anatomy and physiology i - lecture notes - introduction

8/22/2019 Anatomy and Physiology I - Lecture Notes - Introduction

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Why are we here?

Obviously, to learn about human anatomy

and physiology.

But, what does that mean?

Before we begin, weve got to figure a few

things out: Whats a human?

Whats anatomy?

Whatsphysiology?


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What are humans?

Organisms are classified as

human because they are: Animals

Vertebrates Possess backbones

Mammals Possess:

Mammary glands

Hair

Endothermy (i.e., we generate heat internally)

Heterodonty (i.e., we have teeth w/ different shapesand functions)

3 middle ear bones.


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What are humans?

Primates

Possess:

Opposable thumbs (can you touch your pinky

with your thumb?). What advantage does this

confer?

2 clavicles (collarbones)

Only 2 mammary glands. Why only 2? (Think

about how many kids a woman normally gives

birth to.)

Forward facing eyes with stereoscopic vision (fordepth perception)

Hominids

Bipedal (walk on 2 legs)

Possess a large brain size/body size ratio


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What is anatomy?Anatomy is defined as the study of

Structure refers to the shapes, sizes, and

characteristics of the components of thehuman body.

The word anatomy comes from 2 words:Ana which means up or apart

Tomos which means to cut

Why these two words????


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Types of Anatomy

We can divide our study of structure into 2 parts: Study of stuff seen by the naked eye (Gross Anatomy).

Study of stuff seen ONLY with the microscope (Microanatomy).

We can divide microanatomy into:

Histology study of tissues

Cytology study of individual cells.


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Physiology

Physiology is defined as

the study of function so

human physiology

attempts to explain how

and why humans function.

Physiology is where we

figure out how stuff

works. How do muscles contract?

How do we run?

How does our heart beat?


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Some Important Themes

Biology is hierarchical with each level buildingon the level below it.

Each level of biological structure has emergentproperties.

Cells are an organisms basic unit of structureand function.

Structure and function are correlated at all levels

of biological organization!!!!!!!! Regulatory mechanisms ensure a dynamic

balance in living systems.


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Levels of Structure

In order to understand howsomething is built and howsomething works, you mustlook at all of its componentsand analyze them both

individually and together. In doing these collective and

separate analyses, you mustexamine things at multiplestructural levels, i.e., one must

break them down from large tosmall this is calledreductionism

An organism (such as a humanbeing) may be broken down as

illustrated on the left.

Organelle

Cell

Tissue

Organ

Organ System

Organism


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Levels of Structure

The basic unit of life is the cell.

All living organisms are composed of one or morecells.

The human body contains about 100 trillion cells.

There are about 200 different types of cells in thehuman body.

The different types of cells have different features butfor the most part, all cells are made up of organellesand various macromolecules (e.g., proteins, lipids,carbohydrates and nucleic acids).

Organelles themselves are made of thesemacromolecules and macromolecules are polymers ofsmaller molecules which consist of atoms of variouschemical elements.


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A Prototypical Cell


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Important Organelles

Plasma Membrane Separates the cell exterior from thecell interior (cytoplasm).

Nucleus Membrane bound structure that containsdeoxyribonucleic acid (DNA) which is the set ofinstructions for the synthesis of all the bodys proteins.

CAN YOU SEE THE NUCLEUS AND THEPLASMA MEMBRANE IN THE CELL TO THERIGHT?

Mitochondria Structure bound by a double membraneand the site at which the energy stored in sugars and otherorganic molecules is transferred to ATP, the chemicalwhich acts as the currency for energy in the cell.

Ribosomes Not bound by a membrane. Sites of proteinsynthesis. May be free floating in the cytoplasm or

bound to the endoplasmic reticulum.

Are the 2 pictures on this page to the same

scale? How do you know?


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Important Organelles

Rough Endoplasmic Reticulum Membranous set of tubes withribosomes studded along its surface.Site of the synthesis of proteins thatare destined to be exported from thecell.

Smooth Endoplasmic Reticulum ER w/o the attached ribosomes.Site of cellular lipid synthesis,among other things.

Golgi Apparatus Membranebound organelle responsible for

determining the direction of proteinssynthesized in the rough ER.

Lysosomes Membrane boundorganelle that houses digestiveenzymes that can be used to breakdown ingested toxins or worn out

cell parts.


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More Levels of Structure

Similar cells and cell

products come together to

form tissues.

A structure made of 2 ormore tissue types that

perform a particular

function is an organ.

A group of organs with aunique collective function

is an organ system. There

are 11 of these in the

human body.


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Integumentary System

Structures:

- Skin, hair, sweat and oil glands

Functions:

- Forms the external body covering

- Protects deeper tissues from injury

- Involved in vitamin D synthesis

- Prevents desiccation, heat loss, and

pathogen entry- Site of pain and pressure receptors


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Skeletal System

Structures: The 206 bones of the human body

Functions: Protects and supports body organs

What characteristics might bone have that

allows it to support and protect?

Provides a framework that muscles can use tocreate movement

Hemopoiesis (synthesis of blood cells)

Mineral storage

Bone contains 99% of the bodys store of whatmineral? (Hint you can get this mineral from

drinking milk)
http://www.ils.unc.edu/~geisg/info/infovis/skel_mov.gifhttp://members.cox.net/bnovis/bones%20and%20muscles-frame.htm


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Muscular System

Structures: The 600+ muscles of

the body

Functions:

Locomotion Manipulation of the

environment

Maintaining posture

Thermogenesis(generation of heat)
http://members.cox.net/bnovis/bones%20and%20muscles-frame.htm


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Nervous System

Structures: Brain, spinal cord, and

peripheral nerves

Functions:

Fast-acting control

system of the body

Monitoring of the

internal and external

environment andresponding (when

necessary) by initiating

muscular or glandular

activity


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Endocrine System

Structures: Hormone-secreting glands

Pituitary, Thyroid, Thymus,Pineal, Parathyroid, Adrenal,Pancreas, Small Intestine,

Stomach, Testes, Ovaries,Kidneys, Heart

Functions: Long-term control system of

the body Regulates growth,

reproduction, and nutrient useamong other things.


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Cardiovascular System

Structures: Heart, Blood vessels (arteries,

veins, and capillaries)

Functions: The heart pumps blood thru the

blood vessels.

Blood provides the transport

medium for nutrients (glucose,amino acids, lipids), gases (O2,

CO2), wastes (urea, creatinine),

signaling molecules (hormones),

and heat.


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Lymphatic/Immune

System Structures:

Lymphatic vessels, Lymph nodes,

Spleen, Thymus, Red bonemarrow

Functions:

Returning leaked fluid back to

the bloodstream, Disposal of debris

Attacking and resisting foreign

invaders (pathogens i.e., disease-

causing organisms)


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Respiratory System

Structures:

Nasal cavity, pharynx,

trachea, bronchi, lungs Functions:

Constantly supply the

blood with O2, and

remove CO2

Regulate blood pH


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Digestive System

Structures:

Oral cavity, esophagus, stomach, small

intestine, large intestine, rectum, salivaryglands, pancreas, liver, gallbladder

Functions:

Ingestion and subsequent breakdown of foodinto absorbable units that will enter the blood

for distribution to the bodys cells


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Urinary System Structures:

Kidneys, ureters,

urinary bladder,

urethra

Functions:

Removal ofnitrogenous wastes

Regulation of bodys

levels of water,

electrolytes, and

acidity


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Reproductive System

Structures:

Male:

Testes, scrotum, epididymis,vas deferens, urethra, prostate

gland, seminal vesicles, penis

Female:

Ovary, uterine tube, uterus,

cervix, vagina, mammaryglands

Functions:

Production of offspring


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Why Are Levels of Structure Important?

In this class, well study all levels and see how they worktogether to create structures and allow them to function.

In essence, the combination of these different yetconnected levels allows life to proceed.

But we must also be aware of emergent properties. Things are often much more than simply a sum of their parts.

Consider a hammer which is made of a head and a handle. Eitherpiece by itself is of little use to drive a nail but put together, theyperform the task quite easily.

Or consider table salt sodium chloride (NaCl). By themselves,

chlorine is a poisonous gas and sodium an explosive metal. Butwhen bound together, they create something much, much different.

We must be aware of emergent properties as well as

reducing structures to their component parts.


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Can Anatomy & Physiology Be Separated?

NOOOOOOO!!!!! Absolutely not! Structure and function are undeniably

connected. We cannot divorce them.

What do we mean by this?

Can you eat soup with a fork?

Find 2 everyday items and determine

whether/how their structure (anatomy)

relates to their function (physiology)

When you consider the structure of an organ, cell, or anything for

that matter you must also consider its function!


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Stayin Alive

Your body has about 100 trillion cells in it.

For your life to NOT end abruptly, these cells

need to have the correct amount of: Oxygen Nutrients

Waste removal

Heat

Ions (sodium, calcium, etc.)

Lots of other stuff


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The Cells Environment

In order to keep the right amount of stuff in the cell,

weve got to make sure that all the fluid surrounding

our cells (i.e., the extracellular fluid) has the rightassortment of nutrients, ions, etc.

We keep both our cells and the fluid surrounding our

cells in a dynamically stable environment via a process

called HOMEOSTASIS.


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Homeostasis

Defined as the bodys ability to maintain stable

internal conditions in spite of the changing

external conditions. We just said that our body needs to have the right

amount of stuff (i.e., temperature, blood [glucose],

pH etc.) at all times in order to function properly.

First, lets refer to all this stuff as different

variables

Note: the brackets surrounding the word glucose in the above paragraph mean concentration

of glucose, i.e., how much glucose is dissolved in a particular fluid (blood in this case)


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Lets use a thermostat

as an example In order to keep the temperature in my house at

the right level, the thermostat must first measurethe current temperature in the house.

After the thermostat measures the temperature, itcompares the current value to a preset standardvalue. If there is no difference then theres nothing to do.

However, if its too hot or too cold, the thermostat hasto send a signal to the furnace or air conditioner tochange the temperature of the house so that it equals thestandard value.


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Lets clarify some stuff.

In the previous example we had a: Variable temperature

Measuring implement

thermostat Control center also the thermostat A preset or standard value for the variable

Effectors the air conditioner and furnace Similar situations arise in the human body

where there are lots of variables that wewant to maintain at certain precise levels


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Blood Pressure

BP is a variable that weve got tomaintain at a certain level

We have sensory receptors thatmeasure the BP in the body. Theyre

located in the aorta (the big bloodvessel coming out of the heart) and inthe carotid arteries (the large vesselsthat bring blood to the brain).

These pressure receptors measure BPand then send the info (we can callthis input) to a control center in the

brain the particular BP controlcenter is in the medulla oblongata of

the brain


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Blood Pressure

We call the connection btwn the receptorand the control center the afferent

pathway.

In the control center, the input BP iscompared with a set value.

If there is a difference between the current

BP value and the reference BP value thenweve got an error.

And weve got to fix that error!


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Blood Pressure

The control center will signal effector

organs such as the heart in this case to

alter their activity. This process is calledoutput.

The connection between the control center

and the effector organ is called the efferentpathway.


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Blood Pressure

Suppose the current BP is too high.

The effector must act in a way to decrease it sothe medulla oblongata (the control center) wouldsignal the heart to decrease the force and rate of itscontractions; this would decrease BP.

Notice that the original stimulus was an INcrease

in BP and the bodys response was to act so as toDEcrease BP.

The stimulus is opposite the response!


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Negative Feedback

B/c the movement of a variable in one

direction causes the body to enact processes

that cause the variable to move in theopposite direction (so as to return the value

to the correct level) we call it negative

feedback Lets look at BP again:


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Increased

BP

Sensed by pressure

receptors in aortic arch

and carotid sinus

Input sent via

afferent pathway

to medullaoblongata

Current BPcompared with

set point and

error signal

generated

Output sent along

efferent pathway to

heart and blood

vessels

Heart rate & force

of contraction

decrease

Blood

vessel

diameterincreases

BP DECREASES


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Why is Negative Feedbackso

common in the body? Think about it! Every time a variable starts

changing too much, weve got to bring it

back to normal. Weve got to counteract itschange.

THATS NEGATIVE FEEDBACK

Other examples you will encounter:Maintenance of blood [Ca2+], blood [Glucose],

blood pH, and many others

Wh d i f db k d?


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When does a negative feedback process end?

THINK ABOUT IT!

A negative feedbackprocess begins when a

particular variable leaves

its homeostatic range.

The process ends whenthat variable is back

within its normal range.

Negative feedback

processes (or loops) areself-terminating.

MAKE SURE YOU

UNDERSTAND WHY!


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Homeostasis is Important!

Most of the physiological processes that occur in

your body are designed to maintain homeostasis.

ALWAYS KEEP THIS IN MIND! Question: Does the magnitude (i.e., size) of the

error signal influence the magnitude of the

response?

Just to recap, lets look at a couple more figures!


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Homeostasis

isDYNAMIC!

What this means is that the homeostatic variables are NOT kept

rigidly fixed upon a single value. They are kept within a certain

range, and when they exit that range thats when negativefeedback loops turn on to bring them back.

Is your body temperature always exactly 98.6F?


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What about Positive Feedback?

Positive feedback occurs when the responseamplifiesor magnifies the stimulus that producedit.

In other words, a variable is altered and then thebodys response alters that variable even more inthe same direction.

How does this differ from negative feedback?

Which do you suppose is more common in thebody: positive or negative feedback?


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Positive

Feedbackin Childbirth


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PositiveFeedback

in Blood

Clotting


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Dangerous Positive Feedback

Rise in body temperature

Increase in body

metabolism

Increase in body

heatproduction


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What stops a positive feedback loop?


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Water, water everywhere! About 60% of the human body is water

2/3 of this water is found within yourcells so we refer to it as intracellular

fluid (ICF)

The other 1/3 is outside your cells sowe call it extracellular fluid (ECF)

The 2 main types of ECF are: The fluid that surrounds the cells the

tissue fluidor interstitial fluid

Blood!

Minor types of ECF includecerebrospinal fluid and intraocular fluid


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Related Fields of Study

Obviously, anatomy and physiology comeunder the rubric ofbiology the study oflife.

An incredibly integral field ispathology the study of disease. Why is pathology so important in learning

A&P?

Another super important field is

embryology, the study of how a singlezygote (i.e., a fertilized egg) turns into afully-fledged human being with trillionsof cells. Why is embryology so important to A&P?

anatomy and physiology i - lecture notes - introduction

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