Animal Skeletons: Exo vs. Endo

• Skeletons function as a support and protection system in animals.
• Muscular hydrostats, like an elephant's trunk, use fluid to aid movement.

Exoskeletons

• Found outside the body
• Composed of calcium carbonate in mollusks
• Made of chitin (a carbohydrate) and polysaccharides in arthropods.

Endoskeletons

• Located inside the body
• Made up of bone and cartilage

Advantages of Endoskeletons

• They grow with the body.
• Protect organs
• Support body weight
• Protected by outer tissue
• Allow for flexible and complex movement.

Bone Growth

• Starts as cartilage
• Cartilage turns to bone through calcium salt deposits.

Axial Skeleton Components

• Skull
• Vertebral column
• Thoracic cage
• Sacrum
• Coccyx

Skull Composition

• Cranium
• Facial bones

Vertebral Column Regions

• Neck (cervical)
• Thorax (thoracic)
• Lower back (lumbar)
• Pelvis (sacral)
• Tailbone (coccyx)

Rib Cage Details

• Twelve pairs of ribs exist
• The top seven pairs connect to the sternum
• False ribs: the upper three connect via cartilage
• The bottom two pairs are floating ribs (not connected).

Appendicular Skeleton

• Pectoral and pelvic bones
• Pectoral bones provide flexibility
• Pelvic bones provide strength

Joint Classifications

• Fibrous: immobile joints (e.g., cranial bones)
• Cartilaginous: slightly movable joints (e.g., between vertebrae)
• Synovial: freely movable joints (e.g., knees)

Synovial Joint Subtypes

• Hinge joints: move in one direction (e.g., knees, elbow)
• Pivot joints: allow rotational movement (e.g., neck)
• Ball-and-socket joints: permit movement in all planes (e.g., hip and femur)

Arthritis

• Joint inflammation
• Treated with anti-inflammatory drugs or prescription corticosteroids

Muscular System

• Provides movement through muscle contraction and relaxation

Exocrine Glands

• Secrete products into ducts that lead to different organs.

Endocrine Glands

• Secrete products directly into the bloodstream

Hormones

• Influence homeostasis
• Affect reproduction
• Affect digestion
• Affect metabolism
• Affect growth
• Affect osmoregulation

Peptide Hormones

• Peptides, proteins, glycoproteins, and modified amino acids
• Bind to receptors on the plasma membrane
• Faster, short-lived effects

Steroid Hormones

• Derived from cholesterol (a lipid)
• Enter the cell through the plasma membrane
• Slower, longer-lasting effects

Hypothalamus

• Divides into the posterior and anterior pituitary glands

Posterior Pituitary

• Produces ADH (negative feedback)
• Produces oxytocin (positive feedback)

Anterior Pituitary

• Produces thyroid-stimulating hormones
• Produces prolactin
• Produces growth hormone

Thyroid Gland

• T3 and T4 hormones fill the follicles
• Results in a faster metabolic rate

Calcitonin

• Regulates blood calcium levels
• Secreted by the thyroid when blood calcium levels are high

Parathyroid Gland

• Produces PTH
• Increases calcium levels in the blood

Adrenal Gland

• A pair, located atop each kidney
• Produces mineralocorticoids
• Produces glucocorticoids

Glucocorticoids

• Increase glucose levels in the blood
• Used in inflammatory response (e.g., cortisol)

Mineralocorticoids

• Regulate sodium and potassium via aldosterone

Addison's Disease

• Insufficient hormone secretion causing hypotension

Cushing Syndrome

• Excessive glucocorticoid levels
• Causes muscle metabolism

Pancreas

• Has endocrine and exocrine tissue
• Produces and secretes insulin and glucagon

Diabetes

• Diabetes I: insufficient insulin; treated with insulin injections
• Diabetes II: impaired insulin receptors; treated with a low-fat and low-sugar diet

Testes

• Produce testosterone

Ovaries

• Produce estrogen and progesterone

Pineal Gland

• Produces melatonin
• Regulates the sleep cycle

Thymus Gland

• Aids in differentiating monocytes
• WBCs go to specialize here

Gonads

• Organs that produce gametes
• Testes (for sperm)
• Ovaries (for eggs)

Fertilization

• External Fertilization: gametes unite outside the body (aquatic animals)
• Internal Fertilization: gametes unite inside the body

Male Reproduction

• Paired gonads (testes) suspended in the scrotum
• Produces sperm (gametes)
• Produces testosterone (male sex hormone)

Sperm Components

• Head: acromosome and nucleus (genetic makeup)
• Middle piece: used for movement
• Tail: used for movement

Testosterone

• Major sex hormone
• Develops secondary sex characteristics
• Affects height
• Deepens voice
• Develops facial, chest, and back hair

Female Reproduction

• Ovaries produce an oocyte monthly
• Fertilization occurs in the uterine tube
• The fertilized egg moves into the uterus
• Ovaries produce estrogen and progesterone

Uterus

• Thick muscular organ

Cervix

• Narrow end of the uterus

Vagina

• Resident bacteria create an acidic environment to prevent infection

Placenta

• Provides nutrition and oxygen to the baby from the mother
• Produces HCG (pregnancy hormone)

Estrogen and Progesterone

• Essential for normal female development
• Essential for functionality of female reproductive organs
• Causes fat accumulation (more rounded features)

Birth Control Methods

• Abstinence
• Pills
• Condoms
• Vaccines

Contraceptive Vaccines

• Vaccinations against either HCG or sperm

Reproductive Technology

• AID (Artificial Insemination by Donor)
• IVF (In Vitro Fertilization)
• GIFT (Gamete Intrafallopian Transfer)
• Use of a surrogate mother

STDs (Sexually Transmitted Diseases)

• Viral STDs: AIDS, genital herpes, genital warts, hepatitis A & B
• Bacterial STDs: chlamydia, gonorrhea, and syphilis

Vaginal Infections

• Caused by yeast, bacterium, or protozoan

Development

• All changes in an animal's life cycle
• Includes cellular, tissue, and organ changes

Cleavage

• Cell division without growth

Germ Layers

• Ectoderm: outer layer
• Endoderm: inner layer
• Mesoderm: middle layer

First System to Develop

• The Nervous system is the first system to develop

Cellular Differentiation

• Specialization in structure and function

Morphogenesis

• Development of the shape and pattern in the body

Apoptosis

• Programmed cell death

Induction

• Tissues influence the development of other tissues via chemical signals and agents

Notochords

• Dorsal supporting rod
• Later replaced by the vertebrae

Homeotic Genes

• Dictate the shapes and patterns in the body
• Determine which body part arises from which segment
• Mutations cause different expressions in different species

Embryonic and Fetal Development Stages

• Week 1: Development into fetus
• Week 2: Implantation into the uterine wall; HCG secreted to maintain pregnancy
• Week 3: Nervous and circulatory systems appear
• Weeks 4-5: Head enlarges; ears, nose, and eyes become prominent
• Weeks 6-8: Embryo becomes recognizable as human; nervous system gains reflexes
• Week 10: Placenta fully formed, allows exchange of O2, nutrients, and waste; passes antibodies to the child
• Week 16: Heartbeat can be heard
• Week 18: Can hear and respond to sounds
• Week 24: Can survive outside the womb, but lungs are immature and the baby may need steroids

First Two Months of Development

• Major organs form

Last Three to Nine Months of Development

• Organs become larger and more refined

Preventing Birth Defects

• Maintain good health habits
• Avoid harmful substances, radiation, and pathogens
• Avoid alcohol, smoking, and drug abuse
• Avoid medications and supplements not approved for pregnancy
• Avoid X-rays

Aging Process

• Cells decay due to genetic programming

High-Calorie Diets

• Accelerate the aging process

Aging on the Integumentary System

• Causes sagging and wrinkling of skin
• Impairs the ability to maintain homeostasis
• Reduces melanocytes
• Leads to more age spots

Aging on the Cardiovascular System

• Causes longer recovery time for heart rate and blood pressure
• Results in generally increased blood pressure, leading to hypertension

Aging on the Immune System

• Causes decline in antibody response

Aging on the Digestive System

• Causes an increase in bacteria, leading to tooth decay
• Liver becomes less effective in filtering drugs and toxins

Aging on the Respiratory System

• Causes the elasticity of lung tissue to decrease

Aging on the Excretory System

• Leads to difficulty in maintaining salt and pH balance
• Causes urinary incontinence in males; difficulty in urinating

Aging on the Nervous System

• Causes a reduction in brain size
• Discrete aging like Alzheimer's

Aging on the Sensory System

• Stimulation is needed for tasting, smelling, and hearing receptors

Aging on the Musculoskeletal System

• Leads to a decrease in muscle mass
• Causes reduction in bone density and size
• Results in loss of height

Aging on the Endocrine System

• Results in reduced thyroid gland activity
• Lowers metabolic rate

Aging on the Reproductive System

• Results in less testosterone for men
• Causes no estrogen (menopause) for women