Transcript Human Anatomy

Human Anatomy
Levels of Organization

Cells Tissue Organ Organ System
Smallest
Unit of
Life
A group of
cells
working
together
A group of
tissues
working
together
A group of
organs
working
together
4 Types of Body Tissue
Muscle tissue- composed of cells that
contract.
◦ Movement is the result of muscle tissues
contracting in a coordinated fashion
 Nervous tissue- contains cells that receive
and transmit messages in the form of electrical
impulses
 Epithelial tissue- layers of cells that line or
cover all internal and external body surfaces
◦ Often provides a protective barrier
◦ Your skin is epithelial tissue

4 Types of Body Tissue

Connective tissue- binds, supports, and
protects structures in the body
◦ Most abundant and diverse type of tissue
◦ Includes Bone, Cartilage, Tendons, Fat, and
Blood
◦ Connects or holds things together, such as
groups of muscles
◦ Characterized by large cells that are
embedded in large amounts of an intercellular
substance called matrix
Body Systems: (YOU WILL NEED
YOUR BOOK FOR THE DIAGRAMS)
 When
organs
work together
to complete a
specific task, it is
called an Organ
System

There are many organ systems in
your body:
◦
◦
◦
◦
◦
◦
◦
◦
◦
◦
◦
Skeletal
Circulatory
Muscular
Respiratory
Integumentary(skin)
Reproductive
Digestive
Endocrine
Immune
Excretory
Nervous
Body Cavities (p. 910)

When discussing organ systems, many of them are
located in “compartments” in the body called cavities.
◦ Cranial cavity: contains the brain
◦ Spinal cavity: surrounds the spinal chord
◦ Thoracic cavity: contains heart, lungs and organs
of the respiratory system
◦ Abdominal cavity: contains organs of digestive
system
 Diaphragm: separates abdominal and thoracic
cavity
◦ Pelvic cavity: contains organs of reproduction and
excretion
Skeletal




This system provides
support for the entire
body
Ribs protects our vital
organs-like your heart
and lungs
The spine is the
central support for the
body.
The longest bone in
your body is your
femur
Skeletal

Your hands and feet
are so flexible
because they are
made of MANY
bones:
◦ Each foot has 26
bones, while each hand
has 27 bones
◦ That means that over
half your bones are
found in your hands
and feet!!!
Skeletal (p.911)
Axial Skeleton
◦ skull, rib cage, spine
(backbone),
sternum
 Appendicular
Skeleton
◦ arms, legs, pelvis,
scapula, and clavicle
(shaded in on
picture)

Joints (p. 915)

The place where two bones meet
is called a joint
 Fixed joints: prevent
movement. Often connective
tissue is located in a fixed joint
to absorb impact.
 Example: skull
 Semimovable joints: give
limited movement. Generally
allow enough movement to
absorb shock or impact
 Example: spinal chord
 Moveable joints: allow a wide
range of motion.
 Example: knees, shoulders
Joints (p. 916)

Joints that are subject to a lot of pressure
(like your knees) are cushioned and
protected from friction (which would
damage the bones) by cartilage and
synovial fluid (also called synovial sac).
They connect to the bone with
ligaments
◦ Cartilage: connective tissue located
between moveable bones. Acts as a
surface to reduce friction and wear.
◦ Ligaments: tough connective tissue
that hold the bones of a joint in place
◦ Synovial fluid : fluid secreted that
lubricates the bones of the joint to
reduce friction and wear
Joints

Two painful conditions can
exist at the joints:
◦ Rheumatoid arthritis:
immune system attacks
the body at the joints.
Causes inflammation,
swelling and stiff joints
◦ Osteoarthritis:
cartilage begins to wear
thin. The bones begin to
rub together and causes
severe discomfort
Bone anatomy (p. 912)

While your bones are hard on
the outside (compact bone
and periosteum), they are soft
on the inside (spongy bone).
◦ Periosteum: tough membrane
that covers the surface of the
bone (where a lot of nerves are)
◦ Compact bone: located
beneath the periosteum.

You’re hard bone is stronger
and lighter than steel!!
Bone anatomy (p.912)

Beneath compact bone is an area of
connective tissue called spongy bone
or soft tissue called bone marrow.
◦ Spongy bone: strong bone lattice
that is located at points of physical
stress
◦ Bone marrow: serves as a
production center for blood cells
or an energy reserve
 Red bone marrow: produces
red blood cells, white blood cells,
platelets (blood cells don’t have
nuclei to perform mitosis)
 Yellow bone marrow: mostly
fat cells that serve as an energy
reserve
Internal structure of compact bone
(p. 913)

The structure of bone material
◦ Bone is made primarily of cylindrical pieces
made of mineral and protein called lamellae
 When young, your bones are made of cartilage that
eventually harden to bone (ossification)
◦ In the central cylinder of the lamella is a
channel called the Haversian canal
 These channels are where the blood vessels bring
nourishment and carry away wastes.
◦ Surrounding each Haversian canal is a layer of
proteins and bone cells (osteocytes)
Muscular
Muscles are
responsible for your
body's every move.
 There are 3 types of
muscles:
◦ Skeletal
◦ Smooth
◦ Cardiac

Skeletal Muscle
Skeletal muscles move and support the skeleton.
 There are 640 individually named skeletal muscles.
 When these muscles contract or shorten, your bone
moves.
 Skeletal muscles are voluntary muscles (which means
we can consciously control them)

Composition of skeletal muscle
(p. 919)

Skeletal muscle is made of cells called
muscle fibers
◦ Muscle fibers have many nuclei and are
separated by bands called striations
Muscle fibers are gathered in groups
called fascicles
 Muscle fibers are made of the following:

◦ Myofibrils
◦ Myosin
◦ Actin
Composition of skeletal muscle
(p. 920)

Myofibrils are threadlike structures that
make up a muscle fiber
◦ They are made of 2 proteins that enable a
muscle to contract
 Myosin: Thick protein fibers that mesh with actin
proteins
 Actin: Thin protein fibers that overlap with myosin
proteins
 Each actin-myosin bundle is bordered by an area
called a Z line.
 This region from one Z line to the next is called a
sarcomere
Contraction of muscle

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
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There is a “head” on myosin that fits into “grooves”
created by actin
When a muscle contracts the myosin “head” pulls the
actin strand and shortens it
The “head” can then move to another “groove” in the
actin to continue to shorten the actin strand
This process requires ATP
If you work out hard, you don’t have enough oxygen to
go through the Kreb’s cycle . . . oxygen debt
◦ Your muscles begin to run out of ATP (muscle
fatigue)
◦ You must go through lactic acid fermentation (this is
why your muscles get sore . . . lactic acid build up)
Contraction of muscle (p. 921)
Most muscle are arranged as opposite
pairs
 Muscles always pull bones, not push them
so you need to be able to contract in two
different directions

◦ Flexor bends the joint to flex the limb
(biceps pull your arm in)
◦ Extensor flexes to straighten the limb
(triceps allow you to straighten your arm)
Connectors (p. 916)
 Ligaments-connect
bone to bone
 Tendons-connect muscle to bone
◦ Origin: where a muscle attaches to a
stationary bone
◦ Insertions: a muscle attaches to a mobile
bone
Smooth Muscle

Smooth muscles are found in the hollow parts of the body.
◦ They are composed of interlacing sheets of muscle cells. Unlike skeletal
muscle, they have a single nucleus.
◦ There are no striations in smooth muscle (no severe contractions)
◦ This would be in places like the lining or the stomach (moves food),
intestines (moves waste), blood vessels (change the diameter) and the
bladder (moves urine).
◦ A smooth muscle is an involuntary muscle (This means that you
cannot consciously control this muscle-they just work when needed)
◦ They move things through the body with a wave-like motion
(peristalsis)
Cardiac Muscle


Cardiac muscle makes up the heart (along with blood vessels) that
makes up the cardiovascular system
Cardiac muscles contract automatically to squeeze the walls of the
heart inward.
◦ They are similar to both skeletal and smooth muscle.
 They are striated (so they can contract)
 They have a single nuclei
 They are involuntary
◦ The heart beats nonstop about 100,000 times each day.
◦ Cardiac muscles don’t get tired-they work constantly until you
die
Integumentary
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
This system includes
skin, hair, nails, and
various glands
The function of this
system is protection-it
is a barrier from injury
and infection
The glands are
responsible for
secreting sweat and
oils to release waste
or cool the body
Subcutaneous layer
Epidermis (p. 925)

The epidermis is the outermost layer of skin
◦ It is composed of an outer (corneal layer) and
a lower (basal) layer
◦ This outer layer is made mostly of dead skin
cells filled with a protein called keratin
 This makes skin tough and leathery to resist
the outer environment. It also acts as
water-proofing
◦ Skin color for the epidermis is controlled by
the amount of melanin (a brown pigment)
 Melanin is produced in the dermis
Dermis (p. 925)

Inner layer of the skin composed of living cells and
specialized structures
◦ Blood vessels
◦ Sensory neurons
◦ Hair follicles (hair is made of dead cells filled with
keratin. Oil from glands keep them supple)
◦ Glands
 Sweat glands to cool the body
 Oil glands to soften skin, prevent water loss,
etc
 Because the glands produce sweat, the dermis
is responsible for temperature regulation
Subcutaneous layer
A
fatty layer beneath the
dermis that acts as
insulation and storage of
energy (fat cells)
Circulatory



The circulatory system
is made up of the
vessels and the
muscles that help and
control the flow of
fluid around the body.
It consists of the
cardiovascular system
and the lymphatic
system
As blood begins to
circulate, it heads from
the lungs to the heart
Circulatory

Cardiovascular
system
◦ Heart
◦ Blood vessels
◦ Blood

Lymphatic system
◦ Lymph nodes
◦ Lymph vessels
◦ Lymph
Heart
The center of the cardiovascular system
is the heart
 A septum (wall) separates the heart into
2 sections
◦ Right side: pumps blood to the lungs
(oxygen deficient blood)
◦ Left side: pumps blood from the heart
to the rest of the body (oxygen rich
blood)

Heart

Each side of the heart is separated into an
upper and lower chamber
◦ Each upper chamber is called an atrium
 You have a left atrium and right atrium
(depends on what side of the septum
you are)
◦ Each lower chamber is called a ventricle
 You have a left and right ventricle
Movement of blood

To control the flow of blood, you have
flaps ( called valves)that only open in one
direction
◦ The valve that controls blood flow from the
right atrium to the right ventricle is called the
tricuspid valve
◦ The valve that controls blood flow from the
left atrium to the left ventricle is called the
mithral valve
Blood flow – Part 1 (p. 934)
Deoxygenated blood enters the right atrium
through a vessel called the vena cava
◦ Superior vena cava comes from above the
heart
◦ Inferior vena cava comes from below the
heart
 Right atrium sends the deoxygenated blood to
the right ventricle
 Right ventricle contracts and sends the blood
through the pulmonary arteries to the lungs

Blood flow – Part 2 (p. 934)
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
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The deoxygenated blood gains oxygen in the
lungs (discussed in the respiratory system)
Oxygenated blood returns to the left atrium
through the pulmonary veins
Oxygenated blood is pumped into the left
ventricle
Contraction of the left ventricle forces blood
up through a large blood vessel called the
aorta
The blood is then transported to the rest of
the body
Circulatory
It leaves the heart
from the left
ventricle and goes
into the aorta.
 The aorta is the
largest artery in
the body.
 The blood leaving
the aorta is full of
oxygen

Blood vessels

There are 3 primary blood vessels in the circulatory
system
◦ Arteries: largest of the muscular vessels that carry
blood away from the heart
 Made of several arterioles
◦ Veins: vessels that contain several valves that bring
blood to the heart
 Made of several venules
 Vericose veins are caused by poor valves
◦ Capillaries: very small blood vessel where gases (ie.
oxygen) can diffuse to the body tissues surrounding
the capillary.
Blood Vessels: Lumen = cavity
Circulatory

The oxygen rich blood travels throughout
the body through arteries
◦ Arteries are tough, elastic tubes that carry
blood away from the heart.
◦ Arteries branch into capillaries(which are
the smallest blood vessels with walls only one
cells thick)
Circulatory



Much of the gas/nutrient
exchange between the
blood and body cells
occurs in the Capillaries,
which eventually lead to
veins
◦ Body cells get oxygen
from the red blood
cells, then give them
carbon dioxide (a waste
product)
Veins carry the blood to
the heart.
Once the blood reaches
the heart, it is pumped
back into the lungs to
expel the carbon dioxide
and obtain oxygen
Diseases of the circulatory system



Hypertension: also known as “high blood pressure”.
◦ This places stress on the walls of arteries and run the
risk that blood vessels will burst
 Stroke can be caused by a burst blood vessel in the
brain
Hypotension: also known as “low blood pressure”.
◦ Often feels cold because blood is not able to reach
the extremities efficiently
Atherosclerosis: when an artery is blocked by a build
up of fatty material
◦ Increases blood pressure and can lead to a burst
blood vessel
Lymphatic system (p.939)


Part of the circulatory system, the lymphatic system is
responsible for returning fluids (lymph) that have
collected in the blood stream
Important differences
◦ Lymphatic system is one way (not a circuit)
◦ There is no pump (like the heart)
 Skeletal muscles squeeze fluid through vessels
similar to blood vessels
◦ Lymph passes through lymph nodes that act as
filters to remove foreign particles, microorganisms or
other tissue debris
 Lymph nodes have specialized cells called
lymphocytes (specialized white blood cells that
fight disease and infection)
Blood

Blood is made of many different fluids and cell types
◦ Plasma: yellowish fluid that contains about 90%
water and many nutrients, wastes, chemical
messengers, etc
◦ Red blood cells : (erythrocytes): oxygen binds to
the hemoglobin molecule in red blood cells in the
lungs. When they reach the cells in body tissues, they
give up the oxygen to the cells and pick up carbon
dioxide waste through another gas exchange.
 Hemoglobin: an iron containing protein on red
blood cells
Blood

White blood cells (leukocytes): cells of the immune
system used to fight disease and infection
◦ Phagocyte: white blood cell that engulfs infectious
cells (ie bacteria) and destroys them
◦ Antibodies: produced by another white blood cell
that detects infections cells and activates the bodies
immune system
 Antibodies detect different protein markers on red blood
cells. These proteins give us our blood type (A, B, AB, O). If
you don’t have an A or B on your red blood cell, your immune
system will attack foreign blood with those “antigens”.

Platelets: fragments of larger cells that can bind
together at the site of tissue damage (this is what forms
a scab)
Respiratory (p. 947)
The respiratory
system allows us to
breathe
 The diaphragm is a
muscle contracts and
relaxes to move air
in and out of your
lungs
 The lungs are the
actual site of gas
exchange.

Air Pathway (p. 947)

Breathing begins at the nose and mouth
◦ Small hairs in the nose, mucous, and a nasal
cavity lined with cilia trap many particulates
that are swept into the throat to be
swallowed.

The air moves to the pharynx, a tube at
the back of the nasal cavity and mouth
◦ The epiglottis is a flap of cartilage that can
close or open. This prevents food particles
from going into the lungs
Respiratory



The nasal cavity and
throat filter, moisten
and warm the air we
breathe in
Some of the epithelial
tissue that line this
system has cilia which
trap particles that
don’t belong and send
them up for you to
cough out
Some of the cells
produce mucous
Air Pathway (p. 947)
The air continues down the pharynx to the
trachea, a rigid pipe made of cartilage
◦ This is again lined with cilia to trap unwanted
particles
 The trachea branches into 2 bronchi made of
smooth muscle and cartilage
◦ These are also lined with cilia
 The bronchi then separate into several tubes in
the lungs called bronchioles
◦ At the end of these bronchioles are several
aveoli. This is what oxygen and carbon
dioxide are exchange.

Respiratory (p. 947)


The trachea joins the
nasal passage and
throat to the lungs.
The bottom of the
trachea splits into two
branches called
bronchi.
◦ One enters the right
lung and one goes to
the left lung.
◦ Aveoli are at the
end of the bronchi.
Respiratory (p. 947)


The bronchial tree's
job is to spread the air
from the trachea over
a very wide area as
quickly as possible.
The air travels until it
hits little bags called
alveoli, where oxygen
is absorbed into the
blood stream through
capillaries and CO2 is
released.
Immune
The immune system
defends people
against pathogens,
or any invader in
your body.
 Through a series of
steps called the
immune response,
the immune system
attacks organisms
and substances that
invade our systems
and cause disease.

Immune
 Before
you are infected by a disease,
your body has a first line of defense
◦ The skin serves as a physical barrier
to outside pathogens
◦ Mucous membranes secrete
mucous which traps pathogens
which can be expelled or destroyed
by the acid in your stomach
◦ Digestive acids in your stomach
Immune

Many of the symptoms you feel when you are
sick are the result of your body fighting
invaders:
◦ Lymph nodes swell when your sick because
they are producing more white blood cells
◦ Your fever is meant to slow the growth and
reproduction of pathogens (invaders)
 However a fever over 103°F can denature
your proteins
◦ Mucous secretions and coughing expel
pathogens
Immune

If a pathogen gets through your first line of defense, you
have another level of protection . . . nonspecific
immune response
◦ If your body is damaged (cut or other break in the
skin), your body will start an inflammatory
response
 Blood and lymph go to the area of injury
 Histamine is released to attract other cells of
the immune system, allow more fluids to the area
(causes swelling) and begins the blood clotting
process with platelets
 White blood cells called phagocytes come in
and destroy all pathogens and foreign material
Immune

Your last line of defense against pathogens
is the immune system (specific
immunity)
◦ This is a specific response aimed at a specific
infection
◦ This is not an immediate response (this is why
there is a delay between begin exposed to the
disease and showing symptoms)
◦ The immune cells of the immune system are
called lymphocytes or leukocytes
Immune


The cells that are part
of this defense system
are white blood cells,
or leukocytes.
Leukocytes are
produced or stored in
many locations
throughout the body,
including the thymus,
spleen, lymph nodes
and bone marrow.
Immune

The immune system
has it’s own
transportation
vessels which are a
part of the
circulatory system
◦ They are called the
Lymphatic Vessels
◦ Lymph fluid can also
travel in the blood
vessels
Immune Cells

B cells
◦ Made and developed
in the bone marrow
◦ Produce antibodies
that recognize
antigens (any
substance that the
immune system
believes is foreign to
the body)

T cells
◦ Made in the bone
marrow and
developed in the
thymus
◦ Helper T cells
recognize part of the
antigen on the surface
of macrophages
 They call in cytotoxic T
cells
◦ Cytotoxic T cells
destroy cells
CELL-MEDIATED IMMUNITY
Before an immune response can begin, it must
be activated
 In a cell-mediated immune response, a
macrophage (specialized white blood cell that
ingests pathogens) will engulf a foreign
substance and present an antigen on its surface
 Receptor proteins on T helper cells bind with
the antigen and this causes the macrophage to
release a substance called interleukin-1 (IL-1)
 IL-1 activates the T helper cell and the T helper
cell releases a substance called interleukin-2
(IL-2)

CELL-MEDIATED IMMUNITY
IL-2 stimulates the production of more T
helper cells and activates T cytotoxic cells
 The T cytotoxic cells kill all your cells
that have the foreign antigen

◦ Cytotoxic cells destroy your infected cells and
cancer cells

A third type of cell, T suppressor cells
are thought to be responsible for shutting
down the cell-mediated immune response
HUMORAL IMMUNE RESPONSE –
START HERE
The release of interleukin-2 (IL-2) from the cellmediated response also activates B cells
 B cells begin to produce antibodies
◦ B cells that produce antibodies are called
plasma cells
◦ Antibodies are proteins that specifically bind
to the antigen
◦ Antibodies work by binding to foreign
substances so that macrophages can come in
and destroy them, or
◦ Inactivate foreign toxins or viruses

HUMORAL IMMUNE RESPONSE


The first time that your body responds to an
infection/disease is called a primary immune
response
◦ It takes your body about a week to build up enough
of an immune response to fight it off (this is when
you feel sick)
If you are exposed to an infection/disease again, your
body mounts a secondary immune response
◦ After a primary immune response, some of your
plasma cells become memory cells that will
recognize the foreign antigen
◦ Secondary immune response only takes a few hours
(This is why they say you are immune to a disease.
The response is so quick you don’t get sick)
VACCINATIONS

How do vaccines work?
◦ You are injecting just the plasma
membrane/cell wall of a pathogen, or
◦ An attenuated pathogen (one that has
been rendered inactive by heat, but still
has the membrane proteins)
 Your body will create memory cells to
those membrane proteins and you will
be mounting a very rapid secondary
immune response if exposed to the
disease again.
PROBLEMS WITH THE IMMUNE
SYSTEM
Allergies: a physical response to a common
foreign antigen (pet dander, pollen, etc)
 Asthma: a foreign antigen causes the
respiratory bronchioles to over-react and
narrow (reduced airflow)
 Autoimmune disease: your immune cells
recognize some part of your body as foreign.
This causes your immune system to destroy
part of your own body
 HIV: destroys the cell-mediated immunity of
your body. HIV doesn’t kill you. It’s an infection
you get after HIV has destroyed your defenses

Gastrointestinal tract
The gastrointestinal tract, or digestive
tract, is responsible for ingesting and
breaking down nutrients to be used by
the body
 It starts at the mouth and ends with the
anus
 The following is a breakdown of the
digestive tract

Digestive System
MOUTH
ESOPHAGUS
LIVER
GALL BLADDER
STOMACH
PANCREAS
LARGE
INTESTINE
SMALL
INTESTINE
APPENDIX
RECTUM
ANUS
Digestive

The food we eat must
be broken down into
chemicals that the body
can use.
◦ This whole process is
called digestion and
that is the function of
the digestive system.
Digestive
The first step takes place in
your mouth, where food is
broken down into smaller
pieces by the mechanical
action of your teeth
 Your saliva also contains
an enzyme, salivary
amylase, that breaks
down starch (a type of
sugar) into simpler sugars

Digestive
ESOPHAGUS
After being swallowed, the
food travels down your
pharynx to your
esophagus, which is about
10 inches long.
 Since both air and food
travel down the pharynx, a
flap of tissue called the
epiglottis prevents food
from going down the
trachea
 The esophagus is covered
in muscles that push the
food to your stomach.

Digestive
STOMACH

The stomach releases
acids and enzymes that
break down the food
◦ The stomach has several
layers of smooth muscle
that aid in the mechanical
digestion of food.
◦ The stomach also releases
gastric fluids to aid in
chemical digestion
Digestive
After food enters the stomach from the
esophagus, the cardiac sphincter closes to
prevent food and gastric juices from entering
the esophagus
◦ Food remains in the stomach for 3-4 hours
 The smooth muscles of the stomach churn the
stomach to mix the food with the gastric juices
and form chyme
◦ Pepsin is a digestive enzyme that works at
low pH
◦ HCl is the acid released into the stomach to
make sure the pepsin is active

Digestive
When digestion is finish, the stomach
forces the chyme into the small intestine
through the action of peristalsis, wavelike muscle contractions that cause the
substance to move
 Once in the small intestine, the pyloric
sphincter closes to prevent the chyme
from returning to the stomach

Digestive




The small intestine is the final
place for digestion
It is about twenty feet long and
one inch in diameter. It is made
of 3 parts:
 Duodenum
 Jejunum
 Ileum
It releases more chemicals to
break down food
This is also where the nutrients
from food are absorbed through
small finger-like projections
called villi
SMALL INTESTINE
Digestive


Waste products and food
that are not absorbed in
the small intestine pass
into the large intestine
(or colon) through
perstalsis
The large intestine is only
5 feet long, but is much
wider than the small
intestine
LARGE INTESTINE
Digestive
The large intestine
removes water from the
food waste to create feces
 A meal may take up to
three days to pass through
your digestive system. It
spends about three hours in
your stomach and up to 20
hours in your large
intestine!

Digestive

The pancreas is an elongated gland
that is below the stomach. It has many
functions:
◦ It releases hormones to control
blood sugar (ENDOCRINE)
◦ It can release sodium
bicarbonate to neutralize the
stomach acid before chyme
enters the small intestine
(DIGESTIVE)
◦ Produces many enzymes that
help to break down proteins,
carbohydrates, lipids and nucleic
acids (DIGESTIVE)
PANCREAS
Digestive


The Liver :
 Stores glucose as
glycogen (DIGESTIVE)
 Breaks down toxic
substances, bacteria and old
blood cells (EXCRETORY)
 Secretes bile which is
necessary to digest
lipids/fats (DIGESTIVE)
The extra bile from the
liver is stored in the Gall
Bladder (DIGESTIVE)
GALL BLADDER
LIVER
Excretory system
We’ve already discussed how waste is
removed form the gastrointestinal tract
through the large intestine and anus
 The other major way to remove waste is
through the urinary system

◦
◦
◦
◦
Kidneys
Ureter
Urinary bladder
Urethra
Kidneys

Responsible for removing most of the
nitrogenous wastes
◦ Most nitrogenous waste first goes to the liver
in the form of ammonia
◦ Ammonia is extremely toxic so the liver
converts into the less toxic chemical urea

Urea is sent into the blood stream where
it enters the kidneys for disposal
Excretory – SEE p. 994
The kidney is made of several units called
nephrons
◦ Nephrons are tiny tubes that end in a tight
ball of capillaries called Bowman’s capsule
◦ The purpose of the nephrons is to filter the
blood
 Blood first enters Bowman’s capsule where
nutrients in the blood are reabsorbed while the
waste is allowed to pass
 The blood continues to flow through the
nephron and continues to filter out nutrients
and allow the waste to pass

Excretory
The nutrients reabsorbed during the filtration
process are returned to the body
 The fluid and waste that remain form urine and
are transported to the ureter, a narrow
collecting tube attached to the kidney
 Each ureter leads to a storage organ called the
urinary bladder
 When the waste is ready to be evacuated,
muscular contractions force the urine out
through a tube called the urethra

Other avenues of excretion
 In
addition to excretion through
the gastrointestinal tract and
urinary system, we have already
discussed other avenues of waste
removal:
◦ Lungs: removes CO2
◦ Skin: removes wastes, salts and
oils in the subcutaneous layer
Nervous

The nervous system is divided into two
main systems:
◦ The central nervous system (CNS)
◦ The peripheral nervous system
Central Nervous System
The spinal cord and the brain make up
the CNS.
 Its main job is to get the information from
the body and send out instructions.

Central Nervous System

The brain helps to control all of the body
systems and organs, keeping them
working like they should.
◦ The brain communicates with the rest of the
body through the spinal cord and the nerves.
◦ This system also gives instructions to all parts
of the body about what to do and when to do
it
◦ Reflexes are involuntary, self protective
movements and are not controlled by your
brain (they just go to spinal cord and back)
Anatomy of the brain

The brain is composed of 4 basic parts
◦ Cerebrum: The cerebrum is responsible for
higher levels of thinking and communication
 Speech, reasoning
◦ Diencephalon: This is the relay center for the
brain where information entering or leaving
the brain is routed
◦ Brain stem: This is responsible for a lot of
involuntary responses in the body
 Heart rate, homeostasis, respiration, sensory input
◦ Cerebellum: Helps to coordinate movement
Spinal cord

The spinal cord is the central relay
between the brain and the rest of the
body
◦ A flexible spine gives protection to the
nervous tissue that makes up the spinal cord
◦ Signals are both sent are received via the
spinal cord
Peripheral Nervous System
The peripheral
nervous system is
made up of all of the
nerves and the
wiring.
 This system SENDS
the messages from
the brain to the rest
of the body as
electrical signals.

Peripheral Nervous System

Cells of the nervous system are called neurons
◦ Neurons carry messages in the form of an electrical
impulses.
◦ The messages move from one neuron to another to
keep the body functioning.
◦ Unlike other body tissues, nerve cells cannot also be
repaired if damaged due to injury or disease.
Structure of neuron

The cell body contains the organelles
and nucleus of the cell
◦ Dendrites are structures that receive signals
from other neurons
◦ Axons are used to transmit signals away from
nerve
Structure of neuron
The axon of the neuron is covered in a lipid
layer known as the myelin sheath
◦ The myelin sheath acts as an insulator like a
rubber cord
 Schwann cells surround the axon and are
responsible for making the myelin sheath
◦ Gaps in the myelin sheath are known as
nodes of Ranvier
 Axons end in an axon terminal with a gap
between the next neuron known as a synapse

How do neurons work?

Nerves send signals in the form of an
action potential
◦ All neurons contain an electrical charge inside
the cell that is different than outside. This
difference in charge is called a membrane
potential
◦ When the charge is changed (by allowing ions
into or out of the membrane), you can move
a charge along the nerve
 Change the potential in different spots
How do neurons work?
Resting potential
◦ When the neuron is not sending or receiving a signal,
there are more negatively charged proteins and
potassium ions, K+, inside the cell and more sodium
ions, Na+ outside the cell . . . net negative charge
 Action potential
◦ When a signal is sent along the neuron, ion channels
allow the sodium ions into the cell (via a
concentration gradient) through a sodium channel
(facilitated diffusion) . . . net positive charge
◦ This changes the charge of the cell and the signal
causes the next cell in line to start an action potential

How do neurons work?

After the action potential, the cell needs
to regain its state of resting potential
◦ To do this it utilizes the sodiumpotassium pump to pump the sodium
out of the cell
 Active transport using ATP
◦ During this time, the nerve cannot send
another signal and is called the
refractory period
Sending a signal between neurons
A neuron can only send a signal to another
neuron through the synapse
 To do this, a neurotransmitter called
acetylcholine is released from the axon
terminal
 Acetylcholine travels across the neuron and
stimulates the next neuron, muscle or organ
that needs to receive the signal
 After the acetylcholine has sent the signal, an
enzyme called acetylcholine esterase breaks
down the acetylcholine

Acetylcholine
Somatic vs. Autonomic Nervous
System (Peripheral Nervous System)

Somatic
◦ Called the voluntary
nervous system
◦ Motor neurons are the
ones that activate different
muscles and glands
◦ Allows for conscious
control of your muscles
and lets you control your
movement
◦ There is also an
involuntary component
involved in reflexes

Autonomic
◦ Called the involuntary
nervous system
◦ Sympathetic: called
the fight or flight
response (increased
heart rate, pupils
dilate, etc)
◦ Parasympathetic:
resting response
(decrease heart rate,
pupils constrict, etc)
Sensory Organs

There are many different sensory
receptors depending on what they detect
◦ Mechanoreceptor: responds to movement,
pressure and tension
◦ Photoreceptor: responds to light
◦ Chemoreceptor: responds to chemicals
◦ Thermoreceptor: responds to temperature
change
◦ Pain receptor: responds to tissue damage
Hearing and balance
(Diagram on p.1017)
The outer ear is responsible for
“capturing” sound and transmitting it
down the auditory canal
 The auditory canal leads to the
tympanic membrane or eardrum
 Sound vibrations (moving air) cause the
tympanic membrane to vibrate and move
three small bones: the hammer, the
anvil and the stirrup

Hearing and balance
After the three bones are set in motion,
the stirrup transfers vibrations to a
membrane called the oval window
 The oval window leads into the cochlea

◦ The cochlea has 3 fluid filled chambers that
are separated by membranes
◦ Vibrations from the oval window cause hair
cells within the fluid of the cochlea to move
◦ This movement is interpreted and sent by
your auditory nerve to your brain as sounds
Hearing and balance


In addition to hearing, the ears are responsible for
maintaining balance
◦ In the middle ear there is a tube connecting to the
throat, Eustachian tube
 This allows air pressure to equalize on both sides of
the tympanic membrane (popping your ears)
Additionally, in the inner ear, there are 3 fluid filled
chambers called the semicircular canals
◦ Each canal is situated in one of 3 axis
◦ There are mechanoreceptors in the semicircular
canals that can be interpreted as relative position
Vision:
(Diagram on p. 1019)

All sight is based on light striking a place
in the back of the eye called the retina
◦ Light first passes through the cornea, a
protective outer layer of the eye
◦ Next, light passes through the pupil, or the
opening in the eye that controls the amount
of light
 It contracts when very bright
 It dilates when dim or when “fight or flight” is active
◦ The muscles that control the pupil are located
in the pigmented iris
Vision
The light that passes through the iris hits the lens
◦ This is a crystalline structure that allows the light to be
refracted, bent, to produce a clear image
 If your lens cannot be properly “bent”, you will need
some sort of vision correction (glasses, contacts)
 Again, the muscles in the iris controls the amount of light
passing into the eye
 Within the retina are specialized photorecptors called rods
and cones
◦ Rods respond to dim light
◦ Cones respond to bright light
 The signals that hit the rods and cones are sent by the optic
nerve to be interpreted by the brain

Taste and smell

Most people perceive taste because of
chemoreceptors located on the tongue,
or taste buds
◦ Taste buds are located between the bumps on
your tongue, papillae
◦ You have chemoreceptors for: sweet, salty,
sour and bitter
◦ The signals are sent to the brain to interpret
taste.
Taste and smell
Smell works very similar to taste
 Instead of chemoreceptors on your
tongue, smell has specialized
chemoreceptors in your nasal passages
called olfactory receptors

◦ When a chemical binds to an olfactory
receptor, the information is sent to your brain
and interpreted as smell
Touch




You have many mechanoreceptors throughout the
skin
◦ They are concentrated in the face, tongue and
fingertips
You have two types of thermoreceptors in the skin
◦ Sensitive below 20°C (cold receptor)
◦ Sensitive between 30°C and 45°C (heat
receptor)
You have many types of “pain” receptors located
throughout the skin
All receptors travel to the spinal chord and up to
the brain
Endocrine system
Endocrine system

System that produce hormones to
regulate body activities
◦ Hormones are produced by various
endocrine and exocrine glands
throughout the body
 Endocrine glands: ductless gland that secrete
hormones into the blood stream or fluids of nearby
tissues
 Exocrine glands: gland with a tube-like structure
that transport substances to specific locations
inside or outside the body
Hormones

Hormones are chemicals that influence body activity.
They are transported throughout the body using the
blood stream and extracellular fluid
◦ Amino-acid based hormone: water soluble
hormone
 Binds to protein receptors on the cell membrane
 Often the first to trigger a signal in the cell
◦ Steroid hormone: lipid soluble hormone
 Lipid soluble allows the hormone to enter through
the plasma membrane
 Causes the cell to activate existing enzymes or to
initiate protein synthesis for specific enzymes
Organs of the endocrine system
 Hypothalamus
 Pancreas
 Pituitary
 Thymus
 Thyroid
 Pineal
 Adrenal
 Parathyroid
 Gonads
 Digestive
cells
Hypothalamus/Pituitary:
List of hormones released (p. 1035)

Hypothalamus: “controls” much of the
endocrine system
◦ Located in the part of the brain that initiates
many of the responses of the endocrine and
nervous system
◦ The hypothalamus often starts the hormone
response by sending signals to the pituitary
gland
 Releasing hormones: stimulates the pituitary gland
to release hormones (ON SWITCH)
 Release-inhibiting hormones: inhibit the release or
production of hormones (OFF SWITCH)
Thyroid



Thyroid gland: located near the lower part of the
larynx
◦ Thyroid hormones help to maintain normal heart
rate, blood pressure and body temperature
◦ Also helps to transport calcium from the blood to
the bone to generate bone tissue for healthy bone
development and repair
Hyperthyroidism: produce to much thyroid hormone
◦ Symptoms include: hyperactivity, weight loss, high
blood pressure, increased heart rate
Hypothyroidism: do not produce enough thyroid
hormone
◦ Symptoms include: lethargy, lack of growth, weight
gain, low heart rate, low body temp
Adrenals

Adrenal glands: one adrenal is located above
each of the kidneys
◦ Produces epinephrine and norepinephrine
(also known as adrenaline and noradrenaline)
 Initiates fight or flight respons – increased
heart rate and blood pressure, increase
blood sugar levels, increase oxygen flow to
lungs
◦ Also produces cortisol which promotes the
cells to produce glucose from proteins
 This hormone is often released when the
individual is stressed
Gonads
 Gonads
begin producing hormones
when the individual hits puberty
◦ Responsible for the development of
secondary sex characteristics
◦ Responsible for the maintaining the
production or release of the sex
cells
Pancreas

The pancreas is important because of its production
of insulin
◦ Insulin is responsible for regulating the levels of
glucose available in the blood and available to cells
◦ Diabetes mellitus is a condition where cells are
unable to receive blood glucose so there is a high
level of glucose in the blood
 Type 1: The immune system attacks the cells that
produce insulin (usually treated with a daily insulin
injection)
 Type II: A hereditary condition that is usually
triggered by obesity and inactivity (may be treated
with diet and exercise)
Thymus / Pineal / Parathyroid /
Digestive cells
Thymus: produces that hormones that
stimulates the maturation of T-cells
 Pineal: releases melatonin which helps
to regulate sleep patterns
 Parathyroid: causes calcium to be
transferred from the bone to the blood
(opposite of thyroid and must in unison)
 Digestive cells: helps to release various
fluids during digestion (stomach acid,
digestive enzymes, gastric juices)

Homeostasis: How it works
The ability or tendency of an organism or cell to
maintain internal equilibrium by adjusting its
physiological processes
 In animals such as ourselves, the internal
environment of our bodies must have certain
conditions within tolerable limits to continue to
function properly
 Environmental conditions that cause reactions are
called stimuli (plural = stimulus)
 A feedback mechanism occurs when the level
of one substance influences the level of another
substance or activity of another organ.

Negative Feedback

Negative feedback is where various receptors
and effectors bring about a reaction to ensure that
conditions remain favorable
 In negative feedback, a final step in a reaction
inhibits the start of another reaction
◦ A receptor is a structure that monitors internal
conditions, sense changes, and initiate a response
(usually by sending signals to the brain)
◦ Effectors are muscles, organs, or other
structures that receive signals from the brain.
When an effector receives a signal from the brain,
it changes its function in order to correct the
change from normal conditions.
Positive Feedback
Positive feedback mechanisms are
designed to accelerate or enhance the
output created by a stimulus that has
already been activated
 Push levels/conditions in the body out of
normal ranges
 When the body senses a change, it
increases or accelerates that change
 Happens much less often than negative
feedback

Homeostasis

Depending on the physiological conditions, a hormone
can act as a positive or a negative feedback
◦ For example if you release an initial hormone and it
causes subsequent hormones to be released, this is
positive feedback
 Adrenocorticotropic hormone (ACTH): stimulates
the production of cortisol in the adrenals
◦ When a hormone inhibits the release of a hormone,
this is negative feedback
 Release-inhibiting hormones produces by the
hypothalamus prevents the production of hormones
in the pituitary