Animals Bodies and Homeostasis

• All animal cells share similarities such as exchanging materials, obtaining energy, synthesizing molecules, reproducing, and responding to signals
• Animal organization levels include cellular, tissue, organ, and organ system

Animal Organization

• In cellular organization, cells make similar properties group to form tissues, exemplified by Phylum Porifera (sponges)
• With tissue organization, tissues combine to form organs, as seen in Phylum Cnidaria & Phylum Ctenophora (jellyfish)
• Organs link to form an organ system
• Organ organization is when structures combine to make organs found in Phylum Platyhelminthes (Flatworm)
• The organ system is found in advanced animal groups

Tissues

• The structure and function of tissue are similar among its associated cells
• The four types of tissues are epithelial, connective, muscle, and nervous tissues

Epithelial Tissue

• Epithelial tissues are densely packed cell sheets that cover the body, enclose organs, and line body cavities and organs
• Epithelial tissues protect and secrete/absorb ions and organic molecules
• Cuboidal, squamous, and columnar shapes define different cell types and arrangements in tissues
  • Simple: One layer
  • Stratified: Multiple layers
  • Pseudostratified: One layer that appears stratified
• Epithelial tissues are asymmetrical or polarized, with one side resting on the basal lamina (basement membrane)
• Epithelial tissues function as selective barriers

Epithelial Tissue Varieties

• Simple squamous consists of a single layer of flat cells
• Simple cuboidal consists of a single layer of square cells
• Simple columnar consists of a single layer of rectangle cells
• Pseudostratified columnar has one cell thick with all cells at the basement membrane
• Stratified squamous consists of multi-layered flattened cells
• Transitional tissue is stretchable
• All epithelial tissues are involved with secretion/absorption & protection

Connective Tissue

• Connective tissue connects, surrounds, anchors, binds, transports, and supports
• Connective tissues form the extracellular matrix ECM around cells
  • ECM provides a scaffold for attachment
  • ECM is proactive and cushions
  • ECM transmits information
  • ECM provides mechanical strength

Connective Tissue Types

• Blood transports and protects
• Adipose (fat) insulates, provides energy, supports, and protects
• Bone supports and protects
• Cartilage supports and provides flexibility for bone
• Loose connective tissue holds internal organs in place
• Dense connective tissue provides strength and support

Muscle Tissue

• Muscle tissue cells contract to generate mechanical force
• Skeletal muscle is attached to bone or exoskeleton for locomotion; it consists of elongate (tubular cells) and is under voluntary control
• Smooth muscle surrounds tubes and cavities for propulsion and consists of flattened cells under involuntary control
• Cardiac muscle is only in the heart, consists of elongate fibers, and is under involuntary control

Nervous Tissue

• The complex nervous tissue network of neurons (nerve cells) initiates and conducts electrical signals throughout the body
• Electrical signals may stimulate or inhibit other neurons, muscle cells, or glandular cells
• Neuroglial cells, more numerous than neurons, provide metabolic support, maintenance, ion balance, and cleaning for neurons They also produce new glial cells & neurons

Organs and Organ Systems

• Organs are composed of two or more kinds of tissue that may form tubes, sheets, layers, bundles, or strips
• Organ systems consist of different organs working together to perform an overall function
• Spatial arrangement is part of an body plan controlled by genes with homologs in animals
• Hox Genes influences an animal's complexity

Structure and Function

• The organization of a structure predicts its function
• The complexity of form increases the organism's functioning

Homeostasis

• Environmental variables that change include air temperature, food supply, pH, water temperature, water supply, and O2 concentration
• Homeostasis is the process of adjusting to the external environment and maintaining a stable internal environment

Vertebrate Integument and Derivatives

• The integumentary system includes skin and all its accessories
• Functions include protection from abrasion, water loss, pathogens, and UV light Also regulates temperature, excretion, and contains sensory receptors

Skin Layers

• Vertebrate integument, one of the largest organs, is composed of the epidermis and dermis

Epidermis

• The epidermis is the outer, thinner layer where nutrients diffuse from the dermis
• The Epidermis is made of Stratified squamous epithelium

Epidermis Cell Types

• Langerhans cells are defensive cells
• Melanocytes produce pigment melanin for skin coloration and UV light protection
• Merkel cells are touch receptors
• Keratinocytes are the primary cell type that produces insoluble protein, keratin
• Keratin rises from inside to outside and fills cytoplasm, impairing nutrient diffusion, which then kills the cells

Dermis

• The dermis is the inner layer of skin, thicker than the epidermis, and highly vascularized
• It contains sensory structures, vessels, inerves, and glands
• The dermis is the origin of hair, features, and scales of vertebrates
• Sensory structures present include:
  • Meissgners perceive light touch
  • Pacinian perceives deep pressure/vibration

Additional Glands Found in Skin

• Sweat glands:
  • Temperature regulation
  • Produce sweat (primarily water)
  • The body contains 2.5 million
  • Releases heat
• Sebaceous glands:
  • Located all over the body except for palms &soles
  • Are large on the face, neck, and upper chest
  • Produce sebum, which lubricates & softens hair & skin

Hypodermis (Subcutaneous Layer)

• The hypodermis lies beneath the dermis but is not a skin layer
• It provides insulation (from fat tissue- adipose)
• Females have a thicker layer of adipose tissue than males

Introduction to Nutrition

• Nutrients are substances taken in by an organism for survival, growth, development, tissue repair, or reproduction
• Nutrition is the process of consuming and using food & nutrients
• Animals recycle nutrients by consuming food

Heterotrophs

• Heterotrophs cannot manufacture their own food and require already synthesized organic compounds from plants or other animals
• Heterotrophs need to supply materials for survival, maintenance, growth, and reproduction

Gut Tract Types

• Blind gut definition: no cavity between the gut & body wall, one opening (primitive form)
• Tube within tube definition: flow through the digestive tube

Gut Tract Characteristics

• Body cavity lies between the gut and body wall, with a separate opening (mostly advanced)

Digestive Enzymes

• Require H2O
• Carbohydrates breakdown carbohydrates
• Proteases break down proteins
• Lipases breakdown lipids and fats
• Nucleases break down nucleic acids
• Amylase breaks down starch (glucose) and is found in saliva

Food Processing Stages in Animals

• Stage 1 (Ingestion) is when food intake occurs in the body's alimentary canal
• Stage 2 (Digestion) is when food breaks down into smaller molecules (chemical and mechanical)
• Stage 3 (Transport)
• Stage 4 (Absorption) is when ions, water, small molecules, vitamins, and minerals are transported into the circulatory system
• Stage 5 (Egestion) is when undigested material passes from the body

Alimentary Canal

• It is the digestive tract or tube (GI tratct)
• It is composed of 5 regions
• Single Elongated tube with an open at both ends
• It contains smooth muscles in walls
• It is lined by epithelial cells that:
  • Synthesize and secrete digestive enzymes
  • Secrete hormones
  • Transport digestive material
• Contains several specialized regions:
  • Storage area
  • Different environment for different processes

GI Tract Structure

• The same general structure runs from the midpoint of the esophagus to the anus or cloaca
  • Lumen is lined by the slandularells
  • Secretory cells release a protective mucus layer
  • Other cells release hormones
  • Gland cells release acids, enzymes, water, and ions
• Epithelial cells linked by tight junctions and surrounded by layers of tissue made of smooth muscles

Region of Reception

• The beginning of the alimentary canal is the Bucca Cavity- inside mouth and accessory structures
• The injection and digestion site is both chemical and mechanical
• Structures involved are Jaws, teeth, cheek muscles, tongue, salivary gland, and Saliva (enzymes)
• Pharynx is located at the back of the mouth cavity
• The digestive and respiratory system cross paths

Region of Conduction

• The Esophagus is a tube carrying materials from the mouth cavity to the rest of the alimentary canal (the neck region)
• It helps conduct food from the pharnyx to the stomach
• Peristalsis is rhythmic, smooth, wave-like contraction of muscles that propel food down the GI tract

Region of Storage and more Digestion

• The Stomach stores mostly
  • The saclike organ helps store food
  • Muscular nature helps break up food via partial protein digestion
  • The process regulates the rate of emptying into the small intestine
• Secretions in the stomach:
  • Hydrochloric acid (HCI) kills microbes and dissolves particulate matter (parietal cells)
  • Pepsinogen is converted to pepsin to begin protein digestion (chief cells)
  • The Epithelium is coated with alkaline mucus
  • There is no lipid or carbohydrate digestion
• The Lumen (cavity) of the stomach:
  • Pepsinogen + HCl= pepsin (protein breakdown)
  • Peptide bonds proteins into amino acids

Region of Terminal Digestion and Absorption

• Definition: Small intestine carries out all digestion and absorption of food
• Hydrolytic enzymes are found on the apical surface of epithelial cells and are secreted by the pancreas into the lumen
• Products of digestion absorbed across epithelial cells and enter the blood
• Includes Vitamins, minerals, and water absorbed
• Small Intestines length is the person's height x 8 (example: 6ft tall x 8= 48ft long)

Surface Area Specialization

• The small intestine specializes in digestion and absorption
  • Mucosal infoldings
  • Villi are the finger-like projections increase surface area
  • Epithelial cells with microvilli create brush border
• Specializations increase surface area 600-fold and the chance of food particles encountering surface area
• The three regions:
  • Duodenum- has lots of secretions in this region
  • Jejunum
  • Ileum

Surface Area

• Surface modifications that increase surface area include:
  • Plicae circulares: large fold of the epithelial lining ups surface lining 2-3 times
  • Villi- finger like projections: increases surface area 10 times
  • Microvilli- folding of plasma membrane of cells lining membrane: increases surface area 20 times

Water Absorption/Concentration of Solids Region

• The large intestine in mammals is about 1.5 meters
• It lacks plicae, villi, and microvilli
• H2O absorbed through epithelium
• The function is to regain 1400mL/day of H2O for humans
• Compacts and eliminates waste
• Waste:
  • Water 75%
  • Inorganic substrate 5%
  • Roughage 8%
  • Fat 5%
  • Undigested protein, dead cells, bile 2%
  • Limited vitamin synthesis by bacteria
• Anus is the opening of posterior end of alimentary canal for waste release
• Cloaca (some verts.) is:
  • Chamber receiving contents of digestive tract
  • For the reproductive and urinary tract which is a vent opening to the outside

Accessory Digestive Glands

• Are not part of the Alimentary Canal
  • The pancreas secretes enzyme juices through the pancreatic duct into duodenum of small intestine.
  • The liver produces bile assisting in breaking down fat globs into smaller pieces

Biomolecules

• Carbs- polysaccharides convert to mono- and disaccharides
• Proteins- polypeptides convert to amino acids
• Fats convert to glycerol and fatty acids
• Nucleic acids are nucleotides (subunit of nucleic acid)
• Enzyme activity is necessary in chem reaction at biological temp

Nervous System

• The key concepts:
  • Cellular components for nervous system
  • Electrical properties of neurons and rising membrane potential
  • Generation and transportation of electric signals along neurons

The Nervous System

• The central nervous system (CNS) includes the brain and nerve cord
  • The brain and spinal cord are in vertebrates
• Peripheral nervous system (PNS) consists of all neurons and their projections outside CNS
  • In certain inverts with simple nervous systems, the distinction is less clear/ not present
• PNS neurons receive stimuli (smell/taste)
• CNS neurons in the brain recognize food
• PNS neurons helps brain sends signals to PNS to trigger salivation

Cellular Composition of the Nervous System

• There are two classes of the nervous system which are neurons and glia
• Neurons are cells that send and receive electrical and chemical signals to and from each other and other cells throughout the body
  • Present in all animals except sponges

  • varies with function, size, and complexity

Neuron Structure

• The cell body or soma contains the nucleus and organelles
• The Dendrites, extensions of the cell body, single, or branching, receive incoming signals
• The Axon, an extension of the body, carries the signal, typically signal length varies
  • May have branches and wrapped in myelin
  • Axon hillock- near cell body
  • Axon terminals- convey electrical or chem signals to other cells, typically occur in bundles wrapped by connective tissue -> nerve

Glial Cells

• Glial cells surround neurons and perform numerous functions
  • Astrocytes provide metabolic support, form the blood-brain barrier, and maintain a stable concentration of ions in extracellular fluid
  • Microglia participate in immune functions and remove cellular debris

Myelin Sheath

• The myelin sheath is interrupted by non-insulated nodes of Ranvier and is produced by oligodendrocytes (CNS) and Schrein cells (PNS)
• Radial Glial cells can produce other cells and neurons

Neuron Types

• Sensory neurons detect info from outside or internal body conditions.
• Motor neurons send signals away from CNS (efferent neurons) to elicit response
• Interneurons form connections between neurons critical in interpreting info and elicited response

Reflex Arc

• Stimuli from sensory neurons to CNS little or no interpretation is transmitted from signals to motor neurons to elicit a response
• This creates Quick and automatic response
• Figure 42.4

Electrical Properties of Neurons

• The membrane potential is a “gatekeeper”
• Only neurons and muscles cells generate electrical signals
• Cells are polarized due to membrane permeability
• There is a difference in ions inside/outside of neuron causing both chemical & electrical difference

Resting Membrane Potential

• Definition: when a neuron is not sending a signal
  • Selectively permeable to cation (+) and anions (-)
  • More (-) on the inside, more (+) on the outside Anions on the inside are drawn to the cation on the outside so most ions are near the edge of membrane

Electro-Chemical Gradient

• Definition: imbalance due to difference inside/outside of the neuron
  • Chemical K+, Na+, Cl-
  • Charge w/ chemical (+) or (-)

Factors contributing to resting potential

1. Sodium-Potassium Pump- requires ATP expenditure
   • Pumps 3NA for every 2 K
   • Pumps from low to high
2. Ion specific channels allow passive ion movement -*Membrane is more permeable talk -*K channels more frequently open at resting potential
3. Polarity- more (-) inside neurons

Gated Ion Channels

• Voltage Gated- open/close in response to voltage changes
• Chemical Gated- open/close in response to chemical

Nerves Impulse

• Frequency is the "language" of the message

• Higher the frequency, the greater than excitation level

• Resting potential is the imbalance between k+ & Na+ inside /outside

• The membrane is selectively permeable, but channels are closed for Na & Cl

• Outside neuron 10x more Na, 5X more Cl

  • Inside neuron - 30X more K

• Action Potential is the rapid/brief change of a nerve fiber

  • It has the electric potential of the impulse
  • It is self-propagating
  • After passing a given point, the membrane returns to resting

• At gives impulse points, channels Na open, and Na diffuses in

  • K diffuses out but increases at the impulse 3 Sodium/Patassium Pump- Complex of proteins in the membrane Pumps out Na & Carry in K Restores the imbalance

Nerve Impulse Rate

• Varies with system and organism complexity, e.g., a sea anemone (almeter per sc) -Mammal (120 meter per sec)
• Invertebrate animal speed is related to axon diameter
• Vertebrate speed is a combination of axon diameter & layers of myelin (sheath)
• Myelin Sheath is in section (node of ranvier)
• Saltatorial locomotion

Evolution of the Nervous System

• Phylum Cnidaria (jellyfishes) has the simplest neural organization using nerve nets and primitive cells They are not a system
• Phylum Platyhelminthes (flatworms) feature 2 Anterior ganglia each with network branching off They have weak PNS and CNS (no brain or spinal cord)
• Phylum Annelida (segmented worm) has a Brian and ventral nerve cord simpler motor/sensory neurons
• Phylum mollusca (mollusks) includes Squid and octopus maybe equals to fish.
• The arthropods have a similar nervous system to annelps and most mollusks with sophisticated social insect brains
• In the "social insect" there complex social behavior learning =, and a division of labor communication

Vertebrate Nervous System

• Spinal Cord + Brain = Central Nervous System
• BOTH are surrounded by Meninges ; (layers) - 3 of these
  • Dura mater (outer)
  • Arachnoid (middle)
  • Pia mater (inner)
  • There is Cerebrospinal fluid in each layer and within the spinal cord

Spinal cord and brain

• The spinal cord is always dorsal & hollow and enclosed within the vertebral column
• Brain definition: increase in size w/complexity + verte evolution

Brain Divisions

• Include the Hindbrain, Midbrain, and Forebrain

Brian: spinal cord faration - Fish 2:1 - Amphiban 10:1 - Reptales 25:1 - Bird 35:1 - Humans 55:1

Centers of the Brain

• Cerebrum is for reading , thinking, and talking
• The Hypothalamus is the house keep center of the brain and hormone gland
• The Pituitary gland is a hormone gland
• The Corpus Callosum is a thin connection that speeds up message in the brain

Animal Skeletons

• The skeleton offers support protection, and locomotion (movement from one place to another)

Types of Skeletons

• Exoskeleton
• Endoskeletons
• Hydroskeletons- found in some soft bodied invert that use water pressure for propulsion

Exoskeletons

• It is the External Skeleton that surrounds the protects the body surface

• An example is an Arthropod Skeleton

  • Made of chitin
  • Tough and durable
  • Segmented for movement

• Varies in complexity, thickness & durabitlty

Endoskeletons

• Are Internal Structures
• Do not protect surface, only some internal organs
• Found in echinoderms and vertebrate
• Mineral provided firmness
• Echinoderm skeletons composed of spiky network of proteins and minerals with a mineralized place- like structure
• Vertebrate's skeleton is composed entirely of cartilage (cartilaginous fish) or cartilage & bone Biggest Advantage - living growth always growing
• Everything grows

Other Skeleton Functions

• Blood cells & _____ are foremed in marrow calcium mineral storage
• Provides attachment sites for skeletal muscle

Bone

• Is a living , dynamic connective tissue
• It contains Organics components
  • Osteoblasts & osteocytes are the cells that form bone
  • Composed of collagen- triple ne;ica structutures provid strength & flexibility
  • Osteoclasts break down bone
  • Mineral Components
  • Crs