The Human Body Systems

Homeostasis

• a natural process in which our body dynamically regulates our internal middle to keep it stable (in spite of environmental demands)

• this ensures that all of our systems are functioning well

  • shared responsibility of systems

  • good communication of the systems

  • role of emotions

The Immune System

• monitors the invasion of microorganisms in the body (distinction between “self” vs. “non-self” ; protection against potentially harming non-self)

• has the ability to perceive and remember antigens to fight them later

Antigens (Immunogens)

• trigger the production of antibodies by the B cells of the immune system

  • substance in the blood

  • name comes from “antibody generator”

Antibodies

• protect the body from disease by attaching to the virus and destroying it

  • proteins produced by the immune system in response to the presence of an antigen

Pathogens

• antigens that have the potential to create disease

Why do antigens stimulate our immune system to produce antibodies?

• to deactivate antigens to fight disease

• 5 types

Two Broad Categories of Immune Reactions

• Innate (natural) Immunity

  • present at birth

  • not learned through exposure to an intruder (= does not remember specific foreign antigens)

• Specific (acquired) Immunity

  • remembers specific foreign antigens (by creating a kind of immunological memory!)

The Immune System’s Line of Defense

1. Physical Barrier (skin, membrane, mucous)

2. Cells

3. NK (“Natural Killer” Cells)

NK (“Natural Killer”) Cells

• have the specific job of “seeking” and “destroying” cells that are infected, cancerous, or altered in some other way

• immunocompetence

• live for about a week

  • adults have about 2 billion at aby given time

    • people can have issues with number of cells or function of cells

Stem Cells

• origin in bone marrow

• two categories of immune cells

  • Lymphocytes

  • Phagocytes

Lymphocytes

• provide specific immunity

  • T Cells

  • B Cells

  • NK Cells

Phagocytes

• provide non-specific immunity

• engulf and ingest any kind of antigen

Types of T Cells

• Memory T Cells

• Cytotoxic T Cells

• Helper T Cells

• Regulatory (suppressor) T Cells

lmmunocompetence

• extent to which our immune system is functioning properly to ward off foreign microorganisms

Memory T Cells

• remember antigens to enable foster immune response

Cytotoxic T Cells

• produce toxic agents to kill their targets

Helper T Cells

• stimulate B cells to make antibodies

• stimulate T cells to become active

Regulatory (suppressor) T Cells

• suppress immune response

Organs of the Immune System

• Thymus gland

• Bone marrow

• Spleen

• Lymph nodes

Thymus Gland

• 1 of the maturation sites of lymphocytes (T cells)

• located in the middle of the chest above the heart

Bone Marrow

• spongy tissue inside of long bones

• produces blood cells

Spleen

• part of the lymphatic system

• filters blood and stores blood cells

• located on the left side of the abdomen

Lymphatic System

• draining system for the fluid circulating around the body

Lymph Nodes

• part of the lymphatic system

• located throughout the body

  • we have about 800 of them

• act as fillers/trappers for foreign microorganisms (antigens)

Cytokines

• small proteins produced by the immune system that act as chemical messengers of the immune system

  • role of communication

• similarity with neurotransmitters of the nervous system

The Nervous System

• controls our body systems

  • involuntary and voluntary actions

Division of the Nervous System

• Central Nervous System

• Peripheral Nervous System

Central Nervous System

• consists of:

  • brain

  • spinal cord

Divisions of the Peripheral Nervous System

• Somatic Nervous System

• Autonomic Nervous System

Somatic Nervous System

• controls voluntary activity

Autonomic Nervous System

• controls involuntary activity

Divisions of the Autonomic Nervous System

• Sympathetic Nervous System

• Parasympathetic Nervous System

Sympathetic Nervous System

• helps our body mobilize and expend energy

• used in fight or flight/stress response

• stops nonessential functions (digestion)

Parasympathetic Nervous System

• helps our body rest

• slows systems/resume nonessential functions after stress

Brain Stem

• connects the brain to the spinal cord

  • controls basic functions like breathing, sleep/wake cycles, and balance

Cerebellum

• little brain

• contributes to balance and coordination of voluntary movement

Hypothalamus

• portion of the brain that initiates the stress response in the nervous system and endocrine system

• monitors hunger and thirst

• monitors body temperature

• role in sexual activity

Thalamus

• manages synaptic input from the brain

Cerebral Cortex

• largest part of the brain

• outermost layer

• divided into 2 hemispheres by the corpus callosum

  • each hemisphere contains 4 lobes

• seat of conscious sensation and information processing

Frontal Lobes

• responsible for thought processing, voluntary movement, and language

Parietal Lobes

• responsible for processing sensory information (other than visual and audition)

Occipital Lobes

• responsible for vision (contain the visual cortex)

Temporal Lobes

• responsible for interpreting sound

Motor Cortex

• controls voluntary movements

  • facial/head movements

Sensory Cortex

• responsible for sensory activities in specific parts of the body including sensations in the skin, muscles, and joints

Broca’s Area

• responsible for speech production

Wernicke’s Area

• responsible for speech comprehension

The Endocrine System

• complements the nervous system in controlling bodily activities

  • hormones are slow acting

• regulated by the hypothalamus and the pituitary gland

• endocrine glands secrete hormones directly into the bloodstream

Pituitary Gland

• master gland

• secretes up to 8 hormones (involved in stress, growth, sexual development, etc)

• controls the functions of other glands

• under the control of the hypothalamus

Thyroid Gland

• shaped like a butterfly

• responsible for growth and metabolism

Adrenal Glands

• secrete cortisol, epinephrine (adrenaline), and norepinephrine (noradrenaline)

• help our body be aroused during moments of stress

Thymus

• role of immunity

Pancreas

• secretes insulin and other hormones

• role in regulating blood sugar

Insulin

• lowers blood glucose

Diabetes Mellitus

• chronic condition

• stems from the body’s inability to sufficiently produce or properly used insulin

  • Type I: insufficient production

  • Type II: improper use

Ovaries and Testes

• reproductive functions

Temporary Endocrine Gland

• Placenta

  • organ develops in uterus during pregnancy

  • provides oxygen and nutrients to growing fetus

  • removes wastes

Tropic Hormones

• hormones produced to stimulate other glands

  • ACTH (Adrenocorticotropic Hormone)

    • produced by the pituitary gland

The Cardiovascular System

• delivers nutrients to cells for metabolism and to remove waste products of metabolism

• consists of:

  • heart

  • blood vessels

Heart

• Myocardium (medical name for heart muscle)

• beats about 100,00 times/day

• divided into 2 halves (right and left) by the septum

• has 4 chambers

  • 2 atria (upper)

  • 2 ventricles (lower)

Atria

• receive blood returning to the heart and transfer it to the ventricles

Ventricles

• pump blood flow from the heart either to the lungs or to other parts of the body

Blood Vessels

• transport fluids through the body

  • Arteries (Aorta)

  • Veins

Arteries

• transport oxygenated blood pumped by the heart

Veins

• transport deoxygenated blood back to the heart

Aorta

• main artery

• carries oxygen-rich blood away from the heart