Biomed Chapters 9-11

Digestive and Urinary system

ingestion

process of taking food into the body; takes place in the mouth

digestion

process of breaking down the food into small chemical units; occurs in the stomach and small intestine

absorption

process whereby the chemical units pass into the blood and carried to the liver; occurs in small intestine

Metabolism

process in which chemical units are converted into energy for use by all organs of body; mainly in the liver

Excretion

removal of any remaining indigestible material

Parts of the digestive system

* oral cavity (mouth, lips, tongue, teeth)
* pharynx
* esophagus
* stomach
* small intestine (duodendum, jejunum, ileum)
* large intestine (cecum, colon, rectum, anus)
* accessory glands (salivary glands, pancreas, gall bladder, liver)

Oral Cavity Functions

* Prehension- pick up food
* mastication- break up food
* lubricate the food
* carbohydrate digestion (omnivores and herbivores)

Tongue functions

* aid in the ingestion of food
* gustation (sensation of taste)
* help with the formation of food bolus ready for swallowing
* groom the fur
* assist in thermoregulation
* produce vocalization

Deciduous dentition

Milk or temporary teeth and are present in the jaw at birth. They push through as the animal grows and fall out for adult teeth.

Permanent Dentition

adult teeth are larger, last the rest of the animals life and show signs of wear as animals gets older

Tooth types

Incisors (I), Canines (C), Premolars (PM), Molars (M), Carnassials

Salivary glands function

* Lubricate food to make mastication and swallowing easier
* thermoregulation
* omnivores and herbivores secretion from parotid gland contain amylase and begin carbon digestion

Salivary glands that produce saliva

* Zygomatic- close to eyeball
* sublingual- medial to the mandible
* mandibular- caudal to the angle of the jaw
* parotid- between the base of the eat and mandibular glands

Pharynx parts

* nasal passageway→ pharynx
* shared by respiratory and digestive system
* divided into the dorsal nasopharynx (respiratory passageway) and ventral oropharynx (digestive passageway)
* Soft palate extends caudally from hard palate

what does the Eustachian/auditory tube do

connects pharynx to middle ear, allows pressure to equalize

deglutition

swallowing

Stages of deglutition

* Food is rolled into a bolus by tongue and cheeks and passed to back of mouth by base of tongue
* phynegeal muscles contract and force bolus towards the esophagus
* at same time epiglottis closes to prevent food and air form entering the larynx
* a wave of muscular contraction (peristalsis) pushes the food down esophagus
* when food has passed through the pharynx to epiglottis falls open again and air is able to pass to trachea

Peristaltic wave

force food along the tube

antiperistalsis

food goes opposite direction/vomit

Stomach functions

* act as a reservoir for food
* break down food and mix it with gastric juices
* start protein digestion

lesser curvature

inner curve of sac

greater curvature

outer curve of sac

mesentery

covers organs with layer of visceral peritoneum-connected to inner curvature (lesser omentum) and attaches to greater curvature (greater omentum)

Stomach structure

* cardia
* fundus
* pylorus
* cardiac sphincter
* pyloric sphincter

Rugae

deep longitudinal folds and flatten when stomach is full, increases SA for absorption

Gastric pits

within mucousa has three types of cells for secreting gastric juices

Goblet cells

secrete mucus to lubricate food and protect stomach wall form damage by digestive enzymes (autodigestion)

chief cells

in fundus, secrete pepsinogen- precursor to pepsin

parietal cells

in fundus, secrete hydrochloric acid and creates an acid pH which enables pepsin to work

Peristalsis

contributes to rumbling of stomach and movement of food down the esophagus

Rhythmic segmentation

breaks up and mixes food boluses

Pyloric antral muscle contractions

controls rate of gastric emptying, so does pyloric sphincter

Breaking up food

food in the stomach is broken up and digested resulting in soup-like liquid with acid pH known as chyme

chyme

released in spurts through pyloric sphincter into duodumen and digestion continues

* liquid gastric empty 1/2 hr
* solid gastric empty 2-3 hrs

small intestine

main site for enzymic or chemical digestion and absorption of nutrients

Jejunum

longest and most chemical digestion and absorption

Ileum

empties into large intestine and ends at ileocaecal junction to join cecum

Pancreas

endocrine and exocrine parts; exocrine part secretes digestive enzymes and bicarbonate into duodundum via pancreatic duct

gall bladder

reservoir for bile produced by liver

liver functions

* carbohydrate metabolism- stores glycogen→ glucose
* protein metabolism-formation of albumin, globulin, fribrinogen, prothrombin, regulates AAs and produces urea
* fat metabolism- converts fat for energy
* formation of bile
* removes old RBCs
* forms new RBCs in fetus
* storage of vitamins and iron, detoxification, temperature regulation

Pancreatic juices

* bicarbonate- neutralizes the effects of acid in the chyme allowing other enzymes to work
* digestive enzymes- many inactive precursors which prevent autodigestion destructions of pancreas
* protease- acts on proteins

Gastric juices

* Mucus- lubricate food and protect from autodigestion
* HCl-proteins get broken down
* Pepsinogen- converted in to pepsin and then converts proteins in to peptides

Bile salts

emulsifies fat globules to have larger surface area so enzymes can act and activate lipases

Intestinal juices

stimulated by secretin in response of chyme

Types of intestinal juices

* maltase- converts maltose into glucose
* sucrase- converts sucrose into glucose and fructose
* lactase- converts lactose to glucose and galactose
* enterokinase- converts peptides into amino acids
* aminopeptidase- converts peptides into amino acids
* lipase- converts fats to fatty acids and glycerol

Absorption

* simple sugars- absorbed by blood capillaries and carried by hepatic portal vein
* fatty acids- plus glycerol absorbed by lacteals and form chyle and carried to cisterna chyli
* mixed with lymph and carried to heart by thoracic duct and joins blood circulation

Parts of the large intestine

* cecum- important in herbivores- site of fermentation
* colon- ensures body doesn’t lose excessive water, divides into: ascending, transverse, and descending
* rectum- part of colon
* anal sphincter- end of digestive tract, controls passage of faeces

Defaucation

by means of peristalsis, antiperstalisis, rhythmic segmentation and frequent but strong contractions-involuntary until faucal matter enters pelvic cavity

Testis function

* produces spermatozoa
* produce fluid to transport sperm
* secrete testosterone hormone for male characteristics

testes blood supply

* testicular artery (from aorta)
* pampiniform plexus (formed from testicular veins)- surrounds the testicular artery and helps cool the blood passing down testis

Parts of the male reproductive system

* testis
* epididymis
* deferent duct (vas deferens or ductus deferens)
* urethra
* penis
* prostate gland
* bulborethral gland- on in tom cat
* accessory gland

penis function

* convey sperm and fluids from the testis into the female reproductive tract during mating
* convey urine from the bladder to the outside via urethra
* structures
* corpus spongiosum
* corpus cavernosum
* glans penis (barbs in tomcat)
* os penis
* crura
* prepuce

female reproductive system

* ovaries
* uterine tubes
* uterus
* cervix
* vagina and vestibule
* vulva
* vestibule
* mammary glands

function of ovaries

* produce ova for fertilization
* act as endocrine gland by secreting hormone estrogen and progesterone

uterine tubes function

* collects ova form ovaries
* convey ova to uterine horns
* hospitable environment for ova and sperm

parts of uterine tubes

* infundibulem
* fimbriae
* cilia
* mesosalpinx

uterus functions

* provide receptacle in which the embryos can develope into full-term fetuses
* provide correct environment for survival of embryos
* provide the means whereby the developing embryos can receive nutrients from the dam; made possible by placenta

walls of the uterus

* endometrium
* myometrium
* mesometrium or broad ligament

lactation hormones

* progesterone- causes enlargement of mammary glands
* prolactin- production of milk stimulator
* oxytocin- enable glands to release milk

estrous cycle

starting from the primary follicle and proceeding to mature follicle, ovulation, and formation of corpus luteum

function of estrous cycle

* produce ova
* prepare female repro tract to receive fertilized ova
* initiate breeding behaviors

pro-estrus

period in which the reproductive tract is under the influence of estrogen

estrus

period during which the female will allow herself to be mated

met-estrus (di-estrus)

period during which the tract is under the influence of progesterone

an-estrus

period between cycles during which there is little to no ovarian activity

Clinical application

changes in the epithelial lining of vagina can be conventiently used to detect the stage of estrous cycle particulary in dogs

behavioral change

* bitch- monoestrous, spontaneous, ovulatory, puberty 6 months
* queen-polyestrous, induced ovalatory, puberty 4 months

Embryology

study of the development of the embryo

gamete

male or female germ cells- spermatozoa or ova

zygote

fertilized ova

embryo

stage during which the major organs are forming

fetus

stage at which formation of major internal and external structures is complete until time of parturition

conceptus

embryo or fetus, extra embryonic membrane and placenta

neonate

newborn animal

gestation

in the bitch and queen gestation period is 63 days although there is breed variation

fertilization

* spermatozoa approach ovum
* one sperm penetrates ovum
* cell division occurs by mitosis

implantation

* bitch- occurs 14-20 days after ovulation
* queen- occurs 11-16 days after ovulation

germ cell layers

* ectoderm- outer layer forms the skin and nervous system
* mesoderm- middle layer forms the musculoskeletal system and other internal organs
* endoderm- inner layer forms lining of the digestive tract and other visceral systems

Yolk sac

formed from the endodermal cells, but shrivels to nothing, some time before birth-birds and reptiles

amnion

trophoblast and mesoderm expand and eventually push up and surround the developing embryo. forms fluid-filled cavity around the embryo-amniotic cavity

allantois

balloon lie diverticulum starts to develop from the endodermal cells forming the primitive gut

zonary placenta

band that encircles the fetus

allantochorion

produces small finger like villi hat burrow into the endometrium of the uterine horn

marginal haematoma

these are bands of maternal haemorrahage at the margins of the zonary placenta

genetics

science of inheritance and is the method by which characteristics or traits are passed from one generation to another

genes

structures that determine genetic characteristics

chromosomes

genetic arrangement of genes in every cell

diploid

contains 2 complete sets of chromosomes

haploid

have half the number of chromosomes as diploid

homologous

identical

autosomes

determine characteristics (not associated with sex)

DNA structure

* double stranded macromolecule that forms a double helix
* phosphate and sugar= backbone
* 4 nitrogenous basis

nucleotide

* nitrogenous base-pyrimidine and perine
* 5 carbon sugar
* phosphate group

pyrimidines

T and C

Perines

A and G

sex determination

* 2 X chromosomes= female
* 1 X and 1 Y chromsomes= male

barr body

a small densley staining structure in the cell nuclei of female mammals, consisting of condensed inactive x chromosomes

genetic nomenclature

* language of genetics using letters to express genotypes
* expressed in pairs
* ex. dominant= B recessive= b

mendels 1st law of inheritance (law of segregation)

every individual contains 2 alleles (variant form of a given gene) for each trait, one from each parent, alleles segregate during meiosis

Mendel’s 2nd law of inheritance (law of independent assortment

* alleles of one gene sort into the gametes independently of the alleles of another gene