Kharkov National Medical University

1. Kharkov National Medical University Department of Histology, Cytology and Embryology Lecture 1. Introduction. Cytology

2. Histology– is the science that studies microscopic structure and function of the human organism, the organization of the tissues and organs. Cytology– is the science that study the structure and functions of the cell. Embryology– is the science that research embryonic development (formation) of human body

3. Cytology

4. The cell is: - the smallest structural and functional unit, - the elementary level of organization of the multicellular organisms. - a self-regulating, self-regenerating and self-governing biological system cell possesses all features of the whole organism, such as metabolism, growth, irritability, movement, and others.

5. Types of cells in human body

6. Cells produce matrix:

7. Light and electron microscopy -are 2 mane methods in histology

8. Levels of biological systems Biomolecules membranes organelles CELL

9. Membrane contents: 1 – lipids (hydrophilic head) 2 – lipids (hydrophobic tails) 3 – proteins 4 – carbohydrates (only outer cell membrane)

10. Lipids may be: Phospholipids – triglycerides (polar) Cholesterol (non-polar)

11. Phospholipids : Phosphate group (hydrophilic heads) Glycerol Fatty acids (hydrophobic tails)

12. Proteins may constitute close to 50% of membrane contentfunction :in the membranes 1- channels, 2- pumps, 3- receptors, 4- enzymes, 5- integrative, 6- structural

13. Membranes form: Outer cell membrane – cytolemma or plasmalemma Organelles Vesicles Nucleus - nuclear envelop

14. Structure of a typical cell Cell membrane Nucleus Cytoplasm organelles Cytosol = matryx, hialoplasm inclusions

15. Cell junction • - consist of multiprotein complexes that provide contact between neighbouring cells or between a cell and the extracellular matrix.

16. Where Cells contact -- Cell junction G 1 2

17. Cell junction Communicating or Gap junctions junction Tight junction Desmosomes

18. Tight junction present in different types of epithelia two layers of glycocalyx are fused . act as a barrier, that prevents the movement of molecules into the intercellular spaces

20. G

21. Gap junction • allow for direct chemical communication between adjacent cellular cytoplasm through diffusion without contact of the extracellular fluid • numerous in muscle tissue

22. Gap junction • Consists of six connexin proteins, interacting to form a cylinder with a pore in the centre - connexon. • This protrudes across the cell membrane, and when two adjacent cell connexons interact, they form the gap junction channel

23. Desmosome - is the most common type of junction Provides cell attachment

24. Inside the cell : Cytoplasm and nucleus

25. Inside the cell … Cytoplasm consists of: Matrix (hialoplasm, cytozol) Organelles Inclusions

26. Inclusions Inclusions are "nonliving" components of the cell. They include granules with secretions, pigment granules, lipid droplets, and glycogen.

27. Organelles:classification by structure Membranous or "membrane-bound" Non-membranous

28. Organelles:classification by function General (present in every cell, perform general function) Special (in specialised cell, perform special function)

29. Rough (rough-surfaced) endoplasmic reticulum • is a membranous network of sac-like structures cisternae. • the cisternal space (or lumen) is continuous with the perinuclear space but separate from the cytosol.

30. The surface of the RER is studded with ribosomes giving it a "rough" appearance (hence its name). • Function - synthesis of proteins

31. Smooth(-surfaced) endoplasmic reticulum, SER

32. SER consists of tubules that are located near the cell periphery. Function: It synthesizes lipids - phospholipids and steroids. It also carries out the metabolism of carbohydrates (synthesis of glycogen, gluconeogenesis), drug detoxification, and steroid metabolism. Storage of Ca-ions (only in muscle cell)

33. Golgi apparatus also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. It was identified in 1897 by the Italian physician Camillo Golgi and named after him in 1898. Loks as a pack of sacs.

34. Golgi apparatus Golgi complex is connected with endoplasmic reticulum

35. Golgi apparatusFunctions. 1. synthesis of substances, which has begun in endoplasmic reticulum and is accomplished in the Golgicomplex.

36. Golgi apparatusFunctions. 2. formation of compound molecules – glycoproteins, lipoproteins.

37. Golgi apparatusFunctions. 3. production of lysosomes and secretory vesicles.

38. Mitochondrion • is a membrane-enclosed organelle found in most eukaryotic cells.

39. Mitochondrion • A mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins. • Folds of inner membrane – cristae • Inside M. lie matryx

40. Mitochondrion • Mitochondria provide energy for various cellular functions, • Produce ATP molecules • by Krebs cycle

41. Lysosome • Lysosomes are round vesicles that contain acid hydrolase enzymes that break down waste materials and cellular debris. • Lysosomal enzymes help in digesting the materials within phagosomes. They can be described as the stomach of the cell.

42. Lysosome Cycle lysosomes are formed from Golgi complex The nearly produced lysosome is primarylysosome

43. Lysosome Cycle primary lysosome fuses with the phagosome -- secondarylysosome or phagolysosome part of undigesting material may remain within the cell as residual bodies.

45. Non-membranous organelles: Microfilaments Microtubules Centrioles (Cell Center) Ribosomes

47. The cytoskeleton • - is made up of three kinds of protein filaments: • Actin filaments (also called microfilaments) • Intermediate filaments • Microtubules

48. Microfilaments, Microtubules form “Skeleton” of the cell

49. Cell center Centriole = 9 x 3 microtubules; 2 centrioles = cell center = Β-tubulin function -formation of mitotic spindle (mitosis, meiosis), flagella, basal bodies and cilia