endocrine/digestive/nutrition Flashcards
(77 cards)
1
Q
Oxidative Phosphorylation
A
Takes place on the inner membrane of the mitochondria
Yields: 32 ATP NAD+ FAD H2O
2
Q
Oxidation-reduction
A
reactions are coupled reactions that involve the transfer of electrons from one molecule to another, resulting in a transfer of energy between molecules (pp. 920–921).
Ex: the electron transfer chain in the mitochondria
3
Q
ATP synthesis may occur through two mechanisms:
A
- substrate-level phosphorylation:
in which high-energy phosphate groups are transferred directly from phosphorylated substrates to ADP - oxidative phosphorylation:
in which some energy from food fuels is used to create a proton gradient that is used to attach phosphates to ADP (pp. 921–922; Figs. 24.4–24.5). Ex: ETC
4
Q
Cellular Respiration:
A
The first step is the Krebs Cycle in which ATP and strong oxidizers, NADH and FADH2 are formed that are necessary for the next step
The second step is Oxidative Phosphorylation in which oxygen is required to produce more ATP molecules.
5
Q
Glycolysis
A
the breakdown of 1 molecule of glucose to 2 molecules of pyruvate.
This yields 2 ATP and NADH.
Occurs in the cytoplasm
6
Q
Krebs Cycle—
A
Takes place in the matrix of mitochondria
Pyruvate formed in glycolysis is converted to acetyl-CoA
The acetyl-CoA enters the Krebs cycle
For every 2 molecules of pyruvate that enters the Krebs cycle yields:
2 ATP
8 NADH
2 FADH2
6 CO2released
7
Q
Oxidative Phosphorylation—
A
Takes place on the inner membrane of the mitochondria Yields: 32 ATP NAD+ FAD H2O
8
Q
Carbohydrate Metabolism:
The ETC: Yields
A
32 ATP
NAD+
FAD
H2O
9
Q
Glycogenesis
A
When ATP levels increase, glycolysis is inhibited and glucose molecules are combined in long chains to form glycogen
10
Q
Glycogenolysis
A
when blood sugar levels drop, glycogen splitting occurs
11
Q
Glucogenesis
A
When too little glucose is available for metabolism, glycerol and amino acids are converted to glucose.
-occurs in the liver
12
Q
Lipid Metabolism
A
Catabolism of triglycerides involves the splitting of the molecule into glycerol and fatty acids: the glycerol portion is converted to glyceraldehyde phosphate, which enters into glycolysis, and the fatty acids are converted to acetyl CoA through beta oxidation that takes place In the mitochondria.
13
Q
lipogenesis
A
When cellular ATP and glucose levels are high lipogenesis occurs to store the extra sugars.
High levels of acetyl CoA and glyceraldehyde phosphate also stimulated lipogenesis.
Acetyl CoA molecules are condensed to form fatty acid chains. Glyceraldehyde PO4 is converted to glycerol that is further condensed to form triglycerides.
14
Q
Lipolysis
A
The breakdown of stored fats to glycerol and fatty acids
15
Q
3 processes involved in carbohydrate metablism
A
1) glycolysis
2) Krebs Cycle
3) oxidative phosphorylation
16
Q
what 2 initial components are lipids catabolized by the action of lipase?
What is each component converted to in order to enter the Krebs cycle?
A
glycerol/fatty acid
acetyl co-A
17
Q
what is the goal of amino acid modification?
A
The goal of amino acid metabolism is to produce molecules that can be oxidized in the Krebs cycle or converted to glucose
18
Q
complete the following equation and state the enzyme responsible for the reaction: CO2 + H20–>
A
CO2 + H20–>H2CO3 (carbonic acid)–>HCO3- + H+(bicarbinate)
enzyme= carbonic anhydrase
19
Q
what is the meaning of double arrows
A
reaction can go both ways
20
Q
Before amino acids can be oxidized for energy, they must have the amine group removed this process is called
A
deamination
21
Q
Protein Metabolism -
1) Transamination
A
Transfer of an amino group from an amino acid to
α-ketoglutaric acid. This resulting in formation
of Glutamic acid. The original amino acid is
converted to a keto acid
22
Q
Protein Metabolism -
2) Oxidative deamination
A
Occurs in the liver where the amino group (NH3)
of glutamic acid is removed. The NH3 is excreted in urine and the alpha-ketoglutaric acid is regenerated.
23
Q
Protein Metabolism -
3) Keto Acid Modification
A
is used to produce molecules that can be oxidized in the Krebs cycle or converted to glucose from keto acids produced through transamination
- Most important metabolites are pyruvate, acetyl CoA, alpha-ketoglutaric acid
- Deaminated amino acids converted to pyruvate can be reconverted to glucose and be part of gluconeogenesis
24
Q
Insulin
A
Insulin is a hypoglycemic hormone, i.e. it removes glucose out of the blood into cells and lowers blood glucose levels.
Insulin also inhibits any process that might increase blood glucose levels, such as glucogenesis by the liver
25
Decreasing blood glucose levels stimulate the alpha islet cells of the pancreas to secrete ____?
Glucagon
*Glucagon is an insulin antagonist (inhibits effects of insulin)
26
Rising blood glucose levels after a high carb meal acts as a stimulus that stimulates pancreatic beta islet cells to secrete more ____?
insulin
*This stimulates facilitated Diffusion of glucose into tissue cells
27
Glucagon
Glucagon is a hyperglycemic hormone, i.e. it promotes increase in blood glucose levels.
Glucagon stimulates liver hepatocytes to increase glycogenolysis and gluconeogenesis.
Glucagon also stimulates lipolysis by the adipose cells and release fatty acids and glycerol to the blood.
Thus increasing blood glucose levels.
28
Metabolic Role of the Liver
Regulation of Blood Cholesterol and Cholesterol Metabolism:
Cholesterol: is a structural component of bile salts, steroid hormones, and Vit D and a major component of the plasma membrane. It is also a major component of a development signaling protein, hedgehog.
15% of blood cholesterol is dietary, 85% is made from acetyl CoA by the liver
29
Cholesterol Transport
Is bound to small lipid-protein complexes called lipoproteins.
Lipoprotein complexes vary in the percentage of lipid they contain, but all contain triglycerides, phospholipids, and cholesterol, in addition to protein
30
VLDLs
transport triglycerides from the liver to peripheral tissues, mostly to adipose
Once the triglycerides transferred, the VLDL residues are converted to LDLs
31
LDLs
are cholesterol rich, transport cholesterol to peripheral non-liver tissues to use in hormone or membrane synthesis.
LDL binding to its receptor stimulates receptor-mediated endocytosis of the entire particle.
*high levels of LDL are considered a risk, because the cholesterol they contain may be laid down on vessel walls, forming plaques.
32
HDLs
are rich in phospholipids and cholesterol, transport excess cholesterol from peripheral tissues to the liver and provide cholesterol to steroid-producing organs.
It is broken down by the liver and incorporated into bile.
The liver makes the proteins envelopes of the HDL particles and then transfers them into the blood stream
Once in the blood, the HDL particles fill with
Cholesterol picked up from the tissue cells
*High levels of HDL are considered beneficial, as the cholesterol they contain is bound for removal
33
Diets high in ________ ___ stimulate liver synthesis of cholesterol and reduce its elimination from the body, while ________ ____ ___enhance excretion of cholesterol to bile for removal from the body
saturated fats
unsaturated fatty acids
34
The type or sequence of reactions created by cAMP depends on
1) the type of target cell
2) the specific PKA it houses
3) the available substrates within that cell that can be phosphorylated by PKA
35
cAMP is quickly degraded by the intracellular enzyme
phosphodiesterase
36
Hormones known to use the PIP2 mechanism include:
```
1- thyrotropin-releasing hormone (TRH)
2- antidiuretic hormone (ADH)
3- gonadotropin-releasing hormone (GnRH)
4- oxytocin
5- epinephrine
```
37
Insulin and other growth factor hormones activate
a tyrosine kinase receptor that autophosphorylates its own tyrosines
38
3 major types of stimuli:
1- Humoral Stimuli
2- Neural Stimuli
3- Hormonal Stimuli
39
Hypothalamus
Is a part of the brain located in the below the thalamus.
Is made up of neurons and neuroglial cells.
Produces several different hormones that stimulates the pituitary gland
40
Pituitary Gland:
The pituitary gland is the size and shape of a pea and is connected to the hypothalamus via the infundibulum
It has two parts, anterior and posterior.
Posterior lobe is neural tissue that receives, stores, and releases hormones (oxytocin and antidiuretic hormone) made in the hypothalamus and is transported to the posterior pituitary via axons.
Anterior lobe is glandular tissue that produces hormones
41
Pituitary Gland: Posterior Gland
Part of the brain and is formed by ectoderm tissue
is connected to the hypothalamus via a nerve bundle called the hypothalamic- hypophyseal tract that runs through the infundiulum
The tract is made of neurons in the supraoptic and paraventricular nuclei of the hypothalamus
Produces two hormones:
Oxytocin (the cuddling hormone) produced by the paraventricular neurons
ADH produced by the supraoptic neurons
42
Hormones Pituitary Gland: Posterior Gland makes:
Produces two hormones:
Oxytocin (the cuddling hormone) produced by the paraventricular neurons
ADH produced by the supraoptic neurons
43
Pituitary Gland: Anterior Gland
Formed from epithelial tissue and originates from oral mucosa
No direct connection b/t the anterior lobe and hypothalamus
There is a vascular connection
Called the Hypophyseal Portal System
44
Growth Hormone (GH or somatotropin)
GH produced by somatotropic cells of the anterior lobe
Stimulates most cells, but target bone and skeletal muscle
Stimulates the liver and other tissues to secrete insulin-like growth factor I (IGF-I or somatomedin)
IGF-I stimulates proliferation of chondrocytes (cartilage cells), resulting in bone growth.
GH stimulates cell growth, replication, and protein synthesis through release of IGF-I
45
1. Growth Hormone (GH or somatotropin)
Direct action promotes lipolysis to encourage the use of fats for fuel and inhibits glucose uptake
Antagonistic hypothalamic hormones regulate GH
Growth hormone–releasing hormone (GHRH) stimulates GH release
Growth hormone–inhibiting hormone (GHIH or somatostatin ) inhibits GH release
46
2. Thyroid Stimulating Hormone (TSH or Thryotropin)
Travels to the thyroid gland (target cells) where it stimulates the release of thyroid hormones in response to low temperatures, stress, and pregnancy
Thyrotropin releasing hormone (TRH) from the hypothalamus promotes the release of TSH
Rising blood levels of thyroid hormones act on the pituitary and hypothalamus to block the release of TSH
47
3. Adrenocorticotropic Hormone (ACTH or Corticotropin
Travels to the adrenal gland (target cells) where it stimulates the release of corticosteroids (such as cortisol) in the adrenal cortex.
Corticotropin-releasing hormone (CRH) from the hypothalamus promotes the release of ACTH in a daily rhythm
Internal and external factors such as fever, hypoglycemia, and stressors can trigger the release of CRH
48
4. Follicle Stimulating Hormone (FSH)
Travels to the gonads (target cells) and stimulates sperm or egg cell production and maturation and estrogen secretion
Gonadotropin-releasing hormone (GnRH) from the hypothalamus promotes the release of FSH during and after puberty
49
5. Leutinizing Hormone (LH)
Travels to the ovaries in females (target cells) and stimulates ovulation, maturation of follicles (together with FSH) and stimulates the corpus luteum to secrete progesterone.
In males LH travels to the testes (target cells) to stimulate secretion of testosterone.
LH is also referred to as interstitial cell-stimulating hormone (ICSH)
50
6. Prolactin (PL)
Travels to the mammary glands (target cells) and stimulates the development of mammary glands to produce milk.
In males scientists think prolactin influences the sensitivity of cells in the testes (interstitial cells) to the effects of luteinizing hormone (LH)
Prolactin-releasing hormone (PRH) from the hypothalamus stimulates the release of prolactin
Prolactin-inhibiting hormone (PIH) from the hypothalamus inhibits the release of prolactin
Blood levels rise toward the end of pregnancy, suckling stimulates PRH release and encourages continued milk production
51
4 Tropin hormones
regulate the secretion of other endo glands
TSH, ACTH, LH, FSH
52
Oxytocin
Made by neurons of the paraventricular nucleus of the hypothalmus
Stimulates the smooth muscle of the uterus to contract, inducing labor
Stimulates the myoepithelial cells of the breasts to contract which releases milk from breasts when nursing.
Stimulates maternal behavior.
In males it stimulates muscle contractions in the prostate gland to release semen during sexual activity
53
Antidiuretic Hormone (ADH or vasopressin)
Made by neurons of the supraoptic nucleus in the hypothalamus
Signals the collecting ducts of the kidneys to reabsorb more water and constrict blood vessels, which leads to higher blood pressure and thus counters the blood pressure drop caused by dehydration or other reasons
54
Thyroid Gland Histology
Is composed of hollow, spherical follicles
The walls of each folicle are formed by cuboidal or squamous epithelial cells called follicle cells
Produce the glycoprotein thyroglobulinthe central lumen of the follicles stores colloid
Colloid is composed of thyroglobulin molecules with attached iodine atomes
TH is derived from iodinated thryroglobulin
Parafollicular cells calcitonin hormone
55
C Cells
between the thyroid follicles produce calcitonin.
56
Calcitonin
decreases the concentration of calcium in the blood where most of it is stored in the bones; it stimulates osteoblast activity and inhibits osteoclast activity, resulting in new bone matrix formation.
57
Parathyroid hormone (PTH)
most important endocrine regulator of calcium and phosphorus concentration in extracellular fluid
PTH has the opposite effect of calcitonin.
PTH stimulates osteoclasts which increases blood calcium levels.
PTH causes reabsorption of Ca+2 from kidneys so it is not excreted in the urine
PTH stimulates synthesis of calcitriol (hormone made in the kidney which the active form of Vitamin D which increases Ca+2 absorption from small intestine)
58
Mineralocorticoids (e.g. aldosterone)
Stimulates the kidneys to reabsorb sodium if blood pressure drops
It also secretes (eliminates) potassium
59
. Glucocorticoids (e.g. cortisol)
These hormones help you to cope with stress
Cortisol increases the level of sugar in the blood by stimulating the production of glucose from fats and proteins (gluconeogenesis)
It also reduces swelling
In large doses, cortisol inhibits the immune system.
It stimulates gluconeogenesis, mobilization of free fatty acids, glucose sparing.
Also acts as an anti-inflammatory
60
Gonadocorticoids (e.g.testosterone, estrogens, and progesterone )
The adrenal gland also makes small amts of the sex hormones (mostly androgens (testosterone) and lesser amounts of estrogens and progesterone)
Scientists not certain what role these hormones play; but know that when over secreted they can cause problems
61
Adrenal Medulla
derived from the Ectodermal germ layer
secretes the hormones epinephrine and norepinephrine when stimulated by sympathetic neurons of the autonomic nervous system (ANS)
Both epinephrine and norepinephrine contribute to the bodies' "fight or flight" response, just like the sympathetic nervous system.
Epi and Norepi have the same effects as direct stimulation by the sympathetic NS (increase heart rate, breathing rate, blood flow to skeletal muscles, and concentration of glucose in the blood), but their effects are longer lasting
Norepinpehrine is similar to epinephrine, but it is less effective in the conversion of glycogen to glucose.
~75 - 80% epinephrine
~25-30% norepinephrine
62
Pancreas
Located along the lower curvature of the small intestine (duodenum)
The pancreas contains both exocrine and endocrine cells
The exocrine portion secretes digestive enzymes into the duodenum via the pancreatic duct
63
Pancreas
The endocrine portion has clusters of endocrine cells within the pancreas called Islets of Langerhans
Alpha cells secrete glucagon
Beta cells secrete insulin
64
Glucagon does what to blood glucose?
raises blood glucose by increasing the rates of glycogen breakdown and glucose manufacture by the liver
65
Insulin does what to blood glucose?
Insulin lowers blood glucose by increasing the rate of glucose uptake and utilization
66
Diabetes mellitus – general term referring to all states characterized by hyperglycemia
TYPE 1
autoimmune-mediated destruction of insulin-producing β-cells in the pancreas, resulting in absolute insulin deficiency
67
TYPE 2
inherited multifactoral syndrome with combined influence of genetic susceptibility and influence of environmental factors, such as obesity, age, and physical inactivity, resulting in insulin resistance in cells requiring insulin for glucose uptake.
68
glycosuria
Excess glucose is lost through urine
69
GI has four general tasks :
motility
secretion
digestion
absorption
70
Blood Supply: The Splanchnic Circulation
Hepatic Liver
Splenic Spleen
Left gastric branches of Stomach
the Celiac trunk
Mesenteric arteries:
Superior Small Intestines
Inferior Large Intestines
71
Kupffer cell
Main functions include phagocytosis, discharge of signal chemicals (ex: growth factors, cytokines) and enzymes, and clearance of toxins, antigens and antibodies
72
Ito cells
Fat storing cells
73
4 Basic layers of Alimentary Canal
Mucosa
Submucosa
Muscularis
Serosa
74
Parasympathetic NS:
controls vegetative responses such as feeding, breeding etc
75
Sympathetic NS:
allows the body to function under stress and is responsible for the flight or fight response
76
Enteric NS
1) Submucosal Nerve Plexus:
Includes sensory and motor neurons
Regulates the activity of glands and smooth muscles in the mucosa
2) Myenteric Nerve Plexus:
Between the circular and longitudinal muscle layers of the muscularis layer
Major nerve supply to the GI tract wall
Regulates GI tract motility and patterns of segmentation and peristalsis
77
cAMP is quickly degraded by the intracellular enzyme
phosphodiesterase
