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Introduction to Human Anatomy Lecture 65 Notes: Integumentary System


The skin!  This is a rare and oft neglected area.  Today’s lecture costs 57 minutes.


The skin is a mechanical barrier to bacteria, fungi.  The skin is water proof; it keeps water in.  Protection from UV rays.  Sensory organ, especially the fingers.  Thermoreceptors, sweating.  Sweat needs to evaporate to cool .  Vasoconstriction or vasodialation in skin blood vessels.  vitamin D synthesis – the skin is a gland that makes a hormone.

We make calciferol from cholesterol from sunlight.  It increases the absorption of Ca2+ in the small intestine.  Modern man is indoors alot and he wears alot of clothes.  Vitamin D is added to milk.

The skin is the largest organ of the body.  An organ is any structure made of two or more tissues.  A tissue is connective, nervous, muscular or epithelial.  Epithelial – simple/stratfied/pseudostratifed, cubioidal/columnar/squamous.

More blood flow to the skin, heat loss.  Less blood to the skin, heat gain.

There’s an interesting series of relationships between the sun, Vitamin D, and folate.    UV rays increase vitamin D production but reduce folate.  Folate is critical for neural tube development in babies and for mitosis in somatic cells.

Portals of the skin: mouth, anus, nose, urethral canal, vaginal canal.

Layers of the skin

Epitdermis – stratified squamous epithelium.  Keratinized means dead cells on the outside.  Ectoderm.

Dermis – much thicker.  Irregular dense fibrous CT.  Fibroblasts and collagen.  Mesoderm.  Supplied with blood vessels and nerve fivers.  Papillary folds.

Hypodermis – adipose tissue.

2 Types of Motor Neurons:

Somatic motor neurons – voluntary control of skeletal muscles

Autonomic motor neurons – automatic control of visceral/internal organs.

The top layer is the stratum cornium.  Dead cells called keratinocytes.  Nails are made of keratin.  This is what makes the top layer waterproof.

THe bottom layer is the stratum germanititum.  Some cells contain melanin, called melanocytes.

Friction ridges are for grasping traction.  Calluses on the hands and corns on the feet.

Interdigitates means to put the fingers are in between each other.  We don’t want the epidermis to slide over the dermis.  Interdigitating is to prevent slipping.

A blister is fluid accumulating where the epidermis and the dermis separate.

Types of Hair

Lanuga is fetal hair

Down hair is light colored hair of child

Terminal hair is adult hair.  Thicker, darker hair that begins at puberty.

At birth, hair on head and hair on the skin.  At puberty, pubic area, axillary and facial/chest.

The hair follicle is associated with a sebaceous gland.  Associated with a visceral muscle causing piloerection.  It occurs when cold or frightened.

Nobody has hair on the palms of the hand or on the soles of the feet.

Sweat is composed of water, NaCl and urea.  Vaporization of sweat leads to cooling.

The purpose of ear wax is to protect the tympanic membrane.

Colostrum  contains water, antibodies,and lactase.  It is present immediately after childbirth.  Milk begins 3,4 days after childbirth.  Breast milk is high in lactose, fat, calcium and antibodies.  Women usually breast feed until 6 months, when the baby begins to develop teeth.


Battlefield Terrain:

OCOKA Observation, Cover and Concealment, Obstacles, Key Terrain, Avenues of Approach

C elegans: the developmental fate of every somatic cell is known.  959 in hermaphrodite.  Dauer stage.

“Sharp front sight, pumpkin on a post. Sharp front sight, pumpkin on a post.”

ethane: staggered/eclipsed Butane: anti, gauche

Shape, Shine, Silhouette, Shadow, Slow and Still

Just in time

carburetor regulates the flow of air and gasoline into the engine cylinders

Water: OH bond 95.84 pm.  Bond angle 104.5

A whip antenna also known as a monopole antenna looks capacitive if it is shorter than a quarter wavelength, and are tuned to resonance with a series inductor.

Fear is control

‘evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season

more branched isomers tend to have lower boiling points.

Biceps: Coracobrachialis, bicep brachi, brachiallis, supinator, brachioradialis

Arrhenius acid H3O+ donor, bronsted acid H+ donor, lewis acid electron acceptor

Bioavailability = Oral dosage/Systemic circulation

Albumin binds weak acids and hydrophobic drugs.

Vd = Bioavailable Dose/Concentration in Plasma

The thyroid is regulated by the pituitary is regulated by the hypothalamus.

Markovnikov’s Rule: addition of a protic acid HX to an alkene, the acid hydrogen (H) becomes attached to the carbon with fewer alkyl substituents, and the halide (X) group becomes attached to the carbon with more alkyl substituents.

Strong bases make poor leaving groups.  Good leaving groups form stable ions or molecules.

Stable cations favor SN1 reactions.  SN2 reactions are concerted and require little steric hinderance.

Protic solvents form hydrogen bonds.  They produce a cation and anion during the reaction and favor SN1.

3 minutes without air – 3 hours without shelter – 3 days without water – 3 weeks without food.

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