Endocrine + circulation - Lab Flashcards
(33 cards)
Structure and hormones released
- Releasing Hormones
- TRH (Thyrotropin-releasing hormone) → stimulates TSH and prolactin release
- CRH (Corticotropin-releasing hormone) → stimulates ACTH release
- GnRH (Gonadotropin-releasing hormone) → stimulates FSH and LH release
- GHRH (Growth hormone-releasing hormone) → stimulates GH release - Inhibiting Hormones
- GHIH (Growth hormone-inhibiting hormone / somatostatin) → inhibits GH and TSH
- PIH (Prolactin-inhibiting hormone / dopamine) → inhibits prolactin
Anterior Pituitary hormones
adenohypophysis
glandular
-
ACTH (Adrenocorticotropic hormone)
- Stimulates adrenal cortex → ↑ cortisol production (stress response, metabolism) -
TSH (Thyroid-stimulating hormone)
- Stimulates thyroid gland → ↑ T₃ and T₄ → regulates metabolism -
GH (Growth hormone)
- Stimulates growth in bones, muscles, and tissues via IGF-1 from liver -
PRL (Prolactin)
- Stimulates milk production in mammary glands -
FSH (Follicle-stimulating hormone)
- Stimulates ovarian follicle development in females
- Stimulates sperm production in males -
LH (Luteinizing hormone)
- Triggers ovulation and corpus luteum formation in females
- Stimulates testosterone production in males
Posterior Pituitary hormone
-
Antidiuretic Hormone (ADH)
- Increases water reabsorption in kidneys → ↓ urine output
- Helps maintain blood pressure and fluid balance -
Oxytocin (OT)
- Stimulates uterine contractions during labor
- Promotes milk ejection (let-down reflex) during breastfeeding
- Also involved in bonding and emotional responses
Posterior Pituitary
-
Anterior Pituitary (Adenohypophysis)
- Glandular, derived from oral ectoderm
- Dark staining, highly cellular
-
Posterior Pituitary (Neurohypophysis)
- Neural tissue, derived from diencephalon
- Pale staining, fewer cells
- Key Feature: Sharp contrast in staining and structure between anterior (dark, glandular) and posterior (pale, neural) regions
State Structure and hormones release
Thyroid
-
Thyroxine (T4)
- Function: Increases basal metabolic rate; regulates growth and development
- Note: Less active form; converted to T3 in target tissues
-
Triiodothyronine (T3)
- Function: Active form of thyroid hormone; boosts metabolism, heart rate, and CNS activity
- Note: More potent but shorter-acting than T4
-
Calcitonin
- Function: Lowers blood calcium levels by inhibiting osteoclast activity
- Produced by: Parafollicular (C) cells of the thyroid
State Structure and hormones release
Parathyroid
-
Parathyroid Hormone (PTH)
- Function: Raises blood calcium levels
-
Mechanisms:
- Stimulates osteoclasts → bone resorption
- Increases renal calcium reabsorption
- Stimulates calcitriol (active vitamin D) production → enhances intestinal calcium absorption
- Produced by: Chief cells of the parathyroid glands
Identify Tissue and cell type
Thyroid
Thyroid follicles
- Thyroid Follicles: Spherical structures filled with colloid (stored thyroglobulin)
-
Follicular Cells: Simple cuboidal epithelium surrounding each follicle
- Produce thyroxine (T4) and triiodothyronine (T3)
- Height varies with activity (flat when inactive, tall when active)
-
Parafollicular Cells (C-cells): Found between follicles, pale-staining
- Secrete calcitonin, which lowers blood calcium
-
Colloid: Pink eosinophilic material in follicle lumen
- Stores inactive thyroglobulin for later T3/T4 production
- Key Feature: Presence of follicles with colloid and two distinct endocrine cell types
Identify Tissue
Parathyroid
-
Chief Cells (Principal Cells)
- Small, round, with dark-staining nuclei and pale cytoplasm
- Most numerous cell type
- Secrete parathyroid hormone (PTH)
-
Oxyphil Cells
- Larger, polygonal cells with acidophilic (pink) cytoplasm
- Fewer in number; appear in clusters
- Function unclear, but may be inactive or aged chief cells
-
General Structure
- No follicles (unlike thyroid)
- Cells arranged in cords or clusters within a rich capillary network
- Key Feature: Dense cellular tissue with predominant chief cells and scattered oxyphil cells
State structure and list hormones
adrenal cortex
-
Epinephrine
- Function: Increases heart rate, dilates airways, boosts blood glucose
- Source: Adrenal medulla (chromaffin cells)
-
Norepinephrine
- Function: Vasoconstriction → raises blood pressure, promotes alertness
- Source: Adrenal medulla
-
Glucocorticoids (e.g. Cortisol)
- Function: Increases blood glucose, suppresses inflammation, helps resist stress
- Source: Zona fasciculata (adrenal cortex)
-
Aldosterone
- Function: Promotes sodium and water retention, increases blood pressure
- Source: Zona glomerulosa (adrenal cortex)
-
Androgens (e.g. DHEA)
- Function: Weak sex hormones; contribute to pubic hair, libido (mainly in females)
- Source: Zona reticularis (adrenal cortex)
Identify structure
Adrenal Medulla
Identify structure list layers.
-
Zona Glomerulosa (outermost layer)
- Cells: Small, round clusters
- Secretes: Mineralocorticoids (e.g. aldosterone)
- Function: Regulates sodium and potassium balance
-
Zona Fasciculata (middle layer)
- Cells: Large, lipid-rich cells in cords (appear pale)
- Secretes: Glucocorticoids (e.g. cortisol)
- Function: Increases blood glucose, anti-inflammatory
-
Zona Reticularis (innermost cortical layer)
- Cells: Smaller, darker-staining, in network-like arrangement
- Secretes: Androgens (e.g. DHEA)
- Function: Supplement sex hormones, especially in females
Identify tissue and structure
Pancreas, Pancreatic islets (islets of Langerhans)
-
Islets of Langerhans (Endocrine)
- Pale-staining clusters of cells
- Scattered throughout exocrine tissue
- Contain:
- Alpha cells → secrete glucagon
- Beta cells → secrete insulin
- Delta cells → secrete somatostatin
- Rich capillary network for hormone diffusion
- No ducts
-
Acinar Cells (Exocrine)
- Dark-staining, basophilic cytoplasm
- Organized in clusters (acini) around a small duct lumen
- Secrete digestive enzymes into pancreatic ducts
- Round basal nuclei, apical zymogen granules
- Key Feature: Islets are pale and endocrine; acinar cells are dark and exocrine
Identify structure, list hormones
Pancreas
-
Insulin
- Secreted by: Beta cells of the Islets of Langerhans
- Function: Lowers blood glucose by promoting glucose uptake, glycogen synthesis, and lipogenesis
- Triggered by: High blood glucose levels
-
Glucagon
- Secreted by: Alpha cells of the Islets of Langerhans
- Function: Raises blood glucose by stimulating glycogenolysis, gluconeogenesis, and lipolysis
- Triggered by: Low blood glucose levels
darker cells, alpha cells. Lighter cells, beta cells
Identify structure, list hormones
Pineal Gland
- Main Hormone: Melatonin
- Secreted by: Pinealocytes
- Function: Regulates circadian rhythms and sleep-wake cycles
- Stimulated by: Darkness (inhibited by light via the suprachiasmatic nucleus)
- Additional role: Antioxidant effects; may influence reproductive timing in seasonal animals
Identify structure, list hormones
Thymus
Thymosin
- Secreted by: Thymic epithelial cells
- Function: Stimulates the maturation of T lymphocytes (T cells)
- Role: Essential for the development of a functional adaptive immune system, especially in early life
Describe Components of blood
- Type: Specialized connective tissue
-
Plasma
- Fluid matrix (~55% of blood)
- Contains water, electrolytes, proteins (e.g. albumin, globulins, fibrinogen), nutrients, and waste
-
Formed Elements
- Erythrocytes (RBCs) – Transport oxygen and CO₂ via hemoglobin
- Leukocytes (WBCs) – Immune defense (e.g. neutrophils, lymphocytes)
- Platelets (Thrombocytes) – Cell fragments involved in blood clotting
Identify cell type
Erythrocyte
- Count: 4.5–5 million/mm³
- Function: Carry oxygen and CO₂ via hemoglobin
- Microscopy: Biconcave discs, no nucleus, uniform pink stain
Identify cell type
Neutrophils (Granulocyte)
- Count: 3,000–7,000/mm³ (40–70% of WBCs)
- Function: Phagocytose bacteria, first responders
- Microscopy: Multi-lobed nucleus (3–5 lobes), pale cytoplasm with fine granules
Identify cell type
Eosinophils (Granulocyte)
- Count: 100–400/mm³ (2–4% of WBCs)
- Function: Combat parasites; involved in allergy responses
- Microscopy: Bilobed nucleus, large red-orange granules
Identify cell type
Basophils (Granulocyte)
- Count: 20–50/mm³ (<1% of WBCs)
- Function: Release histamine and heparin during allergic reactions
- Microscopy: Bilobed or obscured nucleus, dark purple/blue granules
Identify cell type
Monocytes (Agranulocyte)
- Count: 100–700/mm³ (3–8% of WBCs)
- Function: Differentiate into macrophages; phagocytose pathogens and debris
- Microscopy: Large kidney-shaped nucleus, abundant pale blue cytoplasm
Identify cell type
Lymphocytes (Agranulocyte)
- Count: 1500–3000/mm³ (25–45% of WBCs)
- Function: Adaptive immunity (B cells, T cells, NK cells)
- Microscopy: Large round nucleus filling most of cell, thin rim of cytoplasm
Identify cell type
Platelets (Thrombocytes)
- Count: 250,000–500,000/mm³
- Function: Blood clotting
- Microscopy: Tiny purple-stained cell fragments, no nucleus
typical hemoglobin and hematocrit values in men and women
- Hemoglobin per RBC: ~250 million molecules (oxygen-carrying)
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Hematocrit (% of blood volume as RBCs)
- Males: 42–52%
- Females: 37–48%
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RBC Count (million/µL)
- Males: 4.6–6.2
- Females: 4.2–5.4
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Hemoglobin Concentration (g/dL)
- Males: 13–18
- Females: 12–16
-
Why Sex Differences Exist:
- Androgens stimulate red blood cell production
- Menstrual blood loss contributes to lower female values
