1. Tissue Types: Epithelial Connective Muscular Nervous
Tissues – a group of similar cells working together to perform a function
Tissue Types:
Epithelial
Connective
Muscular
Nervous

2. Histology
The study of tissues at the microscopic level

3. Histology
The human body is composed of approximately 200 distinctly different types of cells.
These cells are organized into four basic categories of tissues that, in turn, are assembled to form organs.
Tissues can be distinguished from each other by variations in cell size, shape, organization, and function.

4. How Do Cells Form Tissues?
Remember adhesion proteins embedded in the cell membrane!

5. Cell Junctions- When cells are touching each other they can be joined in 1 of 3 ways
Tight Junctions – sealed together by attachment proteins so that nothing can pass between the cells (if something passes thru, it must go thru the bilayer not between them)
Typically join cells that form sheetlike layers; digestive tract
Desmosomes – tight junctions with extra protein reinforcement so that the cells won’t rip apart when stretched (in skin). The protein reinforcements bind the attachment proteins to the cytoskeleton of both attaching cells
Gap Junctions – where the cells attach, there are small tubes connecting the two cells together so that ions can pass freely between the cells (cardiac muscle in heart and smooth muscle in digestive tract); cytoplasm becomes linked together.

6. Epithelial Tissue
Location – Lines a space - forms inner lining of body cavities, covers body surface and organs, lines hollow organs and glands
Specific Examples:
Skin
Lines whole digestive and respiratory passages (mucous membranes)
Lines whole urinary system
Membranes lining spinal cord and brain (Meniges)
Lines the inside of the heart cavities
Capillary walls
Alveoli in lungs
Lines the uterus in females, epididymis in males
Makes up the serous membranes (enclosed cavities like pericardium, pleura, and peritonium)
Prostate gland & other glands

8. Functions:
Protection - from leakage or from things getting in that aren’t supposed to
Absorption - nutrients
Secretion – mucous, pepsin, HCl, milk
Filtration – oxygen and carbon dioxide

9. Characteristics: (structure = function)
Fit closely together (tight junctions or desmosomes) – sealed so that nothing can pass between the cells
Two adjectives describe all epithelial tissue
Cells are square, rectangular or “squished”
Cuboidal, columnar, squamous
Tissue is found in one or multiple layers
Simple vs. stratified

11. Characteristics:
Basement membrane – thin (deepest layer of epithelial tissue), nonliving layer of collagen protein (created by cells in the connective tissue) that anchors epithelium to underlying connective tissue.
Apical surface - free surface that is exposed to the outside of body or organ, or the inside of a cavity, gland or tube (lumen)

14. Characteristics:
Avascular - no direct connection to blood vessels; must get nutrients from diffusion from underlying capillaries in connective tissue

15. Side Note: Cancer
Cancer cells secrete a substance that dissolves basement membranes, enabling the cells to invade tissue layers.
Cancer cells also produce less adhesion proteins, or none, which allows them to spread into surrounding tissue. (metastasis)

16. Modified/Specialized Cells
Microvilli – tiny , cylindrical processes extending from the free surface of epithelial cells
Increases surface area of cell membrane which is exposed to substances being absorbed.
small intestines

17. Modified/Specialized Cells
Goblet Cells and cilia - in the trachea, goblet epithelial cells secrete mucus on the free surface of tissue which provides lubrication to trap bacteria and dust (ciliated epithelium then sweeps it away from lungs).

18. Two Types of Epithelial Tissues
Glandular Epithelium
Covering/lining Epithelium
covers the outside surfaces of the body and lines internal organs.
secretes hormones or other products (mucous, milk).
Consists of one or many cells

19. Two Types: Endocrine vs. Exocrine Glands
Exocrine - epithelial tissue that secretes their substances (sweat, saliva, milk, stomach acid, and digestive enzymes) into tubes, or ducts, which carry the secretions to the epithelial surface of cavity or skin
Endocrine - epithelial tissue secretes products (hormones) into tissue fluid or blood

20. Two Types: Endocrine vs. Exocrine Glands
Endocrine Glands Exocrine Glands

21. Types of Epithelium
Simple Squamous – flat, 1-layer, easily damaged
walls of blood vessel lung alveoli
Locations: Capillary walls, alveoli of the lungs Function: diffusion and filtration

22. Types of Epithelium Simple Cuboidal – square, 1-layer
kidney's tubules cut such that they appear as rings of cells around empty spaces
Locations: lining kidney tubules, salivary ducts, pancreatic ducts Functions: secretion, excretion, and absorption

23. Types of Epithelium
Simple Columnar – tall rectangular, 1-layer, thick to protect underlying tissue; used for absorption
Ciliated – cells that line the throat and digestive tract. Funct: trap and move "pollutants" to the mouth where they are swallowed. Cells lining the uterine tube to uterus. Funct: sweeps egg along
Nonciliated – lines uterus and portions of digestive tract (stomach and small intestines), Funct: secretes digestive fluids, absorbs nutrients, protection. )
Microvilli – minute surface extensions found in small intestine, to increase surface area for absorbing substances

24. Types of Epithelium
Statified Squamous – many layers, resistant to damage.
Location: where there is a lot of abrasion – mouth, outermost layer of skin, esophagus, anal canal.
Function: protection
skin

25. Types of Epithelium
Transitional – Stratified, many layers –range from flat to tall cells that can extend or compress in response to body movement, act as barrier.
Location: inner lining of bladder and ureters.
Funct: allows to distend and contract without compromising it.
bladder

26. Outer Covering View
-skin
-organs

27. Cross section view
-glands
-tubes

28. Take Note! Multiple Tissues are On One Slide
Left to right
Epithelial covering, dense fibrous CT, epithelial glands, dense fibrous CT, cartilage

29. Connective Tissue Location - found everywhere
most abundant tissue by weight (proteins!)
Major supporting tissue of the body
Holds everything together

30. Types of Connective Tissue (CT)
Ordinary CT – loose vs. dense depending on the relative number of cells, fibers and ground substance
Loose CT
Areolar
Reticular
Elastic
Dense CT
Regular & Irregular
Specialized CT
Cartilage
Bone
Blood
Adipose

31. Connective Tissue - Functions
Protection (can cushion)
Serve as frameworks
Support
Bind structures
Fill spaces
Store fat
Produce blood
cells
Remember – structure relates to function!

32. CT Characteristics:
Cells are not directly connected to each other (can be fixed cells or wandering cells)
Surrounded by an extracellular matrix (ECM) (protein fibers, other molecules and interstitial fluid) that is made and secreted by the cells
Matrix may be jelly-like, liquid, hard, fibrous
The kinds and amounts of fiber and ground substance determine the character of the matrix, which in turn defines the kind of connective tissue. (structure = function)

33. CT Characteristics Most connective tissue has a good blood supply
Tendons and ligaments have minimal blood supply and cartilage is avascular.
Given this information, why does it makes sense that sports injuries involving tendons and ligaments take a long time to heal?
Given this information, why are knee replacements prevalent in old age?

34. Connective Tissue - Cell Types
CT contain a variety of cells
Fibroblasts – most common type in both loose and dense connective tissues, star-shaped, produce fibers (ex: a protein, collagen) and secrete it from the cell to create the ECM of CT
Mast Cells – release histamine to promote inflammation and allergy/immune response.
Macrophages – originate as WBCs, play role in immunity by carrying out phagocytosis – engulf foreign and dead cells.

35. Extracellular Matrix Fibers: Fibroblasts produce 3 proteins that make up ECM
Collagen fibers – thick threads of protein collagen, major structural protein of body, tough and flexible, can resist pulling force. (p. 157 collagen disorders)
Dense CT – many collagen fibers (tendons-connect muscle to bone & ligaments – connect bone to bone)
Loose CT – sparse collagen fibers (holds internal organs in position)
Elastic fibers - made of springlike protein elastin, strong and stretchable, can resume form (vocal cords and air passages)
Reticular fibers - made of thin collagen fibers, highly branched to form delicate supporting networks (spleen)

36. Types of Connective Tissue:
Bone – most rigid connective tissue
cells (osteoblasts -premature cells /osteocytes -mature cells)
Lacuna – blank space that cells sit in
Lacuna is surrounded by a matrix made of collagen fibers and hardened due to calcium between the cells.
contains canals to connect to blood vessels
Location: skeleton
Function: framework/support, attachement point for muscles, protection, contains red marrow to form RBCs.

37. -Osteoblasts (osteocytes) are bone cells that sit in an open
space called a lacuna.
-This allows for a blood supply with nutrients to reach the cells.
-Good blood supply allows bone to heal when injured as opposed
to avascular tissue like cartilage.

38. Microscope Pics Cross section plane – see circle pattern
Frontal plane – no circle
pattern

39. Types of Connective Tissue:
Cartilage: 3 types - hyaline, elastic and fibrous
cells in lacunae (Chondrocytes) surrounded by semi-hard/gel like matrix (collagen or elastic fibers)
cartilage is tough but flexible, avascular (reason for knee/hip replacements), and without nerves.

40. Locations: joints, between vertebrae (discs), connecting ribs to sternum, ears, nose

41. Cartilage Microscope Pics
Elastic – more flexible because of
elastic fibers,
Location: ear, epiglottis, larynx Function: flexible support
Fibrous – very tough, many collagen fibers
Location: pubic symphysis, intervertebral discs in spinal column, knees Function: supports, withstands compression, “shock absorber”

42. Cartilage Microscope Pics
Hyaline – extremely fine collagen fibers,
looks glassy
Location: ends of bones and
in joints, soft part of nose, rings in trachea,
fetal skeleton, connecting ribs to sternum
Function: precursor to bone, support

43. Types of Connective Tissue:
Dense Fibrous CT (regular and irregular) – few fibroblasts and many collagen fibers made by the fibroblasts, closely packed vs. randomly organized fibers
Location/Function:
Regular - tendons and ligaments;
Fibers run one direction and get pulled on
in one direction; great tensile strength;
binds body parts (ex: achilles tendon)
Irregular – dermis (inner skin);
Sustain tension exerted from
different directions.
Looks like rope =
very strong

44. Types of Connective Tissue:
Areolar (loose fibrous) – few fibroblasts, loose network of collagen and elastic fibers (strong and elastic), lots of liquid space (variety of cells with immune functions)
Locations: beneath the skin and around blood vessels, muscles and nerves
Functions: binds one tissue to another (connects skin to underlying muscle), protection and nourishment to the organs & structures it binds, & stores "body fluid"

45. Types of Connective Tissue:
Reticular (loose fibrous) – fibroblasts, thin collagen fibers (reticular fibers) woven into a 3D mesh, and liquid
Locations: spleen, lymph nodes, liver
Function: gives support to soft organs

46. Types of Connective Tissue:
Elastic CT – consists of elastic and collagen fibers and fibroblast cells
Location: large arteries, bronchial tubes
Function: Elastic fibers can stretch 1 and 1/2 times their length and then recoil, provide elasticity to tissues.
aorta

47. Types of Connective Tissue:
Adipose – fat storing tissue – cells with a big oil vacuole (looks like bubble wrap)
Cells – adipocytes; store fat in droplets in their cytoplasm; accumulate fat, enlarge, pushing nuclei to one side of cell; called signet cells because resemble that type of class ring

48. Adipose
Location – beneath skin, between muscles, around kidneys, behind eyeballs, abdominal membranes, surface of heart, around joints
Function – insulates, cushions, lines whole body underneath skin, energy storage (*Function in adipose tissue is less about the matrix and more about the cells)

49. -Born with certain number of fat cells
-Amount of adipose tissue over time reflects diet (store excess calories as fat) or endocrine disorder.

50. Types of Connective Tissue:
Blood – cells (red, white and platelets) in a liquid matrix (plasma), protein “fibers” are soluble that form during clotting.
Function:
Carries oxygen, carbon dioxide, nutrients, and wastes
Carries immune cells and antibodies to infected or damaged area
Carries minerals
Has lots of proteins for osmotic balance

51. Structure/Function
Blood - cells and extracellular matrix are of equal importance
Liquid matrix allows for material to be dissolved and transported (ex – hormones, glucose, amino acids)
Cells carry material that can not dissolve in liquid (ex – oxygen)
Red blood cells
White blood cells and
Platelets all reside
in Plasma (liquid
matrix)

52. Muscle Tissue
Shape: Muscle cells are also called muscle fibers because the cells are elongated (cylindrical or spindle shaped)
Function: Length of cell allows for contraction; shorten and thicken
Three types

53. Skeletal Muscle Location – attached to bones
Functions – voluntary movement (head, trunk, limbs, facial expressions, write, talk, sing, chew, breathe) and temperature regulation
Characteristics:
Long (up to 2 inches) and cylindrical
Multinucleated
Striated (alternating light and dark markings due to pattern of actin and myosin)
Voluntary control

54. Skeletal Muscle

55. Cardiac Muscle Location – Heart only
Function – Involuntary pumping of blood from heart into blood vessels
Characteristics:
Cells: long, cylindrical,
branched
Single nucleus
Striated
Involuntarily Controlled
Has intercalated discs (gap junctions) – ions that set off contraction spread from cell to cell quickly

56. Cardiac Muscle
Intercalated Disc →

57. Smooth Muscle
Location: Walls of hollow organs (stomach, intestines, bladder, uterus, blood vessels), glands
Function: Squeeze out the contents of an organ such as food through digestive tract or urine from bladder, constricts blood vessels, or squeeze hormones down a duct to the blood
Characteristics
Spindle-shaped
Single central nucleus
No striations
Involuntarily controlled

58. Smooth Muscle vs. Dense CT
Nuclei cells are between the fibers
Long stretched nuclei inside the cells

60. Nervous Tissue Location: Brain, spinal cord, peripheral nerves
Functions:
Communicate quickly with other cells
Send information from the brain and spinal cord to nervous tissue, muscle tissue, glands
Carry input from sensory receptors to the brain and spinal cord

61. Characteristics of Nervous Tissue
Large cell body with axon which is a long extension of cytoplasm (may be up to 3 ft.) Many of the long axons are covered in myelin (a fat) to improve conductivity
Cell body also has many short extensions connecting to other close nerve cells called dendrites

62. Neuron
Cell Body
Dendrites
Axon

64. References http://www.cliffsnotes.com/study_guide/
Holes Human Anatomy and Physiology