Animal Physiology III BIOL 1500 PDF

Animal Physiology III BIOL 1500 Dr. Emlyn Resetarits Physiology III:  Today’s Learning Objectives Identify different feeding methods Explain how the human digestive system works Apply knowledge of human digestive system to compare digestive systems of different...

Animal Physiology III BIOL 1500 Dr. Emlyn Resetarits Physiology III:  Today’s Learning Objectives Identify different feeding methods Explain how the human digestive system works Apply knowledge of human digestive system to compare digestive systems of different animals Define different modes of reproduction across animal kingdom Compare the nervous and endocrine systems Explain how Menstrual and Ovarian Cycles are coordinated by hormones Explain the role of the placenta for pregnancy and of oxytocin for birth Digestive System  Food processing Ingestion- The act of eating or feeding Digestion – food is broken down into molecules small enough for the body to absorb Absorption – animal cells take up small molecules such as amino acids and simple sugars Elimination – undigested material passes out of the digestive system  Ingestion – Different feeding methods Filter feeders – strain small organisms or food particles from the surrounding medium Fluid feeders – suck nutrient-rich from a living host (parasitic) Bulk feeders – eat relatively large pieces of food  How do animals digest animal cells (food) without digesting themselves? Evolutionary adaptation to avoid self-digestion is processing food within specialized extracellular compartments 1) Gastrovascular cavity – digestive compartment with a single opening that functions for digestions and distribution of nutrients throughout the body  How do animals digest animal cells (food) without digesting themselves? 2) More complex animals have a digestive tube with two openings, a mouth and an anus This digestive tube is called a complete digestive tract, or an alimentary canal It can have specialized regions that carry out digestion and absorption in a stepwise fashion – which means an animal can ingest a food while an earlier meal is being digested!  Human Digestive System Oral cavity – teeth break food into smaller pieces -> increasing surface area for chemical digestion and facilitating swallowing Saliva is produced by salivary glands that lubricates food and makes it easier to swallow (mucus)  The stomach stores food and processes it into a liquid suspension through mechanically and chemical processes Mechanical The stomach secretes gastric juice and mixes it with food through a churning action The mixture of ingested food and gastric juice is called chyme Chemical Gastric juice has a low pH of about 2, which kills bacteria and denatures proteins Gastric juice is made up of hydrochloric acid (HCl) and pepsin Pepsin is a protease, which breaks peptide bonds to cleave proteins into smaller polypeptides The stomach breaks food down mechanically and chemically The stomach breaks food down mechanically and chemically  Why don’t HCl and pepsin eat through stomach lining? 1) Mucus secreted by cells in gastric glands protects against self-digestion 2) Cell-division adds a new epithelial layer every three days, replacing cells before they are eroded by digestive juices  Small intestine is the site of most digestion First part of small intestine, the Duodenum, is the location where most digestion (breakdown of molecules into absorbable components) takes place Longest compartment of alimentary canal Chemosensory cells assess its nutrient composition and elicit secretion of the appropriate enzymes from the pancreas, gallbladder, and liver Pancreas produces bicarbonate (basic), which neutralizes acidic chyme  Small intestine is the site of most absorption as well! The small intestine has a huge surface area due to villi and microvilli that are exposed to the intestinal lumen, maximizing rates of absorption Most nutrients are absorbed into the capillaries Fats are too big to diffuse into capillaries, and are instead absorbed in the lymphatic vessels The hepatic portal vein carries all nutrients, except fats, to the liver for processing  Large intestine is in charge of excretion preparation Absorption of water condenses and compacts the digestive contents into a solid mass, the feces In vertebrates, 30-50% of the dry matter of feces consists of intestinal bacteria, which metabolize difficult-to-digest carbohydrates into fatty acids and produces vitamins. These nutrients are absorbed by the large intestine. The cecum aids in the fermentation of plant material and connects where the small and large intestines meet  Longer intestines and cecums aid in digestion and absorption of hard-to-digest materials (such as Carnivores like dogs, plants) Herbivores like which feed primarily rabbits, which feed on on highly digestible difficult-to-digest plant foods such as meat tissues, have a and fruits, have a relatively long short intestine (~ 6 intestinal tract (up to times body length) 10x body length). and small cecum They also have specializations of the cecum or stomach to accommodate a large microbiome that helps break down complex carbohydrates like cellulose Animal Reproduction Types of reproduction across animals  Asexual vs Sexual Reproduction Asexual reproduction is creation of Sexual reproduction is the creation of an offspring without the fusion of egg and offspring by fusion of haploid gametes, male sperm sperm and female eggs, to form a diploid zygote  Examples of Asexual Production Budding – new individuals arise from Fission – parent splits roughly into two outgrowth (e.g., Hydra) (e.g., Sea cucumber) Parthogenesis – development of new Fragmentation - breaking of the body into individual from unfertilized egg pieces followed by regeneration (e.g., Sea (e.g., bee drones) Stars)  Hermaphroditism vs Two Sexes Hermaphroditism - Each individual Separate sexes – Individuals are has both male and female either male or female reproductive systems  Types of hermaphroditism Sequential hermaphrodism – Simultaneous hermaphrodism – individuals have both reproductive individuals have both reproductive systems at some point but not at systems at the same time the same time (e.g., Nudibranchs) (e.g., Clownfish male->female) - Some can self-fertilize - Some cannot self-fertilize  Internal vs External Fertilization External fertilization – Eggs and Internal fertilization – sperm and egg sperm are released into an aqueous come together inside (generally) the female environment where they form zygotes reproductive tract, where the zygote and develop. develops. - Low parental investment - High parental investment - Many gametes, few survive - Few gametes, most survive - Requires aqueous environment - Does NOT require aqueous environment - Does not require movement (good - Requires movement for sessile organisms)  External Fertilization Frogs Corals Mollusks Fish  Mechanisms of Internal Fertilization – How to get sperm into female reproductive system (to meet eggs) Males have an insertable organ (usually called a penis) that delivers sperm into the female reproductive tract. To be insertable, it needs to be sufficiently stiff. Different methods! 1) Erectile tissue - When an erection occurs, blood fills the hollow spaces, causing the tissue to expand and become rigid. E.g., Humans, Cetaceans, Ungulates 2) Baculum – A penis bone that keeps penis rigid (e.g., Apes, Cats, Dogs) 3) Many other crazy strategies that we don’t have time to talk about today! Human Reproduction  Endocrine system communicates via hormones Hormones are molecules produced by endocrine cells. They are transported to tissues via the blood or extracellular fluid (ECF) Each hormone can only influence its target cells—i.e., the cells that express receptors for it  Comparison between nervous and endocrine systems Nervous Endocrine Organization Wired system. There is a Wireless system. There is no specific anatomical anatomical connection between connection (i.e. synapse) each endocrine (or between each nerve cell and neuroendocrine) cell and its its target cell target cell Transport of Neurotransmitters diffuse Hormones usually transported chemical over short distance (e.g., over long distances in blood messengers synaptic cleft) Response msec Hours, days, or months latency & duration Action Coordinates rapid and Produces slower, more general specific responses (e.g., responses (e.g., stimulating knee-jerk reflex, or growth, ovulation, or stress maintaining balance Major endocrine glands  Major endocrine glands for female reproduction Hypothalamus 1) GnRH – Gonadotropin- Releasing Hormone Anterior pituitary 1) FSH – Follicle-stimulating hormone 2) LH – Luteinizing hormone Posterior pituitary 1) Oxytocin Ovaries 1) Estradiol – 2) Progestin - Placenta 1) hCG – human chorionic gonadotropin  Female Reproductive Tract Ovaries Oviduct Follicles Uterus Uterine wall Endometrium Cervix Vagina A follicle is a small, fluid-filled sac within the ovary that contains an immature egg (oocyte)  Menstrual and Ovarian Cycles (Days 1-13) Hypothalamus produces Hypothalamus GnRH which stimulates the GnRH Anterior pituitary to produce small amounts of Anterior pituitary FSH and LH FSH LH FSH and LH together stimulate follicle growth Follicle The follicle produces Estradiol, which initiates Estradiol Initiates buildup the buildup of the uterine of uterine lining lining  DAY 0 7 14 21 28 OVARIAN Pituitary gonadotropin CYCLE levels FSH LH Corpus luteum Degenerating Growing follicle corpus luteum Follicular phase Ovulation Luteal phase UTERINE Ovarian hormone CYCLE levels Estradiol Progesterone Endometrium Menstrual flow Proliferative Secretory  Menstrual and Ovarian Cycles (Days 14) High levels of estradiol Hypothalamus produced by the follicle Stimulated by high levels stimulate the Hypothalamus GnRH of estradiol to release more GnRH Anterior pituitary GnRH stimulates Anterior Triggers pituitary to produce high FSH LH amounts of LH, which triggers ovulation ovulation. Follicle Ovulation Ovulation – the process in which a mature egg is Estradiol released from an ovary and into the abdominal cavity +  DAY 0 7 14 21 28 OVARIAN Pituitary gonadotropin CYCLE levels FSH LH C Degenerating Growing follicle or corpus luteum p us lu te Follicular phase Ovulation Luteal phase u UTERINE m Ovarian hormone CYCLE levels Estradiol Progesterone Endometrium Menstrual flow Proliferative Secretory  Menstrual and Ovarian Cycles (Days 15-28) LH stimulates the remaining DAYS 15-28: follicular tissue to form the Hypothalamus corpus luteum − Inhibited by The corpus luteum secretes GnRH Combination of progesterone and estradiol estradiol and Anterior pituitary progesterone These exert negative feedback on the hypothalamus and FSH LH pituitary to greatly reduce LH and FSH secretion, preventing Follicle Corpus luteum maturation of another egg Estradiol These also stimulate maintenance and Progesterone development of uterine lining  Menstruation occurs if egg is not fertilized The corpus luteum disintegrates, causing the production of progesterone and estradiol to stop. This causes the shedding of the endometrial tissue, resulting in menstruation from days 1-5  DAY 0 7 14 21 28 OVARIAN Pituitary gonadotropin CYCLE levels FSH LH Corpus luteum Degenerating Growing follicle corpus luteum Follicular phase Ovulation Luteal phase UTERINE Ovarian hormone CYCLE levels Estradiol Progesterone Endometrium Menstrual flow Proliferative Secretory  Male Reproductive Tract The male gonads, or testes, produce sperm The testes of many mammals are held outside the abdominal cavity in the scrotum, where the temperature is lower than in the abdominal cavity, allowing for production of normal sperm Semen is composed of sperm plus secretions from three sets of accessory glands that aid the sperm in successfully reaching an egg Egg moves through fallopian tubes (where it MAY encounter sperm) towards uterus  Pregnancy occurs if egg is fertilized Corpus luteum does NOT disintegrate, but continues to produce progesterone and estradiol, which: Prevents maturation of another egg Maintains and readies uterus for implantation and pregnancy  First trimester The implanted embryo secretes hormones that signal its presence and regulate the mother’s reproductive system Human chorionic gonadotropin (hCG), maintains secretion of progesterone and estrogens during early pregnancy Organogenesis, the development of the body organs, occurs Placenta begins to form  Placenta – organ that facilitates gas and nutrient exchange with fetus Around 12 weeks, placenta takes over making progesterone to support pregnancy Why are umbilical arteries deoxygenated? Delivery