Integumentary System - protection, sensation, thermoregulation, vitamin D synthesis
Describe the layers of the skin and the functions of each layer -
Epidermis (top layer)
- made of dead and live tissue - constantly replenishing via keratin formation
- permeated by rete pegs - tiny blood vessels that connect to dermis - nutrient transportation
- Five layers consisting of the stratum corneum, - lucidium, - granulosm, - spinosum, - basale
Corneum "Horny Layer" - Tough outside layer consists of approx. 30 layers of dead cells. The cytoplasm that was in these cells has been replaced by keratin, which is a type of protein. These cells are sometimes referred to as keratinocytes. It thickens in response to pressure and use (palms of hands & soles of feet)
Lucidum "Clear Layer" - Consists of approx. 5 layers of clear, flat, newly deceased cells known as keratinocytes. This layer is not present all over the body, but is usually found in the thick skin on the soles of the feet and the palms of the hands.
Granulosm "Granular Layer" - Consists of approx. 5 layers of flattened, nearly dead (some nuclei still remain) keratinocytes with granules from which a water-repellent lipid is released. This lipid is important because it protects the body from loss of excess fluid while also guarding against the entry of foreign substances into the body via the epidermis layer of the skin.
Spinosum* "Pickle Cell Layer" - Consists of 8-10 layers of many-sided (as opposed to flat as in the stratum granulosum) keratinocytes. These keratinocytes have spine-like projections that interlock (fibrils), that under pressure, form mitosis, causing calluses. Other components of the stratum spinosum include Langerhans cells and some projections of melanocytes*.
Basale "Germinative Layer"- the deepest later of the epidermis (outer-skin). It consists of a single layer of cuboidal (or “columnar”) keratinocytes. These keratinocytes are able to continually divide. As they do so, the new cells push the older cells up through the other layers of the epidermis to the surface of the skin. The stratum basale also contains Langerhans cells, melanocytes*, and Merkel cells.
* Melanocytes - fill the layers with melanin
* Spinosum - “thorn-like, or prickly”
Dermis (middle layer) - connective tissue containing various structures
- made of tough collagen fibers - matrix
- expels sweat through pores (eccrine & apocrine glands, both contain pheromones)
- nerve endings - itch, pain, touch, etc. (Merkel's cells & Meissner's corpuscles - touch, Pacinian - pressure)
- produces oil from sebaceous glands to provide moisture and waterproofing
- vascular system
- grows hair from roots and each are attached to a tiny muscle (arrector pili) that creates "goose bumps"
- blood and lymph supply is found in capillary loops that extend from deeper arterioles in subcutaneous layer
Hypodermis/Subcutaneous (bottom layer)
* Hypo-Dermis/Subcutaneous - "beneath the skin"
- stores & composed of fats - adipose tissue
- stem cells
- attaches the dermis to muscle & bone
- gateway for blood vessels and nerve cells
- regulates body temperatures
- builds new skin cells for deep wounds
Describe the accessory structures of the skin and the functions of each
Hairs - Protection
- Hair on scalp protects the scalp from potentially harmful effects of solar radiation (i.e. sun damage).
- Eyebrows and eyelashes protect the eyes from small particles e.g. fine grains of sand or smoke - not total protection.
- Hair in the nostrils protects against inhalation of small particles such as dust, dirt, or even small insects.-
- Sebaceous Glands - oil - secret sebum
- Sudoriferous Glands - sweat - produce and secret sweat
- Types of Sudoriferous Glands -
- Eccrine sweat glands - terminate at sweat pores at the surface of the epidermis. - located throughout most of the skin (exceptions nail beds, margins of lips, eardrums).
- Apocrine sweat glands - ducts open into hair follicles. Located in the armpits, pubic regions and areolae (pigmented areas) of breasts and are active from puberty.
* mammary glands are modified sudoriferous glands.
- Ceruminous Glands - in the outer ear - (cousin to sebaceous glands) secret cerumen (earwax) to help protect the ear
- Protects the ends of fingers and toes.
- Facilitates grasp and manipulation of small objects.
- Enables scratching / grooming.
List and describe the functions of bones
- Support -The skeleton is the framework of the body, it supports the softer tissues and provides points of attachment for most skeletal muscles.
- Protection- The skeleton provides mechanical protection for many of the body's internal organs, reducing risk of injury to them. For example, cranial bones protect the brain, vertebrae protect the spinal cord, and the ribcage protects the heart and lungs.
- Assisting in Movement - Skeletal muscles are attached to bones, therefore when the associated muscles contract they cause bones to move.
- Storage of Minerals - Bone tissues store several minerals, including calcium (Ca) and phosphorus (P). When required, bone releases minerals into the blood - facilitating the balance of minerals in the body.
- Production of Blood Cells - The red bone marrow inside some larger bones (including, for example, the ....) blood cells are produced.
- Storage of Chemical Energy - With increasing age some bone marrow changes from 'red bone marrow' to 'yellow bone marrow'. Yellow bone marrow consists mainly of adipose cells, and a few blood cells. It is an important chemical energy reserve.
- Bones grow from their ends (extremities). Under normal circumstances bones stop growing when the human reaches his/her late teens or early twenties.
- Long bones, short bones, irregular bones, sesamoid bones
The bones themselves are formed from several different connective tissues, including:
- Osseous (Soft & Hard Bone Tissue)
- Red Bone Marrow
- Yellow Bone Marrow
Compact bone (Hard) - forms the outer layer of all bones and most of the structure of long bones. It contains few spaces and provides protection and support to the bone/s around which it is the outer-layer, as well as helping to enable the long bones to bear the stress placed on them by the weight of the body and the use to which the limbs are put.
The basic unit of Compact Bone is an osteon, which is also known as a Haversian System
Each Haversian System (unit) has a cylindrical structure that consists of four parts:
- A central tube called a Haversian Canal, which contains blood vessels and nerves.
The Haversian Canal is surrounded by alternate layers of:
- Lamellae (the word lamellae literally means "little plates") are concentric rings of a strong matrix formed from mineral salts including calcium and phosphates and collagen (protein) fibers. The mineral salts result in the hardness of the bone structure, while the collagen fibers contribute its strength.
- Lacunae are the small spaces between the lamellae in which contain the bone cells - osteocytes - are located
- The lacunae are linked together by minute channels called canaliculi (link nutrients to osteocytes from canal).
- The canaliculi provide routes by which nutrients (blood vessels and nerves) can reach the osteocytes and waste products can leave them.
- Osteocytes - mature bone cells that monitor and maintain bone matrix operations within osteons.
- Osteobasts - "bone sprout" - construct bones
- Osteoclasts - break down/resorb bones for healthy regeneration
- Stem cells
Spongy Bone/Cancellous (Soft) - a meshwork of bony bars (trabeculae - literally "little beams") with many interconnecting (spongy) spaces containing red bone marrow.
Spongy bone consists of an irregular lattice of thin columns of bone called trabeculae (literally "little beams"), which contain lamellae, osteocytes, lacunae and canaliculi. The spaces between the trabeculae of some spongy bones are filled with red bone marrow.
Blood vessels from the periosteum, penetrate into the trabeculae lattice allowing the osteocytes in the trabeculae to receive nourishment from the blood passing through the marrow cavities.
Red Marrow - blood cell - erythrocytes (RBC) & leucocytes (WBC) - production (hematopoiesis) contained mainly in the epiphises (spongy ends)
Yellow Marrow - found in long bones in the diaphysis (shaft between ends - medullary cavity). YM is fat stored for energy.
Periosteum - fibrous connective tissue that covers the bones and is intertwined with the muscles and ligaments that support joints
Endosteum is the membrane that lines the cavity of a bones.
Discuss the process of bone formation and remodeling
Formation - Cartilage is formed and replaced by bone cells through ossification in utero and into puberty.
* Stress (exercise, weight, etc.) and the body's need for calcium (released into the blood) stimulates the cycle of remodeling
Osteoclasts - breaking down
- respond to low calcium in blood/stress on bone - perceived by osteocytes > parathyroid hormone
- release acidic substance that breaks down minerals, ionize and go back into blood
- release enzymes that digest collagen
- call in osteblasts after apoptosis
- modified phagocyte (monocyte and macrophages)
Osteoblasts - building up
- secrete bone matrix - collagen and polysaccharides
- absorb minerals into blood and deposit into bone matrix
- stimulated by calcitonin
Describe the function and structure of skeletal, cardiac muscle, and smooth muscle
* * * MOVEMENT, BREATHING, BALANCE, HEAT REGULATION * * *
- attached to bone via tendons & aponeurosis (flat tendon)
- made up of bundles of fibers
- straight line arrangements of actin and myosin
- cells are straight, cylindrical, many nuclei (multi-nucleated) on edges
- heart specific
- constant contraction
- specialized junctions - interclated disks - connects cells and assist in transmitting nerve impulses
- contractions preformed by actin and myosin fibers
- branched cell structure with 1 (uni-nucleated) or 2 (bi-nucleated) nuclei
- exists in walls of hollow organs (stomach, bowels, uterus) and blood vessels (aorta)
- short, spindle shaped cells arranged in sheets that forms bands around tubes and organs
- contraction of smooth muscles is done by the movement of actin & myosin fibers
- contraction causes "squeeze"
- designed to move and contract in segments for operations like peristalsis, blood movement, etc.
- eye shaped shaft with 1 (uni-nucleated) nuclei
- no striations
The Layer of Muscle
Tendons - attach muscle to bone - they are tough pale colored cords formed from many parallel bundles of collagen fibers. Tendons are flexible (they bend around other tissues, changing position as they move), yet inelastic.
Tendon sheath - some tendons are surrounded by tubular double-layered sacs that are lined with synovial membrane and contain synovial fluid. These structures are called "tendon sheaths". Their purpose is to minimize friction associated with movement at the joint, and to facilitate movement of the joint.
Fascia - the word "fascia" means bandage - the tissue called fascia takes the form of sheets or broad bands of fibrous connective tissue that cover muscles or organs, forming an outer-wrapping.
> > There are two types of fascia: Superficial Fascia, and Deep Fascia.
Superficial fascia consists of areolar connective tissue and adipose tissue - subcutaneous layer of the skin.
Deep Fascia is more relevant to the study of muscle structures because it is deep fascia that holds the muscles together. It consists of dense fibrous connective tissue.
Perimysium - a fibrous sheath that surrounds and protects bundles of muscle fibers.
Epimysium - fibrous elastic tissue that surrounds muscle.
Endomysium - the fine connective tissue sheath that surrounds/covers each single/individual muscle fiber.
> > epimysium surrounds the total bundle of many fascicles - as compared with perimysium (the fibrous sheath that surrounds and protects individual fascicles, filling the spaces between the fascicles within the bundle of fascicles that forms the muscle itself), and endomysium (the fine connective tissue that surrounds and protects each individual muscle fiber - also known as a "muscle cell", hence filling the spaces between muscle fibers within each muscle fascicle).
Fascicle/fasciculus - literally means bundle of structures - e.g. nerve, muscle fibers
Muscle Fiber/Cell/Myocyte - elongated multi-nucleate modified cell made up of fibrils.
Fibrils - made up of actin & myosin.
Sarcolemma - "plasma membrane" sheath with specialized organelles - myofibril
Neuclei - ("multi-nucleated" cells) dispersed all along the surface of the fibers, just underneath the sarcolemma. Each nucleus regulates the metabolic needs of the surrounding sarcoplasm.
Sarcoplasma Reticulum - a modified smooth endoplasmic reticulum that releases calcium
Myofibril - organelle within the sarcolemma - 10,000+ - which contract and move together
Describe how muscles contract and relax
One neuron and all the skeletal muscle cells it stimulates are a motor unit and when a long threadlike extension of the neuron, called the nerve fiber or axon, reaches the muscle, it branches into a number of axonal terminals, each of which forms junctions with the sarcolemma of a different muscle cell – these junctions are called neuromuscular junctions
Action Potential - the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell.
Axon Terminal - the very end of a branch of a nerve's axon, a long slender nerve fiber that conducts electrical signals to a nerve synapse (the gap between nerve cells). Synaptic end bulb - at the extreme/end of each axon terminal. Each synaptic end bulb contains many synaptic vesicles, each of which contains an important chemical neurotransmitter called acetylcholine (ACh)
Somatic Neuron - (nerve cell) - connects to muscle fiber & stimulates skeletal muscle (can innervate* 3-1000 fibers)
* innervate - supply muscle with nerves
Nerve stimulation > Action Potential > Neuromuscular Junction > Ca Channels open and flood cell > stimulates release of vesicles > Actylcholine > fuses with membrane and empties ACh into synapse > binds to muscle cell > opens channel and releases Na > stimulates AP in muscle cell > SR releases calcium into myofibril > Ca stimulates myofibill to contract > muscle contraction! > SR takes Ca back in until next AP
How does Ca cause an organelle to contract?
Sacomeres - a structural unit of a myofibril in striated muscle
Myofilaments - found within the sarcomeres that actually produce the banding pattern – two types of threadlike proteins
- Thin filaments - Actin - connect to Z disk
- Thick filaments - Myosin - connect to M line in H zone
SR releases Ca into myofibril - changes configuration on protein (tropomyocin) binding site on actin
Myosin reaches (ATP) and grabs actin (toward H zone) to cause muscle fiber to shorten (contract)
* * ATP is required for both contraction and relaxation
Explain the importance of a nerve supply and exercise in keeping muscles healthy
If the nerve supply is damaged, the muscle may no longer be stimulated, causing loss of tone and can become paralyzed, resulting in atrophy. Exercise is crucial in keeping the muscles healthy, supple and toned.
Explain the importance of this module's material in the study of herbal medicine
Having knowledge of the body's many major moving parts and building blocks is important to understand as an herbalists, for these foundations and functions are crucial in supporting our body's natural processes to build, rebuild, replenish and so on.
Understanding the integumantary system specifically is important for herbalists because many diseases and conditions manifest on the skin. It is important to recognize these symptoms and their affects/roots both externally and internally. Many herbal remedies are applied externally, which makes it necessary to have an understanding of how the skin and its layers/functions work.
The musculoskeletal system has many highly complicated processes, voluntary and not, many of which require specific nutrients and vitamins to function. As an herbalist, it is important to study the processes involved with the skeletal, nervous, and muscular system, learning these processes emphasizes the importance of many aspects of the traditions and protocols of herbal care. Along with nutrition, there are many herbal actions that support the systems on many levels; some examples include anti-spasmodic, anti-inflammatory, anti-oxidant, anodyne & lymphatic.