Unit 2 (all cards) Flashcards
True or false: Tight junctions function primarily to prevent cells from pulling apart.
False; it’s to keep stuff from getting in
The type of secretion where the entire cell dies and the cell fragments are mixed with the produced cellular substance is called a ____ secretion.
holocrine
A second degree or “partial thickness burn” is when:
a burn is through the epidermis and part of the dermis.
True or false: Fibrosis repairs a tissue and restores the original cells and function of the tissue.
False; Fibrosis replaces damaged tissue mainly with collagen. This does not restore the original function.
This tissue is found lining the kidney tubules and functions in absorption and excretion.
simple cuboidal epithelium
What tissue comprises tendons and ligaments?
dense regular connective tissue
True or false: Hyperplasia is the term for increased cell production in a tissue.
True
True or false: Melanin has the greatest influence on your skin tone, but hemoglobin and carotene also contribute to the final tone.
True
Sudoriferous glands include what types of glands
Apocrine and merocrine
True or false: Merocrine gland secretions are involved in scent communication, not in thermoregulation.
False; that’s apocrine glands. Merocrine glands are involved in thermoregulation.
___________________ is the most common but least dangerous type of skin cancer, and occurs in the cells of the stratum basale.
basal cell carcinoma
True or false: When looking at the layers of the epidermis, everything superficial to the stratum granulosum is dead.
True
Dense irregular connective tissue is found in the ______ layer of the _____.
reticular layer of the dermis
Due to the force of muscle contraction and stretching from the loading of blood, heart tissue is under a lot of mechanical stress. Because of this you would not be surprised to learn that cardiac muscle cells are connected by:
desmosomes
The growth of bones in length is the result of ____ ossification.
endochondral
If you want to lower blood calcium, which hormone(s) will be released?
Calcitonin
Because of the action of osteoblasts, which way will calcium ion concentration travel?
from blood to bone
To lower blood calcium, which action might a hormone do?
inhibit osteoclast activity
True or false: bones of the fingers are an example of long bones
True
True or false: Red bone marrow is found in all bones of the adult skeleton.
False; primarily found in the axial skeleton
The hardness of bone is thanks to the presence of:
hydroxyapatite and other minerals
The most common bone disease/disorder is:
Osteoporosis
The uniquely shaped ends of long bones are called the:
epiphyses
True or false: The femur of a 5 year old child will have epiphyseal lines.
False; a young child would still have growth plates present.
Give an example of a sesamoid bone
Patella
The pancreas is located below/behind the stomach. What abdominal quadrant would it mostly belong in?
left upper
The pancreas belongs to two different organ systems. It produces important enzymes for breakdown of food, and it produces hormones to regulate our blood glucose. These functions would place it in which two systems?
digestive and endocrine
True or false: An epithelial tissue that has multiple layers of cells is more likely to be found in an area where rapid diffusion takes place.
False
Where would you find transitional epithelium?
Urinary bladder
Which type of tissue is found on the ends of bones in most movable joints?
hyaline cartilage
Which type of tissue lines the trachea and bronchi and has cilia and goblet cells?
pseudostratified columnar epithelium
What is the tissue that makes up tendons and ligaments?
Dense regular connective tissue
What type of tissue is found in the epidermis?
keratinized stratified squamous epithelium
Which type of receptor is found in the lower part of the dermis and detects deep touch/pressure and vibration?
lamellar (Pacinian) corpuscles
What is the deepest layer of the epidermis?
stratum basale
Which layer of the epidermis is composed of the preserved membranes of dead cells?
Stratum corneum
What is the difference between thick and thin skin?
The presence of a stratum lucidum
Microvilli are folds of the cell membrane that increase the surface area of the cell/tissue. Which tissue has microvilli, and where is it found?
simple columnar, digestive tract
Which tissue type has loosely scattered cells and more prominent extracellular matrix?
Connective
If you injure a disk in your back, what kind of cartilage has been damaged?
Fibrocartilage
In our chapter 7 notes we introduced the idea of feedback loops. Feedback loops enable the body to recognize a change, make a decision about the change, and enact responses. Let’s practice recognizing the components of a feedback loop.
The healthy pH range of the blood is 7.35-7.45. When you engage in strenuous exercise, muscles remove oxygen from the blood for energy processes, which lowers the blood oxygen level. At the same time, carbon dioxide blood levels climb, which lowers the blood pH. Chemical sensors in blood vessels detect these changes and send feedback to the brainstem. The brain responds by sending a signal to the muscles of respiration for increasing the rate and depth of breathing, which increases the intake of oxygen and the removal of carbon dioxide from the blood. As carbon dioxide is removed from the blood, the pH rises again. In this example of a feedback loop, the effector and stimulus would be:
Effector: the muscles of respiration
Stimulus: blood pH and CO2 levels
What are the two most durable components of your body?
Bones and teeth (especially the enamel)
Do we have a dead or living skeleton?
Living
True or false: The skeletal system constantly remodels itself and interacts with other organ systems of the body
True
______ is the study of bone
Osteology
What are the 3 main components of the skeletal system?
Bones, cartilages, and ligaments
Define cartilage, ligaments, and tendons
Cartilage is forerunner of bone formation and coats ends of bones.
Ligaments connect bone to bone
Tendons connect muscle to bone
What are the functions of the skeleton?
Support, protection, movement, electrolyte balance, acid-base balance, and blood formation
How does the skeleton aid in support, protection, and movement?
Support: limb bones and vertebrae support body; jaw bone supports teeth; bones support viscera
Protection: of brain, spinal cord, heart, lungs etc
Movement: of limbs, breathing – action of muscles on bones
How does the skeleton aid in maintaining electrolyte and acid base balances, and how does it aid in blood formation?
Electrolyte balance: calcium & phosphate levels
Acid–base balance: buffers blood against large pH changes by altering phosphate and carbonate salt levels
Blood formation: red bone marrow makes red blood cells
Define bone (osseous tissue)
A connective tissue with its matrix hardened by calcium phosphate and other minerals
Define mineralization/ calcification
The hardening process of bone
What do individual bones consist of?
Individual bones (organs) consist of bone tissue, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue
Define sesamoid and sutural bones
Sesamoid (type of short bone) and sutural (wormian) bones
Sesamoid bones develop in a tendon (or ligament) in response to a need for more leverage
Sutural bones are the extra bones in the sutures (especially the lambdoid suture) of the skull
Define compact bone
Has a dense outer shell of bone
Define spongy (cancellous) bone
Made up of an internal honeycomb of trabeculae filled with red or yellow bone marrow
The skeleton’s weight is made up of ___% compact bone and _____% spongy bone
75% compact bone; 25% spongy bone
Define diaphysis and epiphyses
Diaphysis—shaft that provides leverage
Epiphyses—enlarged ends of a long bone
Define the epiphyseal line (metaphysis) and marrow cavity (medullary cavity)
Epiphyseal line: separates diaphysis from epiphysis (aka metaphysis)
Marrow cavity: space in the diaphysis of a long bone that contains bone marrow (aka medullary cavity)
Define articular cartilage
A layer of hyaline cartilage that covers joint surface and allows the joint to move more freely
Describe the two layers of the periosteum
Outer fibrous layer made of collagen
Some fibers continuous with tendons
Perforating fibers —penetrate into bone matrix
Inner osteogenic layer of bone-forming cells
Important to bone growth and healing of fractures
Define the periosteum
2 layers covering most of bone
Define the endosteum
A thin layer of reticular connective tissue lining marrow cavity
Contains osteoblasts and osteoclasts
The nutrient foramina is penetrated by what?
Blood vessels
Describe the epiphyseal plate (growth plate)
Area of hyaline cartilage that separates epiphyses and diaphyses of children’s bones
Enables growth in length
When growth is finished turns into Epiphyseal line
List the 8 features of long bone
Epiphyses Diaphysis Compact bone Spongy bone Marrow cavity Articular cartilage Periosteum Endosteum
Describe the anatomy of a flat bone
Bones with a sandwich-like structure: two layers of compact bone with a middle layer of spongy bone (diploë)
Define and describe the diploë of flat bones
Diploë is the spongy middle layer found in flat bones. It absorbs shock and the marrow spaces are lined with endosteum
Define osteogenic cells
Stem cells (cell division) and develop into osteoblasts
Define osteoblasts
Bone-forming cells
Describe how osteoblasts do their job
Osteoblasts secrete collagen (and other carbohydrate-protein complexes) to form a soft fibrous matrix. This matrix hardens with mineral deposition. They make bone by mitosis and differentiation of osteogenic cells
What two organelles are particularly abundant in osteoblasts?
Rough ER and golgi complexes.
What stimulates osteogenic cells to multiply rapidly? What does this do?
Stress stimulates osteogenic cells to multiply rapidly, which increases the number of osteoblasts which reinforce bone
Define and describe osteocytes
Defined as mature bone cells
They’re found in pockets called lacunae, and connected to each other by canaliculi and gap junctions
Some reabsorb bone matrix & others deposit it; regulates bone remodeling
Describe the role of osteocytes when under stress
They act as strain sensors; when stressed, they produce biochemical signals that regulate bone remodeling (shape and density changes that are adaptive)
Define and describe osteoclasts
Defined as bone-dissolving cells found on bone surface
Derived from fusion of multiple white blood cells (WBC’s)
Usually multinucleate
Secrete enzymes and acids for the break down of bone (resorption)
True or false: Dissolving bone is a part of bone remodeling
True
What are the two main parts of the matrix, and what fraction of the matrix do they each make up?
Organic portion (1/3) and inorganic portion (2/3)
Describe the organic part of the matrix
Synthesized by osteoblasts
Composed of collagen and carbohydrate–protein complexes
Responsible for the flexibility of bone
Makes up 1/3 of the matrix
Describe the inorganic part of the matrix
85% hydroxyapatite (calcium phosphate) 10% calcium carbonate 5% other minerals (fluoride, sodium, potassium, magnesium) Responsible for the hardness of bone Makes up 2/3 of the matrix
If there is a mineral deficiency, what happens to the bone?
Rickets disease
Describe Rickets disease
A disease caused by mineral deficiency and resulting in soft, deformed bones
If there is a defect in collagen deposition, what happens to the bone?
Osteogenesis imperfecta (brittle bone disease)
Describe osteogenesis imperfecta (brittle bone disease)
Results from a defect in collagen deposition
Histology of compact bone reveals that they have _____
Osteons (haversian systems)
Describe the 3 elements of the haversian system of an osteon
1) Lamellae
Columns of the matrix (mainly collagen) that are weight bearing
Run concentric, circumferential, and interstitially
2) Central (Haversian canal)
Contains blood vessels and nerves
3) Perforating (Volkmann’s) canals
Channels that connect blood and nerves from periosteum to the central (Haversian) canal
Describe lamellae in osteons
Columns of the matrix (mainly collagen) that are weight bearing. The columns run concentric, circumferential, and interstitially
Describe the central (Haversian) canal of the osteon
Contains blood vessels and nerves
Describe the perforating (volkmann’s) canals of osteons
Channels that connect blood and nerves from periosteum to the central (Haversian) canal
Run transverse or diagonal
Where do trabeculae develop in spongy bone?
They develop along the bone’s lines of stress
Something described as a “lattice of bone covered with endosteum” is known as what?
Spongy bone
Describe the structure and function of spongy bone
Structure: It’s a lattice of bone covered with endosteum; made up of trabeculae (thin plates of bone) that develop along the bone’s lines of stress, and the spaces are filled with red bone marrow. Has few osteons and no central canals
Function: Provide strength with minimal weight
Define bone marrow
Soft tissue occupying marrow cavities of long bones and small spaces of spongy bone
What are the two types of bone marrow?
Yellow and red
Describe red bone marrow
- Contains hemopoietic tissue—produces blood cells
- Found in nearly every bone in a child
- In adults, it’s found in the skull, vertebrae, ribs, sternum, part of pelvic girdle, and proximal heads of humerus and femur
Describe yellow bone marrow
- Found in adults
- Stores Triglycerides
- Can transform back to red marrow in the event of chronic anemia
Describe where red bone marrow is found in children and adults
Infants – in nearly every bone
- medullary cavity
- all areas of spongy bone
Adults
- head of the femur and humerus
- diploë (spongy bone) of flat bones
- some irregular bones (such as hip and vertebrae)
Define ossification or osteogenesis
The formation of bone
In the human fetus and infant, bone develops by what two methods?
Intramembranous ossification
Endochondral ossification
When does intramembranous ossification occur?
It produces the flat bones of skull and clavicle in fetuses (and ossifies the fontanels, and thickens long bones throughout life)
During intramembranous ossification, bone develops within what kind of membrane?D
A fibrous connective tissue membrane
Describe the life-cycle of an osteocyte formed by intramembranous ossification
Mesenchymal cells turn into osteoblasts which turn into osteocytes (spongy bone)
Describe intramembranous ossification
Bone develops within a fibrous connective tissue membrane (Mesenchymal cells to osteoblasts to osteocytes (spongy bone))
Forms the flat bones of the skull, clavicles, and ossifies the fontanels.
Most of these bones are remodeled (destroyed and reformed) as we grow to adult size.
Describe endochondral ossification
Bone forms by replacing hyaline cartilage
Forms most the bones of the body below the skull (except the clavicle)
Mesenchyme turn into chondroblasts, which die and are replaced by osteoblasts, which form spongy bone, which forms compact bone
What type of ossification is best described as “bone is formed by replacing hyaline cartilage”?
Endochondral ossification
In endochondral ossification, what do primary and secondary ossification form?
Primary Ossification: forms diaphysis
Secondary ossification: forms epiphysis
When do epiphyseal plates close? What does this mean for growth?
Close in late teens to early 20s, which is when bone can no longer grow in length
During infancy and childhood, in endochondral ossification the epiphyses fill with _______ bone
spongy
Describe the role of cartilage in endochondral ossification
Cartilage is limited to the articular cartilage covering each joint surface, and to the epiphyseal plate
Describe the role of the epiphyseal plate in bone growth
Serves as a growth zone for bone elongation, covered with cartilage
True or false: bones grow in two directions, which are length and width
True
True or false: Ossification continues throughout life with the growth and remodeling of bones
True
Describe how bones grow in length
Occurs at Epiphyseal plates
Cartilage cells undergo mitosis, pushing the epiphysis away from the diaphysis
Cartilage cells die and are replaced by bone.
When growth is finished, there’s no more cartilage at the plate, which then becomes an epiphyseal line, and bone can no longer grow in length
Describe achondroplastic dwarfism
Long bones stop growing in childhood
Normal torso, short limbs
Failure of cartilage growth in metaphysis
Spontaneous mutation produces mutant dominant allele
Describe pituitary dwarfism
Lack of growth hormone
Normal proportions with short stature
Describe how bones become wider/thicker
Happens through appositional growth: continual growth in diameter and thickness throughout the lifespan through intramembranous ossification.
Osteoblasts of inner periosteum deposit osteoid tissue
Lay down matrix in layers parallel to surface
Forms circumferential lamellae
Osteoclasts of endosteum enlarge marrow cavity
Define appositional growth and where it happens
The growth of bone horizontally; happens on the surface of bone
About ___% of an adult’s skeleton is remodeled each year
10%
What are the two main types of cells involved in bone remodelling?
Osteoblasts: Bone deposition
Osteoclasts: Bone resorption
Describe Wolff’s Law of Bone
Bone grows or remodels in response to the demands placed on it
Exercise: promotes bone growth
Lack of exercise (bedridden): atrophies bones
Define mineral deposition/ mineralization
The process in which calcium, phosphate, and other ions are taken from blood and deposited in bone
Describe the process of mineral deposition/ mineralization
Osteoblasts produce collagen fibers
Fibers become encrusted with minerals
First few crystals act as seed crystals that attract more calcium and phosphate
Abnormal calcification (ectopic ossification)
Formation of a calculus (calcified mass) in lung, brain, eye, muscle, tendon, or artery (arteriosclerosis)
Define mineral reabsorption
The process of dissolving bone and releasing minerals into blood
Describe the process of mineral reabsorption
Performed by osteoclasts
Pump hydrogen to extracellular fluid (chloride follows). Hydrochloric acid (pH 4) dissolves bone minerals
Produce an enzyme which digests collagen in an acidic environment
Describe the role of osteoclasts and osteoblasts in braces
Braces reposition teeth, which move because osteoclasts dissolve bone ahead of the tooth; osteoblasts deposit bone behind the tooth
Describe the role of the bone matrix in homeostasis
Minerals are deposited in the skeleton and withdrawn from the skeleton when they are needed for other purposes
Phosphate is a component of DNA, RNA, ATP, phospholipids, and pH buffers
Calcium needed in neuron communication, muscle contraction, blood clotting, and exocytosis
What is phosphate a component of?
DNA, RNA, ATP, phospholipids, and pH buffers
What is calcium needed for in the body?
Neuron communication, muscle contraction, blood clotting, and exocytosis
True or false: Calcium and phosphate are used for much more than bone structure
True
Define homeostasis
The ability to detect change, activate mechanisms that oppose it, and thereby maintain relatively stable internal conditions
Describe negative feedback
It allows for a dynamic equilibrium within a limited range around a set point.
The body senses a change and “negates” or reverses it.
The fundamental mechanism to keep body in homeostasis.
Loss of homeostatic control causes what?
Illness or death
Why are feedback loops called feedback loops?
Because feedback mechanisms alter the original changes that triggered them, they are called feedback loops.
Describe the role of homeostasis in body temperature
If too warm, vessels dilate in the skin and sweating begins (heat-losing mechanism).
If too cold, vessels in the skin constrict and shivering begins (heat-gaining mechanism).
What are the 3 main components of feedback loops?
Receptor, integration (control) center, and effector.
Define a receptor in feedback loops
Structure that senses change in the body (chemical, temperature, pain, pressure, volume, etc.)
Define an integration (control) center in a feedback loop
The control center that processes the sensory information, “makes a decision,” and directs the response (e.g., cardiac center of the brain)
Define an effector in a feedback loop
The cell or organ that carries out the final corrective action to restore homeostasis (e.g., the heart)
Define and describe positive feedback loops
It’s a self-amplifying cycle that leads to greater change in the same direction; the feedback loop is repeated (change produces more change).
It’s a normal way of producing rapid changes
(ex: childbirth, blood clotting, protein digestion, and generation of nerve signals)
However, they can sometimes be dangerous
(ex: the vicious cycle of runaway fever)
Calcium homeostasis depends on a balance between what two things?
Intake (diet) and loss (urinary and fecal eliminations)
How is calcium homeostasis maintained?
By calcium exchange between osseous tissue and blood, which is mediated by three hormones
Calcium homeostasis is regulated by what three hormones?
Calcitriol (vitamin D), calcitonin, and parathyroid hormone
Describe the role of calcitriol (vitamin D) in calcium homeostasis
It raises blood calcium levels; mainly, it increases calcium absorption by small intestine, and it also increases calcium resorption from the skeleton.
It weakly promotes kidney reabsorption of calcium ions, so less is lost in urine
Produced by actions of skin, liver, and kidneys
What is calcitriol (vitamin d) needed for in the body? What does a calcitriol deficiency result in?
Calcitriol is necessary for bone deposition; lack of calcitriol results in abnormal softness of bones.
In children, a deficiency results in rickets. In adults, a deficiency results in osteomalacia
Describe the role of calcitonin in calcium homeostasis
Produced by the thyroid gland
Its release is triggered by high blood calcium, and it lowers blood calcium concentration in 2 ways: Inhibits osteoclasts and stimulates osteoblasts
Important in children, weak effect in adults (except may inhibit bone loss in pregnant and lactating women)
What increases blood calcium? What decreases blood calcium?
Calcitriol (vitamin D) and parathyroid hormone increase blood calcium; calcitonin decreases blood calcium
Describe the role of parathyroid hormone in calcium homeostasis
PTH increases blood calcium 4 ways:
1) Stimulates osteoclast population and bone resorption
2) Promotes calcium reabsorption by kidneys
3) Promotes calcitriol synthesis
4) Inhibits osteoblasts, inhibiting bone deposition
Produced by parathyroid glands
Release triggered by low blood calcium
Describe the causes and effects of hypocalcemia
Effects: causes overly excitable nervous system and tetany (muscle spasms) (laryngospasm)
Some cases are caused by vitamin D deficiency or underactive parathyroid glands
Pregnancy and lactation increase risk of hypocalcemia
Define hypocalcemia and hypercalcemia
Hypocalcemia: low blood calcium.
Hypercalcemia: high blood calcium.
Describe the causes and effects of hypercalcemia
Makes nerve and muscles less excitable
Can cause emotional disturbance, muscle weakness, sluggish reflexes, cardiac arrest
Hypercalcemia rarely occurs
Describe bone development from infancy to early adulthood
Infancy and childhood: epiphyseal plate activity is stimulated by Human Growth Hormone (hGH)
Puberty: (testosterone and estrogens) promotes adolescent growth spurts and differentiates the male/female skeleton; bone growth ends (18 - 21 years)
At least __ or more hormones, vitamins, and growth factors affect osseous tissue
At least 20 or more hormones, vitamins, and growth factors affect osseous tissue
Why do girls grow faster than boys and reach full height earlier?
Estrogen has stronger effect than testosterone on bone growth
Describe the effects of anabolic steroids on growth
Causes bone growth to stop and the epiphyseal plate to “close” prematurely
Results in abnormally short adult stature
Define a stress fracture
A break caused by abnormal trauma to a bone
Define a pathological fracture
A break in bone that’s been weakened by disease (cancer or osteoporosis)
Fractures are classified by their structural characteristics; what are they?
Displaced vs nondisplaced
Open vs closed
Define closed reduction
A procedure to treat fractures in which bone fragments are manipulated into their normal positions without surgery
Define open reduction
A procedure to treat fractures that involves surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments
Define a cast
Normally used to stabilize and immobilize healing bone
Describe osteoporosis
The most common bone disease
Affects spongy bone the most since it is the most metabolically active
Subject to pathological fractures of hip, wrist, and vertebral column
Kyphosis (widow’s hump)—deformity of spine due to vertebral bone loss
Complications of loss of mobility are pneumonia and thrombosis
The most common bone disease is __________
osteoporosis
What is kyphosis and why does it happen?
It’s a deformity of the spine due to vertebral bone loss
What demographics are most likely to get osteoporosis?
- Estrogen maintains bone density in both sexes; inhibits resorption by osteoclasts
- Postmenopausal white women at greatest risk; this is because white women begin to lose bone mass as early as age 35 and By 70, average loss is 30% of bone mass
- Osteoporosis also seen in young female athletes with low body fat causing them to stop ovulating and decrease estrogen secretion
- Risk factors: race, age, gender, smoking, diabetes mellitus, diets poor which are poor in: calcium, protein, vitamins C and
What are the treatments for osteoporosis?
- Estrogen replacement therapy (ERT) (slows bone resorption, but increases risk of breast cancer, stroke, and heart disease)
- Certain medications destroy osteoclasts
- Best treatment is prevention: exercise and a good bone-building diet between ages 25 and 40
True or false: Inspection of the skin, hair, and nails is significant part of a physical exam
True
True or false: Skin is NOT the most vulnerable organ
False; skin is the most vulnerable organ. It’s exposed to radiation, trauma, infection, and injurious chemicals
True or false: the skin receives more medical treatment than any other organ system
True
Define dermatology
The scientific study and medical treatment of the integumentary system
What are the six main functions of the skin?
1) Resistance to trauma and infection: Keratin; dermacidin & defensins; acid mantle 2) Other barrier functions: Water (protects against dehydration) UV radiation; melanin Harmful chemicals 3) Vitamin D synthesis: Skin carries out first step; Liver & kidneys complete process 4) Sensation receptors Touch, temperature, pressure, vibration, tickle, itch, and pain sensations 5) Regulation of body temperature Thermoreceptors Vasoconstriction/vasodilation If you are too warm, do cutaneous blood vessels vasodilate or vasoconstrict? Perspiration 6) Nonverbal communication
What are the two layers of the skin (cutaneous membrane)?
Dermis and epidermis
What are the two main parts of the skin?
The cutaneous membrane (the skin) and the subcutaneous layer
What type of cells is the epidermis made of?
Keratinized stratified squamous epithelium
Describe the characteristics of the epidermis
Includes dead cells at skin surface packed with tough keratin protein
5 distinct strata (layers) in thick skin; 4 strata in thin skin
Lacks blood vessels
Depends on the diffusion of nutrients from underlying connective tissue
Contains sparse nerve endings for touch and pain
List the five epidermal cell types
Stem cells, keratinocytes, melanocytes, tactile (merkel) cells, and dendritic cells
Describe stem cells in the epidermis
Undifferentiated cells that give rise to keratinocytes
In deepest layer of epidermis (stratum basale)
Describe keratinocytes
The majority of epidermal cells; Synthesize keratin
Describe melanocytes
Synthesize pigment melanin (shields DNA from UV radiation)
Occur only in stratum basale but have branched processes that distribute melanin to keratinocytes
Describe tactile (merkel) cells
Touch receptor cells in basal layer
Describe dendritic cells
Macrophages (WBCs) that are part of the immune system
Found mainly in stratum spinosum and granulosum
Describe thick skin and where it’s found
Lacks hair follicles and sebaceous (oil) glands
Has stratum lucidum
Generally has more sweat and sensory receptors
Epidermis 0.5 mm thick
Found on palms of hands and soles of feet
Describe thin skin
Possesses hair follicles, sebaceous glands, and sweat glands
Epidermis about 0.1 mm thick
Name the layers of the epidermis from deepest to shallowest
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
Describe the stratum basale
Single layer of stem cells and keratinocytes
Stem cells divide and give rise to keratinocytes that migrate toward skin surface to replace lost cells
Also contains a few melanocytes and tactile cells
Deepest epidermal layer
Describe the stratum spinosum
Several layers of keratinocytes joined together by desmosomes and tight junctions
Named for appearance of cells after histological preparation (spiny)
Also contains some dendritic cells
Describe the stratum granulosum
Three to five layers of flat keratinocytes
Cells contain dark-staining kerotohyalin granules
Describe the stratum lucidum
Thin, pale layer found only in thick skin
Describe the stratum corneum
20-30 layers of dead, scaly, keratinized cells
Resists abrasion, water loss, penetration of bacteria and chemicals
Describe the life history of a keratinocyte
Stem cells divide producing keratinocytes.
New keratinocytes push older ones toward the surface
Over time, keratinocytes flatten, produce more keratin and membrane-coating vesicles that release lipids that waterproofs the cell.
How long does it take keratinocytes to reach the surface layer of skin?
Take about 30-40 days – slower in old age and faster in injured or stressed skin (calluses or corns).
Where does mitosis occur in keratinocytes?
Keratinocytes in the deepest part of stratum spinosum can also divide. Mitosis requires abundant oxygen and nutrients, so once cells migrate away from blood vessels of the dermis, mitosis cannot occur
Describe the function of the epidermal water barrier
Water retention is fostered by tight junctions between skin cells and the waterproofing that occurs in the stratum granulosum
Helps prevent dehydration
Does not prevent the absorption of water by the stratum corneum when we soak in a bath (“prune fingers”)
What are the layers of the dermis? (in order from shallow to deep)
Papillary layer and reticular layer
Describe the papillary layer of the dermis
Most superficial layer of the dermis
Thin zone of areolar tissue in and near the dermal papilla
Anchors epidermis to dermis
Rich in small blood vessels
Contains Tactile (Meissner) corpuscles (touch) and free nerve endings (pain and temperature)
Describe the reticular layer of the dermis
The deeper and thicker layer of dermis
Consists of dense, irregular connective tissue
Packed with oil glands, sweat glands, hair follicles, etc.
Stretch marks (striae): tears in the collagen fibers caused by stretching of the skin due to pregnancy or obesity
Contains Lamellar (Pacinian) corpuscles for pressure reception
Describe the formation of fingerprints
Dermal papillae are more pronounced in thick skin (palms, soles, etc.)
As epidermis conforms to papillae, epidermal ridges are formed
Increases friction – better grip
Describe the hypodermis
Has more areolar and adipose than dermis
Common site of drug injection since it has many blood vessels
Subcutaneous fat used for energy reservoir and thermal insulation
Thicker in women
Thinner in infants and elderly
Describe the 3 main things that contribute to skin color
1) Melanin
Produced by melanocytes, accumulates in keratinocytes
People of different skin colors have the same number of melanocytes but differ on the amounts of melanin
2) Hemoglobin
pigment in red blood cells; adds reddish to pinkish hue to skin
3) Carotene
yellow pigment acquired from egg yolks and yellow/orange vegetables
Concentrates in stratum corneum and subcutaneous fat
Describe melanin
Eumelanin—brownish black
Pheomelanin—reddish yellow (sulfur-containing)
Darker skinned people:
Produce greater quantities of melanin
Melanin breaks down more slowly
Melanin granules more spread out in keratinocytes
Melanized cells seen throughout the epidermis
Lighter skinned people:
Melanin clumped near keratinocyte nucleus
Little melanin seen beyond stratum basale
Exposure to UV light stimulates melanin secretion and darkens skin
This color fades as melanin is degraded and old cells are exfoliated
List the different types of skin color/tone and describe what conditions are associated with them
Cyanosis—blueness due to oxygen deficiency
Erythema—redness due to increased blood flow to skin
Pallor—paleness due to decreased blood flow to skin
Albinism—milky white skin and blue-gray eyes due to genetic lack of melanin synthesizing enzyme
Jaundice—yellowing due to bilirubin in blood (can be caused by compromised liver function)
Hematoma—bruising (clotted blood under skin
Define hair
A slender filament of keratinized cells growing from a tube in the skin called a hair follicle
What are the 3 sections of a hair along its length?
Bulb: Contains matrix cells (mitotically active cells)
Root: the remainder of the hair in the follicle
Shaft: the portion above the skin surface
What are the three layers of a hair visible in a cross-section?
Medulla (core), Cortex, Cuticle (outer layer)
Describe hair receptors
sensory nerve fibers entwining follicles
Detect hair movement
Describe the piloerector muscle (arrector pili)
Smooth muscle attaching follicle to dermis
Contracts to make hair stand on end (goose bumps)
What are the 4 main functions of hair?
Protection
Light touch
Heat retention
Excretion
Describe the composition of fingernails
They’re clear, hard derivatives of stratum corneum composed of thin, dead cells packed with hard keratin
Describe merocrine/eccrine sweat glands
Most numerous of skin glands
Duct opens to surface of skin
Regulates body temperature with perspiration
Describe apocrine sweat glands
Locations: groin, anal region, axilla, areola, beard (men)
Inactive until puberty; responds to stress and sexual stimulation
Ducts lead to nearby hair follicles
Believed to secrete pheromones
Define bromhidrosis
Disagreeable body odor produced by bacterial action on sweat from apocrine glands
Describe sebaceous glands
Most open into a hair follicle, and they utilize a holocrine secretion style to secrete sebum
Describe sebum
The oily secretion of sebaceous glands
Keeps skin and hair from becoming dry, brittle, and cracked
Inhibits growth of bacteria & fungi (ringworm)
Give an example of a modified oil gland
Ciliary Glands
Describe the ceruminous glands in external ear canal
Modified apocrine glands Forms earwax (cerumen)
Describe mammary glands
Milk-producing glands that develop only during pregnancy.
Modified apocrine sweat glands
Rich secretion released through ducts opening at nipple
What causes most skin cancers?
Most cases caused by UV rays of the sun damaging skin cell DNA
What are the three types of skin cancer? Describe their malignancy
1) Basal cell carcinoma Most common but least malignant 2) Squamous cell carcinoma May metastasize if not removed 3) Melanoma Least common but very malignant
Describe basal cell carcinomas
Most common type
Least dangerous because it seldom metastasizes
Forms from cells in stratum basale
Lesion is small, shiny bump with central depression and beaded edges
Describe squamous cell carcinoma
- Arises from keratinocytes of stratum spinosum
- Lesions usually on scalp, ears, lower lip, or back of the hand
- Have raised, reddened, scaly appearance later forming a concave ulcer
- Chance of recovery good with early detection and surgical removal
- Tends to metastasize to lymph nodes and may become lethal
Describe malignant melanoma
Skin cancer that arises from melanocytes
Less than 5% of skin cancers, but most deadly form
Can be successfully removed if caught early, but if it metastasizes it is usually fatal
Greatest risk factor: familial history of malignant melanoma
Highest incidence in men, redheads, and people who had severe sunburn as a child
List the ABCDEs of melanomas
A: Asymmetry B: Border C: Color D: Diameter E: Elevation and/or evolution
Describe burns
The leading cause of accidental death
Fires, kitchen spills, sunlight, ionizing radiation, strong acids or bases, or electrical shock
Deaths result primarily from fluid loss, infection, and toxic effects of eschar (burned, dead tissue)
Debridement: removal of eschar
Burns classified according to depth of tissue involvement
Describe first degree burns
Involves only epidermis; Heals in days
Describe second degree burns
Partial-thickness burn; involves part of dermis
May appear red, tan, or white; blistered and painful
Two weeks to several months to heal and may leave scars
Describe third degree burns
Full-thickness burn; involves epidermis, all of dermis, and often some deeper tissues
Often requires skin grafts
Needs fluid replacement, infection control, supplemental nutrition
The tissue found covering body surfaces, lining body cavities, forming the internal and external linings of many organs, and constituting most gland tissue is _____ tissue
epithelial
Which term is used to describe the free surface of an epithelium? Apical Basal Open Medullary
Apical
Which epithelium lines the respiratory tract from the nasal cavity to the bronchi? Simple cuboidal Transitional Simple columnar Pseudostratified columnar
Pseudostratified columnar
Which surface of an epithelial cell faces the basement membrane?
Basal
Apical
Basal
Which epithelium has tall columnar cells in a single layer interspersed with shorter basal cells and nuclei at varying levels? Stratified columnar Stratified squamous Pseudostratified columnar Simple cuboidal
Pseudostratified columnar
What is the function of transitional epithelium? To allow stretching To absorb nutrients To move fluid through tubules To protect against abrasion
To allow stretching
Which epithelium forms glandular epithelium and lines the kidney tubules? Simple cuboidal Pseudostratified columnar Stratified columnar Simple squamous
Simple cuboidal
Which epithelium is best suited for resisting abrasion and preventing pathogen entry into deeper tissues? Areolar Dense regular Stratified squamous Simple cuboidal
Stratified squamous
Which are functions of connective tissue in the body? (more than one correct answer) Absorption Support and protect organs Bind organs to one another Communication
Support and protect organs
Bind organs to one another
Which cells found in connective tissue engulf foreign particles, activate the immune system, and destroy dead or dying cells? Adipocytes Macrophages Reticulocytes Chondroblasts Fibroblasts
Macrophages
Where would transitional epithelium be found? Lining the lumen of an artery Lining the lumen of a kidney tubule Lining the lumen of the urinary bladder Lining the lumen of the small intestine
Lining the lumen of the urinary bladder
While preparing some chicken wings for cooking you observe white fibers connecting the bones and the muscles to bone. What type of fibers are these? Elastic Reticular Collagenous Myosin
Collagenous
Stratified \_\_\_\_\_\_ epithelium is the most widespread epithelium of the body. cuboidal columnar squamous transitional
squamous
Which tissue class supports and binds tissues together? Nervous Epithelial Connective Muscular
Connective
What are the functions of macrophages? (multiple select question)
They engulf foreign particles.
They transport nutrients in the blood and lymph fluid.
They produce fibers and ground substance.
They destroy dead or dying self cells.
They activate the immune system when they encounter antigens.
They engulf foreign particles.
They destroy dead or dying self cells.
They activate the immune system when they encounter antigens.
What are the three fiber types found in fibrous connective tissue? Intermediate Elastic Reticular Collagenous Actin Myosin
Elastic
Reticular
Collagenous
____ cartilage is found in the esophagus
hyaline
Cartilage in the outer ear is ______.
hyaline cartilage
fibrocartilage
elastic cartilage
elastic cartilage
The type of connective tissue found beneath the skin, within the breast, and on the surface of the heart is \_\_\_\_\_\_ tissue. osseous adipose dense regular cartilage
adipose
The top of the outer ear (where you get helix piercings) is made of ____ cartilage
elastic
What is another name for the axon of a neuron? Dendrite Nerve fiber Neurosoma Neuroglia
Nerve fiber
Which part of a neuron receives incoming signals from other cells? Fiber Axon Dendrite Neurosoma
Dendrite
Skin is an example of a(n) _____ membrane.
cutaneous
The membranes lining the inside surface of the respiratory and digestive tracts are examples of
_______ membranes.
mucous
Which of the following best describes tight junctions?
They consist of transmembrane cell-adhesion proteins around the upper part of a cell and hold neighboring cells together.
They consist of the membrane plaques of adjacent cells anchored together; there is a space between cell membranes.
They consist of connexons surrounding a channel leading from one cell to its neighbor.
They consist of transmembrane cell-adhesion proteins around the upper part of a cell and hold neighboring cells together.
The abdominal cavity is lined with a ____ membrane.
serous
What are the three main types of body membranes?
Mucous, serous, and cutaneous
The acid ______ is the protective film that gives skin its slight acidity.
mantle
Which term refers to the protective film found on skin that is involved in bacterial protection? Fungi colonization Antibiotics Acid microbes Acid mantle
Acid mantle
Skin is classified as thick or thin based on the thickness of which layer?
Stratum corneum
What event occurs to preserve heat in the body?
Vasoconstriction of blood vessels in the skin
Which of the following are functions of the skin? ((Multiple select question.)) Vitamin C synthesis Vitamin D synthesis Sensory reception Thermoregulation
Vitamin D synthesis
Sensory reception
Thermoregulation
Which of the following are features of skin that minimize bacterial and fungal growth during an infection.
((Multiple select question.))
The dryness of the skin inhibits microbial growth.
The cells of the skin shed infrequently.
The acid mantle inhibits microbial growth.
Vitamins secreted through the pores inhibits microbial growth.
The dryness of the skin inhibits microbial growth.
The cells of the skin shed infrequently.
The five types of cells found in the epidermis are:
Stem cells, keratinocytes, tactile cells, dendritic cells, and melanocytes
Cells in the epidermis are nourished by blood vessels located in which of the following? Hyperdermis Dermis Subdermis Hypodermis
Dermis
Which of the following are located in the dermis?
Simple cuboidal epithelium and mast cells
Fat and loose connective tissue
Melanocytes and Langerhans cells
Fibers, glands, blood vessels and nerve endings
Fibers, glands, blood vessels and nerve endings
Which term refers to the wavy upward projections at the boundary of the dermis and epidermis? Areolae Striae Dermal papillae Reticular layers
Dermal papillae
The deepest layer of the dermis is called the _____ layer.
reticular
Why are injections frequently administered into the hypodermis?
The subcutaneous tissue is highly vascular.
Define dendritic cells
Immune cells that guards against pathogens that penetrate into the skin
Define tactile cells
Sensory receptors for touch
What are the two zones of the dermis?
Papillary and reticular layer
_____ is a word that means “abnormal redness of the skin.”
Erythema
What usually causes a hematoma? Blows to the skin Exposure to cold temperatures Abrasion from rough surfaces Hot water spills on the skin
Blows to the skin
Fingernails and toenails are derivatives of which epidermal layer? Stratum corneum Stratum lucidum Stratum granulosum Stratum basale
Stratum corneum
Which substance, excreted by the liver, can accumulate to cause jaundice?
Bilirubin
Which type of sweat gland has a duct that opens by way of a pore on the skin surface? Sebaceous gland Ceruminous gland Apocrine sweat gland Merocrine sweat gland
Merocrine sweat gland
Most tumors occur where exposure to the sun is greatest. These areas would include which of the following? Legs, brain, stomach Stomach, head, heart Head, neck, and hands Scalp, arm, knee
Head, neck, and hands
James has a small shiny lesion that develops a central depression that has not invaded the dermis. A biopsy will most likely show that he has which of the following? Surface melanoma Melanoma Basal cell carcinoma Lymphoma
Basal cell carcinoma
The three types of skin cancer can be distinguished from each other by which of the following?
Zones of tissue injury and the ability to synthesize melanin
Appearance of their lesions and zones of tissue injury
Appearance of their lesion and ability to synthesize melanin
Degree of redness and number of remaining keratinocytes
Appearance of their lesions and zones of tissue injury
Lilly goes to the beach 3 times a week to tan. She develops a lesion on her scalp and ears that later form concave ulcers with raised edges. Lilly most likely has which of the following? Lymphoma Basal cell carcinoma Squamous cell carcinoma Melanoma
Squamous cell carcinoma
The study of bone is called ______
osteology
What is the major producer of blood cells? Carbonate salts Red bone marrow Compact bone Calcium cells
Red bone marrow
The process in which dense regular connective tissue hardens to form bone is called _____
ossification
Bones are classified as one of four types based on their shape. The bones of the cranium are examples of _____ bones
flat
Bones such as the vertebrae are classified as _____ bones
irregular
One function of the skeleton is to store calcium and phosphate to help maintain _______ balance
electrolyte
What is the deposition of calcium salts called? Osteomalacia Ossification Calcification Resorption
Calcification
Bones such as the carpals that have the same length and width are classified as _____ bones.
short
Thin, often curved, bones are classified as what shape? Irregular Short Flat Long
Flat
What is the expanded end of a long bone to which tendons and ligaments attach called? Metaphysis Diaphysis Epiphysis Epiphyseal plate
Epiphysis
Bones that are longer than they are wide are classified as ______ bones.
long
The shaft of a long bone is called the _____
diaphysis
Which allows the passage of blood vessels into a bone?
Perforating canal
Nutrient foramen
Central canal
Nutrient foramen
Which describes the structure of a flat bone?
A layer of compact bone is sandwiched between two layers of spongy bone.
A layer of spongy bone is sandwiched between two layers of compact bone.
A layer of spongy bone is sandwiched between two layers of compact bone.
An epiphyseal line is slightly denser \_\_\_\_\_\_. spongy bone periosteum compact bone cartilage
spongy bone
Which bone cells produce the organic bone matrix? Osteoclasts Osteoblasts Chondrocytes Osteocytes
Osteoblasts
What is the hyaline cartilage found covering the ends of bones within a joint called?
Articular cartilage
What is the term for the bone tissue located between the two layers of compact bone in the skull?
Diploe
The action carried out by osteoclasts is called ______.
osteolysis
The protein and carbohydrate portion of bone matrix forms the ______ matter.
organic
Within compact bone, a central canal is found at the center of which structure? A bone An epiphysis A Volkmann canal An osteon
An osteon
Which structures found in spongy bone line up along the bone’s lines of stress?
Trabeculae
Which of the following is a function of yellow bone marrow?
Storage of calcium
Storage of energy
Production of blood cells
Storage of energy
What is the expanded end of a long bone to which tendons and ligaments attach called?
Epiphysis
What are the two principle forms of ossification that occur in the development of the skeletal system?
Endochondral and intramembranous
As a flat bone is produced by intramembranous ossification, which cells are responsible for the resorption of bone tissue that carves out the spongy bone's trabeculae? Chondrocytes Osteoclasts Chondroblasts Osteoblasts
Osteoclasts
________ cartilage is the tissue which is replaced with bone during endochondral ossification
hyaline
Where does the calcium and phosphate used to mineralize bone come from? The blood The lymph Osteoblasts Hyaline cartilage
The blood
Fatty bone marrow that no longer produces blood cells is called ______ bone marrow
Yellow
If a patient has abnormally high blood calcium levels, they are said to have a condition called ______.
hypercalcemia
Which of the following best describes osteomalacia?
An insufficient vitamin E intake in children
The softening of the bones in adults due to calcium depletion
A decreased osteoblast proliferation in adults
The hardening of the bones in adults due to excess mineral deposits
The softening of the bones in adults due to calcium depletion
Where does bone formation occur during endochondral ossification?
Adipose tissue
Hyaline cartilage model
Fibrous membranous sheet
Hyaline cartilage model
Vitamin D, also known as \_\_\_\_\_\_, raises the blood calcium level. cholesterol calcium calcitriol cholecalciferol
calcitriol
Mineral deposition into bones begin when? In fetal ossification During puberty In the first month of life In the first year of life
In fetal ossification
Which adult condition involves the softening of bones due to demineralization? Osteosarcoma Osteomalacia Rickets Osteomyelitis
Osteomalacia
Which hormone inhibits osteoclasts and stimulates osteoblasts to lower blood calcium levels?
Calcitonin
Parathyroid hormone
Calcitriol
Calcitonin
Calcitriol acts on which organs to raise blood calcium levels? ((Multiple select question)) Bones Kidneys Brain Muscles Small intestines
Bones
Kidneys
Small intestines
Which two ions are deposited by osteoblasts into the bone matrix?
Phosphate and calcium
A low blood calcium level stimulates the release of which hormone?
Parathyroid hormone
Thyroid releasing hormone
Calcitonin
Parathyroid hormone
What does the hormone calcitonin do?
Stimulates osteoclasts and inhibits osteoblasts
Inhibits osteoclasts and stimulates osteoblasts
Stimulates osteoclasts and stimulates osteoblasts
Inhibits osteoclasts and inhibits osteoblasts
Inhibits osteoclasts and stimulates osteoblasts
During fracture healing, cartilage is deposited in granulation tissue to form which of the following? A fracture hematoma A woven bone A hard callus A soft callus
A soft callus
True or false: Most fractures are treated using closed reduction.
True
PTH is a hormone released by parathyroid glands in response to which of the following? Sympathetic innervation Low blood calcium levels High blood potassium levels High blood iron levels
Low blood calcium levels
A degenerative bone disease characterized by a loss of bone mass and an increased risk of fracture is called ______
osteoporosis
Which condition occurs because of a defect in collagen deposition that causes bones to be exceptionally brittle?
Osteogenesis imperfecta
Which hormone inhibits osteoclasts and stimulates osteoblasts to lower blood calcium levels?
Calcitriol
Parathyroid hormone
Calcitonin
Calcitonin
A hard callus is composed of _______
bone
When surgery is needed to set a fracture, this treatment is called a(n) _____ reduction
open
What often causes the loss of bone mass seen in osteoporosis in older women? A loss of androgen A loss of parathyroid hormone A loss of calcitriol A loss of estrogen
A loss of estrogen
What is osteogenesis imperfecta?
A loss of bone mineralization resulting in frequent fractures
A defect in collagen deposition that renders bones exceptionally brittle
An inflammation of osseous tissue due to bacterial infection
A defect in collagen deposition that renders bones exceptionally brittle
Name all of the regions in the abdomen (9 regions)
Top row: hypochondriac, epigastric, left hypochondriac. Middle row: right lumbar, umbilical, left lumbar. Bottom row: right inguinal, hypogastric, left inguinal.
Name the 4 quadrants of the abdomen
Right upper (RUQ), left upper (LUQ), right lower (RLQ), left lower (LLQ)
Frontal region
Forehead
Orbital region
Eyes
Otic region
Ears
Buccal region
Cheeks
Mental region
Chin
Oral region
Mouth
Nasal region
Nose
Cephalic region
Head
Cervical region
Neck
Acromial region
Shoulder
Axillary region
Armpit
Sternal region
Sternum
Pectoral region
Pecs/ breast area
Brachial region
Upper arm
Cubital region
Inner elbow
Anticubital reigon
Outer elbow
Abdominal region
Overall front of abdomen
Umbilical region
Bellybutton
Inguinal region
Where your ovaries are
Coxal area
Hips
Antibrachial region
Forearm
Carpal region
Wrist
Palmar region
Palm
Digital region
Fingers or toes
Manus region
Hand
Pubic region
Where your pubic bone is
Femoral region
Femur
Patellar region
Knee
Crural region
Calves/ lower leg
Tarsal region
Ankle region
Metatarsal region
Long bones of toes
Hallux region
Big toe
Pollex region
Thumb
Pedal region
Feet
Occipital region
Back of head
Vertebral region
Spinal column area
Scapular region
Upper left and right back (scapulas)
Infrascapular region
Middle left and right back
Lumbar region
Lower back around the vertebral region
Gluteal region
Butt
Popliteal region
Back of knee
Calcineal region
Heel of foot
Plantar region
Arch of the foot
Olecranial region
Back of elbow
Define anterior-posterior
Front-back
Define ventral-dorsal
Belly-back
Define superior-inferior
Above and below (applies to axial skeleton)
Define medial-intermediate-lateral
Toward the midline of the body, in-between, and away from the midline of the body
Define ipsilateral-contralateral
Same side of body and opposite side of body
Define proximal-middle-distal
Nearer to the top of the limb, away from the top of the limb
Define superficial-deep
Closer to the body’s surface and away from the body’s surface
Define the sagittal plane
Median plane; cuts the person in half vertically and separates left from right
Define the transverse plane
Horizontal plane; cuts the person in half horizontally at the abdomen
Define the coronal plane
Frontal plane; cuts the person in half vertically; separates front and back
Define oblique plane
Diagonal plane; cuts the person in half diagonally from right acromial to left femoral
Define pericardial cavity
Heart
Define pelvic cavity
Cavity below the abdominal cavity
Abdominopelvic cavity
Contains both the abdominal cavity and the pelvic cavity
What divides the pericardial cavity and the thoracic cavity from the abdominal cavity?
The diaphragm
Define the ventral cavity
Contains all cavities in the torso
Define dorsal cavity
The cranial cavity and the vertebral cavity
Define thoracic cavity
Contains the pleural cavity, pericardial cavity, and mediastinum
Define the pleural cavity
Lung cavity
There are ____ trillion cells of ____ different cell types
There are 50 trillion cells of 200 different cell types
Name the 4 broad categories of tissues
Epithelial tissue
Connective tissue
Nervous tissue
Muscular tissue
Define histology
The study of tissues
Define organ
A structure with discrete boundaries that is composed of two or more tissue types
Define tissue
A group of similar cells and cell products working together to perform a specific role in an organ
The four primary tissues differ from each other in what three ways?
- Types and functions of their cells
- Characteristics of the matrix (extracellular material)
- Relative amount of space occupied by cells versus matrix
The extracellular matrix is composed of what two things?
1) Fibrous proteins
2) Ground substance (clear gel)
What other names can be used for ‘ground substance’?
Tissue fluid, extracellular fluid (ECF), or interstitial fluid
What are the six functions of epithelial tissue?
Covers body surfaces and lines body cavities
Protect deeper tissues from injury and infection
Produce and release chemical secretions
Excretion and absorption
Selectively filter substances
Makes up most glands
Describe the characteristics of epithelial tissue
Cells are very close together High rate of mitosis (regenerative) Apical and basal surfaces Basal surfaces faces basement membrane Apical surfaces may have microvilli or cilia Avascular but innervated
The ______ _______ anchors the epithelium to the connective tissue below it
basement membrane
Describe the differences between simple and stratified epithelium
Simple epithelia: -Contain one layer of cells -Named by shape of cells -All cells touch basement membrane Stratified epithelia: -Contain more than one layer -Named by shape of apical cells -Some cells rest on top of others and do not touch basement membrane
In _____ epithelia, not all cells touch the basement membrane
stratified
In ______ epithelia, all cells touch the basement membrane
simple
What are the four types of simple epithelia?
Simple squamous
Simple cuboidal
Simple columnar
Pseudostratified columnar
Describe pseudostratified columnar cells
Every cell reaches the basement membrane but not all cells reach the free surface; Falsely appears stratified
What are goblet cells?
Wineglass-shaped mucus-secreting cells in simple columnar and pseudostratified epithelia
Describe simple squamous epithelium and where it can be found
- Permits rapid diffusion or transport of substances
- Secretes serous fluid
- Locations: air sacs of lungs (alveoli), inner lining of blood vessels & heart (endothelium), and serosa
Describe simple cuboidal epithelium and where it can be found
- Absorption and secretion, mucus production and movement
- Locations: Kidney tubules and certain glands (thyroid, mammary and salivary glands)
Describe simple columnar epithelium and where it can be found
- Single row of tall, narrow cells; oval nuclei in basal half of cell
- Absorption and secretion; secretion of mucus
- Brush border of microvilli, ciliated in some organs, may possess goblet cells
- Locations: lining of GI tract, uterus, and uterine tubes
Describe pseudostratified epithelium and where it can be found
- Secretes and propels mucus
- Has cilia and goblet cells
- Looks multilayered, but all cells touch basement membrane
- Nuclei at several layers
- Locations: respiratory tract
Describe stratified epithelia
- Range from 2 to 20 or more layers of cells
- Some cells rest directly on others
- Only the deepest layer attaches to basement membrane
Describe the types of stratified epithelia
- Three stratified epithelia are named for the shapes of their apical surface cells
- Includes stratified squamous (only one expected to recognize and know functions)
- The fourth type is transitional epithelium
What is the most widespread epithelium in the human body?
Stratified squamous epithelium
Describe stratified squamous epithelia and its two types
-Deepest layers undergo continuous mitosis
-Daughter cells push toward the surface and become flatter as they migrate upward
-Top layer is exfoliated
-Two kinds
Keratinized—top layer is dead
Non-keratinized—top layer not dead
Describe keratinized stratified squamous epithelium and where it’s located
Resists abrasion; retards water loss through skin; resists penetration by pathogenic organisms
Locations: epidermis; palms and soles heavily keratinized
Describe non-keratinized stratified squamous epithelium and where it’s located
Resists abrasion and penetration of pathogens
Locations: tongue, oral mucosa, esophagus, and vagina
Describe transitional epithelium and where it’s located
Permits stretching (distension); surface cells change from round to flat when stretched Locations: ureter and urinary bladder
Describe the functions of connective tissue
Binding and Support Physical protection Immune protection Movement Storage Transport
_____ tissue is the most diverse and abundant type of tissue
Connective
Give examples of each of the functions of connective tissues
Connecting organs—tendons and ligaments
Support—bones and cartilage
Physical protection—cranium, ribs, sternum
Immune protection—white blood cells attack foreign invaders
Movement—bones provide lever system
Storage—fat, calcium, phosphorus
Heat production—metabolism of brown fat in infants
Transport—blood
Describe the characteristics of connective tissue
-Cells occupy less space than matrix (usually a large amount of extracellular matrix)
-Most cells are not in direct contact with each other
-Highly variable vascularity
Loose connective tissues have many blood vessels, whereas cartilage has few or no blood vessels
List and describe the 5 basic categories of connective tissue
- Fibrous Connective Tissue (Connective Tissue Proper): most diverse category; fibroblasts produce fibers and ground substance of matrix.
- Adipose Tissue: may be classified with loose connective tissue proper
- Cartilage (has 3 types): chondroblasts form matrix
- Bone (Osseous tissue): osteoblasts form matrix
- Blood
List and describe the three types of fibers that can be found in fibrous connective tissue
- Collagen fibers: tough, flexible, and stretch-resisant
- Reticular fibers: branching collagen fibers that forms a network
- Elastic fibers (Elastin): Allows stretch and recoil
What is fibrous connective tissue made of?
Fibers and a ground substance
Describe the ground substance of fibrous connective tissues
Usually has a gelatinous to rubbery consistency
Describe collagen fibers and where they’re found
Found in fibrous connective tissue, it is the most abundant protein: 25%. Tendons, ligaments, and deep layer of the skin are mostly collagen.
What is the most abundant proteines
Collagen (25%)
Describe reticular fibers and where they can be found
Found in fibrous connective tissue, it is thin collagen fibers coated with glycoprotein. Forms the framework of the spleen and lymph nodes.
Describe elastic fibers
Found in fibrous connective tissues, they branch and rejoin each other
What are the two main types of fibrous connective tissue? Describe them.
Loose connective tissue and dense connective tissue.
Loose connective tissue has more gel-like ground substance between cells, and its two types are areolar and reticular.
Dense connective tissue has fibers that fill spaces between cells, and its two types are dense regular and dense irregular.
What are the two main types of fibrous loose connective tissue?
Areolar and reticular
What are the two main types of fibrous dense connective tissue?
Dense regular and dense irregular
Describe areolar tissue (a type of fibrous loose connective tissue) and where it’s found
All 3 fibers are found; loosely organized; abundant blood vessels.
Wraps & cushions organs; underlies epithelia, in serous membranes, between muscles, passageways for nerves and blood vessels.
Areolar tissue—loosely organized fibers, abundant blood vessels, and a lot of seemingly empty space
Possess all six cell types
Fibers run in random directions
Mostly collagenous, but elastic and reticular also present
Found in tissue sections from almost every part of the body
Surrounds blood vessels and nerves
Nearly every epithelium rests on a layer of areolar tissue
Blood vessels provide nutrition to epithelium and waste removal
Ready supply of infection-fighting leukocytes that move about freely in areolar tissue
Describe reticular tissue (a type of fibrous loose connective tissue) and where it’s found
Mesh of reticular fibers and fibroblasts
Forms supportive framework for lymphatic organs
Found in lymph nodes, spleen, thymus, and bone marrow
Describe dense regular connective tissue (a type of fibrous dense connective tissue) and where it’s found
Densely packed, parallel collagen fibers
Tendons attach muscles to bones and ligaments hold bones together
Describe dense irregular connective tissue (a type of fibrous dense connective tissue) and where it’s found
Dense, randomly arranged, collagen fibers
Withstands unpredictable stresses
Locations: dermis of skin; organ capsules
Describe adipose tissue
Space between adipocytes occupied by areolar tissue, reticular tissue, and blood capillaries
Functions: Energy storage, insulation, cushioning
Fat is the body’s primary energy reservoir
The quantity of stored triglyceride and the number of adipocytes are quite stable in a person
Fat is recycled continuously
New triglyceride synthesized while old molecules hydrolyzed and released to blood
Describe cartilage
Stiff connective tissue with flexible matrix
Describe what chondroblasts do
They produce the matrix that will trap them
Describe chondrocytes
Cartilage cells that are trapped in lacunae (cavities)
Describe perichondrium
A sheath of dense irregular connective tissue that surrounds elastic and most hyaline cartilage (not articular cartilage); contains reserve population of chondroblasts
Describe the characteristics of cartilage
-No blood vessels, which means that diffusion brings nutrients and removes wastes and it heals slowly.
-Matrix contains collagen fibers
-Types of cartilage vary with fiber composition
(Hyaline cartilage, fibrocartilage, and elastic cartilage)
List the 3 types of cartilage
Hyaline cartilage, fibrocartilage, and elastic cartilage
Describe hyaline cartilage and where it’s found
Clear, glassy appearance because of fineness of collagen fibers
Locations: articular cartilage, costal cartilage, respiratory cartilage, fetal skeleton
Describe elastic cartilage and where it’s found
Contains abundant elastic fibers; covered with perichondrium
Provides flexible, elastic support
Locations: external ear and epiglottis
Describe fibrocartilage and where it’s found
Contains large bundles of collagen fibers
Resists compression and absorbs shock
Locations: pubic symphysis, menisci of knee, and intervertebral discs
Describe bone
Bone (osseous) tissue has a hard calcified matrix with collagen fibers
Define osteoblasts and osteocytes
Osteoblasts produce the matrix
Osteocytes are mature bone cells within lacunae
What are the two types of bone?
Spongy bone: porous appearance
Compact bone: denser, calcified tissue with no visible spaces
Describe compact bone
Compact bone is arranged in cylinders that surround central canals that run longitudinally through shafts of long bones
What type of tissue is blood, and what does it do?
Fluid connective tissue that transports cells and dissolved matter from place to place
Describe what blood is made of
Plasma (blood’s ground substance) and formed elements (cells and cell fragments)
List and describe the formed elements of blood
Erythrocytes—red blood cells (RBCs)
Leukocytes—white blood cells (WBCs)
Platelets—cell fragments involved in clotting
What are the two types of excitable tissues?
Muscle and nervous
Define excitability
The ability to respond to stimuli by changing membrane potential
Define membrane potential
An electrical charge difference (voltage) that occurs across the cell membrane
Describe what happens when changes in voltage happen in muscle and nerve cells
In nerve cells: changes in voltage result in rapid transmission of signals to other cells
In muscle cells: changes in voltage result in contraction, shortening of the cell
Define nervous tissue
A tissue specialized for communication by electrical and chemical signals
What are the two components of nervous tissue?
Neurons (nerve cells) and neuroglia (glial cells)
Describe neurons
Detect stimuli
Respond quickly
Transmit information rapidly to other cells
Cannot replicate/ divide
Describe neuroglia
Protect and assist neurons
“Housekeepers” of nervous system
More numerous than neurons
Can replicate/ divide
What are the three parts of a neuron?
Axon, dendrites, and neurosoma
Describe muscular tissue and its functions
- Elongated cells that are specialized to contract (shorten) in response to stimulation
- Primary job is to exert physical force on other tissues and organs
- Creates movements involved in body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation
- Important source of body heat
List the 3 types of muscle
Skeletal, cardiac, and smooth
Describe skeletal muscle tissue
Long thin cells called muscle fibers; multinucleate
Most skeletal muscles attach to bone
Striations—alternating dark and light bands
Voluntary—conscious control over skeletal muscles
Describe cardiac muscle tissue
Cardiomyocytes are branched, shorter than skeletal muscle fibers; uninucleate
Intercalated discs join cardiomyocytes end to end
Provide electrical and mechanical connection
Striated and involuntary (not under conscious control)
Describe smooth muscle tissue
Short, fusiform myocytes; uninucleate
Non-striated and involuntary
Most is visceral muscle—making up parts of walls of hollow organs
Describe the 3 parts of the neuron
Neurosoma (cell body) -Contains nucleus & other organelles -Controls protein synthesis Dendrites -Multiple short, branched processes -Receive signals from other cells -Transmit messages to neurosoma Axon (nerve fiber) -Sends outgoing signals to other cells -Can be more than a meter long
Define cell junctions
Connections between two cells
Most cells are anchored to what?
Each other or the matrix
Describe the purpose of cell junctions
Cells communicate with each other, resist mechanical stress, and control what moves through the gaps between them
What are the 3 types of cell junctions?
Tight junctions, desmosomes, and gap junctions
Describe tight junctions and where they’re found
- Seals off intercellular space, making it difficult for substance to pass between cells
- Found in the epidermis, stomach, and small intestines
Describe desmosomes and where they’re found
- A type of cell junction that keeps cells from pulling apart—resist mechanical stress.
- Found in cardiac muscle, the uterine cervix, and the epidermis
Describe gap (communication) junctions and where they’re found
- Formed by ring-like connexons; the cells now share part of their cell membrane.
- Ions, nutrients, and other small solutes pass between cells
- Found in cardiac and smooth muscle, embryonic tissue, lens and cornea
True or false: gap junctions are absent in skeletal muscle
True
Define and describe glands
- A cell or organ that secretes substances for use elsewhere in the body or releases them for elimination from the body
- Usually composed of epithelial tissue with a connective tissue framework and capsule
Describe the differences between secretion and excretion
Secretion—product useful to the body
Excretion—waste product
Describe exocrine glands
- Maintain their contact with surface of epithelium by way of a duct
- Surfaces can be external (examples: sweat, tear glands) or internal (examples: pancreas, salivary glands)
Describe endocrine glands
-They have no ducts; instead, they secrete hormones directly into blood
Give some examples of organs that have both endocrine and exocrine responsibilities
The liver, gonads, and pancreas
Define hormones
Chemical messengers that stimulate cells elsewhere in the body
Give examples of endocrine glands
Thyroid, adrenal, and pituitary glands
Describe unicelluar glands and give examples
- Found in an epithelium that is predominantly nonsecretory
- Can be exocrine or endocrine
- Examples: mucus-secreting goblet cells in trachea or endocrine cells of stomach
What are the different characteristics we can use to describe exocrine glands?
Duct shape:
simple (unbranched) vs. compound (branched)
Gland shape:
Tubular: narrow secretory portion
Acinar: secretory cells form dilated sac (acinus or alveolus)
Tubuloacinar: both tubular and acinar portions
Describe the 3 different modes of secretion
1) Merocrine
- Uses vesicles that release their secretion by exocytosis.
- Used by eccrine glands.
2) Apocrine
- Lipid droplet covered by membrane and cytoplasm buds from cell surface
- Mode of milk fat secretion by mammary gland cells
3) Holocrine:
- Cells accumulate a product until they disintegrate
- Secrete a mixture of cell fragments and synthesized substances
- Ex: sebaceous glands of hair and skin, eyelid glands.
Describe the merocrine mode of secretion
- Uses vesicles that release their secretion by exocytosis.
- Used by eccrine glands.
Describe the apocrine mode of secretion and give an example
- Lipid droplet covered by membrane and cytoplasm buds from cell surface
- Mode of milk fat secretion by mammary gland cells
Describe the holocrine mode of secretion and give examples
- Cells accumulate a product until they disintegrate
- Secrete a mixture of cell fragments and synthesized substances
- Ex: sebaceous glands of hair and skin, eyelid glands.
True or false: Membranes may be only epithelial, only connective, or a mix of epithelial, connective, and muscular tissues
True
What is the largest membrane in the body?
Cutaneous membrane (the skin)
Define and describe the cutaneous membrane
- Cutaneous membrane (the skin) is the largest membrane in the body.
- Composed of stratified squamous epithelium (epidermis) resting on a layer of connective tissue (dermis)
- Relatively dry layer serves protective function
What are the two main types of internal membrane?
Mucous membranes and serous membranes.
Describe mucous membranes (mucosa)
- Layers consists of epithelium, areolar tissue (lamina propria), and smooth muscle (muscularis mucosa)
- Lines cavities/passages that open to the external environment
- Produces mucus (thicker, stickier)
What 4 organ systems have mucous membranes?
Reproductive, digestive, respiratory, and urinary
Describe serous membranes (serosa)
- Composed of simple squamous epithelium resting on a layer of areolar tissue
- Internal membrane; lines cavities with no connection to the outside
- Produces serous fluid
What are some membranes made up of only epithelium?
Anterior surfaces of cornea and lens of eye
What are 4 membranes made up of only connective tissues?
Dura mater (meninges)
Synovial membranes
Periosteum
Perichondrium
Define tissue growth
Increasing the number of cells or size of existing cells
Define hyperplasia
Growth through cell multiplication
Define hypertrophy and give two examples
The enlargement of preexisting cells
Examples: Muscle growth through exercise, accumulation of body fat
Define and describe neoplasia
The development of a tumor (neoplasm)
-It can be benign or malignant, and is composed of abnormal, nonfunctional tissue
What are the 3 types of tissue growth?
Hypertrophy, hyperplasia, and neoplasia
Define, describe, and give examples of the two modes of tissue repair
1) Regeneration: replacement of dead or damaged cells by the same type of cell as before
- Restores normal function
- Examples: repair of minor skin or liver injuries
2) Fibrosis: replacement of damaged cells with scar tissue
- Scar holds organs together, but does not restore function
- Examples: repair of severe cuts and burns, scarring of lungs in tuberculosis
List the steps of healing a skin wound
1) Inflammation: brings white blood cells, platelets, etc to the area. Creates swollenness, warmth, and redness.
2)Initial patch up and cleaning:
Blood clot forms; forms scab that temporarily seals the wound and blocks infection.
Macrophages clean up the scene.
3) New capillaries sprout from nearby vessels.
Fibroblasts deposit new collagen
Begins 3-4 days after the injury and lasts up to 2 weeks.
4) Regeneration, fibrosis, and remodeling: epithelial cells around the wound multiply and migrate beneath the scab (tissue regenerates)
Fibrosis: Underlying connective tissue undergoes fibrosis
Remodeling (maturation) phase begins several weeks after injury and may last up to 2 years
Categorize body tissues by how well they repair themselves into groups of good, moderate, poor, and almost no repair
Good: epithelial, bone, blood, areolar, dense irregular
Moderate: dense regular, smooth muscle
Poor: cartilage, skeletal muscle
Almost none: cardiac muscle, neurons (in CNS)
Name the four primary classes into which all adult tissues are classified.
Epithelial tissue, connective tissue, nervous tissue, and muscular tissue
Define histology
The study of tissues
Compare the general features of the four major tissue types.
All 4 tissues types are similar to each other in the following ways:
All tissue types are made up of cells.
All tissue types have an extracellular matrix
All cells and tissues occupy space
Contrast the general features of the four major tissue types.
The 4 tissue types vary in:
The types and functions of their cells
The characteristics of their matrix (extracellular material)
The relative amount of space occupied by their cells versus their matrix
Describe the unique functions of the epithelium
- It covers body surfaces and lines body cavities
- It protects deeper tissues from injury and infection
- It produces and releases chemical secretions; also involved with excretion and absorption
- It selectively filters substances
- It makes up most glands
Describe the unique characteristics of epithelium
- Its cells are very close together
- Its cells have a high rate of mitosis (regenerative)
- Has apical and basal surfaces
Name and describe the 3 types of simple epithelium
1) Simple squamous
Permits rapid diffusion or transport of substances
It secretes serous fluid
Found in: air sacs of lungs (alveoli), inner lining of blood vessels & heart (endothelium), and serosa
2) Simple cuboidal
It’s good at absorption and secretion, mucus production, and movement
Found in: Kidney tubules and certain glands (thyroid, mammary and salivary glands)
3) Simple columnar
Specializes in absorption and secretion; secretion of mucus
Has a brush border of microvilli, ciliated in some organs, and may possess goblet cells. It’s the only tissue with microvilli.
Made up of a single row of tall, narrow cells; oval nuclei in basal half of cell
Found in: the lining of the GI tract, the uterus, and uterine tubes
4) Pseudostratified columnar
Secretes and propels mucus
Has cilia and goblet cells
Looks multilayered, but all cells touch the basement membrane
Has nuclei at several layers
Found in the respiratory tract
Describe stratified squamous epithelium
The most widespread epithelium in the body
Deepest layers undergo continuous mitosis
Daughter cells push toward the surface and become flatter as they migrate upward, and the top layer is exfoliated
Name and describe the two types of stratified squamous epithelium
1) Keratinized stratified squamous epithelia
Resists abrasion; retards water loss through skin; resists penetration by pathogenic organisms.
Top layer of cells are dead.
Locations: epidermis; palms and soles heavily keratinized
2) Non-Keratinized stratified squamous epithelia
Resists abrasion and penetration of pathogens
Top layer of cells is not dead.
Locations: tongue, oral mucosa, esophagus, and vagina
Name the two main types of stratified epithelia. Can these be broken down into more types?
Stratified squamous epithelia and transitional epithelia. There are two types of stratified squamous epithelia: keratinized and non-keratinized.
Describe transitional epithelia and where it’s located
A type of stratified epithelia that permits stretching (distension); surface cells change from round to flat when stretched
Locations: ureter and urinary bladder
Explain how the structural differences between epithelia relate to their functional differences.
1) Microvilli are only found in simple columnar epithelial tissue, and since microvilli increase surface area of a cell exponentially, this allows simple columnar epithelium to be excellent at absorption and secretion (since increased cell surface area equals increased absorption rate). The microvilli and celiation in some organs (such as in the uterine tubes) allows for cells such as eggs to be moved around.
2) Simple squamous epithelia has a lot of empty space, which is how it permits rapid diffusion and transportation of substances, and is why it’s found in the alveoli of the lungs (since they need to absorb oxygen).
3) Simple cuboidal epithelium are able to absorb and secrete easily because they appear flattened, so there is less surface area substances need to pass through.
4) Transitional epithelium’s top layer of cells (surface cells) are able to change from round to flat when stretched out, which makes them perfect for areas that need to stretch such as the urinary bladder (which needs to stretch to hold urine).
Describe the properties that most connective tissues have in common.
-Their cells occupy less space than matrix (usually there’s a large amount of extracellular matrix)
-Most of their cells are not in direct contact with each other
-They have a highly variable vascularity
(Loose connective tissues have many blood vessels whereas cartilage has few or no blood vessels)
What is the most diverse and abundant type of tissue
Connective tissue
Discuss the types of cells found in connective tissue.
1) Fibrous Connective Tissue (Connective Tissue Proper)
Made up of fibers (collagen, reticular, and elastic fibers) and ground substance of the matrix produced by fibroblasts.
2) Adipose Tissue
Adipocytes (fat cells) contain a large amount of space reserved for storing fats.
3) Cartilage
Chondroblasts form the matrix, which is then occupied by chondrocytes (cartilage cells)
4) Bone (Osseous tissue)
Osteoblasts form the matrix, which is then occupied by osteocytes.
5) Blood
Made up of plasma, platelets, WBCs, and RBCs.
What are the two main types of fibrous connective tissue? Can they be broken down into further categories.
Loose and dense connective tissue are the two main types. The two types of loose fibrous connective tissue are areolar and reticular. The two types of dense connective tissue are dense regular and dense irregular
Define and describe areolar tissue. Also, where is it found?
- One of the two types of loose connective tissue, which is a type of fibrous connective tissue.
- All 3 fibers/ 6 total cell types are found; loosely organized; abundant blood vessels; lots of empty space.
- Mostly collagenous, but elastic and reticular also present
- Wraps & cushions organs; underlies epithelia, in serous membranes, between muscles, passageways for nerves and blood vessels
- Fibers run in random directions
- Found in tissue sections from almost every part of the body
- Surrounds blood vessels and nerves
- Nearly every epithelium rests on a layer of areolar tissue
- Blood vessels provide nutrition to epithelium and waste removal
- Ready supply of infection-fighting leukocytes that move about freely in areolar tissue
Define and describe reticular tissue. Also, where is it found?
- One of the two types of loose connective tissue, which is a type of fibrous connective tissue.
- Mesh of reticular fibers and fibroblasts
- Forms supportive framework for lymphatic organs
- Found in lymph nodes, spleen, thymus, and bone marrow
Define and describe dense regular tissue
- One of the two types of dense connective tissue, which is one of the types of fibrous connective tissue.
- Densely packed, parallel collagen fibers
- Tendons attach muscles to bones and ligaments hold bones together
Define and describe dense irregular tissue
- Dense, randomly arranged, collagen fibers
- Withstands unpredictable stresses
- Locations: dermis of skin; organ capsules
Describe adipose tissue
- A type of connective tissue
- Space between adipocytes occupied by areolar tissue, reticular tissue, and blood capillaries.
- The quantity of stored triglyceride and the number of adipocytes are quite stable in a person.
- Fat is recycled continuously; new triglycerides synthesized while old molecules hydrolyzed and released to blood
- Functions: Energy storage, insulation, cushioning
- Fat is the body’s primary form of energy storage.
Describe cartilage
Stiff connective tissue with flexible matrix; chondroblasts produce the matrix that will trap them in lacunae (cavities) and become chondrocytes.
Contains reserve population of chondroblasts
List and describe the 3 types of cartilage and where they can be found
1) Hyaline cartilage
Clear, glassy appearance because of fineness of collagen fibers
Surrounded by perichondrium
Locations: articular cartilage, costal cartilage, respiratory cartilage, fetal skeleton
2) Elastic cartilage
Contains abundant elastic fibers; covered with perichondrium
Provides flexible, elastic support
Locations: external ear and epiglottis
3) Fibrocartilage
Contains large bundles of collagen fibers; no perichondrium.
Resists compression and absorbs shock
Locations: pubic symphysis, menisci of knee, and intervertebral discs
Describe bone (osseous tissue)
Has a hard calcified matrix with collagen fibers; made by osteoblasts who build and become osteocytes in lacunae. A type of connective tissue
Describe the two types of bone (osseous tissue)
1) Spongy bone
Porous appearance with visible holes.
2) Compact bone
Compact bone is arranged in cylinders that surround central canals that run longitudinally through shafts of long bones
Describe blood
-A fluid connective tissue
-Transports cells and dissolved matter from place to place
-Plasma—blood’s ground substance
Formed elements—cells and cell fragments:
-Erythrocytes—red blood cells (RBCs)
-Leukocytes—white blood cells (WBCs)
-Platelets—cell fragments involved in clotting
Explain what distinguishes excitable tissues from other tissues.
They have the ability to respond to stimuli by changing membrane potential.
Name the cell types that compose nervous tissue.
Neurons and neuroglia.
Identify and describe the major parts of a nerve cell.
1) Neurosoma (cell body) Contains nucleus & other organelles Controls protein synthesis 2) Dendrites Multiple short, branched processes Receive signals from other cells Transmit messages to neurosoma 3) Axon (nerve fiber) Sends outgoing signals to other cells Can be more than a meter long
Name the three kinds of muscular tissue and describe them
1) Skeletal:
Long thin cells called muscle fibers; multinucleate
Most skeletal muscles attach to bone
Striations—alternating dark and light bands
They only type of muscle that is voluntary, meaning conscious control over skeletal muscles.
2) Cardiac:
Cardiomyocytes are branched, shorter than skeletal muscle fibers; uninucleate
Intercalated discs join cardiomyocytes end to end
Provide electrical and mechanical connection
Striated and involuntary (not under conscious control)
3) Smooth:
Short, fusiform myocytes; uninucleate
Non-striated and involuntary
Most is visceral muscle—making up parts of walls of hollow organs
Define cell junctions and describe what they do
Cell junctions are connections between two cells; most cells are anchored to each other through a cell junction or their matrix
Cells communicate with each other, resist mechanical stress, and control what moves through the gaps between them
List and describe the 3 types of cell junctions
1) Tight junctions:
Seals off intercellular space, making it difficult for substance to pass between cells
Found in the epidermis, stomach, and small intestines
2) Desmosomes
A type of cell junction that keeps cells from pulling apart—resist mechanical stress.
Found in cardiac muscle, the uterine cervix, and the epidermis
3) Gap junctions
Formed by ring-like connexons; the cells now share part of their cell membrane.
Ions, nutrients, and other small solutes pass between cells
Found in cardiac and smooth muscle, embryonic tissue, lens and cornea
Describe the two main kinds of glands
1) Exocrine glands: maintain their contact with surface of epithelium by way of a duct
Their surfaces can be external (examples: sweat, tear glands) or internal (examples: pancreas, salivary glands)
Classified by duct shape and gland shape.
2) Endocrine glands: have no ducts; secrete hormones directly into blood
Examples: thyroid, adrenal, and pituitary glands.
Describe unicellular glands and give examples
Found in an epithelium that is predominantly nonsecretory; can be exocrine or endocrine
Examples: mucus-secreting goblet cells in trachea or endocrine cells of stomach
Define a gland and describe its typical anatomy
- A gland is defined as a cell or organ that secretes substances for use elsewhere in the body or releases them for elimination from the body
- They are usually composed of epithelial tissue with a connective tissue framework and capsule
Name and describe the three different modes of glandular secretion.
1) Merocrine
Uses vesicles that release their secretion by exocytosis.
Used by eccrine glands.
2) Apocrine
Lipid droplet covered by membrane and cytoplasm buds from cell surface
Mode of milk fat secretion by mammary gland cells
3) Holocrine
Cells accumulate a product until they disintegrate (entire cell dies and is secreted, hence why these glands’ substances are oily)
Secrete a mixture of cell fragments and synthesized substances
Ex: sebaceous glands of hair and skin, eyelid glands.
Describe the types and composition of the body’s membranes.
1) Cutaneous membrane (the skin)
Largest membrane in the body
Stratified squamous epithelium (epidermis) resting on a layer of connective tissue (dermis)
Relatively dry layer serves protective function
2) Mucosal membranes
Layers consists of epithelium, areolar tissue (lamina propria), and smooth muscle (muscularis mucosa)
An internal membrane that lines cavities/passages that open to the external environment
Produces mucus (thicker, stickier)
This membrane can be found in 4 organ systems: reproductive, digestive, respiratory, and urinary.
3) Serous membranes
Composed of simple squamous epithelium resting on a layer of areolar tissue
Internal membrane; lines cavities with no connection to the outside
Produces serous fluid
4) Membranes made of only epithelium:
Anterior surfaces of cornea and lens of eye
5) Membranes made of only connective tissue:
Dura mater (meninges), synovial membranes, periosteum, perichondrium
Name and describe the modes of tissue growth.
1) Hyperplasia: growth through cell multiplication
2) Hypertrophy: enlargement of preexisting cells
Examples: muscle growth through exercise, accumulation of body fat
3) Neoplasia: development of a tumor (neoplasm)
Tumor can be benign or malignant
Composed of abnormal, nonfunctional tissue
Name and describe the ways the body repairs damaged tissues.
1) Regeneration: replacement of dead or damaged cells by the same type of cell as before
Restores normal function
Examples: repair of minor skin or liver injuries
2) Fibrosis: replacement of damaged cells with scar tissue
Scar holds organs together, but does not restore function
Examples: repair of severe cuts and burns, scarring of lungs in tuberculosis
List the functions of the skin and relate them to its structure.
1) Resistance to trauma and infection:
- Keratin
- Dermacidin & defensins
- Acid mantle acts as an antimicrobial barrier.
- There are very few spaces between cells in the epidermis to protect against trauma and infection.
2) Other barrier functions
- Water (protects against dehydration): The stratum corneum is a layer of dead cell membranes, which provides a layer of protection against water.
- UV radiation: melanin aids in UV protection
- Harmful chemicals
3) Vitamin D synthesis
- Skin carries out first step; Liver & kidneys complete process
4) Sensation receptors
- Touch, temperature, pressure, vibration, tickle, itch, and pain sensations
5) Regulation of body temperature
- Thermoreceptors
- Vasoconstriction/vasodilation; if you are too warm, cutaneous blood vessels vasodilate
- Perspiration
6) Nonverbal communication
- Facial expressions
- The color of skin based on factors such as blood flow/ hemoglobin and carotene can display signs of illness without verbal communication.
Describe the histological structure of the epidermis, dermis, and subcutaneous tissue.
1) The epidermis consists of keratinized stratified squamous epithelial tissue
2) The dermis consists of two layers:
- Papillary layer: A thin layer of areolar connective tissue
- Reticular layer: A thicker layer of dense irregular connective tissue.
3) Subcutaneous tissue: Consists primarily of adipose connective tissue, but also contains areolar connective tissue.
Describe the difference between thick and thin skin.
Unlike thin skin, thick skin does not contain hair follicles and it has an extra thin white/clear epidermal layer that is not present in thin skin called the stratum lucidum. This causes dermal papillae to be more pronounced in thick skin.
Describe the normal and pathological colors that the skin can have
1) Cyanosis: blueness due to oxygen deficiency
- Oxygen deficiency is usually due to events that cause respiratory distress. This includes things such as drowning, severe asthma attacks, lung failure, pertussis in infants, choking, etc.
2) Erythema: redness due to increased blood flow to skin.
- Increased blood flow to the skin can be caused by injuries such as heat burns, sunburns, consumption of alcohol, or strong emotions such as embarrassment or anger.
3) Pallor: paleness due to decreased blood flow to skin
- Decreased blood to the skin often happens during or immediately prior to syncope or during illness. Malnutrition can also be a cause of pallor.
4) Albinism: milky white skin and blue-gray eyes due to genetic lack of melanin synthesizing enzyme
- This is only due to genetic mutations and cannot develop during a person’s lifetime after birth.
5) Jaundice: yellowing due to bilirubin in blood (can be caused by compromised liver function)
- Often seen in newborn babies or those with liver failure.
6) Hematoma: bruising (clotted blood under skin)
- Usually happens due to blunt force to the skin
Describe the basic structure of a hair and its accessory structures (piloerector muscle, etc.)
1) Bulb: Contains matrix cells (mitotically active cells). Located beneath the surface of the skin and is wider than the rest of the hair.
2) Root: the remainder of the hair in the follicle
Located beneath the surface of the skin and is just above the bulb.
3) Shaft: the portion of the hair that’s above the skin surface
4) Three layers of a hair can be seen in a cross section: Medulla (core), Cortex, Cuticle (outer layer)
5) Hair receptors: Sensory nerve fibers that are entwined with follicles that detect hair movement
6) Piloerector muscle: Smooth muscle that attaches the follicle to dermis; contracts to make hair stand on its end, which causes goose bumps
Discuss the basic functions of hair.
1) Protection: The hair on your scalp provides your head with more protection against sunburns.
2) Light touch: Hair helps you sense light touch due to the presence of hair receptors.
3) Heat retention: The hair on your head provides an extra layer to trap warm air.
4) Excretion: Sebaceous glands found on hair follicles excrete sebum, which helps keep skin and hair from drying out.
Describe the basic structure and function of nails.
Nails are clear, hard derivatives of stratum corneum. They’re composed of thin, dead cells packed with hard keratin.
Provides the tops of our fingertips and toes with an extra layer of protection.
Name two types of sweat glands, and describe the structure and function of each
1) Merocrine sweat glands
- Most numerous type of skin glands
- The gland’s duct opens to the surface of the skin
- Regulates body temperature by allowing for perspiration
2) Apocrine sweat glands
- Found in the regions of the groin, anal region, axilla, areola, and beard (males)
- These glands are inactive until puberty; responds to stress and sexual stimulation
- Ducts lead to nearby hair follicles
- Believed to secrete pheromones
Describe the location, structure, and function of sebaceous glands.
Most sebaceous glands open into a hair follicle, meaning they aren’t present in thick skin.
They utilize a holocrine secretion style and secrete sebum, which is an oily secretion that keeps skin and hair from becoming dry, brittle, and cracked. It also inhibits the growth of bacteria & fungi (ringworm)
Name some other cutaneous glands
1
1) Ceruminous glands in external ear canal
- Modified apocrine sweat glands
- Forms earwax (cerumen)
2) Mammary Glands
- Milk-producing modified apocrine sweat glands that develop only during pregnancy
- Two rows of mammary glands can be found in most mammals
Describe the three most common forms of skin cancer.
1) Basal cell carcinoma
- Most common form of skin cancer, but the least malignant
- Most often on the head, neck, and hands
- Most common in fair-skinned people and the elderly
- Forms from cells in stratum basale
- Lesion is small, shiny bump with central depression and beaded edges
2) Squamous cell carcinoma
- May metastasize if not removed; tends to metastasize to lymph nodes and may become lethal. However, the chance of recovery is good with early detection and surgical removal
- Arises from keratinocytes of stratum spinosum
- Lesions usually found on the scalp, ears, lower lip, or back of the hand
- They typically have a raised, reddened, scaly appearance later forming a concave ulcer
3) Melanoma
- Least common (less than 5% of skin cancers) but very malignant. Can be successfully removed if caught early, but if it metastasizes it is usually fatal
- Skin cancer that arises from melanocytes
- Greatest risk factor: familial history of malignant melanoma
- Highest incidence in men, redheads, and people who had severe sunburn as a child
Describe melanomas
Least common (less than 5% of skin cancers) but very malignant. Can be successfully removed if caught early, but if it metastasizes it is usually fatal
Skin cancer that arises from melanocytes
Greatest risk factor: familial history of malignant melanoma
Highest incidence in men, redheads, and people who had severe sunburn as a child
Describe basal cell carcinoma
Most common form of skin cancer, but the least malignant
Most often on the head, neck, and hands
Most common in fair-skinned people and the elderly
Forms from cells in stratum basale
Lesion is small, shiny bump with central depression and beaded edges
Describe squamous cell carcinoma
May metastasize if not removed; tends to metastasize to lymph nodes and may become lethal. However, the chance of recovery is good with early detection and surgical removal
Arises from keratinocytes of stratum spinosum
Lesions usually found on the scalp, ears, lower lip, or back of the hand
They typically have a raised, reddened, scaly appearance later forming a concave ulcer
Describe the three classes of burns.
1) First-degree burn
- Involves only the epidermis and heals in days.
2) Second-degree burn
- A partial-thickness burn; involves part of dermis
- May appear red, tan, or white; often blistered and painful
- Takes two weeks to several months to heal and may leave scars
3) Third-degree burn
- A full-thickness burn; involves epidermis, all of dermis, and often some deeper tissues
- Often requires skin grafts
- Typically requires fluid replacement, infection control, and supplemental nutrition
Name the tissues and organs that compose the skeletal system.
Major organs: Bones.
Major tissues: Bones are made up of bone tissue, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue
Describe the major functions of the skeletal system and give examples
1) Support: Limb bones and vertebrae support the body; jaw bone supports the teeth; bones support viscera
2) Protection: Cranial bones protect the brain, vertebrae protect the spinal cord, ribs protect the heart and lungs, etc
3) Movement: Allows for movement of limbs and breathing (requires action of muscles on bones).
4) Electrolyte balance: Helps regulate calcium & phosphate levels
5) Acid–base balance: Buffers the blood against large pH changes by altering phosphate and carbonate salt levels
6) Blood formation: Red bone marrow produces red blood cells.
Distinguish between bones as a tissue and as an organ.
Bones (organs) have multiple types of tissue; each individual bone in your body is a separate organ.
One of the types of tissue found in bones (organs) is called bone tissue, also called osseous tissue.
Describe the types of bones classified by shape and give examples
1) Flat bones: cranial bones, sternum, ribs, scapula, hip.
- These bones are usually for protection
2) Long bones: femur, humerus, radius and ulna, metatarsals, metacarpals, digits of manus and pedal regions, etc
- These bones are usually in appendages, for movement
3) Short bones: carpal (wrist) bones, tarsal (ankle) bones
4) Irregular bones: vertebrae, some skull bones (inner ear bones)
5) Sesamoid (type of short bone): patella
- Sesamoid bones develop in a tendon (or ligament) in response to a need for more leverage.
6) Sutural (wormian) bones
- Sutural bones are the extra bones in the sutures (especially the lambdoid suture) of the skull.
- Everyone has a different number of sutures in their cranium (i.e. some people only have 1, while others may have 4, depending on how their cranium formed).
Identify the internal structural components of compact bone
- The dense outer shell of bone
- Made up of subunits called osteons, which contain:
1) Lamellae - Columns of the matrix (mainly collagen) that are weight bearing
- Run concentric, circumferential, and interstitially
2) Central (Haversian canal) - Contains blood vessels and nerves
3) Perforating (Volkmann’s) canals - Channels that connect blood and nerves from periosteum to the central (Haversian) canal; run transverse or diagonal.
Osteons are made up of what 3 components?
Lamellae, central (haversian) canal, and perforating (volkmann’s) canals
Identify the internal structural components of spongy bone
- A lattice of bone covered with endosteum and an internal honeycomb of trabeculae filled with red or yellow bone marrow
- Trabeculae (thin plates of bone) develop along the bone’s lines of stress.
- Spaces filled with red bone marrow
- Few osteons and no central canals
- Provides strength with minimal weight
Describe and distinguish between the two types of bone marrow.
1) Red marrow
- Contains hemopoietic tissue; produces blood cells.
- Found in almost all bones in children, and found primarily in the axial skeleton of adults.
2) Yellow marrow
- Found in adults
- Stores triglycerides; functions as energy storage.
- Can transform back to red marrow in the event of chronic anemia.
Describe the intramembranous ossification mode of bone formation
- Bone develops within a fibrous connective tissue membrane
- Mesenchymal cells»_space;> osteoblasts»_space;> osteocytes (spongy bone)
- Forms the flat bones of the skull, clavicles, and ossifies the fontanels.
- Most of these bones are remodeled (destroyed and reformed) as we grow to adult size.
- Thickens long bones throughout our lives.
Describe the endochondral ossification mode of bone formation
- Bone forms by replacing hyaline cartilage
- Forms most the bones of the body below the skull (except the clavicle)
- Mesenchyme»_space;turns into» chondroblasts»_space; die and are replaced by»_space; osteoblasts»_space;turn into» spongy bone»_space;turn into» compact bone
Compare and contrast the function of osteoblasts and osteoclasts during bone growth, repair, and remodeling.
- Osteoblasts: create bone
- Osteoclasts: break down bone.
- During bone growth, osteoblasts create bone. –During bone remodeling, osteoclasts break down bone and osteoblasts create bone.
Name and describe the process by which minerals are added to bone tissue.
- Mineral deposition (mineralization): the process in which calcium, phosphate, and other ions are taken from blood and deposited in bone.
- During this process, osteoblasts produce collagen fibers, and the collagen fibers then become encrusted with minerals.
- The first few mineral crystals act as “seed crystals” that attract more calcium and phosphate
Name and describe the process by which minerals are removed from bone tissue.
- Mineral resorption: the process of dissolving bone and releasing minerals into blood
- This process is performed by osteoclasts; they pump hydrogen to extracellular fluid (chloride follows). Hydrochloric acid (pH 4) dissolves bone minerals.
- They also produce an enzyme which digests collagen in an acidic environment.
Describe the role of the bones in regulating blood calcium and phosphate levels.
- When blood calcium or phosphate is LOW, the process of mineral resorption takes place. For example, if blood calcium is low, then some of the calcium stored in the bones will be resorbed into the blood stream.
- When blood calcium or phosphate is HIGH, the process of mineral deposition takes place. For example, if blood calcium is high, then some of the calcium from the blood stream will be deposited into the bones.
Explain the role of calcitriol in regulation of bone physiology and describe its effect
- Calcitriol (aka vitamin D) is a hormone that raises blood calcium levels.
- Mainly, it increases calcium absorption by the small intestine, but it also increases calcium resorption from the skeleton, and weakly promotes kidney reabsorption of calcium ions, so less are lost in urine.
- It’s produced by actions of skin, liver, and kidneys.
- Calcitriol is necessary for bone deposition, so lack of calcitriol results in abnormal softness of bones; in children, this causes rickets, and in adults, this causes osteomalacia.
Explain the role of calcitonin in regulation of bone physiology and describe its effect
- Calcitonin is produced by the thyroid gland and lowers blood calcium levels; its release is triggered by high blood calcium.
- It lowers blood calcium concentration in 2 ways; it inhibits osteoclasts and stimulates osteoblasts.
- It’s important in children, but has a weak effect in adults (except may inhibit bone loss in pregnant and lactating women)
Explain the role of parathyroid hormone in regulation of bone physiology and describe its effect
- Parathyroid hormone is produced by the parathyroid glands, and increases blood calcium; its release triggered by low blood calcium.
- PTH increases blood calcium 4 ways; it stimulates osteoclast population and bone resorption, promotes calcium reabsorption by kidneys, promotes calcitriol synthesis, and inhibits osteoblasts, inhibiting bone deposition
Explain the hormonal regulation of skeleton growth.
- Epiphyseal plate activity is stimulated by Human Growth Hormone (hGH); hGH stimulates growth at the epiphyseal plates in children.
- Estrogen has a stronger effect on skeleton growth than testosterone; both of those hormones begin to affect bone growth during puberty, and they differentiate the male and female skeleton.
- Males typically continue to grow for a longer period of time than females.
- At least 20 or more hormones, vitamins, and growth factors affect osseous tissue.
- Anabolic steroids administered during childhood/ adolescence can also prematurely stop bone growth.
Describe the bone disease ostoporosis
- The most common bone disease
- Affects spongy bone the most since it is the most metabolically active
- Subject to pathological fractures of hip, wrist, and vertebral column
- Kyphosis (widow’s hump): deformity of spine due to vertebral bone loss
- Complications of loss of mobility are pneumonia and thrombosis
- Estrogen maintains bone density in both sexes; inhibits resorption by osteoclasts
- Postmenopausal white women are at the greatest risk; white women begin to lose bone mass as early as age 35. By age 70, their average loss is 30% of bone mass.
- Osteoporosis also seen in young female athletes with low body fat causing them to stop ovulating and decrease estrogen secretion
- Risk factors: race, age, gender, smoking, diabetes mellitus, diets poor which are poor in: calcium, protein, vitamins C and D
- Treatments: Estrogen replacement therapy (ERT) (slows bone resorption, but increases risk of breast cancer, stroke, and heart disease); PTH derivative can also be used as a treatment but can cause bone cancer; certain medications destroy osteoclasts.
- However, best treatment is prevention: exercise and a good bone-building diet between ages 25 and 40
Describe the bone disease osteomalacia
Caused by low levels of calcitriol (vitamin D) in adults; leads to abnormally soft bones. This is because calcitriol is necessary for bone deposition.
Describe the bone disease Ricket’s
Caused by low levels of calcitriol (vitamin D) in children; leads to abnormally soft bones. This is because calcitriol is necessary for bone deposition.
Describe the bone disease osteogenesis imperfecta
A deficit in collagen deposition.
Name and describe the types of fractures.
- Non-displaced: A fracture where the bones remain aligned.
- Displaced: A fracture where the bones become misaligned.
- Comminuted: A fracture in which the bone breaks into several pieces
- Greenstick: An incomplete fracture in which the bone is bent; occurs most often in children.
Explain the ways in which a fracture can be repaired.
- Closed reduction: A procedure in which bone fragments are manipulated into their normal positions without surgery
- Open reduction: Involves surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments
- Cast: normally used to stabilize and immobilize healing bone
Explain how the body heals fractures
The body repairs fractures by forming a hematoma, then a soft callus, then a hard callus, then bone remodeling.
Predict factors or situations affecting the skeletal system that could disrupt homeostasis.
- Lack of vitamin D in your diet could lead to osteomalacia, disrupting homeostasis.
- Radiation therapy can cause damage to red bone marrow, which can lead to decreased blood cell production, which can lead to disruption of homeostasis.
Predict the types of problems that would occur in the body if the skeletal system could not maintain homeostasis.
Lack of homeostatic control causes illness, injury, or death.
