A2 Exam 1

Stories You Should Know – Bio 212 Lecture: Reproductive

 

1. The Story of Puberty

  • Initiated by Gonadotropin-Releasing Hormone (GnRH) → Stimulates the anterior pituitary to release Follicle-Stimulating Hormone (FSH) & Luteinizing Hormone (LH)

Male

  • FSH & LH stimulate testosterone production

  • Effects:

    • Initiates spermatogenesis

    • Increases libido

    • Promotes secondary sexual characteristics

Female

  • FSH & LH stimulate ovarian follicle maturation → leads to estrogen production

  • Effects:

    • Initiates fertility

    • Develops secondary sexual characteristics

2. The Story of Gamete Formation

Ovarian Follicle Development

  1. Primordial Follicle

    • Primary oocyte + surrounding follicle cells

    • Present at birth, arrested in meiosis I until puberty

    • 1.5 million at birth

  2. Primary Follicle

    • Primary oocyte + granulosa cells (secrete estrogen)

    • 20 primordial follicles mature each month, but many die

  3. Secondary Follicle

    • Primary oocyte + multiple granulosa layers

    • Thecal cells secrete androgens → converted to estrogen

  4. Antral (Vesicular) Follicle

    • Fluid-filled antrum enlarges → aids ovulation

  5. Corpus Luteum

    • Secretes progesterone & estrogen → supports endometrium

  6. Corpus Albicans

    • Degenerated corpus luteum → forms a scar

Ovarian Cycle Phases & Hormones

  1. Follicular Phase (Days 1-13)

    • Primary follicles release inhibin → inhibits FSH

    • One secondary follicle matures → LH increases follicle volume

    • Meiosis I produces:

      • Polar body

      • Secondary oocyte

  2. Ovulation (Day 14)

    • LH peak triggers secondary oocyte release

    • Oocyte lifespan: ~1 day (fertile window)

  3. Luteal Phase (Days 15-28)

    • Remaining follicle → Corpus Luteum

    • Secretes progesterone & estrogen → builds endometrium

    • If no fertilization → hormone levels drop, endometrium sheds (menses)

Menstrual Cycle Phases & Hormones

  • Menarche: First menstrual cycle

  • Menopause: End of menstruation

  1. Menstrual Phase

    • Progesterone drops → endometrium sloughs

  2. Proliferative Phase

    • Estrogen increases → endometrium grows

  3. Ovulation

  4. Secretory Phase

    • Progesterone & estrogen rise → prepare for implantation

Spermatogenesis

  1. Spermatogonium (46 Chromosomes) → divides by mitosis into:

    • New spermatogonium (46)

    • Primary spermatocyte (46)

  2. Primary Spermatocyte (46) → undergoes meiosis I → produces two secondary spermatocytes (23 each)

  3. Secondary Spermatocytes (23) → undergo meiosis II → produces four spermatids (23 each)

  4. Spermatids → mature into spermatozoa (sperm)

3. Biological Female Reproductive Anatomy

Uterus

  • Pear-shaped organ with thick muscular walls

  • Functions:

    • Supports embryo/fetus

    • Ejects baby or endometrial lining

  • Regions:

    • Fundus: Superior, used for fetal growth measurement

    • Body: Muscular middle region

    • Cervix: Lower portion, examined in PAP test

    • Layers:

      • Myometrium: Thick muscular layer

      • Endometrium:

        • Basal layer (permanent)

        • Functional layer (sheds during menstruation)

      • Perimetrium: Outer serosal layer

Ovary

  • Paired, almond-sized

  • Functions:

    • Produce ova

    • Secrete hormones (estrogen, progesterone)

    • Contain ovarian follicles

Vagina

  • Muscular tube (~10 cm)

  • Functions:

    • Intercourse

    • Passage for menses & childbirth

Breast

  • Exocrine gland with lobes, ducts & alveoli

  • Function: Milk production & secretion

4. Biological Male Reproductive Anatomy

Testes

  • Descend from the abdomen → reside in scrotum (optimal sperm temperature)

  • Functions:

    • Produce sperm (seminiferous tubules)

    • Secrete testosterone

  • Cells:

    • Sertoli cells (sustentacular) → nourish sperm

    • Interstitial cells → secrete testosterone

Scrotum

  • Skin-covered sac, temperature regulation

  • Cremasteric reflex: Testes retract when inner thigh is touched

Penis

  • Vascular structure made of:

    • Corpora cavernosa (paired)

    • Corpus spongiosum (single)

  • Regions:

    • Root, Body, Glans

Prostate

  • Walnut-sized gland

  • Functions:

    • Secretes alkaline fluid (30% of semen)

    • Produces PSA protein

5.  Homologues Between Male & Female Structures

Male

Female

Testes

Ovaries

Penis

Clitoris

Scrotum

Labia majora

Prepuce (foreskin)

Clitoral hood

Bulbourethral glands

Vestibular glands

 

Clinical Correlations

  • PCOS: Ovarian dysfunction, excess androgens

  • Endometriosis: Endometrial tissue growth outside uterus

  • BPH: Benign prostate enlargement

  • Erectile Dysfunction: Reduced blood flow to penis

  • Breast Cancer: Can originate in lobules or ducts

Stories You Should Know – Bio 212 Lecture: Blood

Prof. CL

1. The Story of Blood

Composition & Characteristics

  • 55% Plasma, 45% Formed Elements (RBCs, WBCs, Platelets)

Functions of Blood

  • Transportation: Oxygen, nutrients, hormones

  • Regulation: pH, temperature, fluid balance

  • Protection: Clotting, immune response

Plasma Composition & Function

  • 92% Water, 8% Solutes (proteins, electrolytes, wastes)

  • Function: Medium for transport, maintains homeostasis

Formed Elements & Their Lineage

  • Red Blood Cells (RBCs): Oxygen transport, from myeloid stem cells

  • White Blood Cells (WBCs): Immune response, from myeloid & lymphoid stem cells

  • Platelets: Clotting, from megakaryocytes

2. The Story of Red Blood Cells (Erythrocytes)

Characteristics

  • Biconcave, no nucleus, flexible, filled with hemoglobin

Function

  • Transport oxygen via hemoglobin

Formation (Erythropoiesis)

  • Stimulated by erythropoietin (EPO) from kidneys

Destruction of RBCs

  • Liver & spleen remove aged RBCs

  • Hemoglobin breakdown:

    • Iron → Recycled

    • Biliverdin → Bilirubin → Excreted

Hemoglobin

  • Iron-dependent protein that binds oxygen

Hematocrit

  • % of blood volume occupied by RBCs

    • High = Polycythemia

    • Low = Anemia

3. The Story of White Blood Cells (Leukocytes)

Types & Functions

Granulocytes

  • Neutrophils (50-70%): First responders, phagocytosis

  • Eosinophils (1-4%): Attack parasites, allergy response

  • Basophils (<1%): Release histamine, allergy response

Agranulocytes

  • Lymphocytes (20-40%):

    • T-cells: Attack infected cells

    • B-cells: Produce antibodies

    • Natural Killer (NK) Cells

  • Monocytes (2-8%): Differentiate into macrophages, phagocytosis

Abnormal WBC Counts

  • High = Infection, leukemia

  • Low = Immunosuppression, chemotherapy

4. The Story of Platelets (Thrombocytes)

Formation & Function

  • From megakaryocytes, regulated by thrombopoietin (THPO)

  • Function: Clotting (hemostasis)

Hemostasis Phases

  1. Vascular Spasm – Vasoconstriction

  2. Platelet Plug Formation – Platelets adhere to collagen

  3. Coagulation (Clotting) – Formation of fibrin mesh

Coagulation Pathways

  • Intrinsic Pathway: Triggered by blood vessel damage

  • Extrinsic Pathway: Triggered by tissue damage

  • Common Pathway: Both lead to thrombin formation, converting fibrinogen → fibrin (clot)

Key Ion for Clotting

  • Calcium (Ca²⁺) is essential

Abnormal Platelet Counts

  • Too Many = Risk of thrombosis

  • Too Few = Risk of excessive bleeding

5. The Story of a Complete Blood Count (CBC)

What It Measures

  • RBCs, WBCs, Platelets, Hemoglobin, Hematocrit

  • Can Detect: Infections, anemia, clotting disorders

6. The Story of Blood Types

ABO Blood Group System

  • Type A: A antigen, anti-B antibody

  • Type B: B antigen, anti-A antibody

  • Type AB: A & B antigens, no antibodies (Universal Recipient)

  • Type O: No antigens, A & B antibodies (Universal Donor)

Rh Factor

  • Rh+: Has antigen D

  • Rh-: No antigen D

Rh & Pregnancy

  • Rh- mother & Rh+ baby → Risk of hemolytic disease of the newborn (HDN)

  • Prevention: RhoGAM injection

Stories You Should Know – Bio 212 Lecture: The Heart

Prof. CL

1. The Story of the Heart

Heart Chambers & Their Contents

  • Right Atrium (RA)

    • Receives deoxygenated blood from:

      • Superior & Inferior Vena Cava (SVC, IVC)

      • Coronary Sinus (blood from myocardium)

    • Contains pectinate muscles

    • Features the fossa ovalis (remnant of fetal foramen ovale)

    • Outflow: Through tricuspid valve → Right Ventricle

  • Right Ventricle (RV)

    • Pumps blood to lungs

    • Thicker walls than RA (trabeculae carneae present)

    • Inflow: From RA via tricuspid valve (connected to chordae tendineae & papillary muscles)

    • Outflow: Through pulmonary semilunar valve → pulmonary trunk → pulmonary arteries

  • Left Atrium (LA)

    • Receives oxygenated blood from four pulmonary veins

    • Smooth walls (pectinate muscles only in auricle)

    • Outflow: Through mitral (bicuspid) valve → Left Ventricle

  • Left Ventricle (LV)

    • Pumps blood to systemic circulation

    • Thickest walls (10-15mm)

    • Inflow: From LA via mitral valve

    • Outflow: Through aortic semilunar valve → aorta

Heart Borders

  • Right Border: Right atrium

  • Left Border (Pulmonary Border): Left ventricle

  • Anterior Surface: Right ventricle (deep to sternum)

  • Posterior Surface: Left atrium

Heart Valves & Functions

  • Atrioventricular (AV) Valves

    • Tricuspid Valve: Between RA → RV

    • Mitral (Bicuspid) Valve: Between LA → LV

    • Function: Prevent backflow into atria; chordae tendineae & papillary muscles prevent inversion

  • Semilunar (SL) Valves

    • Pulmonary Valve: Between RV → pulmonary trunk

    • Aortic Valve: Between LV → aorta

    • Function: Prevent backflow into ventricles

2. The Story of Heart Location & Layers

Heart Location

  • Mediastinum, within the pericardial sac

  • Apex: Bottom, rests on diaphragm

  • Base: Top, positioned posteriorly

Pericardial Sac & Layers

  • Fibrous Pericardium: Outer layer, prevents overstretching

  • Serous Pericardium:

    • Parietal Layer (attached to fibrous pericardium)

    • Visceral Layer (Epicardium): Adheres to heart surface

Pericardial Fluid

  • Between parietal & visceral layers

  • Function: Lubrication, reduces friction

Heart Wall Layers

  1. Epicardium (Visceral Pericardium) – Outer protective layer

  2. Myocardium – Cardiac muscle, 95% of heart thickness

  3. Endocardium – Inner lining, continuous with blood vessels

3. The Story of Blood Flow Through the Heart

Pulmonary vs. Systemic Circulation

  • Right Side (Pulmonary Circuit): Pumps deoxygenated blood to lungs

  • Left Side (Systemic Circuit): Pumps oxygenated blood to body

Sequence of Blood Flow

  1. SVC, IVC, Coronary Sinus → Right Atrium

  2. Right Atrium → Tricuspid Valve → Right Ventricle

  3. Right Ventricle → Pulmonary Semilunar Valve → Pulmonary Trunk → Pulmonary Arteries

  4. Pulmonary Capillaries (gas exchange: CO₂ out, O₂ in)

  5. Pulmonary Veins → Left Atrium

  6. Left Atrium → Mitral Valve → Left Ventricle

  7. Left Ventricle → Aortic Semilunar Valve → Aorta → Body

Coronary Circulation

  • Heart cannot use the blood within its chambers → Coronary arteries supply myocardium

Coronary Arteries & Their Regions

  • Right Coronary Artery

    • Marginal Branch

    • SA Node Branch (60% of people)

    • Posterior Descending Artery (sometimes from left)

    • Supplies: RA, RV, ¼ of LV, SA node (60%)

  • Left Coronary Artery

    • Left Anterior Descending (LAD) – "Widowmaker"

    • Circumflex Artery

    • Posterior Descending Artery (sometimes from right)

    • Supplies: LA, ¾ of LV, SA node (40%)

Coronary Veins

  • Great Cardiac Vein (anterior interventricular sulcus)

  • Middle Cardiac Vein

  • Small Cardiac Vein

  • All drain into the Coronary Sinus → Right Atrium

Clinical Correlations

Pericardial Conditions

  • Pericardial Effusion: Fluid accumulation → Cardiac Tamponade (emergency!)

  • Pericarditis: Inflammation → Chest pain (mimics heart attack), pericardial friction rub

Valve Disorders

  • Mitral Valve Prolapse: Valve flaps bulge into atrium, causing backflow (murmur)

  • Aortic Stenosis: Narrowed valve → LV hypertrophy, reduced outflow

Myocardial Infarction (Heart Attack)

  • Cause: Blocked coronary artery → ischemia, muscle death

  • Symptoms: Chest pain, shortness of breath

  • Treatments:

    • Angioplasty (balloon widens vessel)

    • Stenting (keeps vessel open)

    • Thrombolysis (clot-dissolving drugs)

    • CABG (Bypass Surgery) (new vessel bypasses blockage)