Lab # 1 Endocrine System

THIS IS A STUDY GUIDE, NOT AN ALL INCLUSIVE REVIEW. THERE MIGHT BE THINGS NOT COVERED BY THIS STUDY GUIDE THAT MIGHT BE ASKED IN YOUR QUIZZES and PRACTICAL TESTS. STUDENTS ARE RESPONSIBLE FOR STUDYING THEIR MANUAL AND FOR ALL THE MATERIAL COVERED DURING THE LABORATORY PERIOD, AS PER THE COURSE SYLLABUS

There are Two Organ Systems Dedicated to Maintaining the Internal Conditions (Homeostasis): It employs electrical and chemical means to send messages from cell to cell. 1- Nervous System 2- Endocrine System It communicates by means of chemical messengers (hormones) secreted into to the blood. Endocrine gland Target cell (skeletal muscle cell) Hormone Target cell (skeletal muscle cell)

The Hypothalamus and the Pituitary Gland The hypothalamus and the pituitary gland have the greatest influence in regulating the entire endocrine system. Pituitary gland Hypothalamus Thalamus The hypothalamus secrets releasing hormones that trigger secretions of the anterior pituitary gland. The pituitary gland secrets hormones that control other glands.

Corpus callosum Septum pellucidum Fornix Pineal gland Anterior commissure Thalamus Intermediate mass Hypothalamus Mamillary body Optic chiasm Pituitary gland Epi- thalamus Infundibulum

Three Mechanisms of Hypothalamic Control over Endocrine Function Secretion of regulatory hormones to control activity of anterior lobe of pituitary gland 1 Production of ADH and Oxytocin 2 Control of sympathetic output to adrenal medulla 3 Tropic hormones secreted by anterior lobe of pituitary gland control other endocrine organs Release of ADH and oxytocin Secretion of epinephrine and norepinephrine

Anterior lobe or Adenohypophysis: AnteriorPosterior Third ventricle of brain Pars tuberalis (around the infundibulum) Pars distalis (main portion of anterior lobe) Infundibulum (stalk) Posterior lobe, Neurohypophysis or Par nervosaHypothalamus: Pars intermedia (in the interior) Anatomy of the Hypothalamus and the Pituitary Gland

PRL Prolactin (PRL) After birth stimulates the mammary glands to synthesize milk. Thyroid-stimulating hormone (TSH) It stimulates secretion of thyroid hormone. TSH Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Gonadotropins: It stimulates the development of ovarian follicles, secretion of ovarian sex hormones, and sperm production. It stimulates ovulation, stimulates corpus luteum to secrete progesterone, stimulates testes to secrete testosterone. FSH LH ACTH It stimulates the adrenal cortex to secrete glucocorticoids. Adrenocorticotropic hormone (ACTH) GH Liver Fat, muscle, bone It stimulates mitosis and cellular differentiation and thus promotes tissue growth throughout the body Growth hormone (GH) The Anterior Pituitary Produces Seven Hormones Releasing hormones are produced by the hypothalamus. Releasing hormones target the anterior pituitary (adenohypo- physis ) Melanocyte stimulating hormone (MSH) Releasing hormones It stimulates the melanocytes of skin to produce melanin. MSH

Oxytocin (OT) Posterior pituitary or Neurohypophysis stores and releases: It stimulates uterine contractions and propulsion of semen. It stimulates labor contractions during childbirth. Antidiuretic hormone (ADH) It increases water retention thus reducing urine volume and prevents dehydration. It is also called vasopressin because it can cause vasoconstriction. Oxytocin (OT) Antidiuretic hormone (ADH) Oxytocin (OT) Antidiuretic hormone (ADH) The Hypothalamus Produces two Hormones: Oxytocin (OT) and Antidiuretic Hormone

2- Thyroid Gland Right lobe Left lobe Isthmus

T4 or Thyroxine T3 or Triiodothyronine Calcitonin

Thyroid Hormones 1- T4 or thyroxine 2- T3 or triioodothyronine Follicular hormones (they are produced by the follicular cells) 1- They increase the rate of oxygen uptake and the basal metabolic rate 2- They enhance the effects of sympathetic stimulation (increasing heart rate, blood pressure, nervousness, and sweating) 3- They help to maintain body temperature 4- They help to regulate growth, development, and intracellular metabolism by increasing protein synthesis and lipid breakdown 5- They stimulate RBC formation, and speed up bone turnover 1- T4 or thyroxine 2- T3 or triiodothyronine 3- Calcitonin

It is released in response to high levels of calcium in the blood Calcitonin hormone is released by thyroid gland Inhibits osteoclasts to resorb bone, and encourages calcium salt deposit in bone matrix [Calcium] in blood

3- Parathyroid Glands Thyroid gland, posterior view Parathyroid glands

The Parathyroid Hormone It increases calcium blood levels by targeting bone and kidneys [Calcium] in blood Parathyroid hormone is released by parathyroid gland Stimulates the osteoclasts to resorb bone, releasing calcium to the blood [Calcium] in blood 1- In bones 2- In kidneys - It increases calcium reabsortion - It increases formation and secretion of calcitriol Increases absorption of calcium and phosphate from the intestines [Calcium] in blood

4-Thymus Gland The thymus is located in the mediastinum. It atrophies after puberty. The thymus is divided into two thymic lobes. Septa divide lobes into smaller lobules. Functions: T cells migrate into medulla. Mature T cells leave thymus by medullary blood vessels. 1- It secretes thymic hormones that stimulate stem cell divisions and T cell differentiation. The lymphocytes divide in the cortex.

5- Suprarenal Glands

Mineralocorticoids (Aldosterone) Glucocorticoids (Cortisol, Cortisone and Corticosterone) Sex hormones ( androgens) Medulla (It is considered part of Sympathetic Autonomic nervous System) Catecholamines (Epinephrine and Norepinephrine)

Hormones of the Adrenal Cortex 1- Mineralocorticoides (Aldosterone) -It increases sodium and water reabsortion in kidneys -It increases potassium secretion in kidneys Aldosterone secretion is regulated by the renin-angiotencin mechanism Blood pressure or plasma solute concentration Renin-angiotencin mechanism Aldosterone secretion 2- Glucocorticoids (Corticosterone and Cortisol) -They help the body to resist stressors -They depress the immune system and the inflammatory response 3- Gonadocorticoids or Sex Hormones (Androgens) -They are masculinizing hormones. -In females they stimulate sexual drive. After menopause they are converted to estrogens. Blood Pressure

-Blood glucose levels They increase: -Cardiac activity -Blood pressure -Glycogen breakdown -Triglyceride breakdown Hormones of the Adrenal Medulla Catecholamines (Epinephrine and Norepinephrine)

6- Pancreas

Endocrine pancreasExocrine pancreas Pancreatic acini They secrete large quantities of an alkaline, enzyme rich fluid 1- Beta cells: 2- Alpha cells: 3- Delta cells: 4- F cells: Insulin Glucagon Somatostatin Pancreatic polypeptide Islets of Langerhans

Pancreas 1- Glucagon (released by alpha cells) Liver Blood glucose 2- Insulin (released by beta cells) (beta cells) Insulin - It increases the rate of glucose uptake by cells - It increases cellular metabolism - It increases the storage of lipid and glycogen - Increases aminoacids absorption and protein synthesis -It stimulates the liver to produce glucose -It stimulates to breakdown glycogen Glucagon Blood glucose Pancreas ( alpha cells) - Blood glucose Blood glucose

Interstitial cells Sustentacular cells They produce Androgens (testosterone) They produce Inhibin Androgens: They promote maturation of male sexual organs, and production and maturation of sperm Inhibin: It inhibits the secretion of FSH The Testes Germ cells They become spermatozoa 7- Testes and Ovaries

The Ovaries

Primary oocytes Primary follicles Secondary follicles Tertiary follicles Corpus luteum : Follicles Follicles: Estrogens Progesterone Prepares the uterus for implantation Establishes the menstrual cycle Maintains pregnancy Prepares mammary glands for milk secretion Stimulate development of the secondary sexual characteristics Stimulate follicle maturation Stimulate maturation of the female re[productive system The Ovaries

7b- The Ovaries