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Human Physiology
By Chelsea Finn
The Nervous System
There are 100 billion neurons in the human brain
The Nervous System Standards
 Students know how the nervous system and endocrine systems
regulate conditions in the body.
 Students know the functions of the nervous system and the role
of neurons in transmitting electrochemical impulses.
 Students know the role of sensory neurons, interneurons, and
motor neurons in sensation, thought, and response
Components of the Nervous System
Includes:
 Central Nervous System
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includes brain and spinal cord
brain has three parts:
cerebrum, cerebellum, and
medulla oblongata
the cerebrum is conscious,
while the other two parts are
part of the unconscious brain
 Peripheral Nervous System
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responsible for involuntary
actions such as heart beat and
the digestive system
divided into sympathetic and
parasympathetic systems
these two systems check on
each other to create a balance
Nervous System Functions
 Receives and compares input of
external conditions and the body’s
external state
 Acts as a control system for all
actions
 Responds to stimuli
Parts and Types of Neurons (Nerve Cells)
Parts of Neurons:
 Dendrite: receive and transmit information
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from another nerve cell into cell body
Cell Body: contains nucleus, mitochondria,
and other organelles typical to eukaryotic
cells
Axon: guides electrochemical messages
away from the cell body
Types of Neurons:
 Sensory Neurons: usually have short
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axons and long dendrites, carry messages
from receptors to the central nervous
system
Interneurons: found only in the central
nervous system
Motor Neurons: have a long axon and a
short dendrite, transmit messages from
the central nervous system to muscles
How Nerves Function

Receives sensory input in various
forms from electrochemical impulses
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These impulses travel along the the
lengths of cells up to 250 miles per
hour
Body Regulation through loops:
 Signals from senses go to the neurons.
 Depending on the impulse, the nerve cell
will either send the impulse to the brain,
or react immediately
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For example, if a person steps on a nail,
an impulse will go to a nerve and the
neuron will automatically pick up the foot,
without sending the impulse to the brain.
Another example is if a person starts to
feel cold, a neuron will send that impulse
to the brain and then the person will
choose what to do, because it’s not that
important to get warmer
The Circulatory System
Students know how the complementary activity of major
body systems provides cells with oxygen and nutrients and
removes toxic waste products such as carbon dioxide
Circulatory System
Includes:
 Red blood cells that carry oxygen
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from the lungs to other parts of the
body
Arteries that carry blood away from
the heart
Veins that carry blood back to the
heart
Capillaries that are the point of
exchange of blood and the tissues
two pumps in the heart
Specialized organs for the exchange
of acquired materials, such as
oxygen from the external
environment
Circulatory System Functions
 Delivers oxygen, nutrients, and hormones to
cells in the body
 Removes waste such as carbon dioxide,
ammonia, and other metabolic wastes
The Heart
 Heart has two pumps:
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One to pump deoxygenated
blood to the lungs
The other to pump oxygenated
blood to all other organs and
tissues
 Contracts in a rhythm to pump
blood
Skeletal System
The body has 206 bones
Functions of the Skeletal System
 Forms and shapes our bodies with
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206 bones
Supports, protects, and allows
bodily movement
Produces blood for the body
Stores minerals such as calcium
and phosphorus
Protects vital organs inside body
Parts of the Skeleton
Axial Skeleton
 Consists of bones that protect
organs of the head, neck, and
trunk
 Forms the axis of the body
 Contains the skull, sternum, ribs,
and spine
Appendicular Skeleton
 Attaches limbs to axial skeleton
 Contains upper extremities
(arms), lower extremities (legs),
the shoulder girdle, and the
pelvic girdle
Types of Bone
Short Bones:
 Short and cube-shaped
 Found in ankles and wrists
Long Bones:
 Longer than they are wide
 Work as levers
 Ex. Femur, Humerous
Flat Bones:
 Broad Surfaces for:
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Protection of Organs
Attachment of Muscles
 Ex. Ribs, Bones in the Skull
Irregular Bones:
 Bones that don’t fall into other
categories
 Ex. Bones in the Vertebra
Bone Composition
Many bones contain both spongy bone
and compact bone.
Compact bone:
 Dense and hard
 Forms the protective outer layer of all
bones
Spongy Bone:
 Inside the compact bone
 Has many tiny holes like a sponge or
sponge cake (porous)
Is in most bones

The bone cells are imbedded in
inorganic salts like calcium and
phosphorus for strength
Collagen fibers give the bone flexibility
Muscular System
Students know the cellular and molecular basis of muscle
contraction, including the roles of actin, myosin, Ca+2, and
ATP.
Types of Muscle
Skeletal Muscle:
 Responsible for moving limbs, trunk,
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and face
Responsible for voluntary movement
Made up of elongated cells called
muscle fibers
Mostly controlled by Central
Nervous System
Cardiac Muscle:
 Only found in heart
 Involuntary
Smooth Muscle:
 Usually not voluntary
 Spindle-shaped
 Found in stomach, intestines, and
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walls of blood vessels
Can contract without nervous
stimulation
Functions of Muscular System
 Determines the shape of our
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bodies and how we move
40 to 50 percent of our mass
Allows motion and movement of
our bodies
Maintains our posture
Produces heat
Muscle Structure
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Attached to bones by tendons that are made of connective tissue
Skeletal muscles have bundles called fasicles
Fasicles are made up of many muscle fibers
Muscle fiber contains many myofibrils
Muscle Contraction
1.
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An action potential, or wave of electrical discharge, reaches the
muscle cell via T tubules
The action potential causes calcium to leak out and immediately
combine with thin myofilamints
This exposes the active site on the actin molecules
The active site on the actin molecules are now free to bind with the
cross-bridges of the mysoin molecules of the thick myofilament
After this attachment, stored energy is released as the cross-bridges
pivot, using a power stroke o move toward the middle of the
contracting unit. All of the contracting units of a cell move together
to make the cell contract
Calcium ion concentration in the cytoplasm quickly returns to normal
due to the active transport of calcium ions into the extracellular fluid
and into the sarcoplasmic reticulum.
As calcium detaches from the troponin, the actin active sites become
blocked, breaking the bridge connections, and the cell relaxes
Integumentary System
Students know the role of the skin in providing nonspecific
defenses against infection.
Skin Function and How it Functions
Protects the body:
 Serves as barrier against
infection on injury
 Helps regulate body
temperature through
sweat
 Removes waste products
through the air
 Serves as protection
against UV light from the
sun
 Produces vitamin D
Sweat Pore
Parts of the Integumentary System
Epidermis
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The outer layer
Composed of many sheets of flat
epithelial cells
Made of mostly dead cells
Most cells under go rapid cell division
Newer cells push outward and older cells
loose their content and start to produce
keratin
Keratin is a tough protein that makes up
calluses, hair, and nails
Does not contain blood vessels
Dermis
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Contains blood vessels, nerve endings,
glands, sense organs, smooth muscles,
and hair follicles.
Helps control body temperature by
expanding and shrinking blood vessels
Hair and Nails
 Hair is produced by cells called
hair follicles
 Nails grow from rapidly dividing
cells in the nail matrix located
near the tips of fingers and toes
 Hair protects and insulates the
body
 Nails grow .5 to 1.2 mm per day
Respiratory System
Students know how the complementary activity of major
body systems provides cells with oxygen and nutrients and
removes toxic waste products such as carbon dioxide.
Functions of Respiration
Functions
 Get oxygen into the body and carbon dioxide and waste gases out of the body
 helps maintain body temperature and eliminate excess water from the body
Parts of the Respiratory System
Parts
 Nose- a passage way for air and also a sense
 Pharynx- (throat) passage way for air and food
 Larynx- the voice box, lined with mucus membrane
 Trachea- windpipe, tube composed of cartilage, lined with mucus membrane, lies in front of
esophagus
 Bronchi- C shaped rings of cartilage, sweeps out dust particles
 Lungs- main organ of respiration, millions of alveoli and blood capillaries exchange oxygen
and carbon dioxide
Gas Exchange
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Gas exchange happens in the alveoli
The alveoli are the tiny sacs found in
the lungs
Their walls are extremely thin, enough
to allow gas to diffuse through them
The alveoli are lined with pulmonary
capillaries, which have walls thin
enough to permit gas exchange.
The inhaled gases diffuse from the
alveoli to the blood in the capillaries,
while carbon dioxide diffuses in the
opposite direction from the capillaries to
the alveoli
Now, pulmonary blood has oxygen and
the lungs are holding carbon dioxide.
Then, exhalation occurs and gets rid of
the carbon dioxide
Excretory System
Students know the homeostatic role of the
kidneys in the removal of nitrogenous wastes
and the role of the liver in blood detoxification
and glucose balance.
Parts of the Excretory System
 Kidney- bean-shaped organ,
made up of tiny units called
nephrons, it filters the blood,
re-absorbs the blood, and
secrets the waste
 Ureter- the waste that has been
filtered out is secreted through
this tube
 Bladder- a hollow organ, walls
are made of muscle, where the
ureters empty into
 Urethra- receives the urine from
the urinary bladder and
disposes it
Function of the Excretory System
 Disposes of waste such as toxins, excess water, other solutes, and
normal components of the blood that are present in greater-thannormal concentrations
 Regulates blood pressure, metabolism, and blood compisition and
volume
How the Excretory System Functions
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The kidney filters out blood of
its small molecules and ions.
It reclaims needed amounts of
useful materials.
The kidney secretes blood
through ureters
Ureters empty out into the
bladder
The urethra receives the urine
from the bladder and disposes
of it
Endocrine System
Students know how feedback loops in the nervous and
endocrine systems regulate conditions in the body.
Parts of the Endocrine System
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Hypothalamus and Pituitary Glandboth found in brain, both produce
growth hormone or growth
horrmone-releasing hormones
Thyroid Gland- found in the neck
Liver- produces insulin like growth
factor
Pancreas- produces insulin
Adrenal Glands- produce
testosterone and adrenoline
Stomach- produce gastrin
Ovaries- produce estrogen
Testes- produce testosterone
Functions of the Endocrine System
 Regulates mood, tissue function,
metabolism, sexual function, and
reproductive processes
 Controls glands that secrete
hormones that circulate through
the body through the
bloodstream to affect cells in
specific organs
 Regulates growth and
development
 Helps nervous system in
regulating the body through loops
How the Endocrine Functions
 Endocrine glands secrete their
products into the blood or
interstitial fluid without storing the
product.
 Hormones are carried in the
bloodstream to different cells in
the body and act as messengers
 The cells interpret the messages
and act on them
Digestive System
Students know the individual functions and sites of secretion
of digestive enzymes (amylases, proteases, nucleases,
lipases), stomach acid, and bile salts.
Functions of the Digestive System
 Uses enzymes to Process and
break down the chemical
compounds in food into
molecules that can be absorbed
and used by the cells as energy
 Builds and replaces cells and
tissues that are constantly dying
Parts of the Digestive System
Mouth:
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Food is partially broken down
here by chewing and salivary
enzymes
Esophagus:
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Food is pushed down this tube
by rhythmic muscles
Stomach:
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Food is bathed in gastric acid
Small Intestine:
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Food is broken down by bile,
pancreatic enzymes, and other
digestive enzymes.
Large Intestine:
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Water and electrolytes are
removed from food
The Digestive Process
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Food is partly broken down by
chewing in the mouth and salivary
enzymes that break down the
starches in smaller molecules
Food goes through the esophagus
using rhythmic movements that
allow humans to eat or drink upside down
In the stomach, food is churned in
gastric acid
Food then passes through the
duodenum, the jejunum, and the
ileum in the small intestine. Bile,
pancreatic enzymes, and other
digestive enzymes help break
down the food.
The food then passes through the
large intestine where water and
electrolytes are removed from the
food.
At the end of the process, solid
food is stored in the rectum until
excreted by the anus
Digestive Enzymes
Amylases- digests starch into small segments of multiple sugars and into
individual soluble sugars
 Gastric Amylase- degrades starch (little significance)
 Pancreatic Amylase- degrades most hydrocarbons besides starch,
glycogen, and cellulose
Nucleases- degrade nucleic acids
Lipases- found in the first part of the small intestine, break down fatty
acids
Pepsin- the main gastric acid in the stomach, breaks down proteins in
smaller peptide fragments
The Reproductive System
Students know how hormones (including digestive,
reproductive, osmoregulatory) provide internal feedback
mechanisms for homeostasis at the cellular level and in
whole organisms.
Functions of the Reproductive System
 To ensure the survival of the
species by
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Producing egg and sperm cells
Transporting and sustaining
these cells
Nurturing the development of
offspring
Producing hormones
Parts of the Reproductive System
Females:
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Fallopian Tubes- eggs travel through
these
Uterus- where baby matures
Cervix- bottom end of the uterus
Ovaries- where eggs are produced
Vagina- repository for sperm
Males:
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Testes- where sperm is produced
Scrotum- sac where testes are held
Epididymis- where sperm is stored,
where sperm mature
Vas deferens- tubes which carry sperm
from scrota to urethra
Prostate Gland- the largest of the
accessory glands which puts its
secretions directly into the urethra
Penis- where the urethra goes through
How the Reproductive System Functions
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Uses hormones
There are 2 types of hormones:
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Reproductive System uses estrogen, a
steroid, to mature females
Estrogen is responsible for:
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development of breasts
further development of the uterus and
vagina
broadening of the pelvis
growth of pubic and axillary hair
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increase in adipose (fat) tissue
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Steroids
Protein and Polypeptide hormones
Reproductive system uses testosterone to
mature males
Testosterone is responsible for:
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Development of sex organs
Deepening of voice
Facial Hair
Etc.
Immune System
Immune System Standards
Students know the role of the skin in providing nonspecific defenses
against infection.
Students know the role of antibodies in the body's response to infection.
Students know how vaccination protects an individual from infectious
diseases.
Students know there are important differences between bacteria and
viruses with respect to their requirements for growth and replication,
the body's primary defenses against bacterial and viral infections, and
effective treatments of these infections.
Students know why an individual with a compromised immune system (for
example, a person with AIDS) may be unable to fight off and survive
infections by microorganisms that are usually benign.
Students know the roles of phagocytes, B-lymphocytes, and T-lymphocytes
in the immune system.
Functions of the Immune System
 Detects and eliminates
pathogens such as
viruses or parasitic
worms using an intricate
network of tissues,
organs, cells, and
chemicals
 Even though the
immune system is highly
effective, humans use
vaccination processes to
further protect humans
from infectious diseases
Parts of the Immune System
Bone Marrow- where all immune system
cells originate
Thymus- produces mature T cells
Lymphatic System- network of vessels
carrying lymph, or tissue-cleansing
fluid, from the tissues into the veins
of the circulatory system, it absorbs
nutrients from the small intestines,
Tonsils- found in throat, act as a filter
against disease organisms
Spleen- lies under diaphagm, acts as a
filter against foreign organisms that
infect the bloodstream, filters out old
red blood cells from the bloodstream
Skin- acts as physical barrier of defense
How the Immune System Functions
 leukocytes circulate
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through the body
between the organs and
nodes by means of the
lymphatic vessels
There are 2 types of
leukocytes: lymphocytes
and phagocytes
Phagocytes chew up
invading organisms
Lymphocytes allow the
body to remember and
recognize previous
invaders
The two types of
lymphocytes are called B
lymphocytes (B cells) and
T lymphocytes (T cells).
B cells produce antibodies
in response to foreign
proteins of bacteria,
viruses, and tumor cells.
Bibliography
 http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookNERV.ht
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http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Circulation.ht
ml
http://www.sirinet.net/%7Ejgjohnso/muscle.html
http://www.besthealth.com/besthealth/bodyguide/reftext/html/skin_sy
s_fin.html
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookRESPSYS
.html
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http://kidshealth.org/parent/general/body_basics/endocrine.html
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/
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