Human Body Systems Review

Nervous System

• Controls body activities, made of brain, spinal cord, nerves, and senses.
• Allows reaction to stimuli (changes in environment).

Central Nervous System (CNS)

• Consists of the brain and spinal cord; controls everything.
• Spinal cord sends messages to the brain and connects the brain to the rest of the nervous system.

Brain

• Controls everything and is made of over 10 billion nerves.
• Protected by the skull and divided into three parts: cerebrum, cerebellum, and brain stem.

Parts of the Brain

• Cerebrum: Largest part, controls thinking, memory, speaking, movement, and identifies sensory information.
• Cerebellum: Controls balance and posture, located below and behind the cerebrum.
• Brain Stem: Connects the brain to the spinal cord; controls heartbeat, breathing, and blood pressure.

Lobes of the Brain

• Frontal Lobe: Memory formation, emotions, decision making/reasoning, and personality.
• Parietal Lobe: Senses and integrates sensation, spatial awareness, and perception.
• Occipital Lobe: Processes vision and visual stimuli.
• Temporal Lobe: Hearing, organization/comprehension of language, and memory.

Circulatory System

• Transports substances (nutrients, gases, immune components, clotting factors) and regulates body temperature.

Types of Vessels

• Arteries: Carry oxygenated blood from the heart.
• Veins: Carry de-oxygenated blood back to the heart.
• Capillaries: Microscopic vessels for diffusion of gases, wastes, and nutrients.

Heart

• Pumps blood throughout the body, made of cardiac muscle, 2 atria, and 2 ventricles.
• SA node (pacemaker) regulates heartbeat phase one and signals AV node for phase two.

Blood Pressure

• Measures force of blood against vessel walls; systole (contraction) / diastole (relaxation).
• Ideal normal is 120/80.

Blood Flow

• Deoxygenated blood flows into the right atrium, to the right ventricle, then to the lungs (pulmonary arteries) to pick up oxygen and drop off CO_2.
• Oxygenated blood flows into the left atrium, to the left ventricle, then out the aorta to oxygenate tissues.

Blood Components

• Plasma: Clear yellowish portion, mostly water, transports nutrients, hormones, and waste.
• Red blood cells: Carry oxygen, mostly hemoglobin, made in bone marrow.
• Platelets: Cell fragments used in clotting.
• White blood cells: Made in marrow, recognize and kill invaders.

Cardiovascular Diseases

• Atherosclerosis: Blockage of arteries by blood clots or fatty deposits, leading to heart attack or stroke.
• Excessive sodium: Leads to high blood pressure.

Sexual Reproduction

• Fusion of haploid gametes to form a diploid zygote, generating genetic variation.

Male Reproductive System

• Testes: Produce sperm in seminiferous tubules via meiosis, located outside the abdominal cavity in the scrotum for optimal temperature.
• Epididymis: Where sperm mature and are stored.
• Vas deferens: Connects to the urethra, which passes through the penis.
• Seminal vesicles: Add fructose and prostaglandins to sperm, forming semen.

Female Reproductive Structures

• Ovary: Produces ova in follicles.
• Oviduct (Fallopian tube): Carries egg to the uterus.
• Uterus: Receives fertilized egg for development.
• Cervix: Opening to the uterus.
• Vagina: Birth canal.

Menstrual Cycle

• Phases: flow (menstruation), follicular (ovulation), luteal (uterus prepares for pregnancy).
• Interrupted by pregnancy, continues until menopause.

Fertilization

• Sperm (23 chromosomes) joins with egg (23 chromosomes), restoring diploid number of 46 chromosomes.

Human Development Before Birth

• Sperm's acrosome weakens egg's membrane for penetration, forming a barrier to prevent other sperm from entering.
• Zygote undergoes mitosis, becoming a morula by day three, then a blastocyst by day five.
• Blastocyst implants in the endometrium around day six.

Fetus

• After the second month, cartilage becomes bone, movement is evident.

Three Trimesters

• First Trimester: Tissues, organs, and organ systems develop; embryo becomes a fetus by week eight.
• Second Trimester: Growth period, fetal heartbeat can be heard.
• Third Trimester: Rapid growth, fat accumulates for insulation.

Immune System

• Body’s defense against pathogens (bacteria, viruses, fungi, protists, parasitic worms).

First Line of Defense

• Skin: Physical barrier, secretes chemicals.
• Mucus and Cilia: Trap and sweep away foreign particles in the respiratory system.
• Stomach Acid: Breaks down swallowed bacteria.

Second Line of Defense

• White Blood Cells (WBCs): Attack invaders within the body.
• Phagocytes: Engulf foreign particles.
• Interferon: Released by virus-infected cells, interferes with viral ability to attack other cells.
• T-Cells: Kill infected human cells and cancer cells.
• Inflammatory Response: Histamines dilate capillaries, raise temperature, activate pain receptors, and attract WBCs.

Divisions of the Immune System

• Cell-mediated: Phagocytes and T-cells.
• Antibody-mediated: Controlled by antibodies, the third line of defense.

Third Line of Defense

• Antibodies: Proteins that latch onto, damage, clump, and slow foreign particles.

Antibody Production

• WBCs break up invading particles and show pieces to T-cells, who identify specific B-cells to produce antibodies.

Immunity

• Resistance to disease.

Types of Immunity

• Active: You produce antibodies through exposure to the antigen (either actual disease or vaccine).
• Passive: You don’t produce antibodies; antibodies are passed from mother to baby during pregnancy.

Viral Infections

• Antibiotics do not work on viruses.

Noninfectious Disorders

• Genetic Disorders: Diseases caused by inherited genes (e.g., albinism, sickle cell anemia).
• Degenerative Diseases: Result of body parts wearing out (e.g., arthritis).
• Metabolic Diseases: Result from errors in biochemical pathways (e.g., Type I diabetes).
• Cancer: Abnormal cell growth.