1. Human Anatomy I: Tissues, Skin & Bones

2. Some Basic Ideas Anatomy describes the physical parts of an organism
Physiology describes the way in which those parts work, alone and in combination
Most organisms are organized into different levels:
Cells
Tissues: groups of cells performing some specific function
Organs: groups of tissues performing some specific function
Organ systems: groups of organs performing some specific function

3. Tissue Types There are 4 main kinds of tissues Epithelial Tissue
Connective Tissue
Muscle Tissue
Nerve Tissue
Most organs are a combination of two or more tissues

4. Epithelial Tissue Serves as covering or lining of various body parts
Involved in both absorption of material and secretion of material
Cells can vary in shape:
Squamous cells are flat; found in areas where diffusion important
Cuboidal cells are cubes; involved in secretion and absorption
Columnar cells are rectangular: also used for secretion and absorption
Tissue can vary in # of layers:
Simple epithelium has one layer
Stratified epithelium has 2 or more; can be different cell types

5. Clockwise from upper left: simple columnar; simple cuboidal; stratified squamous

6. Connective Tissues Perform a variety of functions
All consist of two components:
Living cells, scattered in a…
Non-living matrix secreted by these cells
Some examples include:
Bones
Cartilage
Adipose (fatty) tissue
Blood
Ligaments
tendons

7. Major Organ Systems

8. Integumentary System Or, more commonly, skin! Major functions include:
A barrier to injury or invasion by other organisms
A (very large) sensory organ
Production of body covering (hair, scales, feathers)
Production of various substances (toxins, pheromones, lubricants, etc.)
Body cooling (via sweat)
Assistance with respiration

9. General Anatomy of the Skin I
Outermost layer is the epidermis
Living epithelial cells towards interior
Outer layer of dead cells, many filled with keratin (helps prevent water loss)

10. General Anatomy of the Skin II
Middle layer is the dermis
Contains primarily connective tissue, plus nerves, blood vessels, muscles, sensory organs
Hairs and glands appear to come from this region, but actually are infoldings of the epidermis

11. General Anatomy of the Skin III
Inner layer is the hypodermis, or subcutaneous layer
Mostly a layer of adipose tissue, which helps…
Cushion underlying organs
In heat retention
Also contains some nerves and blood vessels

13. 2 Primary Skin Glands in Humans
Sweat Glands, with two types:
Eccrine sweat glands occur over most of body
Release a clear fluid, mostly water with dissolved salts
Apocrine sweat glands are found mostly in groin, armpits, face
Release more viscous and odor-causing fluid
Sebaceous Glands
Release a thicker, oily/waxy fluid called sebum
Helps lubricate hair follicles

14. Human skin also possesses a number of different kinds of sensory receptors (for temperature, pressure or touch, pain)

15. Skeletal System Major functions include:
Protection for internal organs
Attachment points for muscles
Some animals possess a hydrostatic skeleton
Body is a fluid-filled “bag” under pressure which animal can push against
Others have an external skeleton, or exoskeleton
Still others possess an internal skeleton

16. Above are some hydrostatic skeletons, in a roundworm and an earthworm
Above are some hydrostatic skeletons, in a roundworm and an earthworm. To the right is a shed exoskeleton of a cicada.

17. Anatomy of the Human Skeleton
The axial skeleton consists of bones along the midline of the body
Includes skull, spinal column, ribcage, sternum
The appendicular skeleton is everything else
Includes arm bones, leg bones, pelvic girdle, pectoral (shoulder) girdle

18. Axial skeleton
Appendicular skeleton

19. 3 Components of Skeleton
Bones: the hardest part of the skeleton
Cartilage: more flexible than bone
Ligaments: a type of connective tissue linking two bones
NOTE: tendons link muscles to bones, but we’ll look at these with muscles

20. Bone Structure Bones may be long, short, flat, or irregular in shape
Most bones have a dense region of compact bone, and a less dense region of spongy (or cancellous) bone
Within the spongy bone of long and flat bones is red marrow
Involved in production of red blood cells
Within the shaft region of long bones is yellow marrow
Mostly fat storage
Can be converted to red marrow in emergencies

21. Long bones above, flat bones below

22. The Inside of Bones The living cells in bones are called osteocytes
Osteocytes are found within spaces called lacunae
Osteocytes produce bone, which is the non-living matrix part
Osteocytes are arranged (at least in compact bone) in groups called osteons, or a Haversian system
In the middle of each osteon is a canal containing blood vessels to nourish the osteocytes

23. Joints
Joints occur where two bones come into contact and can move relative to each other
At the end of each bone is a layer of cartilage
Ligaments link bones
Fluid usually fills space between bones to reduce friction and wear