UNIT XII – ANIMAL PHYSIOLOGY IIDigestive, Reproductive, Nervous, Muscular Systems

Big Campbell – Ch. 41, 46, 47, 48, 49, 50Baby Campbell – Ch 21, 27, 28, 30

Hillis – Ch 32, 33, 34, 36, 39

ANIMAL NUTRITION & DIGESTION

I. NUTRITION• Undernourishment

Caloric deficiency• Overnourishment

Excessive food intake Obesity

• Malnourishment Essential nutrient deficiency

• Macronutrients Essential nutrients

Materials that must be obtained in preassembled form

Essential amino acids 8 amino acids that must be

obtained in the diet Essential fatty acids

Unsaturated fatty acids

I. NUTRITION, cont

• Micronutrients: Vitamins - Organic coenzymes

Water Soluble: B Vitamins – Required for general metabolism Vitamin C – Required for connective tissue production

Fat Soluble: Vitamin A – Vision Vitamin D – Ca2+

Vitamin E - ??? Vitamin K – blood clotting

Minerals - Inorganic cofactors Na Ca Fe K P I Cl

I. NUTRITION, contFeeding Types & Adaptations

• Opportunistic Herbivore Carnivore Omnivore

• Feeding Adaptations Suspension-feeders

Sift food from water Baleen whale

Substrate-feeders Live in or on their food Earthworm

Fluid-feeders Suck fluids from a host Mosquito

Bulk-feeders Eat large pieces of food Most animals

II. DIGESTIONOverview Of Food Processing

• Ingestion• Digestion

Enzymatic hydrolysis Intracellular: breakdown within cells (sponges) Extracellular: breakdown outside cells (most animals)

Gastrovascular cavity vs. alimentary canal • Absorption• Elimination

III. HUMAN DIGESTION• Peristalsis - rhythmic waves of contraction by smooth muscle• Sphincters - ring-like valves that regulate passage of material• Accessory glands - salivary glands; pancreas; liver; gall bladder

III. HUMAN DIGESTION, cont

• Oral cavity Salivary amylase

Bolus – wad of food formed from mechanical, chemical digestion

• Pharynx Epiglottis

• Esophagus Food tube Contents moved

through cardiac sphincter

III. HUMAN DIGESTION, cont

• Stomach Gastric juices – Made up

of Mucus

Pepsin/pepsinogen

HCl

Partially-digested stomach contents known as chyme

Pass through pyloric sphincter to small intestine

III. HUMAN DIGESTION, cont

Small Intestine Site of most digestion,

nutrient absorption Divided into 3 regions

• Duodenum First 12 inches Na Bicarbonate

Bile

Hydrolytic enzymes

III. HUMAN DIGESTION, cont• Jejunun & Ileum

Villi/microvilli Contain vessels from circulatory system , lymphatic system

Nutrient absorption carried out through diffusion, active transport Capillary networks

Amino acids, monosaccharides aborbed into circulatory system Transported to liver via hepatic portal vein

Lacteal Vessels from lymphatic system Transport chylomicrons – water-soluble droplets of fats mixed with cholesterol

• Hepatic portal vessel – carries contents from nutrient-rich capillaries to liver

III. HUMAN DIGESTION, cont

III. HUMAN DIGESTION, cont

• Large Intestine or Colon Cecum / Appendix Water reabsorbed from secreted

digestive juices Contents moved along by peristalsis

Diarrhea Constipation

Huge population of normal bacterial flora

Feces – undigested food (cellulose), dead bacteria

• Rectum Waste storage 2 sphincters Waste expelled through anus

III. HUMAN DIGESTION, cont

III. HUMAN DIGESTION, cont• Hormones Involved in Digestion

– Leptin Produced by adipose cells Increased amount of adipose tissue = increased levels of leptin = decreased appetite

– Gastrin Produced by stomach Food triggers release of gastrin → returns to stomach wall → stimulates secretion of

gastric juice– Enterogastrone

Produced by duodenum Inhibits peristalsis and acid secretion by stomach, slows digestion when chyme with high

fat concentration enters duodenum– Secretin

Produced by duodenum Stimulates pancreas to release Na bicarbonate to neutralize chyme

– Cholecystokinin (CCK) Produced by duodenum Stimulated by presence of amino acids/fatty acids in duodenum → Triggers release of

pancreatic digestive enzymes, bile from gallbladder

IV. DIGESTIVE EVOLUTIONARY ADAPTATIONS

• Dentition - Animal’s assortment of teeth• Digestive system length• Symbiosis• Ruminants

IV. EVOLUTIONARY ADAPTATIONS, cont

Ruminant Digestion

HUMAN REPRODUCTION

I. GAMETE PRODUCTION

II. REPRODUCTION – MALE HUMAN ANATOMY• Testes

Contained in scrotum Importance of temperature Seminiferous tubules – sperm formation Leydig Cells – produce testosterone & other

hormones Sertoli Cells

• Epididymis coiled tubules that sperm pass through from

testis• Vas deferens

Muscular tube that propels sperm during ejaculation

• Ejaculatory Duct Combines sperm from both testes; leads to

urethra• Glands

Seminal vesicles – Add fluid to protect nourish sperm, including fructose, mucus, enzymes; produces semen

Prostate gland - Secretes anticoagulant, nutrients into semen

Bulbourethral glands – Secretes acid neutralizer before ejaculation

• Penis/Urethra Ejaculation - Release of semen Blockage of urine flow controlled by

sphincters

II. REPRODUCTION – MALE, cont

• Human Sperm

III. REPRODUCTION – FEMALE HUMAN ANATOMY• Ovaries

Follicle – Egg capsule; nourishes and protects egg

Egg released during ovulation Corpus luteum – Secretes estrogen

and progesterone to maintain uterine lining; formed from follicle after egg is released

• Oviduct Also known as fallopian tube Egg moved along through action of

cilia• Uterus

Thick, muscular organ also known as womb

Endometrium – inner lining Cervix – opens into vagina

IV. REPRODUCTIVE CYCLES

• Estrous Cycle Seen in animals Uterine lining is reabsorbed by the uterus if pregnancy does not occur; no

bleeding Causes more pronounced behavioral changes Animals typically only copulate during ovulation; known as estrus

• Menstrual Cycle Seen in humans, other primates Oogenesis occurs during the ovarian cycle Ovarian cycle is synchronized with menstrual cycle through the action of

hormones Divided into phases

Follicular phase – growth of follicle Ovulation – release of egg Luteal phase – degeneration of corpus luteum

V. MENSTRUAL REPRODUCTIVE CYCLE

Follicular Phase• Small amounts of FSH and LH are secreted by the pituitary• The follicle is stimulated to grow, leading to secretion of estrogen (estradiol)• Initially, low levels of estrogen inhibit secretion of FSH, LH (negative

feedback)

V. MENSTRUAL REPRODUCTIVE CYCLE, cont

Ovulation• As estrogen concentration continues to increase increase in growing follicle,

at a critical concentration, estrogen concentration switches to positive feedback mechanism.

• FSH and LH production increase, especially LH• Causes release of follicle

V. MENSTRUAL REPRODUCTIVE CYCLE, cont

Luteal Phase• LH stimulates remaining follicular tissue to transform into corpus luteum• Due to effects of LH, corpus luteum secretes progesterone, estrogen• Increasing concentrations of progesterone, estrogen exert negative feedback on

pituitary, decreasing release of FSH, LH• As levels continue to decrease, corpus luteum disintegrates• Results in sharp decrease in estrogen, progesterone levels• At a certain point, levels drop beneath concentration required for negative feedback to

pituitary → pituitary then begins secreting FSH, LH → cycle begins again

VI. FERTILIZATION• Fertilization:

Sperm reaches egg Head of sperm contains a vesicle known as the acrosome; contains enzymes that help sperm penetrate

egg Acrosomal reaction – hydrolytic enzymes act on egg jelly coat Surface proteins on sperm bind with receptor molecules on egg Sperm cell membrane fuses with egg cell membrane Cell membrane of egg depolarizes, becomes impenetrable to sperm to prevent multiple fertilization

(polyspermy) Triggers increase in metabolic activity in fertilized egg (including completion of meiosis II)

EMBRYONIC DEVELOPMENT

I. EMBRYONIC DEVELOPMENT

I. EMBRYONIC DEVELOPMENT

Cleavage• Cleavage produces a ball of cells

known as a blastula Cells known as blastomeres Cavity formed known as blastocoel

• Nutrients stored in the egg known as yolk

• Two sides of the blastula Vegetal pole – Side with high yolk

concentration; larger cells due to yolk; divide more slowly

Animal pole – Side with low yolk concentration; smaller cells; divide at a faster rate

I. EMBRYONIC DEVELOPMENT - Amniotes• Forms within a shell or

uterus• Extraembryonic

membranes Yolk sac – Contains

blood vessels that transport nutrients from yolk to embryo

Amnion – Fluid-filled sac; protection

Chorion – Formation of placenta

Allantois – Disposal sac for nitrogenous wastes; incorporated into umbilical cord in mammals

II. GASTRULATION• Formation of blastopore • Cells migrate to form three embryonic tissue layers

Ectoderm – outer layer; develops into epidermis, nervous system Mesoderm – middle layer; develops into skeletal, muscular, excretory

systems, heart Endoderm – inner layer; forms digestive tract & associated organs,

respiratory organs, etc• Simple digestive cavity formed from endoderm known as archenteron• Gastrula formed

III. ORGANOGENESIS

Organogenesis

IV. FETAL DEVELOPMENT• Gestation – pregnancy• First Trimester

Organogenesis By week 8, human fetus has all adult features Corpus luteum maintained by HCG; prevents

menstruation; also used to detect pregnancy• Second Trimester

Refinement of human features Corpus luteum degenerates; placenta begins

secreting progesterone• Third Trimester

Rapid growth Respiratory, circulatory systems prepare for

breathing• Parturition - birth

Estrogen levels increase; trigger formation of oxytocin receptors

Fetus, mother’s pituitary gland secrete oxytocin which triggers uterine contractions, preparation for lactation

Following birth, mother’s pituitary gland secretes prolactin; stimulates milk production, continued uterine contractions

NERVOUS SYSTEM

Phineus Gage1823 - 1860

I. NERVOUS SYSTEM

Human Nervous System

II. CELLS OF THE NERVOUS SYSTEM• Glia

o Support cellso Mostly nonconducting cells that provide support, insulation, protection

Astrocyctes Schwann cells - PNS Oligodendrocytes - CNS

• Neuron o Basic unit of function o Three types

Sensory Neurons Convey signals from sensory receptors to CNS

Interneurons Integrate, interpret data; relay signals to other neurons

Motor Neurons Convey signals from CNS to effector cells (glands or muscles)

II. CELLS OF THE NERVOUS SYSTEM, cont

A Closer Look at a Neuron Dendrite Cell Body Axon

o Myelin Sheatho Nodes of Ranvier

Axon (Synaptic) Terminal Synapse

II. CELLS OF THE NERVOUS SYSTEM, cont

III. NEURAL SIGNALING• Membrane potential (voltage differences across the plasma membrane)• Selective permeability of plasma membrane creates

intracellular/extracellular ion concentration gradiento High concentration of Na + outside

• Net negative charge of about -70mV

III. NEURAL SIGNALING, cont• Neurons, muscle cells → excitable cells; cells that can change membrane potentials• Gated Ion Channels → open/close response to stimuli → photoreceptors; vibrations in air

(sound receptors); chemical (neurotransmitters) & voltage (membrane potential changes)• Hyperpolarization → opening of K+ channels; results in outflow of K+; increase in electrical

gradient• Depolarization → opening of Na+ channels; results in inflow of Na+

III. NEURAL SIGNALING, cont• Threshold – Stimulus strong enough

to increase voltage to ~ -50mV; triggers an action potential

• Caused by movement of ions through Na+, K+ voltage-gated channels

• Sequence of events: Resting State – Channels closed Depolarization – Na+ channels

open; inside of cell becomes + Repolariztion - Na+ channels

close; K+ channels open slowly → K+ ions leave → cell returns to negative

Hyperpolarization – Created by K+ gates; close very slowly → K+ ions continue flowing out of cell → brief period where cell is more negative than resting state. Known as refractory period – neuron is insensitive to depolarization until resting potential is restored

III. NEURAL SIGNALING, cont• Movement of the action potential is self-propagating• Regeneration of “new” action potentials only after refractory period• Forward direction only• Speed of action potential related to

Axon diameter Nodes of Ranvier; known as saltatory conduction

III. NEURAL SIGNALING, contTransmission of Impulse Across a

Synapse• Synaptic Cleft – small gap between

sending neuron and receiving cell• Synaptic vesicles contain

neurotransmitter molecules• Action potential causes synaptic

terminal to depolarize → Ca2+ channels open → Ca2+ flows in → causes vesicles to fuse with axon terminal membrane

• Neurotransmitters “spit out”; diffuse across synapse Excitatory Postsynaptic

Potentials (EPSPs) Inhibitory Postsynaptic

Potentials (IPSPs)• Examples of neurotransmitters

include acetylcholine, dopamine, epinephrine, norepinephrine, serotonin

III. NEURAL SIGNALING, cont

III. NEURAL SIGNALING, contA Review

IV. VERTEBRATE PNS

IV. VERTEBRATE PNS, cont

• Nerves Bundles of

sensory & motor neurons

12 pairs of cranial nerves

31 pairs of spinal nerves

IV. VERTEBRATE PNS, cont• Reflex - “Automatic” response; sensory to motor neurons

V. VERTEBRATE CNS

• Brain

• Spinal Cord

• Protected by

V. VERTEBRATE CNS, cont

Human Brain• Forebrain

Cerebrum Cerebral Cortex Corpus Callosum

Thalamus Hypothalamus

• Midbrain – Receives & transmits sensory info to forebrain

• Hindbrain Cerebellum Pons Medulla oblongata

V. VERTEBRATE CNS, cont

ANIMAL MOVEMENT

I. INTRODUCTION TO MOVEMENT

• Gravity, friction must be overcome• Types of Movement

Swimming Flying Locomotion on land

• Importance of Skeleton Support Protection Essential to Movement Hydrostatic Skeleton

Found in Exoskeleton

Found in Endoskeleton

Found in

II. SKELETAL MUSCLE FUNCTION

• Typically at least 2 attachment sites Origin Insertion

• Muscles of appendicular skeleton make up antagonistic pairs Flexor Extensor

• Muscles Bundle of muscle fibers

Multinucleated cells Composed of myofibrils

II. SKELETAL MUSCLE FUNCTION, cont• Muscle myofibrils made up of two

types of myofilaments Thin Filaments

Two strands of actin Wrapped with protein complex

made up of tropomyosin and troponin complex

Thick filament Myosin

• Contracting unit of muscle tissue known as sarcomeres

• Sliding Filament Theory When stimulated, actin & myosin

filaments slide past each other; overlap increases

Shortens sarcomere length

II. SKELETAL MUSCLE FUNCTION, contSliding-Filament Model, I

• Myosin binds ATP; hydrolyzed to ADP + Pi

• Myosin head changes shape; termed high energy configuration• Myosin head binds to specific site on actin; forms a cross bridge

• ADP and Pi released; myosin relaxes to low energy configuration

• Causes actin to slide toward center of sarcomere• Binding of new ATP releases myosin head

II. SKELETAL MUSCLE FUNCTION, contMuscle Contraction Regulation, I

• Relaxation Tropomyosin

blocks myosin binding sites on actin

• ContractionCalcium binds to

troponin complexTropomyosin

changes shape Exposes myosin

binding sites

II. SKELETAL MUSCLE FUNCTION, contMuscle Contraction Regulation, II

• Stimulated by action potential in a ________________ neuron

• _____________________ triggers depolarization of muscle fiber by opening _____________ voltage-gated channels

• Action potential spreads to infoldings of cell membrane called T (transverse) tubules

• Sarcoplasmic reticulum = specialized ER that actively transports calcium ions

• When action potential reaches places where T tubules touch sarcoplasmic reticulum → Ca 2+ released

• Ca 2+ then binds to troponin, allowing myosin binding sites to be revealed

III. OVERVIEW OF SKELETAL MUSCLE FUNCTION

IV. SKELETAL MUSCLE ADAPTATIONS

• Energy Availability Adaptations

Creatine Phosphate

Myoglobin

• Fast-twitch Fibers• Slow-twitch Fibers