Tissues, Organ Systems and Homeostasis

At Last!! Systems!

To refresh:

Atoms form molecules

Molecules (like proteins, carbohydrates, lipids, and nucleic acids) form cell organelles as well

as just float around in cells and between cells.

Amino Acid

Cell Organelles

•  carry out specific jobs in the cells, like making certain molecules or digesting waste materials

Cells •  Are the basic unit of

life that is capable of carrying out all the functions of living things independently

•  Work together to form tissues

•  Metabolism •  Homeostasis •  Ability to reproduce/Genetic

material •  Growth and Development •  Response to stimuli

Homeostasis •  The body must

maintain conditions within certain parameters

•  This means control over things like: •  temperature

•  pH •  blood gases (oxygen,

carbon dioxide)

Homeostatic mechanisms operate to maintain the body within tolerable limits by using:

•  a. Sensory receptor cells detect specific changes in the environment.

•  b. Integrators act to direct impulses to the place where a response can be made.

•  c. Effectors perform the appropriate response.

•  5 senses, temperature sensors, etc

•  Brain and spinal cord

•  Muscles and glands

Everything has a role to play in homeostasis

•  The combined contribution of cells and the tissues they form, and the organs and systems formed from these all work to maintain a stable internal environment for a living being

What do the pieces of the body do to help?

•  Cells are bathed in fluid: 4 Gallons of extra-cellular fluid (between cells- called interstitial fluid)

•  Each cell carries out metabolic activities to ensure the survival of the cell

•  Cells of each tissue act together to perform one or more duties that contribute to the survival of an organism as a whole by forming organs that work together in a system

Feedback Mechanisms (2 types)

Positive •  Causes the situation to intensify •  Cough up germs, produce more mucus, cough

more, irritate throat, cough more, more mucus… •  Sexual response •  Oxytocin production in labor causes uterine

cramping, which causes production of oxytocin which causes cramping which causes more oxytocin production….

Negative feedback •  Causes the situation to stop/ reverse

conditions •  Like a thermostat turns off the heat when it

gets to a preset temperature •  Usually things are just turned on or off;

you produce insulin (or other hormone) and when you have enough, production stops; when you need more, you produce more

On to the

Integumentary System (the Skin)

Skin: Your Birthday Suit (also, a marvel of biology)

Skin (a little closer)

Skin description: Use the vocabulary from the image to write a description of skin

Skin: The Integumentary System from the Latin integere- to cover

•  Demonstrates all of the tissues working together to keep on organism alive

•  The average person has 9 pounds of skin •  The skin is about 15-20 square feet

Functions of the skin:

•  prevents dehydration •  Prevents microbial

invasion/ infection •  Prevents abrasion •  Stores blood •  Provides cushioning

•  Insulation (temp, physical)

•  Receives stimuli (touch, temp, pressure)

•  Temperature regulation

•  Produces vitamin D •  Pheromone secretion •  Excrete salt waste

(small counts)

Skin Structure

• 3 layers (top)

•  Epidermis •  Dermis •  Subcutaneous

Layer (AKA the Hypodermis)

The Epidermis •  Has no nerves •  Dead layers of flat epithelial cells; the very top is

called the stratum corneum •  Contains keratin: a tough protein that

waterproofs the skin •  Quite a bit gets rubbed off each day (dust) •  Skin color is due to

–  melanocytes (pigmented cells- genetics and sun exposure play roles)

–  blood flow –  carotene

Layers of the Epidermis

•  Stratum corneum •  Stratum lucidum •  Stratum granuosum •  Stratum spinosum •  Stratum basale (basal cell layer)

The Dermis of the skin Made from mostly connective tissue

–  Irregular and dense CTs •  Role is mainly to protect underlying tissues Contains:

–  Blood vessels –  Lymph vessels –  Nerve endings –  Sweat glands –  Oil glands –  Hair –  Nails

More on the dermis and sweat glands…

• Sweat (sudoriferous) glands are present to control temperature, but respond to – Stress (frightened, upset, etc) – pain, and – sexual stimuli

Types of Sweat Glands

– Two types: • Eccrine glands (mostly temperature

regulation sweat) – Foredead, neck, back,

» palms and soles from stress • Apocrine glands (“scented” sweat

glands; sweat is broken doen by bacteria, producing a scent)

– Found in the axillary and inguinal areas

More on the dermis and sweat glands…

•  Sweat is made up of – water, – salts, – ammonia, – vitamin C, – other wastes and – (possibly) pheromones

Pheromones •  Are chemicals secreted by the body that other animals of

the same species respond to (communication molecules) –  Usually associated with reproduction, but not always

•  Are well documented in animals –  Syrian golden hampsters (dimethyl disulfide to attract,

aphrodisin to copulate) –  Cockroaches (periplanone B) –  Ethiopian civet cat and Himalayan musk deer (musk) –  Pigs (androstenone)

•  Usually have no smell associated with them •  Secreted in very small amounts •  Some evidence for pheromone presence in humans

–  VNO (vomeronasal organ) in people; used to detect pheromones in animals

Functions of Pheromones:

Oil glands…. •  Otherwise known as sebacious glands •  Lubricate hair and skin by producing

sebum (fatty substance that includes lipids and cellular debris made in holocrine glands)

•  Oil kills microbes (bacteria) •  None present on soles of feet or the palms

of the hands (but they are present on the fingertips)

We leave prints behind…

•  The oil produced from our fingers seeps into the ridges and is left behind when we touch an object –  (Locard’s exchange principle: we leave things

behind wherever we go, and pick up things wherever we go

•  Every contact leaves a trace •  Lint, hair, fingerprints, tracks, saliva, etc)

A few things about prints… •  Ridge patterns and the details in small areas of friction

ridges are unique and never repeated.

•  Friction ridges develop on the fetus in their definitive form before birth.

•  Ridges are persistent throughout life except for permanent scarring. –  They can not be burned or scratched off- they will grow back!

•  Friction ridge patterns vary within limits which allow for classification.

Fingerprints

•  AKA friction ridge patterns – b/c the ridges help increase the friction when

we pick up an object, helping us hold onto it •  Fingerprints are “the result of genetic

factors and random physical stresses and tensions during development on the stratum basale”, the lowest layer in the epidermis.

Print Formation

•  Formation begins at 10 weeks after conception

•  Is complete at 24 weeks gestation(6 mo of pregnancy) – (**some sources say complete at 14

wks)

Dermal papillae

Print patterns

•  5% of prints contain arches

•  65% of all prints contains loops

•  30% of all prints contain whorls

Print patterns

http://www.fbi.gov/hq/cjisd/takingfps.html

How unique are you?

•  Chances are one in a quintillion (1 in 100,000,000,000,000,000,000) that someone will have the same print (singular, not for all 10 fingers) as you – identical twins have similar patterns, but

the prints are not the same – Boimetric identification: using

fingerprints, ear prints, iris patterns to ID you, as they are each unique

Matching prints

Minutia points are the small

marks in the

loops, arches,

or whorls

Biometrics take the print and make a digital map that is

unique

Skin and Sensation

•  Pacinian corpuscles – Heavy pressure, pain

•  Meissner’s corpuscles –  light touch

•  Thermoreceptors – Temperature (warm and cold)

•  Pain receptors – Acute (quick) – Chronic (slower)

The Subcutaneous Layer: The Hypodermis

•  The hypodermis is made up of – Adipose

•  To insulate (temperature regulation) – Loose connective tissue

•  Collagen •  Elastin

–  Both to protect –  Fibers run parallel to the skin

– Rete cutaneum: network of blood vessels at “border” of dermis

Hair…

(a slight diversion for a moment or two…)

I went looking for a picture of hair…

I found a few…

There were more than a few I had to share…

It was sort of like a train wreck…

Bad vacation destinations...

Yes, even more…

I guess it had to stop somewhere….

Hair….

•  Keratinized cells that push up and overlap each other- made from dead skin cells

(This is the graphic I went looking for in the first place…)

Scalp

Hair

•  Develops from a follicle – Holds the root – Nourished from dermal blood supply found in

the connective tissue around the follicle – New hair cells push old hair cells up and away

from the new growth – The old cells get keratinized and die

Hair Growth Cycle

•  90% of your hair is in a growth phase •  Grows 2-6 years •  Falls out- rests for 3 months •  Gets replaced by new growth

–  If not replaced, baldness (allopecia) •  Androgenic or areata

•  Normally lose 20-100 hairs per day – Stressors can alter this

Nails

•  Nail plate (nail itself) •  Nail Bed (under the nail) •  Lunula (half-moon area;

nail grows from there •  Cuticle

Temperature regulation: Homeostasis (Negative Feedback)

•  Sensory receptors (input) –  thermoreceptors in skin

•  Warm receptors •  Cold receptors

– Hypthalamus •  Effectors (response)

–  Muscles in skin (arrector pilli) –  Muscles of body –  Blood vessels –  Sweat (eccrine) glands

•  Integrators –  Hypothalamus (region of brain)

Too high

Too low

Just right…37°C (98.6°F) •  (give or take; the average is merely the average, there is a

range that is normal of +/- .9 F •  Your average temperature changes over the course of the

day •  The location of where the temperature is taken makes a

difference •  Oral •  Axillary •  Rectal •  Forehead

Temperature Regulation

•  Radiation: primary means of loss of body heat – Heat goes out into the air

•  Conduction: something touching your skin carries body heat away

•  Convection: hot air from the body moves up, and cool air replaces it

•  Evaporation: sweat (or other liquid on surface) takes heat energy to evaporate off

Too hot?

•  You sweat to cool yourself –  Eccrine glands secrete sweat –  Stop sweating when you have reached an appropriate

temp (negative feedback) •  Increase in the diameter of surface blood

vessels (vasodilation) –  Allows more heat from blood to escape through skin

•  Deeper blood vessels constrict (vasoconstriction)

•  Extreme overheating: hyperthermia (heat exhaustion) •  Caused by:

–  Being in extreme temperature •  ie being trapped in a hot car (temporary, but caused by

environment, not individual) –  Fever (pyrexia) / illness (temporary, in normal temp environment)

•  Attempt to kill organisms by denaturing their proteins

•  Can kill you! •  Uncontrolled temperatures (above 105°F) in people, it

can denature proteins (specifically enzymes) needed to survive and kill you

Dehydration

•  a major cause of overheating ( because if you can’t sweat anymore to cool off, you overheat)

•  Symptoms of dehydration –  Fatigue – Dizziness – Headache – Nausea/ vomiting – Muscle cramps

Hyperthermia, con’t

•  If sweat can’t evaporate, the body can’t cool itself – Reduces radiative cooling

•  Especially if the air is hotter than the body – Reduces conductive cooling – Reduces convective cooling

Too cold?

•  Constriction of blood vessels (vasoconstriction) near surface – Diverts blood from surface to visceral organs

•  Hair stands on end (goosebumps- arrector pilli making hair stand up)

•  Shivering- muscle contraction creates – Shivering is multiple repeated contractions

that create a lot of heat

Skin Cancer •  Skin cancer is the most common form of cancer

in the United States. More than 3.5 million skin cancers in over two million people are diagnosed annually.

•  Each year there are more new cases of skin cancer than the combined incidence of cancers of the breast, prostate, lung and colon.

•  One in five Americans will develop skin cancer in the course of a lifetime.

•  The good news is that skin cancer is the most treatable form of cancer. It’s also one of the most preventable forms.

What is skin cancer?

•  Skin cancer is the uncontrolled growth of abnormal skin cells. It occurs when unrepaired DNA damage to skin cells (most often caused by ultraviolet radiation from sunshine or tanning beds) triggers mutations, or genetic defects, that lead the skin cells to multiply rapidly and form malignant tumors.

•  Malignant means…very bad, threatening to a life, extremely harmful or dangerous

Melanoma, basal cell carcinomas, and squamous cell carcinomas are the most common types.

What to look for: •  Do a complete body check once a month, and

have a dermatologist check you once a year. •  You are looking for any changes that fit one or

more of the following: – Asymmetrical shape – Borders that are not even – Color that changes – Diameter larger than a pencil eraser – Evolution- any changes in color, size, texture, etc

•  The earlier a skin cancer is detected, the better the chances of survival

What to look for:

Human skin in UV (ultraviolet) & visible light

•  As you can see UV light behaves completely differently than visible light and shows all of the sun damage & hyper pigmentation. The melanin in the skin absorbs ultraviolet light to protect the skin. The more tan the skin, the more melanin is released from melanocytes and the more absorption of ultraviolet light occurs. You can also see that the eyes appear entirely black in the UV image, this is because eye chromophores absorb UV rays for protection against UV light damage.

Skin damage- visible under UV

photography

Types of UV Radiation: UVA, UVB, and UVC

•  UVA rays have the longest wavelengths, •  UVB have the mid level- wavelengths •  UVC rays which have the shortest

wavelengths. •  UVA and UVB rays are transmitted

through the atmosphere, all UVC and some UVB rays are absorbed by the Earth’s ozone layer. So, most of the UV rays you come in contact with are UVA with a small amount of UVB.

UVB rays reach the the epidermis only UVA rays can penetrate the dermis

Things that affect your risk for skin cancer

•  Genetics – Family history of skin cancers – Fair skin (but darker-skinned people can also

get skin cancers, too, and usually detect them later than those with fair skin.

– Fair hair (red heads especially!) – Light colored eyes (blue especially)

•  Behaviors – Sun exposure:

•  Use of sunscreen correctly, time outside, covering up or not (including sunglasses)

Tanning? •  Tanning = highly increased risks of skin

cancer •  There is NO safe amount of tanning •  All tanning (outdoor and tanning beds

indoors) are associated with increased risks of invasive skin cancers –  In fact, indoor tanning is MORE intense and

concentrated than sun exposure outdoors in terms of UVA radiation, the type that causes more aging

Impacts of tanning •  Photo-aging can cause:

– Wrinkles –  Invasive cancers

•  Even if you NEVER get a skin cancer, you will look older at a younger age when it comes to wrinkles and age spots – And while you can treat these (not cure), they

are expensive and uncomfortable to treat •  Lasers, facelifts, and expensive creams that don’t

really do much

Smoking and Sun Damage- Twins

Twin A Twin B

Left side damage due to UV exposure

How do you reduce your risk? •  Seek the shade, especially between 10 AM and 4 PM. •  Do not burn. •  Avoid tanning and UV tanning booths. •  Cover up with clothing, including a broad-brimmed hat and UV-

blocking sunglasses. •  Usa a broad spectrum (UVA/UVB) sunscreen with an SPF of 15 or

higher every day. For extended outdoor activity, use a water-resistant, broad spectrum (UVA/UVB) sunscreen with an SPF of 30 or higher.

•  Apply 1 ounce (2 tablespoons) of sunscreen to your entire body 30 minutes before going outside. Reapply every two hours, or immediately after swimming or excessive sweating.

•  Keep newborns out of the sun. Sunscreens should be used on babies over the age of six months.

Factors that affect exposure

•  Geography •  Altitude •  Time of year •  Time of day •  Weather conditions •  Reflection

UV Index: Provides information about the risk of UV exposure at that time; part of the weather forcast

Sunscreen is your friend

However, you probably aren’t using nearly enough or applying it frequently enough to really