Anatomy

Endocrine organ function

Secrete hormones that work to maintain homeostasis directly into the bloodstream

Hormones

Chemical messengers that act upon effectors to regulate bodily functions. Specific hormones bind to specific receptors in order to create a response.

Main endocrine organs

Pituitary gland, Hypothalamus, Thyroid gland, Adrenal glands, Pineal gland, Parathyroid glands, pancreas

Organs with secondary endocrine functions

Heart, Thymus, Adipose tissue, Digestive tract, Kidneys, Gonads (Testes/Ovaries)

Hypothalamus

The key endocrine organ that serves as a link between the neural and endocrine systems. It also secretes regulatory hormones and contains autonomic nervous system centers.

Hypothalamus hormone production

Oxytocin and antidiuretic hormones(ADH) that travel through hypothalamic neurons are eventually released by the posterior part of the pituitary gland

Alternative name for the posterior pituitary gland

Neurohypophysis

Alternative name for the anterior pituitary gland

Adenohypophysis

Main hormones released by the posterior pituitary gland

Oxytocin and ADH

ADH

Targets the kidneys and works to reabsorb water(water retention) to increase blood volume and pressure

Oxytocin

Targets the mammary glands and the uterus in females, causes milk ejection in the mammary glands and uterine wall contraction.
Targets the prostate gland and ductus deferens, causes contraction in both structures.

Thyroid gland

Sits in the inferior neck just in front of the trachea, secretes T3 and T4 (hormones that influence metabolism in the body), also secretes calcitonin (hormone that works to lower blood calcium levels)

Parathyroid glands

Four nodules lie on the posterior surface of the thyroid gland, releases parathyroid hormones which work to increase blood calcium levels

Adrenal glands

Sit on top of the superior side of the kidneys and have a pyramidal shape, contains 2 main parts: adrenal cortex (outer portion) and adrenal medulla (inner portion)

Adrenal medulla

Secretes norepinephrine (noradrenaline) and epinephrine (adrenaline)

Adrenal cortex

Secretes cortisol, which works to increase blood sugar, aldosterone, which helps promote water retention to increase blood volume and pressure, and androgens, which are sex hormones that include estrogen and testosterone

Pancreas

Located in the abdomen and sits posterior to the stomach, functions as both and exocrine and endocrine gland, endocrine portion relies on the bloodstream to move the hormones made by the pancreas, exocrine portion relies on the ducts within the pancreas to move digestive enzymes, the head is tucked into the “U” shaped curve of the duodenum of the small intestine

Main hormones produced by the pancreas

Glucagon, which works to increase blood sugar levels, and insulin, which works to decrease blood sugar levels

Kidneys as secondary endocrine organs

Secretes renin, which stimulates a series of steps that ultimately lead to the production/release of aldosterone (renin works to increase sodium and water retention)

Kidneys in regulating blood calcium levels

Perform the activation step that is needed when low blood calcium levels require an active form of vitamin D to be converted from an inactive form to stimulate our digestive tract to absorb more dietary calcium (sunlight converts a hormone into inactive vitamin D3), this is all done to increase blood calcium

Kidneys in regulating blood oxygen levels

Release a hormone called erythropoietin (EPO), which stimulates the creation of more red blood cells so that we can carry more oxygen in the body (done to increase blood oxygen levels)

Primary functions of the urinary system

Maintaining electrolyte and fluid balance, eliminating waste from the body, regulating blood pressure and volume, maintaining acid/base balance

Large structure of the urinary tract

Kidney, ureter, urinary bladder, urethra

Protective layers of the kidney

Renal capsule, fascia, substantial amount of fat

The kidneys are PARTIALLY covered by the ribcage

True

Hilum

The spot where the renal artery, renal vein, and the ureter physically link up with the kidney

Sequential movement of urine

Superior to inferior from the minor calyx, major calyx, renal pelvis, and ureter

Kidney bloodflow through the nephrons

Afferent arterioles, glomerulus, efferent arteriole, peritubular capillaries, venules

Glomerulus

The small capillary bed in close proximity to the Bowman’s capsule of the nephron

Nephron

The fundamental filtering unit of the kidney that leads into the collecting duct

Key parts of the nephron

Bowman’s capsule, proximal convoluted tubule, descending/ascending limbs of the nephron loop, distal convoluted tubule

Detrusor muscle

Smooth muscles found in the wall of the urinary bladder

Internal urethral sphincter

Made of smooth muscle, involuntary

External urethral sphincter

Made of skeletal muscle, voluntary

The kidneys sit in the retroperitoneal space of the abdominal cavity

True

Axial muscles

Muscles that position the head and vertebral column, muscles that move the rib cage

Four categories of axial muscles

Head and neck muscles, vertebral column muscles, rib cage and body wall muscles, pelvic floor muscles

Main chewing muscles

Masseter, temporalis, pterygoids

Extraocular muscles

Superior rectus, medial rectus, inferior rectus, lateral rectus

Sternocleidomastoid actions

Unilateral: Ipsilateral lateral flexion, contralateral lateral rotation
Bilateral: Flexion of the neck

Suprahyoid muscles action (digastric, mylohoid, stylohyoid)

Elevate and fixate the hyoid bone and larynx in the neck

Infrahyoid muscles action (sternohyoid, omohyoid, sternothyroid, thyrohyoid)

Depress and fixate the hyoid bone and larynx in the neck

Erector spinae actions

Unilateral: Ipsilateral lateral flexion and rotation

Bilateral: Extension of the vertebral column

Splenius actions

Unilateral: Ipsilateral lateral flexion and rotation

Bilateral: Extension of the cervical spine

Diaphragm movement during breathing

During inspiration, the diaphragm contracts and descends to allow for lung expansion. During expiration, the diaphragm relaxes and ascends to allow for lung contraction.