Chapter 7: Endocrine And Exocrine Flashcards
1
Q
Agonist vs antagonist
A
- Agonist: any molecule that binds to the receptor and elicits the response
- Antagonist: any molecule that binds to the receptor and prevents the response
2
Q
Chemical signalling mechanisms
A
- Autocrine: signals itself
- Paracrine: signals nearby
- Endocrine: signals far and travels via blood
3
Q
Types of hormones: peptides
A
- Anterior pituitary: FSH, LG, ACTH, TSH, Prolactin, endophins, GH
- Posterior pituitary: ADH, Oxytocin
- Parathyroid hormone: PTH
- Thyroid: calcitonin
- Stomach: gastrin, ghrelin, leptin
- Small intestine: CCK
- Pancreas: glucagon, insulin, somatostatin
- Liver: angiotensinogen
- Kidney: renin
- Heart: ANP
4
Q
Types of hormones: steroids
A
- Derived from cholesterol (3 cyclohexane and 1 cyclopentane)
- Formation begins in cytosol and is carried via albumin
- Important steroid hormones
3a. Glucocorticoids and mineralcorticoids of adrenal cortex: cortisol and aldosterone
3b. Gonadal hormones: estrogen, progesterone and testosterone
5
Q
Types of hormones: amino hormones
A
- Tyrosine derived
1a. Stored in thyroid follicles and slowly released: T3 and T4
1b. Catecholamines: dopamine, epinephrine and norepinephrine - Tryptophan derived
2a. Serotonin and melatonin - Histidine derived
3a. Histamine: from mast cells and basophils
6
Q
Types of hormones: amino hormones
A
- Tyrosine derived
1a. Stored in thyroid follicles and slowly released: T3 and T4
1b. Catecholamines: dopamine, epinephrine and norepinephrine - Tryptophan derived
2a. Serotonin and melatonin - Histidine derived
3a. Histamine: from mast cells and basophils
7
Q
Ligand gated ion channel receptors
A
- Ion channel that when bound by hormone opens or closes
8
Q
Intracellular receptors
A
- In cytosol or nucleus and associated with steroid or thyroid hormones
9
Q
GPCR
A
- Integral protein whose TM region spans the membrane 7 times
- When inactive, its alpha subunit is bound to GDP
10
Q
Enzyme linked receptor
A
- TM protein that is either an enzyme itself or is attached directly to an enzyme inside the cell
11
Q
Second messenger systems
A
- CAMP: GPCR activated adenylyl cyclase which converts ATP to cAMP which activates protein kinase A or PKA
- Phospholipid breakdown: phospholipase C (PLC) cleaves PIP2 to DAG and IP3 which binds to Ca2+ and opens it on ER…DAG and Ca2+ then activate PKC
- Calcium and calmodulin: Ca2+ may activate calmodulin which phosphoylates more enzymes
12
Q
Endocrine glands: hypothalamus
A
- Master gland
- Regulates anterior pituitary by releasing tropic hormones and inhibiting hormones into hypophyseal portal system
2a. Tropic hormones are hormones that cause release of other hormones
13
Q
Endocrine glands: anterior pituitary
A
- Only releases peptide hormones
1a. FSH
1b. LH
1c. ACTH: stimulates adrenal cortex to release glucocorticoids (Stress hormones) via GPCR that uses cAMP to activate protein kinase
1d. TSH: stimulates thyroid to release T3 and T4
1e. Prolactin: promotes lactation
1f. Endorphins: natural pain killer
1g. GH: targets all cells of the body for growth
14
Q
Endocrine glands: Posterior pituitary
A
- Oxytocin: increases uterine contraction and causes milk ejection
- ADH/vasopressin: reduces and concentrates urine which increases blood pressure
15
Q
Endocrine glands: Adrenal cortex
A
- Mineralocorticoids: aldosterone
1a. Increases Na+/Cl- reabsorption and K+/H+ secretion which increases blood pressure & blood volume - Glucocorticoids: cortisol
16
Q
Endocrine glands: Adrenal medulla
A
- Epinephrine and norepinephine synthesized here for fight/flight response
17
Q
Endocrine glands: thyroid
A
- T3 and T4 are secreted by follicular cells of thyroid
1a. Effect is to increase basal metabolic rate - Calcitonin: released by C cells (parafollicular) in response to high Ca2+ levels in blood…decreases osteoclast activity
18
Q
Endocrine glands: Parathyroid
A
- PTH: acts on bone, kidneys and gut to increase blood Ca2+ and decrease blood Phosphate
19
Q
Endocrine glands: Pancreas (Islets of Langerhans)
A
- Beta cells release insulin: when high glucose
- Alpha cells release glucagon: when low glucose
20
Q
Male reproductive system
A
- Seminiferous tubules of the testes produce sperm: spermatogonia becomes spermatocytes becomes spermatids and then spermatozoa
- Serotoli cells by FSH surround and nurture sperm
2a. When too much sperm, serotonin cells secrete inhibin which inhibits FSH - Leydig cells by LH: release testosterone
21
Q
Sperm pathway
A
- Seminiferous tubules->stored in epididymus-> Vas deferns -> urethra
22
Q
Semen components
A
- Seminal fluid via seminal vesicles, prostate and bulbourethral glands
- Sperm from seminiferous tubules
23
Q
Oogenesis
A
- Oogenesis begins in ovaries of fetus and all cells get arrested as primary oocytes at birth
- At puberty: FSH stimulates growth of granulosa cells around primary oocyte and produce zona pellucida forming primary follicles
- Theca cells differentiate and form around follicle to form secondary follicle
- When LH is secreted, theca cells secrete aldoststenedione which is converted to estradiole via granulosa cells when FSH is present
- Estradiole prepares uterine wall & inhibits anterior pituitary from releasing LH until ovulation
- Ovulation=LH surge =high LH=high estrogen =burst of follicles which release egg (Secondary oocyte now) to oviduct via fimbrae
6a. Remaining follicle is left to become corpus luteum that secretes estrogen/progesterone during pregnancy and if no pregnancy gets degraded - Repeat
24
Q
Menstrual cycle
A
- Follicular phase: grow follicles
- Ovulation: LH surge
- Luteal phase: death of corpus luteum
- Menstruation
25
Fertilization
1. Sperm enters vagina
2. Sperm has acrosome reaction once it touches egg…allows sperm to cleave past granulosa cells and zonal pellucida
3. Cortical reaction occurs which prevents other sperm from entry
4. Ova finalizes meiosis becoming a ovum
5. Fertilization: when nuclei of sperm and ovum mix
26
Growth of zygote
1. Cleavage of zygote: rapid cell divisions which create morula
2. Morula divides until it forms fluid filled blastocyst which lodges into uterus in a process called implantation
2a. Before implantation, blastocyst secretes HCG that prevents degeneration of corpus luteum which maintains estrogen and progesterone
27
Gastrulation
1. Ectoderm: nervous system
2. Mesoderm: muscles
3. Endoderm: respiratory and digestive system