The Human Body

Chapters 35-40

Organization of the Body

The levels of organization in a multicellular organism include:

• cells• tissues• organs• organ

systems• body

Homeostasis

Homeostasis is the process by which organisms keep internal conditions relatively constant despite changes in external environments.

There are 11 Body SystemsNervous, Integumentary, Skeletal, Muscular, Circulatory, Respiratory

Digestive, Excretory, Endocrine, Reproductive, Lymphatic

• Structures: Brain, spinal cord, peripheral nerves

• Function: Recognizes and coordinates the body’s response to changes in its environment

Nervous System (Control Center)

Neurons

• Structures of a Neuron

Axon terminals

Myelin sheath

Cell body

Nodes Axon

Dendrites

Nucleus

1) Central Nervous System – Brain and Spinal Cord

2) Peripheral Nervous System– Somatic NS – regulates conscious control

like movement– Autonomic NS – regulates involuntary

activites like your heart beat.

The Human Nervous System has 2 Divisions:

Parts of The Human Brain

Thalamus

Pineal gland

Cerebellum

Spinal cord

Hypothalamus

Pituitary gland

Cerebrum

Brain stemPons

Medulla oblongata

•Eyes - vision

•Ears - hearing

•Nose – smell

•Mouth – taste

•Skin - touch

There are 5 senses the:

Integumentary System(Barrier)

• Structures: Skin, hair, nails, sweat and oil glands

• Function: Serves as a barrier against infection and injury; regulates body temperature; provides protection against the sun

• The skin is the largest organ in the body.

• The top layer; Epidermis is made of dead flat cells.

• The second layer is called the dermis and is made of blood vessels, nerve endings, glands, & hair follicles

• Microorganisms invade cuts and cause infections

The Skin

Epidermis – dead flat cells

Dermis

Hypodermis

Hair follicle

Sweat pore

Nerves

Muscle

Sweat gland

Fat

Sebaceous gland

Hair Blood vessels

Respiratory System (Breathing)

• Structures: Nose, pharynx, larynx, trachea, bronchi, bronchioles, lungs

• Function: Provides oxygen needed for cellular respiration and removes carbon dioxide

Epiglottis

Trachea

Nose Pharynx

Larynx

Lungs

Bronchus

Mouth

Diaphragm

Bronchioles

Breathing

Inhale with your nose because this is where air is filtered, warmed,& moistened.

Contraction of the diaphragm

causes breathing

Digestive System (Eating)

• Structures: Mouth, pharynx, esophagus, stomach, small and large intestines, rectum

• Function: Absorbs food and eliminates wastes

Mouth

Salivary glands

Stomach

Pancreas

Large intestine

Small intestine

Pharynx

Esophagus

Liver

Gallbladder

Rectum

• The Digestive System

Excretory System (Liquid Waste)

• Structures: Skin, lungs, kidneys, ureters, urinary bladder, urethra

• Function: Eliminates liquid waste products from the body

How much water should you drink?

• The minimum amount of water that you should drink everyday is 2 liters.

• Then on top of that drink milk, juice, and other liquids.

Skeletal System (Shape)

Structures: Bones, cartilage, ligaments, tendons

• Function: Supports the body; protects organs; allows movement; stores minerals; makes blood cells

The Skeleton

• The adult human skeleton is composed of 206 bones.

• Infants have more bones in their heads for delivery of birth and then close to make sutures on the skull.

Axial Skeleton

Skull

Sternum

Ribs

Vertebral column

The axial skeleton (blue) supports the central axis of the body and is made up of the skull, sternum, ribs, and Vertebral Column.

Muscular System (Movement)

• Structures: Skeletal muscle, smooth muscle, cardiac muscle

• Function: Works with skeletal system to produce movement; helps circulate blood and food through the digestive system

There are three different types of muscle tissue:

•Skeletal – (move bones)

•Smooth – (organs)

•Cardiac – (heart)

•40% of you body is muscle

Circulatory System (Heart)• Structures: Heart,

blood vessels, blood

• Function: Brings nutrients to cells; fights infection; removes wastes; helps regulate temperature

There are 3 types of Blood Vessels

1. Arteries – carries oxygenated blood from the heart to the rest of the body

2. Capillaries – delivers blood to the organs

3. Veins – carry de-oxygenated blood to the heart from the body

• Valves – prevent backwards flow of blood

Structures of the Heart

Blood

• The human body contains 4-6 liters of blood.

• Plasma – mostly water and other enzymes, salts, hormones, and waste

• Red Blood Cells – carries oxygen

• White Blood Cells – fights off infection

• Platelets – allows blood to clot

Lymphatic System (Immune)

• Structures: White blood cells, spleen, lymph nodes and vessels

• Function: Helps protect the body from disease;

Endocrine System (Hormones)• Structures: glands,

pancreas, ovaries (in females), testes (in males)

• Function: Controls growth, development and metabolism; maintains homeostasis

Testes and Ovaries

Testes produce testosterone which controls deepening of the voice & sperm production

Ovaries produce :

1. Estrogen which controls breast development, widen of hips, and egg development.

2. Progesterone prepares the uterus for a fertilized egg.

Adrenal Glands

The adrenal glands release epinephrine and norepinephrine, which help the body respond to stress, also know as the “Fight or Flight Response.”

Reproductive System (Making Babies)

• Structures: Testes, epididymis, vas deferens, urethra, and penis (in males), ovaries, fallopian tubes, uterus, vagina (in females)

• Function: Produces reproductive cells; in females, nurtures and protects developing embryo

The Male Reproductive System

Urinary bladder

Vas deferens

Pubic bone

Urethra

Penis

Seminal vesicle

Rectum

Prostate gland

Bulbourethral gland

Scrotum

Testis

Epididymis

Sperm Production

• The testes are located in an external sac called the scrotum.

• The scrotum is located outside the body cavity, where it is between 1 and 3 degrees cooler than normal body temperature needed for proper sperm development.

• Semen consists of sperm and seminal fluid that protect the sperm.

Female Reproductive System

Fallopian tube

Ovary

Uterus

Urinary bladder

Pubic bone

Urethra Vagina

Rectum

Cervix

The Menstrual Cycle

The menstrual cycle takes about 28 days and has four phases:

1. Follicular phase – hormones change and uterus prepares for fertilized egg

2. Ovulation – egg leaves ovary and moves to oviduct or Fallopian Tubes

3. Luteal phase – best change for fertilization in the fallopian tubes

4. Menstruation – lining of the uterus, blood, and unfertilized egg exit the body

Menstruation

– Lasts anywhere from 3–7 days

– Menstruation does not occur if the egg becomes fertilized because development of the human begins with fertilization (when sperm and egg join and creates a zygote

– A new menstrual cycle starts on the first day of menstruation.

Fertilization

Fertilization and Implantation

1

Stages of Embryo Development during the first 3 months

“First Trimester”1. Fertilization

2. Cell Division of Zygote

3. Embryo becomes Morula

4. Embryo becomes a Blastocyst

5. Implantation

6. Gastrulation

7. Chorion becomes Placenta

8. Embryo becomes a Fetus

During the second and third trimesters, the fetus will grow and develop until the fetus is fully developed which takes about 9 months, 40 weeks, or 280 days.

Uterus

Amniotic Fluid

Fetus

Amniotic sac

Placenta

Umbilical cord