Brain Stem
Consisting of the pons and medulla oblongata, the brain stem is attached to the spinal cord and has three parts:
- Midbrain: Contains the corpora quadrigemina, which are visual and auditory reflex centers.
- Pons: Controls breathing.
- Medulla Oblongata: Controls heart rate, blood pressure regulation, breathing, swallowing, and vomiting.
Gyrus and Sulcus
- Gyrus: Ridges on the surface of the cerebral hemisphere.
- Sulcus: Grooves on the surface of the cerebral hemisphere.
Gonads
The primary sex organs:
- Males: Testes (produce sperm and testosterone).
- Females: Ovaries (produce oocytes, estrogen, and progesterone).
Dura Mater
A double-layered covering that provides protection for the central nervous system.
Pia Mater
Clings to the surface of the brain.
Cerebrospinal Fluid
Formed by the choroid plexus (capillaries in the ventricles of the brain). It acts as a watery cushion to protect the brain and circulates in and around it.
Grave’s Disease
A malfunction in the body’s immune system releases abnormal antibodies that mimic TSH. The gland secretes an overabundance of hormones, causing metabolism to go into high gear, resulting in a pounding heart, sweating, and weight loss, and ultimately causing hyperthyroidism.
Oxytocin
Stimulates contractions of the uterus and causes the milk let-down reflex in a breastfeeding woman.
Adrenal Medulla
The inner neural tissue region produces two similar hormones:
- Epinephrine (adrenaline)
- Norepinephrine (noradrenaline)
These hormones prepare the body to deal with short-term stress (“fight or flight”) by increasing heart rate, blood pressure, and blood glucose levels, and dilating small passageways of the lungs.
Morphogens
Signaling molecules that determine morphogenesis. They work on a concentration gradient, having different effects on cell development in the embryo.
Glomerular Capsule (Bowman’s Capsule)
Surrounds the glomerulus and is involved in the formation of urine. Plasma fluid is filtered out of capillaries into the capsule and continues to the tubule, including the proximal tubule, loop of Henle, distal tubule, and collecting ducts that drain urine into the renal pelvis.
Podocytes
Highly selective glomerular capillary cells that are less permeable to large proteins and whole cells.
Loop of Henle
Site where tubular reabsorption occurs.
Blastocyst
A structure formed in the early development of mammals. It possesses an inner cell mass (ICM) which subsequently forms the embryo. The outer layer of the blastocyst consists of cells collectively called the trophoblast.
Seminiferous Tubules
Tightly coiled structures that function as sperm-forming factories.
Epididymis
A tightly coiled tube found on the testis and along the posterior lateral side. It functions to mature and store sperm cells (at least 20 days) and expels sperm with the contraction of muscles in the epididymis walls to the vas deferens.
Testosterone
Interstitial cells produce androgens such as testosterone.
Scrotum
A divided sac of skin outside the abdomen that maintains the testes at 3 °C lower than normal body temperature to protect sperm viability.
Myometrium
One of the three layers of the uterus.
Umbilical Cord
Forms to attach the embryo’s circulation to the placenta.
Implantation
The blastocyst becomes buried within the endometrium (day 6 or 7).