Download Chapter 30/34: Intro to Your Body Organization of the Human Body

Chapter 30/34: Intro to Your Body
Organization of the Human Body
How does the body get 100 trillion cells to work together and perform
different jobs? What are the levels of organization?
Cells  tissues  organs  organ systems
Cell: basic unit of structure and function in living things
Specialized cells: a cell that is uniquely suited to perform a particular
function/job (muscle cell, White Blood Cell, etc)
Tissues: a group of cells that perform a single function (muscle tissue)
4 types of tissue:
1. Epithelial tissue: covers surface of body and lines
internal organs (skin, surrounds stomach, liver, etc)
2. Connective tissue: holds organs in place and binds parts
of the body together (tendons, ligaments)
3. Nervous tissue: receives and processes information,
messages from the body and environment and responds
(brain, neurons)
4. Muscle tissue: controls internal movement of materials
in body, external movement (heart, bicep)
Organs: a group of tissues that work together to perform a function
(stomach, skin, heart, liver,
Organ system: a group of organs that perform closely related functions.
We have 11 organ systems in our body
Nervous System
Structure:
brain, spinal cord, peripheral nerves
Function:
Recognizes and coordinates the body’s response to
changes in its internal and external environments
Integumentary System
Structure:
skin, hair, nails, sweat and oil glands
Function:
Protects against infection and injury;
helps regulate body temperature
Respiratory System
Structure:
nose, pharynx, larynx, trachea, bronchi,
bronchioles, lungs, alveoli
Function:
Provides oxygen needed for cellular
respiration and removes carbon dioxide
waste from the body
Digestive System
Structure:
mouth, pharynx, esophagus, stomach, small and
large intestines, rectum
Function:
processes food into a form that the cells can use
for fuel; absorbs food
Urinary/Excretory system
Structures:
skin, lungs, kidneys, ureters, urinary
bladder, urethra
Function:
Eliminates waste products from the body
Skeletal system
Structures:
bones, cartilage, ligaments, tendons
Function:
supports the body and protects
internal organs. Works with muscles
to create movement.
Muscular System
Structures:
skeletal muscle, smooth muscle, cardiac muscle
Function:
Body movement; helps circulate blood and
move food through the circulatory system
Cardiovascular / Circulatory System
Structures:
heart, blood vessels
(arteries, veins, capillaries)
Function:
brings oxygen, nutrients, and hormones to cells
Endocrine System
Structures:
hypothalamus, pituitary, pineal, thyroid,
parathyroid, adrenals, pancreas, ovaries,
testes
Function:
controls growth development, and
metabolism; maintains homeostasis
Lymphatic / Immune System
Structures:
WBCs, thymus, spleen, lymph nodes, lymph
vessels
Function:
fights off invading germs, provides protection
from diseases and parasites
Reproductive System
Structures:
testes, epididymis, vas deferens, urethra, penis, ovaries, Fallopian
tubes, uterus, vagina
Function:
produces reproductive cells (GAMETES); in females nurtures and
protects developing embryo
Endocrine System
Glands: Pineal, Hypothalmus, Pituitary, Thyroid, Parathyroid, Thymus,
Adrenals, Pancreas, Ovaries, Testes
These endocrine glands secrete: HORMONES
What are hormones?
Chemical messengers released in one part of the body that travel
through the blood to affect activities of cells in other parts of body.
Hormones affect other cells by binding to specific chemical receptors on
certain cells.
Target Cell: has a receptor for a particular hormone and can respond to
the hormone.
Control of the Endocrine System
To better understand how the endocrine system works, let’s take a look
at one of the body’s most important hormones - thyroxine.
What does thyroxine do?
Increases metabolic rate and body temperature; regulates growth
and development
Which gland produces thyroxine? Thyroid Gland
Thyroxine affects nearly all the body’s cells, increasing their metabolic
rate. It also increases the rate at which cells grow.
Metabolic rate: rate at which cells use food and oxygen
The hypothalamus of the brain also has receptors for thyroxine.
When levels of thyroxine drop, most cells slow down their activity, but
some cells of the hypothalamus increase their activity. These cells
trigger production of another hormone called thyroid-releasing
hormone (TRH). TRH travels from the hypothalamus to the pituitary
gland and causes cells in the pituitary gland to release thyroidstimulating hormone (TSH) which triggers the thyroid gland to release
more thyroxine.
Feedback Regulation
When there is too little thyroxine in the blood, the thyroid gland is
stimulated by TSH to make more thyroxine. When there is too much
thyroxine in the blood, TSH is blocked and the thyroid makes less.
Negative feedback: regulates amount of hormone being produced.
If there is too much of a hormone circulating in blood, further
production of the hormone will be blocked. Keeps conditions in body
relatively constant.