Chapter 35 Human Body Systems
Impulses
The messages carried by the Nervous System are electrical signals
The choroid is
The middle layer of eye that is rich in blood vessels
The sclera is
The outer layer of eye that maintains its shape Serves as the point of attachment for muscles that move the eye
The retina is
The inner layer of eye that contains photoreceptors
Cell Body
The largest part of a typical neuron It contains the nucleus
Each half of the Cerebrum deals with the opposite side of the body
The left half of the cerebrum controls the right side of the body The right half of the cerebrum controls the left side of the body
How is the body organized?
The levels of organization in a multicellular organism include: • cells • tissues • organs • organ systems
Neurons
Cells that transmit impulses
The human nervous system has two major divisions
Central Nervous System and Peripheral Nervous System
Dendrites
Extend from the cell body and carry impulses from the environment toward the cell body
Nervous Tissue
Transmits nerve impulses throughout the body
Neurotransmitters
Chemicals used by a neuron to transmit an impulse across a synaspe to another cell
These sense organs include
1. Eyes (Sight) 2. Ears (Hearing) 3. Nose (Smell) 4. Mouth (Taste) 5. Skin (Touch)
What are the five types of sensory receptors?
1. Pain Receptors 2. Thermoreceptors 3. Mechanoreceptors 4. Chemoreceptors 5. Photoreceptors
The eye has three layers
1. the retina 2. the choroid 3. the sclera
How many organ systems are there in the body?
11
Cells
A cell is the basic unit of structure and function in living things. Individual cells in multicellular organisms are specialized.
Fetal alcohol syndrome (FAS)
A group of birth defects caused by the effects of alcohol on the fetus.
What is an organ?
A group of different types of tissues that work together to perform a single function
Organ Systems
A group of organs that perform closely related functions
Cerebellum
A large structure of the hindbrain that controls fine motor skills. Coordinates and balances the actions of the muscle
Cerebrospinal Fluid
Acts as a shock absorber that protects the central nervous system
What are the structures of the Respiratory System?
Nose, Pharynx, Larynx, Trachea, Bronchi, Bronchioles, and Lungs
A reflex is
A quick, automatic response to a stimulus
Sensory Receptors
A specialized neuron that detects a particular category of physical events
Threshold Stimulus
A stimulus must be of adequate strength to cause a neuron to transmit an impulse. The minimum level of a stimulus that is required to activate a neuron
What is the effect of alcohol on the body?
Alcohol is a depressant that slows down the rate at which the central nervous system functions.
Muscle Tissue
Along with bones, enables the body to move.
How is a nerve impulse transmitted?
An impulse begins when a neuron is stimulated by another neuron or by the environment.
Tissues
An integrated group of cells with a common structure, function, or both.
Drug
Any substance, other than food, that changes the structure or function of the body
Cerebrum
Area of the brain responsible for all voluntary activities of the body Site of intelligence, learning, and judgment
Lens
Behind the iris Muscles attached to the lens change its shape to adjust focus to see near or distant objects
What are the structures of the Skeletal System?
Bones, Cartilage, Ligaments, and Tendons
What are the structures of the Nervous System?
Brain, spinal cord, sensory receptors, nerves
What is the function of the Circulatory System?
Brings oxygen, nutrients, and hormones to cells Fight infection Removes cell wastes Helps to regulate body temperature
Motor Neurons
Carry impulses from the brain and spinal cord to muscles and glands
Sensory Neurons
Carry impulses from the sense organs to the spinal cord and brain
Cocaine
Causes the sudden release in the brain of a neurotransmitter called dopamine.
Interneurons
Connects sensory and motor neurons and carry impulses between them
Brain Stem
Connects the brain and spinal cord
What are the functions of the Nervous System?
Controls and Coordinates functions throughout the body and responds to internal and external stimuli
What is the function of the Endocrine System?
Controls growth, development and metabolism Maintains homeostasis
Hypothalamus
Controls recognition and analysis of hunger, thirst, fatigue, anger, and body temperature
What is the function of the Digestive System?
Converts food into simpler molecules that can be used by the cells of the body Absorbs food Eliminates wastes
Hearing
Ears can distinguish both the pitch and loudness of vibrations
What is the function of the Excretory System?
Eliminates wastes products from the body in ways that maintain homeostasis
What are the four basic types of tissues in the human body?
Epithelial, Connective, Nervous, and Muscle
Photoreceptors
Found in eyes Sensitive to light
Mechanoreceptors
Found in the skin, skeletal muscles, and inner ears Sensitive to touch, pressure, stretching of muscles, sound, and motion
The human ear has two sensory functions
Hearing & Balance
What are the structures of the Circulatory System?
Heart, Blood, Blood Vessels
What is the function of the Lymphatic/Immune System?
Helps protect the body from disease Collects fluids lost from blood vessels and returns the fluid to the circulatory system
What are the structures of the Endocrine System?
Hypothalamus, Pituitary, Thyroid, Parathyroid, Adrenals, Ovaries (in females) and Testes (in males)
A reflex arc
Includes a sensory receptor, sensory neuron, motor neuron, and effector that are involved in a quick response to a stimulus.
Epithelial Tissue
Includes glands and tissues that cover interior and exterior body surfaces
Stimulants
Increase heart rate, blood pressure, and breathing rate. Increases the release of neurotransmitters at some synapses in the brain.
Chemoreceptors
Located in nose and taste buds Sensitive to chemicals in the external environment
Thermoreceptors
Located in the skin, body core, and hypothalamus Detect variations in temperature
Pain Receptors
Located throughout the body except in the brain. They respond to chemicals released by damaged cells Pain usually indicates danger, injury, or disease
Axon
Long fiber that carries impulses away from the cell body of a neuron
Opiates
Mimic endorphins which normally help to overcome sensations of pain.
What are the structures of the Digestive System?
Mouth, Pharynx, Esophagus, Stomach, Small and Large Intestines, Rectum
Feedback Inhibition
Process in which a stimulus produces a response that opposes the original stimulus
What is the function of the Reproductive System?
Produces reproductive cells In females, nurtures and protects developing embryo
What is the function of the Respiratory System?
Provides oxygen needed for cellular respiration and removes excess carbon dioxide from the body
Connective Tissue
Provides support for the body and connects all of its parts
Thalamus
Recieves messages from sensory receptors throughout the body and relays the information to the proper region of the cerebrum
What is the function of the Nervous System?
Recognizes and coordinates the body's response to changes in its internal and external environments
What are the functions of the Central Nervous System?
Relays messages, Processes information and Analyzes information
Cones
Respond to light of different colors, producing color vision
Rods
Sensitive to light, but not color
What is the function of the Integumentary System?
Serves as a barrier against infection and injury Helps regulate body temperature Provides protection against ultraviolet radiation from the sun
What are the structures of the Muscular System?
Skeletal Muscle, Smooth Muscle, Cardiac Muscle
What are the structures of the Integumentary System?
Skin, Hair, Nails, Sweat and Oil Glands
What are the structures of Excretory System?
Skin, Lungs, Kidneys, Uterus, Urinary bladder, and Urethra
Depressants
Slow down heart rate and breathing rate, lower blood pressure, relax muscles, and relieve tension.
Drugs differ in the ways in which they affect the body
Some kill bacteria and are useful in treating disease. Others affect a particular system of the body. Others cause changes to the brain and synapses.
What are the different classes of drugs that directly affect the central nervous system?
Stimulants & Depressants
Specialized Cells
Suited to perform a particular function
What is the function of the Skeletal System?
Supports the body Protects internal organs Allows movement Stores mineral reserves Provides a site for blood cell formation
What are the structures of the Reproductive System?
Testes, Epididymis, Vas Deferens, Urethra, and Penis (in males) Ovaries, Fallopian Tubes, Uterus, and Vagina (in females)
Homeostasis
The process by which organisms keep internal conditions relatively constant despite changes in external environments
Taste Buds
The sense organs that detect taste
What are the two divisions of the peripheral system?
The sensory division of the peripheral nervous system transmits impulses from sense organs to the central nervous system.
Myelin Sheath
There are gaps in the myelin sheath, called nodes, where the membrane is exposed. Impulses jump from one node to the next.
Meninges
Three layers of connective tissue in which the brain and spinal cord are wrapped
Addiction
Uncontrollable dependence on a drug
Cochlea
Vibrations of the oval window create pressure waves in the fluid-filled cochlea of the inner ear
What are the structures of the Lymphatic/ Immune Systems?
White blood cells, Thymus, Spleen, Lymph Nodes, Lymph vessels
Semicircular Canals
Within the inner ear, just above the cochlea are three semicircular canals.
What is the function of the Muscle System?
Works with skeletal muscle to produce voluntary movement Helps to circulate blood and move food through the digestive system