Week 2 GP Flashcards
Compare and contrast the key stages of gametogenesis between oocytes and spermatocytes
- Oogenesis:
-Begins prenatally in females.
-Meiosis I is dorment until puberty; -Meiosis II completes only upon fertilization
-Produces one mature oocyte and polar bodies. - meiotic divisions unequal in the cytoplasm
- Spermatogenesis:
-Continuous post-puberty in males.
-Results in four viable spermatids. - equal divison of cells in Meitoic divisions
Explain Meiosis by its key features to genetic variability (2)
- Crossing Over (Prophase I): Exchange of genetic material increases variability.
- Independent Assortment (Metaphase I): Random alignment of chromosomes leads to diverse gametes.
Explain fertilization and zygotic cleavage
- Fertilization: Sperm binds to and penetrates oocyte, leading to zygote formation.
- Zygotic Cleavage: Rapid mitotic divisions without growth, forming a morula and then a blastocyst
Explain Blastogenesis and implantation and give complications
- Blastogenesis: Formation of the blastocyst, which contains the inner cell mass (embryoblast) and trophoblast.
- Implantation: Blastocyst embeds into the endometrium.
- Consequences of Failure: Ectopic pregnancy or infertility.
Identify the three germ layers
- Ectoderm: Epidermis CNS, PNS, eyes, internal ears, connective tissues of the head
- Mesoderm: muscles, bones, CVS, blood cells, cartilages, dermis
- Endoderm: Epithelial lining of the resp tract and GI (gut lining, liver, pancreas)
what are the location (3), composition (2), and function of serosal membranes
- Found in body cavities (pleura, peritoneum, pericardium).
- Composed of mesothelium and connective tissue;
Functions: Reduce friction via secretion
What is the structure-function of epithelial tissues (3)
o Simple squamous: Gas exchange in alveoli.
o Stratified squamous: Protection in the skin.
o Pseudostratified columnar: Mucus secretion in respiratory tract.
- Histological identification: Staining reveals nuclei arrangement and cytop
Explain the Cell junctions (3) and the functions
- Types: Tight junctions, desmosomes, gap junctions.
- Functions: Barrier formation, mechanical support, communication.
Explain the different epithelial glands (3)
- Exocrine Glands: a gland product is released on the surface
Merocrine (sweat),
Apocrine (mammary)
Holocrine (sebaceous).
Endocrine: A glans product is released into the blood
What is the Embryonic origin and cell types (4)
- Derived from mesoderm.
- Cell types: Fibroblasts, adipocytes, macrophages, mast cells.
What are the types and fibers of connective tissue
- Loose (e.g., areolar) vs. Dense (e.g., tendons).
- Fibers: Collagen (strength), elastic (flexibility), reticular (support).
Name some connective tissue disorders
Ehlers-Danlos syndrome (collagen defect),
Marfan syndrome (elastic fiber abnormality).
What are the bone cell types (4)
- Osteoblasts: Bone formation.
- Osteocytes: Maintain bone.
- Osteoclasts: Bone resorption.
- Bone lining cells: Cover inactive bone.
What is the bone organisation (6 steps)
Osteoprogenitor cells (derived from mesenchymal cells) > Osteoblasts > Osteoid (unmineralised) > Mineralisation occurs in lacunae> Osteocytes
Explain Ossification (2 types)
Intramembranous: direct bone formation (skull)
Endochondral: Cartilage replaced by bone (long bones)
Explain bone disorders/ conditions (3)
Osteoporosis (decreased amount of bone mineralisation, primary idiopathic, menopause, aging)
-Secondary- GI, endocrine disorders, malnutrition vit D/Ca2+ deficiency
-Drugs: Corticosteroids;
Rickets (children) or Oestomalacia (adults) Vit D deficiency, poor bone mineralisation
Osteogenesis imperfecta
What are the components and blood cell function (6)
Plasma, RBCs (02 tx), WBCs (immune defense) Platelets (clotting)
- Plasma (55% of blood volume):
-Composed of water (90-92%), proteins (7-8%), and dissolved solutes (1-2%).
o Proteins:
-Albumin: Maintains osmotic pressure and acts as a transport protein.
-Globulins: Include immunoglobulins (antibodies) for immune responses and transport proteins.
-Fibrinogen: Essential for clot formation.
o Solutes: Electrolytes (e.g., Na⁺, K⁺, Cl⁻), nutrients (e.g., glucose), waste products (e.g., urea), and hormones.
- Formed Elements (45% of blood volume):
o Erythrocytes (Red Blood Cells):
-Biconcave cells responsible for oxygen and carbon dioxide transport.
Contain hemoglobin, a protein that binds oxygen.
o Leukocytes (White Blood Cells):
- Play roles in immunity. Divided into granulocytes (e.g., neutrophils, eosinophils, basophils) and agranulocytes (e.g., lymphocytes, monocytes).
o Thrombocytes (Platelets):
-Fragments of megakaryocytes that are crucial for blood clotting.
Myeloid vs. lymphoid lineages
- Myeloid: RBCs, platelets, neutrophils.
- Lymphoid: B cells, T cells, NK cells.
Myeloid Lineage:
-Cells derived from myeloid progenitor cells include: Erythrocytes, Platelets, Granulocytes (neutrophils, eosinophils, basophils)
-Monocytes (which differentiate into macrophages or dendritic cells)
Function: Involved in oxygen transport, clotting, innate immunity, and phagocytosis.
Lymphoid Lineage:
-Cells derived from lymphoid progenitor cells include: T Lymphocytes (T cells): Mediate cell-mediated immunity, B Lymphocytes (B cells): Produce antibodies for humoral immunity, Natural Killer (NK) Cells: Destroy virus-infected and tumor cells.
-Function: Primarily adaptive immunity (B and T cells) and innate immunity
Give a summary of Anemia and give conditions (3)
Anemia is a condition characterized by a decrease in RBC count or hemoglobin concentration, leading to reduced oxygen-carrying capacity. It can result from various erythrocyte dysfunctions
Iron deficiency anemia, sickle cell anemia, thalassemia
Explain the types of Anemia (3), Patho and symptoms
- Types of Anemia:
Microcytic Anemia:
-Cause: Iron deficiency or chronic disease.
-Feature: Small, pale RBCs (low mean corpuscular volume - MCV).
Macrocytic Anemia:
-Cause: Vitamin B12 or folate deficiency.
-Feature: Large RBCs (high MCV).
Normocytic Anemia:
-Cause: Acute blood loss or chronic disease.
-Feature: Normal-sized RBCs but reduced overall count.
- Pathophysiology:
-Reduced Production: E.g., bone marrow failure, iron deficiency.
-Increased Destruction (Hemolysis): E.g., sickle cell disease, hereditary spherocytosis.
-Loss of RBCs: E.g., bleeding or trauma. - Symptoms: Fatigue, pallor, shortness of breath, and tachycardia due to impaired oxygen delivery to tissues
Characteristics and types of muscle (3)
- Smooth: Involuntary, non-striated.
- Skeletal: Voluntary, striated.
- Cardiac: Involuntary, striated with intercalated discs
Explain the Cross-bridge cycle (3 steps)
- ATP binds to myosin; myosin detaches from actin.
- ATP hydrolysis resets myosin head.
- Myosin binds to actin; power stroke occurs.
Embryonic origin (1) and cellular components (5)
- Origin: Ectoderm.
- Cells: Neurons, astrocytes, oligodendrocytes, microglia, Schwann cells.
Embryonic Origins of Nervous Tissue (2)
The nervous tissue originates from the ectoderm, one of the three primary germ layers formed during early embryogenesis.
- Neurulation:
-The neural plate, a thickened ectodermal region, forms under the influence of signaling from the notochord.
-The neural plate folds to form the neural tube, which develops into the central nervous system (CNS), including the brain and spinal cord. - Neural Crest Cells:
-Cells at the edges of the neural plate migrate and form the neural crest, giving rise to the peripheral nervous system (PNS) components, including sensory neurons, autonomic ganglia, Schwann cells, and other tissues
Explain the cellular components of nervous tissue
Nervous tissue consists of two primary cell types:
- Neurons:
-The functional units of the nervous system, specialized for signal transmission.
-Parts of a neuron:
-Soma (cell body): Contains the nucleus and organelles for metabolic activity.
Dendrites: Receive input signals.
Axon: Conducts impulses away from the soma.
Axon terminals: Transmit signals to other neurons or effector cells. - Neuroglia (Glial Cells):
-Supportive cells that maintain homeostasis, protect neurons, and facilitate signal transmission.
CNS Glial Cells:
Astrocytes: Support neurons, form the blood-brain barrier, and regulate neurotransmitter levels.
Oligodendrocytes: Produce myelin in the CNS.
Microglia: Act as immune cells within the CNS.
Ependymal Cells: Line the ventricles and produce cerebrospinal fluid.
PNS Glial Cells:
Schwann Cells: Produce myelin in the PNS.
Satellite Cells: Support and protect neuron cell bodies in ganglia.
Explain Neural Cell Structures and Their Functions (6)
- Soma (Cell Body):
o Houses the nucleus and organelles.
o Responsible for protein synthesis and metabolic activity. - Dendrites:
o Short, branched projections that receive signals from other neurons or sensory stimuli. - Axon:
o A long projection that transmits impulses (action potentials) to other neurons or effectors.
o Contains specialized regions such as the axon hillock (trigger zone for action potentials). - Synapse:
o Junction between neurons or between a neuron and its target cell.
o Facilitates chemical or electrical signal transmission. - Myelin Sheath:
o Fatty layer around axons, insulating them and increasing signal conduction speed. - Nodes of Ranvier:
o Gaps in the myelin sheath that allow saltatory conduction, speeding up action potential propagation.
What is the purpose of Myelin
Purpose of Myelin:
-Myelin insulates axons, preventing signal loss and ensuring efficient nerve impulse transmission.
-Increases conduction velocity via saltatory conduction, where impulses jump between Nodes of Ranvier.
Differences between Myelin in CNS vs PNS
CNS: Oligodendrocytes; one cell myelinates multiple axons.
PNS: Schwann cells; one cell myelinates one axon segment.
CNS:
-Myelin is produced by oligodendrocytes.
-One oligodendrocyte can myelinate multiple axons.
PNS:
-Myelin is produced by Schwann cells.
-One Schwann cell myelinates a single segment of one axon.
Damage to myelin in the CNS (e.g., multiple sclerosis) and PNS (e.g., Guillain-Barré syndrome) leads to distinct clinical outcomes due to differences in regeneration capacity (better in the PNS).
Explain cartilage and types (3)
Contains:
ECM, Fibres (collagen and elastin), Cells (chondrocytes)
- Avascular (no blood supply) – receives nutrients via diffusion
- Limited ability to repair (slow)
- Types: Hyaline, Elastic, Fibrocartilage
Hyaline:
- Location: skeletal template (endochondral ossification), nasal cavity, tracheobronchial tubes and costal cartilage.
- Protein: Type II collagen and proteoglycans.
Elastic:
- Location: auricle (outer part) of the ear, epiglottis, laryngeal cartilages
- Properties: flexible but maintains shape.
- Protein: elastic fibres (and sometimes Type II collagen and proteoglycans).
Fibrocartilage:
- Location: intervertebral discs, articular discs of the knee, mandible, sternoclavicular joints and public symphysis.
- Properties: tensile strength – made up of chondrocytes, fibroblasts surrounded by Type I collagen.
